/********************************************************************
 * COPYRIGHT:
 * Copyright (c) 2002-2010, International Business Machines Corporation and
 * others. All Rights Reserved.
 ********************************************************************/

//
//   regextst.cpp
//
//      ICU Regular Expressions test, part of intltest.
//

#include "intltest.h"
#if !UCONFIG_NO_REGULAR_EXPRESSIONS

#include "unicode/regex.h"
#include "unicode/uchar.h"
#include "unicode/ucnv.h"
#include "unicode/ustring.h"
#include "regextst.h"
#include "uvector.h"
#include "util.h"
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#define SUPPORT_MUTATING_INPUT_STRING   0


//---------------------------------------------------------------------------
//
//  Test class boilerplate
//
//---------------------------------------------------------------------------
RegexTest::RegexTest()
{
}


RegexTest::~RegexTest()
{
}


void RegexTest::runIndexedTest( int32_t index, UBool exec, const char* &name, char* /*par*/ )
{
    if (exec) logln("TestSuite RegexTest: ");
    switch (index) {

        case 0: name = "Basic";
            if (exec) Basic();
            break;
        case 1: name = "API_Match";
            if (exec) API_Match();
            break;
        case 2: name = "API_Replace";
            if (exec) API_Replace();
            break;
        case 3: name = "API_Pattern";
            if (exec) API_Pattern();
            break;
        case 4:
#if !UCONFIG_NO_FILE_IO
            name = "Extended";
            if (exec) Extended();
#else
            name = "skip";
#endif
            break;
        case 5: name = "Errors";
            if (exec) Errors();
            break;
        case 6: name = "PerlTests";
            if (exec) PerlTests();
            break;
        case 7: name = "Callbacks";
            if (exec) Callbacks();
            break;
        case 8: name = "Bug 6149";
             if (exec) Bug6149();
             break;
        case 9: name = "UTextBasic";
          if (exec) UTextBasic();
          break;
        case 10: name = "API_Match_UTF8";
          if (exec) API_Match_UTF8();
          break;
        case 11: name = "API_Replace_UTF8";
          if (exec) API_Replace_UTF8();
          break;
        case 12: name = "API_Pattern_UTF8";
          if (exec) API_Pattern_UTF8();
          break;
        case 13: name = "PerlTestsUTF8";
          if (exec) PerlTestsUTF8();
          break;
        case 14: name = "PreAllocatedUTextCAPI";
          if (exec) PreAllocatedUTextCAPI();
          break;
        case 15: name = "Bug 7651";
          if (exec) Bug7651();
          break;

        default: name = "";
            break; //needed to end loop
    }
}


//---------------------------------------------------------------------------
//
//   Error Checking / Reporting macros used in all of the tests.
//
//---------------------------------------------------------------------------
#define REGEX_CHECK_STATUS {if (U_FAILURE(status)) {dataerrln("RegexTest failure at line %d.  status=%s", \
__LINE__, u_errorName(status)); return;}}

#define REGEX_ASSERT(expr) {if ((expr)==FALSE) {errln("RegexTest failure at line %d.\n", __LINE__);};}

#define REGEX_ASSERT_FAIL(expr, errcode) {UErrorCode status=U_ZERO_ERROR; (expr);\
if (status!=errcode) {dataerrln("RegexTest failure at line %d.  Expected status=%s, got %s", \
    __LINE__, u_errorName(errcode), u_errorName(status));};}

#define REGEX_CHECK_STATUS_L(line) {if (U_FAILURE(status)) {errln( \
    "RegexTest failure at line %d, from %d.  status=%d\n",__LINE__, (line), status); }}

#define REGEX_ASSERT_L(expr, line) {if ((expr)==FALSE) { \
    errln("RegexTest failure at line %d, from %d.", __LINE__, (line)); return;}}

void RegexTest::assertUText(const char *expected, UText *actual, const char *file, int line) {
    UErrorCode status = U_ZERO_ERROR;
    UText expectedText = UTEXT_INITIALIZER;
    utext_openUTF8(&expectedText, expected, -1, &status);
    utext_setNativeIndex(actual, 0);
    if (utext_compare(&expectedText, -1, actual, -1) != 0) {
        char buf[201 /*21*/];
        char *bufPtr = buf;
        UChar32 c = utext_next32From(actual, 0);
        while (c != U_SENTINEL && bufPtr < buf+200/*20*/) {
            if (0x20<c && c<0x7e) {
                *bufPtr = c;
            } else {
                *bufPtr = '.';
            }
            bufPtr++;
            c = UTEXT_NEXT32(actual);
        }
        *bufPtr = 0;
       
        errln("Failure at file %s, line %d, expected \"%s\" (%d chars), got \"%s\" (%d chars)", file, line, expected, utext_nativeLength(&expectedText), buf, utext_nativeLength(actual));
    }
    utext_close(&expectedText);
}

#define REGEX_ASSERT_UTEXT(expected, actual) assertUText((expected), (actual), __FILE__, __LINE__)


//---------------------------------------------------------------------------
//
//    REGEX_TESTLM       Macro + invocation function to simplify writing quick tests
//                       for the LookingAt() and  Match() functions.
//
//       usage:
//          REGEX_TESTLM("pattern",  "input text",  lookingAt expected, matches expected);
//
//          The expected results are UBool - TRUE or FALSE.
//          The input text is unescaped.  The pattern is not.
//
//
//---------------------------------------------------------------------------

#define REGEX_TESTLM(pat, text, looking, match) {doRegexLMTest(pat, text, looking, match, __LINE__);doRegexLMTestUTF8(pat, text, looking, match, __LINE__);}

UBool RegexTest::doRegexLMTest(const char *pat, const char *text, UBool looking, UBool match, int32_t line) {
    const UnicodeString pattern(pat, -1, US_INV);
    const UnicodeString inputText(text, -1, US_INV);
    UErrorCode          status  = U_ZERO_ERROR;
    UParseError         pe;
    RegexPattern        *REPattern = NULL;
    RegexMatcher        *REMatcher = NULL;
    UBool               retVal     = TRUE;

    UnicodeString patString(pat, -1, US_INV);
    REPattern = RegexPattern::compile(patString, 0, pe, status);
    if (U_FAILURE(status)) {
        dataerrln("RegexTest failure in RegexPattern::compile() at line %d.  Status = %s",
            line, u_errorName(status));
        return FALSE;
    }
    if (line==376) { RegexPatternDump(REPattern);}

    UnicodeString inputString(inputText);
    UnicodeString unEscapedInput = inputString.unescape();
    REMatcher = REPattern->matcher(unEscapedInput, status);
    if (U_FAILURE(status)) {
        errln("RegexTest failure in REPattern::matcher() at line %d.  Status = %s\n",
            line, u_errorName(status));
        return FALSE;
    }

    UBool actualmatch;
    actualmatch = REMatcher->lookingAt(status);
    if (U_FAILURE(status)) {
        errln("RegexTest failure in lookingAt() at line %d.  Status = %s\n",
            line, u_errorName(status));
        retVal =  FALSE;
    }
    if (actualmatch != looking) {
        errln("RegexTest: wrong return from lookingAt() at line %d.\n", line);
        retVal = FALSE;
    }

    status = U_ZERO_ERROR;
    actualmatch = REMatcher->matches(status);
    if (U_FAILURE(status)) {
        errln("RegexTest failure in matches() at line %d.  Status = %s\n",
            line, u_errorName(status));
        retVal = FALSE;
    }
    if (actualmatch != match) {
        errln("RegexTest: wrong return from matches() at line %d.\n", line);
        retVal = FALSE;
    }

    if (retVal == FALSE) {
        RegexPatternDump(REPattern);
    }

    delete REPattern;
    delete REMatcher;
    return retVal;
}


UBool RegexTest::doRegexLMTestUTF8(const char *pat, const char *text, UBool looking, UBool match, int32_t line) {
    UText               pattern    = UTEXT_INITIALIZER;
    int32_t             inputUTF8Length;
    char                *textChars = NULL;
    UText               inputText  = UTEXT_INITIALIZER;
    UErrorCode          status     = U_ZERO_ERROR;
    UParseError         pe;
    RegexPattern        *REPattern = NULL;
    RegexMatcher        *REMatcher = NULL;
    UBool               retVal     = TRUE;

    utext_openUTF8(&pattern, pat, -1, &status);
    REPattern = RegexPattern::compile(&pattern, 0, pe, status);
    if (U_FAILURE(status)) {
        dataerrln("RegexTest failure in RegexPattern::compile() at line %d (UTF8).  Status = %s\n",
            line, u_errorName(status));
        return FALSE;
    }
    
    UnicodeString inputString(text, -1, US_INV);
    UnicodeString unEscapedInput = inputString.unescape();
    LocalUConverterPointer UTF8Converter(ucnv_open("UTF8", &status));
    ucnv_setFromUCallBack(UTF8Converter.getAlias(), UCNV_FROM_U_CALLBACK_STOP, NULL, NULL, NULL, &status);
    
    inputUTF8Length = unEscapedInput.extract(NULL, 0, UTF8Converter.getAlias(), status);
    if (U_FAILURE(status) && status != U_BUFFER_OVERFLOW_ERROR) {
        // UTF-8 does not allow unpaired surrogates, so this could actually happen
        logln("RegexTest unable to convert input to UTF8 at line %d.  Status = %s\n", line, u_errorName(status));
        return TRUE; // not a failure of the Regex engine
    }
    status = U_ZERO_ERROR; // buffer overflow
    textChars = new char[inputUTF8Length+1];
    unEscapedInput.extract(textChars, inputUTF8Length+1, UTF8Converter.getAlias(), status);
    utext_openUTF8(&inputText, textChars, inputUTF8Length, &status);
    
    REMatcher = REPattern->matcher(&inputText, RegexPattern::PATTERN_IS_UTEXT, status);
    if (U_FAILURE(status)) {
        errln("RegexTest failure in REPattern::matcher() at line %d (UTF8).  Status = %s\n",
            line, u_errorName(status));
        return FALSE;
    }

    UBool actualmatch;
    actualmatch = REMatcher->lookingAt(status);
    if (U_FAILURE(status)) {
        errln("RegexTest failure in lookingAt() at line %d (UTF8).  Status = %s\n",
            line, u_errorName(status));
        retVal =  FALSE;
    }
    if (actualmatch != looking) {
        errln("RegexTest: wrong return from lookingAt() at line %d (UTF8).\n", line);
        retVal = FALSE;
    }

    status = U_ZERO_ERROR;
    actualmatch = REMatcher->matches(status);
    if (U_FAILURE(status)) {
        errln("RegexTest failure in matches() at line %d (UTF8).  Status = %s\n",
            line, u_errorName(status));
        retVal = FALSE;
    }
    if (actualmatch != match) {
        errln("RegexTest: wrong return from matches() at line %d (UTF8).\n", line);
        retVal = FALSE;
    }

    if (retVal == FALSE) {
        RegexPatternDump(REPattern);
    }

    delete REPattern;
    delete REMatcher;
    utext_close(&inputText);
    utext_close(&pattern);
    delete[] textChars;
    return retVal;
}


//---------------------------------------------------------------------------
//
//    REGEX_ERR       Macro + invocation function to simplify writing tests
//                       regex tests for incorrect patterns
//
//       usage:
//          REGEX_ERR("pattern",   expected error line, column, expected status);
//
//---------------------------------------------------------------------------
#define REGEX_ERR(pat, line, col, status) regex_err(pat, line, col, status, __LINE__);

void RegexTest::regex_err(const char *pat, int32_t errLine, int32_t errCol,
                          UErrorCode expectedStatus, int32_t line) {
    UnicodeString       pattern(pat);

    UErrorCode          status         = U_ZERO_ERROR;
    UParseError         pe;
    RegexPattern        *callerPattern = NULL;

    //
    //  Compile the caller's pattern
    //
    UnicodeString patString(pat);
    callerPattern = RegexPattern::compile(patString, 0, pe, status);
    if (status != expectedStatus) {
        dataerrln("Line %d: unexpected error %s compiling pattern.", line, u_errorName(status));
    } else {
        if (status != U_ZERO_ERROR) {
            if (pe.line != errLine || pe.offset != errCol) {
                errln("Line %d: incorrect line/offset from UParseError.  Expected %d/%d; got %d/%d.\n",
                    line, errLine, errCol, pe.line, pe.offset);
            }
        }
    }

    delete callerPattern;

    //
    //  Compile again, using a UTF-8-based UText
    //
    UText patternText = UTEXT_INITIALIZER;
    utext_openUTF8(&patternText, pat, -1, &status);
    callerPattern = RegexPattern::compile(&patternText, 0, pe, status);
    if (status != expectedStatus) {
        dataerrln("Line %d: unexpected error %s compiling pattern.", line, u_errorName(status));
    } else {
        if (status != U_ZERO_ERROR) {
            if (pe.line != errLine || pe.offset != errCol) {
                errln("Line %d: incorrect line/offset from UParseError.  Expected %d/%d; got %d/%d.\n",
                    line, errLine, errCol, pe.line, pe.offset);
            }
        }
    }
    
    delete callerPattern;
    utext_close(&patternText);
}


//---------------------------------------------------------------------------
//
//      Basic      Check for basic functionality of regex pattern matching.
//                 Avoid the use of REGEX_FIND test macro, which has
//                 substantial dependencies on basic Regex functionality.
//
//---------------------------------------------------------------------------
void RegexTest::Basic() {


//
// Debug - slide failing test cases early
//
#if 0
    {
        // REGEX_TESTLM("a\N{LATIN SMALL LETTER B}c", "abc", FALSE, FALSE);
        UParseError pe;
        UErrorCode  status = U_ZERO_ERROR;
        RegexPattern::compile("^(?:a?b?)*$", 0, pe, status);
        // REGEX_FIND("(?>(abc{2,4}?))(c*)", "<0>ab<1>cc</1><2>ccc</2></0>ddd");
        // REGEX_FIND("(X([abc=X]+)+X)|(y[abc=]+)", "=XX====================");
    }
    exit(1);
#endif


    //
    // Pattern with parentheses
    //
    REGEX_TESTLM("st(abc)ring", "stabcring thing", TRUE,  FALSE);
    REGEX_TESTLM("st(abc)ring", "stabcring",       TRUE,  TRUE);
    REGEX_TESTLM("st(abc)ring", "stabcrung",       FALSE, FALSE);

    //
    // Patterns with *
    //
    REGEX_TESTLM("st(abc)*ring", "string", TRUE, TRUE);
    REGEX_TESTLM("st(abc)*ring", "stabcring", TRUE, TRUE);
    REGEX_TESTLM("st(abc)*ring", "stabcabcring", TRUE, TRUE);
    REGEX_TESTLM("st(abc)*ring", "stabcabcdring", FALSE, FALSE);
    REGEX_TESTLM("st(abc)*ring", "stabcabcabcring etc.", TRUE, FALSE);

    REGEX_TESTLM("a*", "",  TRUE, TRUE);
    REGEX_TESTLM("a*", "b", TRUE, FALSE);


    //
    //  Patterns with "."
    //
    REGEX_TESTLM(".", "abc", TRUE, FALSE);
    REGEX_TESTLM("...", "abc", TRUE, TRUE);
    REGEX_TESTLM("....", "abc", FALSE, FALSE);
    REGEX_TESTLM(".*", "abcxyz123", TRUE, TRUE);
    REGEX_TESTLM("ab.*xyz", "abcdefghij", FALSE, FALSE);
    REGEX_TESTLM("ab.*xyz", "abcdefg...wxyz", TRUE, TRUE);
    REGEX_TESTLM("ab.*xyz", "abcde...wxyz...abc..xyz", TRUE, TRUE);
    REGEX_TESTLM("ab.*xyz", "abcde...wxyz...abc..xyz...", TRUE, FALSE);

    //
    //  Patterns with * applied to chars at end of literal string
    //
    REGEX_TESTLM("abc*", "ab", TRUE, TRUE);
    REGEX_TESTLM("abc*", "abccccc", TRUE, TRUE);

    //
    //  Supplemental chars match as single chars, not a pair of surrogates.
    //
    REGEX_TESTLM(".", "\\U00011000", TRUE, TRUE);
    REGEX_TESTLM("...", "\\U00011000x\\U00012002", TRUE, TRUE);
    REGEX_TESTLM("...", "\\U00011000x\\U00012002y", TRUE, FALSE);


    //
    //  UnicodeSets in the pattern
    //
    REGEX_TESTLM("[1-6]", "1", TRUE, TRUE);
    REGEX_TESTLM("[1-6]", "3", TRUE, TRUE);
    REGEX_TESTLM("[1-6]", "7", FALSE, FALSE);
    REGEX_TESTLM("a[1-6]", "a3", TRUE, TRUE);
    REGEX_TESTLM("a[1-6]", "a3", TRUE, TRUE);
    REGEX_TESTLM("a[1-6]b", "a3b", TRUE, TRUE);

    REGEX_TESTLM("a[0-9]*b", "a123b", TRUE, TRUE);
    REGEX_TESTLM("a[0-9]*b", "abc", TRUE, FALSE);
    REGEX_TESTLM("[\\p{Nd}]*", "123456", TRUE, TRUE);
    REGEX_TESTLM("[\\p{Nd}]*", "a123456", TRUE, FALSE);   // note that * matches 0 occurences.
    REGEX_TESTLM("[a][b][[:Zs:]]*", "ab   ", TRUE, TRUE);

    //
    //   OR operator in patterns
    //
    REGEX_TESTLM("(a|b)", "a", TRUE, TRUE);
    REGEX_TESTLM("(a|b)", "b", TRUE, TRUE);
    REGEX_TESTLM("(a|b)", "c", FALSE, FALSE);
    REGEX_TESTLM("a|b", "b", TRUE, TRUE);

    REGEX_TESTLM("(a|b|c)*", "aabcaaccbcabc", TRUE, TRUE);
    REGEX_TESTLM("(a|b|c)*", "aabcaaccbcabdc", TRUE, FALSE);
    REGEX_TESTLM("(a(b|c|d)(x|y|z)*|123)", "ac", TRUE, TRUE);
    REGEX_TESTLM("(a(b|c|d)(x|y|z)*|123)", "123", TRUE, TRUE);
    REGEX_TESTLM("(a|(1|2)*)(b|c|d)(x|y|z)*|123", "123", TRUE, TRUE);
    REGEX_TESTLM("(a|(1|2)*)(b|c|d)(x|y|z)*|123", "222211111czzzzw", TRUE, FALSE);

    //
    //  +
    //
    REGEX_TESTLM("ab+", "abbc", TRUE, FALSE);
    REGEX_TESTLM("ab+c", "ac", FALSE, FALSE);
    REGEX_TESTLM("b+", "", FALSE, FALSE);
    REGEX_TESTLM("(abc|def)+", "defabc", TRUE, TRUE);
    REGEX_TESTLM(".+y", "zippity dooy dah ", TRUE, FALSE);
    REGEX_TESTLM(".+y", "zippity dooy", TRUE, TRUE);

    //
    //   ?
    //
    REGEX_TESTLM("ab?", "ab", TRUE, TRUE);
    REGEX_TESTLM("ab?", "a", TRUE, TRUE);
    REGEX_TESTLM("ab?", "ac", TRUE, FALSE);
    REGEX_TESTLM("ab?", "abb", TRUE, FALSE);
    REGEX_TESTLM("a(b|c)?d", "abd", TRUE, TRUE);
    REGEX_TESTLM("a(b|c)?d", "acd", TRUE, TRUE);
    REGEX_TESTLM("a(b|c)?d", "ad", TRUE, TRUE);
    REGEX_TESTLM("a(b|c)?d", "abcd", FALSE, FALSE);
    REGEX_TESTLM("a(b|c)?d", "ab", FALSE, FALSE);

    //
    //  Escape sequences that become single literal chars, handled internally
    //   by ICU's Unescape.
    //

    // REGEX_TESTLM("\101\142", "Ab", TRUE, TRUE);      // Octal     TODO: not implemented yet.
    REGEX_TESTLM("\\a", "\\u0007", TRUE, TRUE);        // BEL
    REGEX_TESTLM("\\cL", "\\u000c", TRUE, TRUE);       // Control-L
    REGEX_TESTLM("\\e", "\\u001b", TRUE, TRUE);        // Escape
    REGEX_TESTLM("\\f", "\\u000c", TRUE, TRUE);        // Form Feed
    REGEX_TESTLM("\\n", "\\u000a", TRUE, TRUE);        // new line
    REGEX_TESTLM("\\r", "\\u000d", TRUE, TRUE);        //  CR
    REGEX_TESTLM("\\t", "\\u0009", TRUE, TRUE);        // Tab
    REGEX_TESTLM("\\u1234", "\\u1234", TRUE, TRUE);
    REGEX_TESTLM("\\U00001234", "\\u1234", TRUE, TRUE);

    REGEX_TESTLM(".*\\Ax", "xyz", TRUE, FALSE);  //  \A matches only at the beginning of input
    REGEX_TESTLM(".*\\Ax", " xyz", FALSE, FALSE);  //  \A matches only at the beginning of input

    // Escape of special chars in patterns
    REGEX_TESTLM("\\\\\\|\\(\\)\\[\\{\\~\\$\\*\\+\\?\\.", "\\\\|()[{~$*+?.", TRUE, TRUE);
}


//---------------------------------------------------------------------------
//
//    UTextBasic   Check for quirks that are specific to the UText
//                 implementation.
//
//---------------------------------------------------------------------------
void RegexTest::UTextBasic() {
    UErrorCode status = U_ZERO_ERROR;
    UText pattern = UTEXT_INITIALIZER;
    utext_openUTF8(&pattern, "abc", -1, &status);
    RegexMatcher matcher(&pattern, 0, status);
    REGEX_CHECK_STATUS;
    
    UText input = UTEXT_INITIALIZER;
    utext_openUTF8(&input, "abc", -1, &status);
    REGEX_CHECK_STATUS;
    matcher.reset(&input);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT("abc", matcher.inputText());
    
    matcher.reset(matcher.inputText());
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT("abc", matcher.inputText());
    
    utext_close(&pattern);
    utext_close(&input);
}


//---------------------------------------------------------------------------
//
//      API_Match   Test that the API for class RegexMatcher
//                  is present and nominally working, but excluding functions
//                  implementing replace operations.
//
//---------------------------------------------------------------------------
void RegexTest::API_Match() {
    UParseError         pe;
    UErrorCode          status=U_ZERO_ERROR;
    int32_t             flags = 0;

    //
    // Debug - slide failing test cases early
    //
#if 0
    {
    }
    return;
#endif

    //
    // Simple pattern compilation
    //
    {
        UnicodeString       re("abc");
        RegexPattern        *pat2;
        pat2 = RegexPattern::compile(re, flags, pe, status);
        REGEX_CHECK_STATUS;

        UnicodeString inStr1 = "abcdef this is a test";
        UnicodeString instr2 = "not abc";
        UnicodeString empty  = "";


        //
        // Matcher creation and reset.
        //
        RegexMatcher *m1 = pat2->matcher(inStr1, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(m1->lookingAt(status) == TRUE);
        REGEX_ASSERT(m1->input() == inStr1);
        m1->reset(instr2);
        REGEX_ASSERT(m1->lookingAt(status) == FALSE);
        REGEX_ASSERT(m1->input() == instr2);
        m1->reset(inStr1);
        REGEX_ASSERT(m1->input() == inStr1);
        REGEX_ASSERT(m1->lookingAt(status) == TRUE);
        m1->reset(empty);
        REGEX_ASSERT(m1->lookingAt(status) == FALSE);
        REGEX_ASSERT(m1->input() == empty);
        REGEX_ASSERT(&m1->pattern() == pat2);

        //
        //  reset(pos, status)
        //
        m1->reset(inStr1);
        m1->reset(4, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(m1->input() == inStr1);
        REGEX_ASSERT(m1->lookingAt(status) == TRUE);

        m1->reset(-1, status);
        REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);
        status = U_ZERO_ERROR;

        m1->reset(0, status);
        REGEX_CHECK_STATUS;
        status = U_ZERO_ERROR;

        int32_t len = m1->input().length();
        m1->reset(len-1, status);
        REGEX_CHECK_STATUS;
        status = U_ZERO_ERROR;

        m1->reset(len, status);
        REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);
        status = U_ZERO_ERROR;

        //
        // match(pos, status)
        //
        m1->reset(instr2);
        REGEX_ASSERT(m1->matches(4, status) == TRUE);
        m1->reset();
        REGEX_ASSERT(m1->matches(3, status) == FALSE);
        m1->reset();
        REGEX_ASSERT(m1->matches(5, status) == FALSE);
        REGEX_ASSERT(m1->matches(4, status) == TRUE);
        REGEX_ASSERT(m1->matches(-1, status) == FALSE);
        REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);

        // Match() at end of string should fail, but should not
        //  be an error.
        status = U_ZERO_ERROR;
        len = m1->input().length();
        REGEX_ASSERT(m1->matches(len, status) == FALSE);
        REGEX_CHECK_STATUS;

        // Match beyond end of string should fail with an error.
        status = U_ZERO_ERROR;
        REGEX_ASSERT(m1->matches(len+1, status) == FALSE);
        REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);

        // Successful match at end of string.
        {
            status = U_ZERO_ERROR;
            RegexMatcher m("A?", 0, status);  // will match zero length string.
            REGEX_CHECK_STATUS;
            m.reset(inStr1);
            len = inStr1.length();
            REGEX_ASSERT(m.matches(len, status) == TRUE);
            REGEX_CHECK_STATUS;
            m.reset(empty);
            REGEX_ASSERT(m.matches(0, status) == TRUE);
            REGEX_CHECK_STATUS;
        }


        //
        // lookingAt(pos, status)
        //
        status = U_ZERO_ERROR;
        m1->reset(instr2);  // "not abc"
        REGEX_ASSERT(m1->lookingAt(4, status) == TRUE);
        REGEX_ASSERT(m1->lookingAt(5, status) == FALSE);
        REGEX_ASSERT(m1->lookingAt(3, status) == FALSE);
        REGEX_ASSERT(m1->lookingAt(4, status) == TRUE);
        REGEX_ASSERT(m1->lookingAt(-1, status) == FALSE);
        REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);
        status = U_ZERO_ERROR;
        len = m1->input().length();
        REGEX_ASSERT(m1->lookingAt(len, status) == FALSE);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(m1->lookingAt(len+1, status) == FALSE);
        REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);

        delete m1;
        delete pat2;
    }


    //
    // Capture Group.
    //     RegexMatcher::start();
    //     RegexMatcher::end();
    //     RegexMatcher::groupCount();
    //
    {
        int32_t             flags=0;
        UParseError         pe;
        UErrorCode          status=U_ZERO_ERROR;

        UnicodeString       re("01(23(45)67)(.*)");
        RegexPattern *pat = RegexPattern::compile(re, flags, pe, status);
        REGEX_CHECK_STATUS;
        UnicodeString data = "0123456789";

        RegexMatcher *matcher = pat->matcher(data, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(matcher->lookingAt(status) == TRUE);
        static const int32_t matchStarts[] = {0,  2, 4, 8};
        static const int32_t matchEnds[]   = {10, 8, 6, 10};
        int32_t i;
        for (i=0; i<4; i++) {
            int32_t actualStart = matcher->start(i, status);
            REGEX_CHECK_STATUS;
            if (actualStart != matchStarts[i]) {
                errln("RegexTest failure at line %d, index %d.  Expected %d, got %d\n",
                    __LINE__, i, matchStarts[i], actualStart);
            }
            int32_t actualEnd = matcher->end(i, status);
            REGEX_CHECK_STATUS;
            if (actualEnd != matchEnds[i]) {
                errln("RegexTest failure at line %d index %d.  Expected %d, got %d\n",
                    __LINE__, i, matchEnds[i], actualEnd);
            }
        }

        REGEX_ASSERT(matcher->start(0, status) == matcher->start(status));
        REGEX_ASSERT(matcher->end(0, status) == matcher->end(status));

        REGEX_ASSERT_FAIL(matcher->start(-1, status), U_INDEX_OUTOFBOUNDS_ERROR);
        REGEX_ASSERT_FAIL(matcher->start( 4, status), U_INDEX_OUTOFBOUNDS_ERROR);
        matcher->reset();
        REGEX_ASSERT_FAIL(matcher->start( 0, status), U_REGEX_INVALID_STATE);

        matcher->lookingAt(status);
        REGEX_ASSERT(matcher->group(status)    == "0123456789");
        REGEX_ASSERT(matcher->group(0, status) == "0123456789");
        REGEX_ASSERT(matcher->group(1, status) == "234567"    );
        REGEX_ASSERT(matcher->group(2, status) == "45"        );
        REGEX_ASSERT(matcher->group(3, status) == "89"        );
        REGEX_CHECK_STATUS;
        REGEX_ASSERT_FAIL(matcher->group(-1, status), U_INDEX_OUTOFBOUNDS_ERROR);
        REGEX_ASSERT_FAIL(matcher->group( 4, status), U_INDEX_OUTOFBOUNDS_ERROR);
        matcher->reset();
        REGEX_ASSERT_FAIL(matcher->group( 0, status), U_REGEX_INVALID_STATE);

        delete matcher;
        delete pat;

    }

    //
    //  find
    //
    {
        int32_t             flags=0;
        UParseError         pe;
        UErrorCode          status=U_ZERO_ERROR;

        UnicodeString       re("abc");
        RegexPattern *pat = RegexPattern::compile(re, flags, pe, status);
        REGEX_CHECK_STATUS;
        UnicodeString data = ".abc..abc...abc..";
        //                    012345678901234567

        RegexMatcher *matcher = pat->matcher(data, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(matcher->find());
        REGEX_ASSERT(matcher->start(status) == 1);
        REGEX_ASSERT(matcher->find());
        REGEX_ASSERT(matcher->start(status) == 6);
        REGEX_ASSERT(matcher->find());
        REGEX_ASSERT(matcher->start(status) == 12);
        REGEX_ASSERT(matcher->find() == FALSE);
        REGEX_ASSERT(matcher->find() == FALSE);

        matcher->reset();
        REGEX_ASSERT(matcher->find());
        REGEX_ASSERT(matcher->start(status) == 1);

        REGEX_ASSERT(matcher->find(0, status));
        REGEX_ASSERT(matcher->start(status) == 1);
        REGEX_ASSERT(matcher->find(1, status));
        REGEX_ASSERT(matcher->start(status) == 1);
        REGEX_ASSERT(matcher->find(2, status));
        REGEX_ASSERT(matcher->start(status) == 6);
        REGEX_ASSERT(matcher->find(12, status));
        REGEX_ASSERT(matcher->start(status) == 12);
        REGEX_ASSERT(matcher->find(13, status) == FALSE);
        REGEX_ASSERT(matcher->find(16, status) == FALSE);
        REGEX_ASSERT(matcher->find(17, status) == FALSE);
        REGEX_ASSERT_FAIL(matcher->start(status), U_REGEX_INVALID_STATE);

        status = U_ZERO_ERROR;
        REGEX_ASSERT_FAIL(matcher->find(-1, status), U_INDEX_OUTOFBOUNDS_ERROR);
        status = U_ZERO_ERROR;
        REGEX_ASSERT_FAIL(matcher->find(18, status), U_INDEX_OUTOFBOUNDS_ERROR);

        REGEX_ASSERT(matcher->groupCount() == 0);

        delete matcher;
        delete pat;
    }


    //
    //  find, with \G in pattern (true if at the end of a previous match).
    //
    {
        int32_t             flags=0;
        UParseError         pe;
        UErrorCode          status=U_ZERO_ERROR;

        UnicodeString       re(".*?(?:(\\Gabc)|(abc))", -1, US_INV);
        RegexPattern *pat = RegexPattern::compile(re, flags, pe, status);
        REGEX_CHECK_STATUS;
        UnicodeString data = ".abcabc.abc..";
        //                    012345678901234567

        RegexMatcher *matcher = pat->matcher(data, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(matcher->find());
        REGEX_ASSERT(matcher->start(status) == 0);
        REGEX_ASSERT(matcher->start(1, status) == -1);
        REGEX_ASSERT(matcher->start(2, status) == 1);

        REGEX_ASSERT(matcher->find());
        REGEX_ASSERT(matcher->start(status) == 4);
        REGEX_ASSERT(matcher->start(1, status) == 4);
        REGEX_ASSERT(matcher->start(2, status) == -1);
        REGEX_CHECK_STATUS;

        delete matcher;
        delete pat;
    }

    //
    //   find with zero length matches, match position should bump ahead
    //     to prevent loops.
    //
    {
        int32_t                 i;
        UErrorCode          status=U_ZERO_ERROR;
        RegexMatcher        m("(?= ?)", 0, status);   // This pattern will zero-length matches anywhere,
                                                      //   using an always-true look-ahead.
        REGEX_CHECK_STATUS;
        UnicodeString s("    ");
        m.reset(s);
        for (i=0; ; i++) {
            if (m.find() == FALSE) {
                break;
            }
            REGEX_ASSERT(m.start(status) == i);
            REGEX_ASSERT(m.end(status) == i);
        }
        REGEX_ASSERT(i==5);

        // Check that the bump goes over surrogate pairs OK
        s = UNICODE_STRING_SIMPLE("\\U00010001\\U00010002\\U00010003\\U00010004");
        s = s.unescape();
        m.reset(s);
        for (i=0; ; i+=2) {
            if (m.find() == FALSE) {
                break;
            }
            REGEX_ASSERT(m.start(status) == i);
            REGEX_ASSERT(m.end(status) == i);
        }
        REGEX_ASSERT(i==10);
    }
    {
        // find() loop breaking test.
        //        with pattern of /.?/, should see a series of one char matches, then a single
        //        match of zero length at the end of the input string.
        int32_t                 i;
        UErrorCode          status=U_ZERO_ERROR;
        RegexMatcher        m(".?", 0, status);
        REGEX_CHECK_STATUS;
        UnicodeString s("    ");
        m.reset(s);
        for (i=0; ; i++) {
            if (m.find() == FALSE) {
                break;
            }
            REGEX_ASSERT(m.start(status) == i);
            REGEX_ASSERT(m.end(status) == (i<4 ? i+1 : i));
        }
        REGEX_ASSERT(i==5);
    }


    //
    // Matchers with no input string behave as if they had an empty input string.
    //

    {
        UErrorCode status = U_ZERO_ERROR;
        RegexMatcher  m(".?", 0, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(m.find());
        REGEX_ASSERT(m.start(status) == 0);
        REGEX_ASSERT(m.input() == "");
    }
    {
        UErrorCode status = U_ZERO_ERROR;
        RegexPattern  *p = RegexPattern::compile(".", 0, status);
        RegexMatcher  *m = p->matcher(status);
        REGEX_CHECK_STATUS;

        REGEX_ASSERT(m->find() == FALSE);
        REGEX_ASSERT(m->input() == "");
        delete m;
        delete p;
    }
    
    //
    // Regions
    //
    {
        UErrorCode status = U_ZERO_ERROR;
        UnicodeString testString("This is test data");
        RegexMatcher m(".*", testString,  0, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(m.regionStart() == 0);
        REGEX_ASSERT(m.regionEnd() == testString.length());
        REGEX_ASSERT(m.hasTransparentBounds() == FALSE);
        REGEX_ASSERT(m.hasAnchoringBounds() == TRUE);
        
        m.region(2,4, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(m.matches(status));
        REGEX_ASSERT(m.start(status)==2);
        REGEX_ASSERT(m.end(status)==4);
        REGEX_CHECK_STATUS;
        
        m.reset();
        REGEX_ASSERT(m.regionStart() == 0);
        REGEX_ASSERT(m.regionEnd() == testString.length());
        
        UnicodeString shorterString("short");
        m.reset(shorterString);
        REGEX_ASSERT(m.regionStart() == 0);
        REGEX_ASSERT(m.regionEnd() == shorterString.length());
        
        REGEX_ASSERT(m.hasAnchoringBounds() == TRUE);
        REGEX_ASSERT(&m == &m.useAnchoringBounds(FALSE));
        REGEX_ASSERT(m.hasAnchoringBounds() == FALSE);
        REGEX_ASSERT(&m == &m.reset());
        REGEX_ASSERT(m.hasAnchoringBounds() == FALSE);
        
        REGEX_ASSERT(&m == &m.useAnchoringBounds(TRUE));
        REGEX_ASSERT(m.hasAnchoringBounds() == TRUE);
        REGEX_ASSERT(&m == &m.reset());
        REGEX_ASSERT(m.hasAnchoringBounds() == TRUE);
    
        REGEX_ASSERT(m.hasTransparentBounds() == FALSE);
        REGEX_ASSERT(&m == &m.useTransparentBounds(TRUE));
        REGEX_ASSERT(m.hasTransparentBounds() == TRUE);
        REGEX_ASSERT(&m == &m.reset());
        REGEX_ASSERT(m.hasTransparentBounds() == TRUE);

        REGEX_ASSERT(&m == &m.useTransparentBounds(FALSE));
        REGEX_ASSERT(m.hasTransparentBounds() == FALSE);
        REGEX_ASSERT(&m == &m.reset());
        REGEX_ASSERT(m.hasTransparentBounds() == FALSE);
        
    }
    
    //
    // hitEnd() and requireEnd()
    //
    {
        UErrorCode status = U_ZERO_ERROR;
        UnicodeString testString("aabb");
        RegexMatcher m1(".*", testString,  0, status);
        REGEX_ASSERT(m1.lookingAt(status) == TRUE);
        REGEX_ASSERT(m1.hitEnd() == TRUE);
        REGEX_ASSERT(m1.requireEnd() == FALSE);
        REGEX_CHECK_STATUS;
        
        status = U_ZERO_ERROR;
        RegexMatcher m2("a*", testString, 0, status);
        REGEX_ASSERT(m2.lookingAt(status) == TRUE);
        REGEX_ASSERT(m2.hitEnd() == FALSE);
        REGEX_ASSERT(m2.requireEnd() == FALSE);
        REGEX_CHECK_STATUS;

        status = U_ZERO_ERROR;
        RegexMatcher m3(".*$", testString, 0, status);
        REGEX_ASSERT(m3.lookingAt(status) == TRUE);
        REGEX_ASSERT(m3.hitEnd() == TRUE);
        REGEX_ASSERT(m3.requireEnd() == TRUE);
        REGEX_CHECK_STATUS;
    }


    //
    // Compilation error on reset with UChar *
    //   These were a hazard that people were stumbling over with runtime errors.
    //   Changed them to compiler errors by adding private methods that more closely
    //   matched the incorrect use of the functions.
    //
#if 0
    {
        UErrorCode status = U_ZERO_ERROR;
        UChar ucharString[20];
        RegexMatcher m(".", 0, status);
        m.reset(ucharString);  // should not compile.

        RegexPattern *p = RegexPattern::compile(".", 0, status);
        RegexMatcher *m2 = p->matcher(ucharString, status);    //  should not compile.

        RegexMatcher m3(".", ucharString, 0, status);  //  Should not compile
    }
#endif

    //
    //  Time Outs.  
    //       Note:  These tests will need to be changed when the regexp engine is
    //              able to detect and cut short the exponential time behavior on
    //              this type of match.
    //
    {
        UErrorCode status = U_ZERO_ERROR;
        //    Enough 'a's in the string to cause the match to time out.
        //       (Each on additonal 'a' doubles the time)
        UnicodeString testString("aaaaaaaaaaaaaaaaaaaaa");
        RegexMatcher matcher("(a+)+b", testString, 0, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(matcher.getTimeLimit() == 0);
        matcher.setTimeLimit(100, status);
        REGEX_ASSERT(matcher.getTimeLimit() == 100);
        REGEX_ASSERT(matcher.lookingAt(status) == FALSE);
        REGEX_ASSERT(status == U_REGEX_TIME_OUT);
    }
    {
        UErrorCode status = U_ZERO_ERROR;
        //   Few enough 'a's to slip in under the time limit.
        UnicodeString testString("aaaaaaaaaaaaaaaaaa");
        RegexMatcher matcher("(a+)+b", testString, 0, status);
        REGEX_CHECK_STATUS;
        matcher.setTimeLimit(100, status);
        REGEX_ASSERT(matcher.lookingAt(status) == FALSE);
        REGEX_CHECK_STATUS;
    }
    
    //
    //  Stack Limits
    //
    {
        UErrorCode status = U_ZERO_ERROR;
        UnicodeString testString(1000000, 0x41, 1000000);  // Length 1,000,000, filled with 'A'
        
        // Adding the capturing parentheses to the pattern "(A)+A$" inhibits optimizations
        //   of the '+', and makes the stack frames larger.
        RegexMatcher matcher("(A)+A$", testString, 0, status);
        
        // With the default stack, this match should fail to run
        REGEX_ASSERT(matcher.lookingAt(status) == FALSE);
        REGEX_ASSERT(status == U_REGEX_STACK_OVERFLOW);
        
        // With unlimited stack, it should run
        status = U_ZERO_ERROR;
        matcher.setStackLimit(0, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(matcher.lookingAt(status) == TRUE);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(matcher.getStackLimit() == 0);

        // With a limited stack, it the match should fail
        status = U_ZERO_ERROR;
        matcher.setStackLimit(10000, status);
        REGEX_ASSERT(matcher.lookingAt(status) == FALSE);
        REGEX_ASSERT(status == U_REGEX_STACK_OVERFLOW);
        REGEX_ASSERT(matcher.getStackLimit() == 10000);
    }
        
        // A pattern that doesn't save state should work with
        //   a minimal sized stack
    {
        UErrorCode status = U_ZERO_ERROR;
        UnicodeString testString = "abc";
        RegexMatcher matcher("abc", testString, 0, status);
        REGEX_CHECK_STATUS;
        matcher.setStackLimit(30, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(matcher.matches(status) == TRUE);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(matcher.getStackLimit() == 30);
        
        // Negative stack sizes should fail
        status = U_ZERO_ERROR;
        matcher.setStackLimit(1000, status);
        REGEX_CHECK_STATUS;
        matcher.setStackLimit(-1, status);
        REGEX_ASSERT(status == U_ILLEGAL_ARGUMENT_ERROR);
        REGEX_ASSERT(matcher.getStackLimit() == 1000);
    }
    

}


//---------------------------------------------------------------------------
//
//      API_Replace        API test for class RegexMatcher, testing the
//                         Replace family of functions.
//
//---------------------------------------------------------------------------
void RegexTest::API_Replace() {
    //
    //  Replace
    //
    int32_t             flags=0;
    UParseError         pe;
    UErrorCode          status=U_ZERO_ERROR;

    UnicodeString       re("abc");
    RegexPattern *pat = RegexPattern::compile(re, flags, pe, status);
    REGEX_CHECK_STATUS;
    UnicodeString data = ".abc..abc...abc..";
    //                    012345678901234567
    RegexMatcher *matcher = pat->matcher(data, status);

    //
    //  Plain vanilla matches.
    //
    UnicodeString  dest;
    dest = matcher->replaceFirst("yz", status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(dest == ".yz..abc...abc..");

    dest = matcher->replaceAll("yz", status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(dest == ".yz..yz...yz..");

    //
    //  Plain vanilla non-matches.
    //
    UnicodeString d2 = ".abx..abx...abx..";
    matcher->reset(d2);
    dest = matcher->replaceFirst("yz", status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(dest == ".abx..abx...abx..");

    dest = matcher->replaceAll("yz", status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(dest == ".abx..abx...abx..");

    //
    // Empty source string
    //
    UnicodeString d3 = "";
    matcher->reset(d3);
    dest = matcher->replaceFirst("yz", status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(dest == "");

    dest = matcher->replaceAll("yz", status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(dest == "");

    //
    // Empty substitution string
    //
    matcher->reset(data);              // ".abc..abc...abc.."
    dest = matcher->replaceFirst("", status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(dest == "...abc...abc..");

    dest = matcher->replaceAll("", status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(dest == "........");

    //
    // match whole string
    //
    UnicodeString d4 = "abc";
    matcher->reset(d4);
    dest = matcher->replaceFirst("xyz", status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(dest == "xyz");

    dest = matcher->replaceAll("xyz", status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(dest == "xyz");

    //
    // Capture Group, simple case
    //
    UnicodeString       re2("a(..)");
    RegexPattern *pat2 = RegexPattern::compile(re2, flags, pe, status);
    REGEX_CHECK_STATUS;
    UnicodeString d5 = "abcdefg";
    RegexMatcher *matcher2 = pat2->matcher(d5, status);
    REGEX_CHECK_STATUS;
    dest = matcher2->replaceFirst("$1$1", status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(dest == "bcbcdefg");

    dest = matcher2->replaceFirst(UNICODE_STRING_SIMPLE("The value of \\$1 is $1."), status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(dest == "The value of $1 is bc.defg");

    dest = matcher2->replaceFirst("$ by itself, no group number $$$", status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(dest == "$ by itself, no group number $$$defg");

    UnicodeString replacement = UNICODE_STRING_SIMPLE("Supplemental Digit 1 $\\U0001D7CF.");
    replacement = replacement.unescape();
    dest = matcher2->replaceFirst(replacement, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(dest == "Supplemental Digit 1 bc.defg");

    REGEX_ASSERT_FAIL(matcher2->replaceFirst("bad capture group number $5...",status), U_INDEX_OUTOFBOUNDS_ERROR);


    //
    // Replacement String with \u hex escapes
    //
    {
        UnicodeString  src = "abc 1 abc 2 abc 3";
        UnicodeString  substitute = UNICODE_STRING_SIMPLE("--\\u0043--");
        matcher->reset(src);
        UnicodeString  result = matcher->replaceAll(substitute, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == "--C-- 1 --C-- 2 --C-- 3");
    }
    {
        UnicodeString  src = "abc !";
        UnicodeString  substitute = UNICODE_STRING_SIMPLE("--\\U00010000--");
        matcher->reset(src);
        UnicodeString  result = matcher->replaceAll(substitute, status);
        REGEX_CHECK_STATUS;
        UnicodeString expected = UnicodeString("--");
        expected.append((UChar32)0x10000);
        expected.append("-- !");
        REGEX_ASSERT(result == expected);
    }
    // TODO:  need more through testing of capture substitutions.

    // Bug 4057
    //
    {
        status = U_ZERO_ERROR;
        UnicodeString s = "The matches start with ss and end with ee ss stuff ee fin";
        RegexMatcher m("ss(.*?)ee", 0, status);
        REGEX_CHECK_STATUS;
        UnicodeString result;

        // Multiple finds do NOT bump up the previous appendReplacement postion.
        m.reset(s);
        m.find();
        m.find();
        m.appendReplacement(result, "ooh", status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == "The matches start with ss and end with ee ooh");

        // After a reset into the interior of a string, appendReplacemnt still starts at beginning.
        status = U_ZERO_ERROR;
        result.truncate(0);
        m.reset(10, status);
        m.find();
        m.find();
        m.appendReplacement(result, "ooh", status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == "The matches start with ss and end with ee ooh");

        // find() at interior of string, appendReplacemnt still starts at beginning.
        status = U_ZERO_ERROR;
        result.truncate(0);
        m.reset();
        m.find(10, status);
        m.find();
        m.appendReplacement(result, "ooh", status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == "The matches start with ss and end with ee ooh");

        m.appendTail(result);
        REGEX_ASSERT(result == "The matches start with ss and end with ee ooh fin");

    }

    delete matcher2;
    delete pat2;
    delete matcher;
    delete pat;
}


//---------------------------------------------------------------------------
//
//      API_Pattern       Test that the API for class RegexPattern is
//                        present and nominally working.
//
//---------------------------------------------------------------------------
void RegexTest::API_Pattern() {
    RegexPattern        pata;    // Test default constructor to not crash.
    RegexPattern        patb;

    REGEX_ASSERT(pata == patb);
    REGEX_ASSERT(pata == pata);

    UnicodeString re1("abc[a-l][m-z]");
    UnicodeString re2("def");
    UErrorCode    status = U_ZERO_ERROR;
    UParseError   pe;

    RegexPattern        *pat1 = RegexPattern::compile(re1, 0, pe, status);
    RegexPattern        *pat2 = RegexPattern::compile(re2, 0, pe, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(*pat1 == *pat1);
    REGEX_ASSERT(*pat1 != pata);

    // Assign
    patb = *pat1;
    REGEX_ASSERT(patb == *pat1);

    // Copy Construct
    RegexPattern patc(*pat1);
    REGEX_ASSERT(patc == *pat1);
    REGEX_ASSERT(patb == patc);
    REGEX_ASSERT(pat1 != pat2);
    patb = *pat2;
    REGEX_ASSERT(patb != patc);
    REGEX_ASSERT(patb == *pat2);

    // Compile with no flags.
    RegexPattern         *pat1a = RegexPattern::compile(re1, pe, status);
    REGEX_ASSERT(*pat1a == *pat1);

    REGEX_ASSERT(pat1a->flags() == 0);

    // Compile with different flags should be not equal
    RegexPattern        *pat1b = RegexPattern::compile(re1, UREGEX_CASE_INSENSITIVE, pe, status);
    REGEX_CHECK_STATUS;

    REGEX_ASSERT(*pat1b != *pat1a);
    REGEX_ASSERT(pat1b->flags() == UREGEX_CASE_INSENSITIVE);
    REGEX_ASSERT(pat1a->flags() == 0);
    delete pat1b;

    // clone
    RegexPattern *pat1c = pat1->clone();
    REGEX_ASSERT(*pat1c == *pat1);
    REGEX_ASSERT(*pat1c != *pat2);

    delete pat1c;
    delete pat1a;
    delete pat1;
    delete pat2;


    //
    //   Verify that a matcher created from a cloned pattern works.
    //     (Jitterbug 3423)
    //
    {
        UErrorCode     status     = U_ZERO_ERROR;
        RegexPattern  *pSource    = RegexPattern::compile(UNICODE_STRING_SIMPLE("\\p{L}+"), 0, status);
        RegexPattern  *pClone     = pSource->clone();
        delete         pSource;
        RegexMatcher  *mFromClone = pClone->matcher(status);
        REGEX_CHECK_STATUS;
        UnicodeString s = "Hello World";
        mFromClone->reset(s);
        REGEX_ASSERT(mFromClone->find() == TRUE);
        REGEX_ASSERT(mFromClone->group(status) == "Hello");
        REGEX_ASSERT(mFromClone->find() == TRUE);
        REGEX_ASSERT(mFromClone->group(status) == "World");
        REGEX_ASSERT(mFromClone->find() == FALSE);
        delete mFromClone;
        delete pClone;
    }

    //
    //   matches convenience API
    //
    REGEX_ASSERT(RegexPattern::matches(".*", "random input", pe, status) == TRUE);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(RegexPattern::matches("abc", "random input", pe, status) == FALSE);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(RegexPattern::matches(".*nput", "random input", pe, status) == TRUE);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(RegexPattern::matches("random input", "random input", pe, status) == TRUE);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(RegexPattern::matches(".*u", "random input", pe, status) == FALSE);
    REGEX_CHECK_STATUS;
    status = U_INDEX_OUTOFBOUNDS_ERROR;
    REGEX_ASSERT(RegexPattern::matches("abc", "abc", pe, status) == FALSE);
    REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);


    //
    // Split()
    //
    status = U_ZERO_ERROR;
    pat1 = RegexPattern::compile(" +",  pe, status);
    REGEX_CHECK_STATUS;
    UnicodeString  fields[10];

    int32_t n;
    n = pat1->split("Now is the time", fields, 10, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==4);
    REGEX_ASSERT(fields[0]=="Now");
    REGEX_ASSERT(fields[1]=="is");
    REGEX_ASSERT(fields[2]=="the");
    REGEX_ASSERT(fields[3]=="time");
    REGEX_ASSERT(fields[4]=="");

    n = pat1->split("Now is the time", fields, 2, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==2);
    REGEX_ASSERT(fields[0]=="Now");
    REGEX_ASSERT(fields[1]=="is the time");
    REGEX_ASSERT(fields[2]=="the");   // left over from previous test

    fields[1] = "*";
    status = U_ZERO_ERROR;
    n = pat1->split("Now is the time", fields, 1, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==1);
    REGEX_ASSERT(fields[0]=="Now is the time");
    REGEX_ASSERT(fields[1]=="*");
    status = U_ZERO_ERROR;

    n = pat1->split("    Now       is the time   ", fields, 10, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==5);
    REGEX_ASSERT(fields[0]=="");
    REGEX_ASSERT(fields[1]=="Now");
    REGEX_ASSERT(fields[2]=="is");
    REGEX_ASSERT(fields[3]=="the");
    REGEX_ASSERT(fields[4]=="time");
    REGEX_ASSERT(fields[5]=="");

    n = pat1->split("     ", fields, 10, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==1);
    REGEX_ASSERT(fields[0]=="");

    fields[0] = "foo";
    n = pat1->split("", fields, 10, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==0);
    REGEX_ASSERT(fields[0]=="foo");

    delete pat1;

    //  split, with a pattern with (capture)
    pat1 = RegexPattern::compile(UNICODE_STRING_SIMPLE("<(\\w*)>"),  pe, status);
    REGEX_CHECK_STATUS;

    status = U_ZERO_ERROR;
    n = pat1->split("<a>Now is <b>the time<c>", fields, 10, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==6);
    REGEX_ASSERT(fields[0]=="");
    REGEX_ASSERT(fields[1]=="a");
    REGEX_ASSERT(fields[2]=="Now is ");
    REGEX_ASSERT(fields[3]=="b");
    REGEX_ASSERT(fields[4]=="the time");
    REGEX_ASSERT(fields[5]=="c");
    REGEX_ASSERT(fields[6]=="");
    REGEX_ASSERT(status==U_ZERO_ERROR);

    n = pat1->split("  <a>Now is <b>the time<c>", fields, 10, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==6);
    REGEX_ASSERT(fields[0]=="  ");
    REGEX_ASSERT(fields[1]=="a");
    REGEX_ASSERT(fields[2]=="Now is ");
    REGEX_ASSERT(fields[3]=="b");
    REGEX_ASSERT(fields[4]=="the time");
    REGEX_ASSERT(fields[5]=="c");
    REGEX_ASSERT(fields[6]=="");

    status = U_ZERO_ERROR;
    fields[6] = "foo";
    n = pat1->split("  <a>Now is <b>the time<c>", fields, 6, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==6);
    REGEX_ASSERT(fields[0]=="  ");
    REGEX_ASSERT(fields[1]=="a");
    REGEX_ASSERT(fields[2]=="Now is ");
    REGEX_ASSERT(fields[3]=="b");
    REGEX_ASSERT(fields[4]=="the time");
    REGEX_ASSERT(fields[5]=="c");
    REGEX_ASSERT(fields[6]=="foo");

    status = U_ZERO_ERROR;
    fields[5] = "foo";
    n = pat1->split("  <a>Now is <b>the time<c>", fields, 5, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==5);
    REGEX_ASSERT(fields[0]=="  ");
    REGEX_ASSERT(fields[1]=="a");
    REGEX_ASSERT(fields[2]=="Now is ");
    REGEX_ASSERT(fields[3]=="b");
    REGEX_ASSERT(fields[4]=="the time<c>");
    REGEX_ASSERT(fields[5]=="foo");

    status = U_ZERO_ERROR;
    fields[5] = "foo";
    n = pat1->split("  <a>Now is <b>the time", fields, 5, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==5);
    REGEX_ASSERT(fields[0]=="  ");
    REGEX_ASSERT(fields[1]=="a");
    REGEX_ASSERT(fields[2]=="Now is ");
    REGEX_ASSERT(fields[3]=="b");
    REGEX_ASSERT(fields[4]=="the time");
    REGEX_ASSERT(fields[5]=="foo");

    status = U_ZERO_ERROR;
    n = pat1->split("  <a>Now is <b>the time<c>", fields, 4, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==4);
    REGEX_ASSERT(fields[0]=="  ");
    REGEX_ASSERT(fields[1]=="a");
    REGEX_ASSERT(fields[2]=="Now is ");
    REGEX_ASSERT(fields[3]=="the time<c>");
    status = U_ZERO_ERROR;
    delete pat1;

    pat1 = RegexPattern::compile("([-,])",  pe, status);
    REGEX_CHECK_STATUS;
    n = pat1->split("1-10,20", fields, 10, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==5);
    REGEX_ASSERT(fields[0]=="1");
    REGEX_ASSERT(fields[1]=="-");
    REGEX_ASSERT(fields[2]=="10");
    REGEX_ASSERT(fields[3]==",");
    REGEX_ASSERT(fields[4]=="20");
    delete pat1;


    //
    // RegexPattern::pattern()
    //
    pat1 = new RegexPattern();
    REGEX_ASSERT(pat1->pattern() == "");
    delete pat1;

    pat1 = RegexPattern::compile("(Hello, world)*",  pe, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(pat1->pattern() == "(Hello, world)*");
    delete pat1;


    //
    // classID functions
    //
    pat1 = RegexPattern::compile("(Hello, world)*",  pe, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(pat1->getDynamicClassID() == RegexPattern::getStaticClassID());
    REGEX_ASSERT(pat1->getDynamicClassID() != NULL);
    UnicodeString Hello("Hello, world.");
    RegexMatcher *m = pat1->matcher(Hello, status);
    REGEX_ASSERT(pat1->getDynamicClassID() != m->getDynamicClassID());
    REGEX_ASSERT(m->getDynamicClassID() == RegexMatcher::getStaticClassID());
    REGEX_ASSERT(m->getDynamicClassID() != NULL);
    delete m;
    delete pat1;

}

//---------------------------------------------------------------------------
//
//      API_Match_UTF8   Test that the alternate engine for class RegexMatcher
//                       is present and working, but excluding functions
//                       implementing replace operations.
//
//---------------------------------------------------------------------------
void RegexTest::API_Match_UTF8() {
    UParseError         pe;
    UErrorCode          status=U_ZERO_ERROR;
    int32_t             flags = 0;

    //
    // Debug - slide failing test cases early
    //
#if 0
    {
    }
    return;
#endif

    //
    // Simple pattern compilation
    //
    {
        UText               re = UTEXT_INITIALIZER;
        utext_openUTF8(&re, "abc", -1, &status);
        RegexPattern        *pat2;
        pat2 = RegexPattern::compile(&re, flags, pe, status);
        REGEX_CHECK_STATUS;

        UText input1 = UTEXT_INITIALIZER;
        UText input2 = UTEXT_INITIALIZER;
        UText empty  = UTEXT_INITIALIZER;
        utext_openUTF8(&input1, "abcdef this is a test", -1, &status);
        utext_openUTF8(&input2, "not abc", -1, &status);
        utext_openUChars(&empty, NULL, 0, &status);
        
        int32_t input1Len = strlen("abcdef this is a test");
        int32_t input2Len = strlen("not abc");


        //
        // Matcher creation and reset.
        //
        RegexMatcher *m1 = pat2->matcher(&input1, RegexPattern::PATTERN_IS_UTEXT, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(m1->lookingAt(status) == TRUE);
        REGEX_ASSERT_UTEXT("abcdef this is a test", m1->inputText());
        m1->reset(&input2);
        REGEX_ASSERT(m1->lookingAt(status) == FALSE);
        REGEX_ASSERT_UTEXT("not abc", m1->inputText());
        m1->reset(&input1);
        REGEX_ASSERT_UTEXT("abcdef this is a test", m1->inputText());
        REGEX_ASSERT(m1->lookingAt(status) == TRUE);
        m1->reset(&empty);
        REGEX_ASSERT(m1->lookingAt(status) == FALSE);
        REGEX_ASSERT(utext_nativeLength(&empty) == 0);

        //
        //  reset(pos, status)
        //
        m1->reset(&input1);
        m1->reset(4, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT_UTEXT("abcdef this is a test", m1->inputText());
        REGEX_ASSERT(m1->lookingAt(status) == TRUE);

        m1->reset(-1, status);
        REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);
        status = U_ZERO_ERROR;

        m1->reset(0, status);
        REGEX_CHECK_STATUS;
        status = U_ZERO_ERROR;

        m1->reset(input1Len-1, status);
        REGEX_CHECK_STATUS;
        status = U_ZERO_ERROR;

        m1->reset(input1Len, status);
        REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);
        status = U_ZERO_ERROR;

        //
        // match(pos, status)
        //
        m1->reset(&input2);
        REGEX_ASSERT(m1->matches(4, status) == TRUE);
        m1->reset();
        REGEX_ASSERT(m1->matches(3, status) == FALSE);
        m1->reset();
        REGEX_ASSERT(m1->matches(5, status) == FALSE);
        REGEX_ASSERT(m1->matches(4, status) == TRUE);
        REGEX_ASSERT(m1->matches(-1, status) == FALSE);
        REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);

        // Match() at end of string should fail, but should not
        //  be an error.
        status = U_ZERO_ERROR;
        REGEX_ASSERT(m1->matches(input2Len, status) == FALSE);
        REGEX_CHECK_STATUS;

        // Match beyond end of string should fail with an error.
        status = U_ZERO_ERROR;
        REGEX_ASSERT(m1->matches(input2Len+1, status) == FALSE);
        REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);

        // Successful match at end of string.
        {
            status = U_ZERO_ERROR;
            RegexMatcher m("A?", 0, status);  // will match zero length string.
            REGEX_CHECK_STATUS;
            m.reset(&input1);
            REGEX_ASSERT(m.matches(input1Len, status) == TRUE);
            REGEX_CHECK_STATUS;
            m.reset(&empty);
            REGEX_ASSERT(m.matches(0, status) == TRUE);
            REGEX_CHECK_STATUS;
        }


        //
        // lookingAt(pos, status)
        //
        status = U_ZERO_ERROR;
        m1->reset(&input2);  // "not abc"
        REGEX_ASSERT(m1->lookingAt(4, status) == TRUE);
        REGEX_ASSERT(m1->lookingAt(5, status) == FALSE);
        REGEX_ASSERT(m1->lookingAt(3, status) == FALSE);
        REGEX_ASSERT(m1->lookingAt(4, status) == TRUE);
        REGEX_ASSERT(m1->lookingAt(-1, status) == FALSE);
        REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);
        status = U_ZERO_ERROR;
        REGEX_ASSERT(m1->lookingAt(input2Len, status) == FALSE);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(m1->lookingAt(input2Len+1, status) == FALSE);
        REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);

        delete m1;
        delete pat2;
        
        utext_close(&re);
        utext_close(&input1);
        utext_close(&input2);
        utext_close(&empty);
    }


    //
    // Capture Group.
    //     RegexMatcher::start();
    //     RegexMatcher::end();
    //     RegexMatcher::groupCount();
    //
    {
        int32_t             flags=0;
        UParseError         pe;
        UErrorCode          status=U_ZERO_ERROR;
        UText               re=UTEXT_INITIALIZER;
        utext_openUTF8(&re, "01(23(45)67)(.*)", -1, &status);
        
        RegexPattern *pat = RegexPattern::compile(&re, flags, pe, status);
        REGEX_CHECK_STATUS;
        
        UText input = UTEXT_INITIALIZER;
        utext_openUTF8(&input, "0123456789", -1, &status);

        RegexMatcher *matcher = pat->matcher(&input, RegexPattern::PATTERN_IS_UTEXT, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(matcher->lookingAt(status) == TRUE);
        static const int32_t matchStarts[] = {0,  2, 4, 8};
        static const int32_t matchEnds[]   = {10, 8, 6, 10};
        int32_t i;
        for (i=0; i<4; i++) {
            int32_t actualStart = matcher->start(i, status);
            REGEX_CHECK_STATUS;
            if (actualStart != matchStarts[i]) {
                errln("RegexTest failure at line %d, index %d.  Expected %d, got %d\n",
                    __LINE__, i, matchStarts[i], actualStart);
            }
            int32_t actualEnd = matcher->end(i, status);
            REGEX_CHECK_STATUS;
            if (actualEnd != matchEnds[i]) {
                errln("RegexTest failure at line %d index %d.  Expected %d, got %d\n",
                    __LINE__, i, matchEnds[i], actualEnd);
            }
        }

        REGEX_ASSERT(matcher->start(0, status) == matcher->start(status));
        REGEX_ASSERT(matcher->end(0, status) == matcher->end(status));

        REGEX_ASSERT_FAIL(matcher->start(-1, status), U_INDEX_OUTOFBOUNDS_ERROR);
        REGEX_ASSERT_FAIL(matcher->start( 4, status), U_INDEX_OUTOFBOUNDS_ERROR);
        matcher->reset();
        REGEX_ASSERT_FAIL(matcher->start( 0, status), U_REGEX_INVALID_STATE);

        matcher->lookingAt(status);
        
        UnicodeString dest;
        UText destText = UTEXT_INITIALIZER;
        utext_openUnicodeString(&destText, &dest, &status);
        UText *result;
        
        result = matcher->group((UText *)NULL, RegexMatcher::MATCHER_DEST_IS_UTEXT, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT_UTEXT("0123456789", result);
        utext_close(result);
        result = matcher->group(&destText, RegexMatcher::MATCHER_DEST_IS_UTEXT, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == &destText);
        REGEX_ASSERT_UTEXT("0123456789", result);
        
        result = matcher->group(0, NULL, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT_UTEXT("0123456789", result);
        utext_close(result);
        result = matcher->group(0, &destText, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == &destText);
        REGEX_ASSERT_UTEXT("0123456789", result);
        
        result = matcher->group(1, NULL, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT_UTEXT("234567", result);
        utext_close(result);
        result = matcher->group(1, &destText, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == &destText);
        REGEX_ASSERT_UTEXT("234567", result);
        
        result = matcher->group(2, NULL, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT_UTEXT("45", result);
        utext_close(result);
        result = matcher->group(2, &destText, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == &destText);
        REGEX_ASSERT_UTEXT("45", result);
        
        result = matcher->group(3, NULL, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT_UTEXT("89", result);
        utext_close(result);
        result = matcher->group(3, &destText, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == &destText);
        REGEX_ASSERT_UTEXT("89", result);

        REGEX_ASSERT_FAIL(matcher->group(-1, status), U_INDEX_OUTOFBOUNDS_ERROR);
        REGEX_ASSERT_FAIL(matcher->group( 4, status), U_INDEX_OUTOFBOUNDS_ERROR);
        matcher->reset();
        REGEX_ASSERT_FAIL(matcher->group( 0, status), U_REGEX_INVALID_STATE);

        delete matcher;
        delete pat;
        
        utext_close(&destText);
        utext_close(&input);
        utext_close(&re);
    }

    //
    //  find
    //
    {
        int32_t             flags=0;
        UParseError         pe;
        UErrorCode          status=U_ZERO_ERROR;
        UText               re=UTEXT_INITIALIZER;
        utext_openUTF8(&re, "abc", -1, &status);

        RegexPattern *pat = RegexPattern::compile(&re, flags, pe, status);
        REGEX_CHECK_STATUS;
        UText input = UTEXT_INITIALIZER;
        utext_openUTF8(&input, ".abc..abc...abc..", -1, &status);
        //                      012345678901234567

        RegexMatcher *matcher = pat->matcher(&input, RegexPattern::PATTERN_IS_UTEXT, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(matcher->find());
        REGEX_ASSERT(matcher->start(status) == 1);
        REGEX_ASSERT(matcher->find());
        REGEX_ASSERT(matcher->start(status) == 6);
        REGEX_ASSERT(matcher->find());
        REGEX_ASSERT(matcher->start(status) == 12);
        REGEX_ASSERT(matcher->find() == FALSE);
        REGEX_ASSERT(matcher->find() == FALSE);

        matcher->reset();
        REGEX_ASSERT(matcher->find());
        REGEX_ASSERT(matcher->start(status) == 1);

        REGEX_ASSERT(matcher->find(0, status));
        REGEX_ASSERT(matcher->start(status) == 1);
        REGEX_ASSERT(matcher->find(1, status));
        REGEX_ASSERT(matcher->start(status) == 1);
        REGEX_ASSERT(matcher->find(2, status));
        REGEX_ASSERT(matcher->start(status) == 6);
        REGEX_ASSERT(matcher->find(12, status));
        REGEX_ASSERT(matcher->start(status) == 12);
        REGEX_ASSERT(matcher->find(13, status) == FALSE);
        REGEX_ASSERT(matcher->find(16, status) == FALSE);
        REGEX_ASSERT(matcher->find(17, status) == FALSE);
        REGEX_ASSERT_FAIL(matcher->start(status), U_REGEX_INVALID_STATE);

        status = U_ZERO_ERROR;
        REGEX_ASSERT_FAIL(matcher->find(-1, status), U_INDEX_OUTOFBOUNDS_ERROR);
        status = U_ZERO_ERROR;
        REGEX_ASSERT_FAIL(matcher->find(18, status), U_INDEX_OUTOFBOUNDS_ERROR);

        REGEX_ASSERT(matcher->groupCount() == 0);

        delete matcher;
        delete pat;
        
        utext_close(&input);
        utext_close(&re);
    }


    //
    //  find, with \G in pattern (true if at the end of a previous match).
    //
    {
        int32_t             flags=0;
        UParseError         pe;
        UErrorCode          status=U_ZERO_ERROR;
        UText               re=UTEXT_INITIALIZER;
        utext_openUTF8(&re, ".*?(?:(\\Gabc)|(abc))", -1, &status);

        RegexPattern *pat = RegexPattern::compile(&re, flags, pe, status);
        
        REGEX_CHECK_STATUS;
        UText input = UTEXT_INITIALIZER;
        utext_openUTF8(&input, ".abcabc.abc..", -1, &status);
        //                      012345678901234567

        RegexMatcher *matcher = pat->matcher(&input, RegexPattern::PATTERN_IS_UTEXT, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(matcher->find());
        REGEX_ASSERT(matcher->start(status) == 0);
        REGEX_ASSERT(matcher->start(1, status) == -1);
        REGEX_ASSERT(matcher->start(2, status) == 1);

        REGEX_ASSERT(matcher->find());
        REGEX_ASSERT(matcher->start(status) == 4);
        REGEX_ASSERT(matcher->start(1, status) == 4);
        REGEX_ASSERT(matcher->start(2, status) == -1);
        REGEX_CHECK_STATUS;

        delete matcher;
        delete pat;
        
        utext_close(&input);
        utext_close(&re);
    }

    //
    //   find with zero length matches, match position should bump ahead
    //     to prevent loops.
    //
    {
        int32_t                 i;
        UErrorCode          status=U_ZERO_ERROR;
        RegexMatcher        m("(?= ?)", 0, status);   // This pattern will zero-length matches anywhere,
                                                      //   using an always-true look-ahead.
        REGEX_CHECK_STATUS;
        UText s = UTEXT_INITIALIZER;
        utext_openUTF8(&s, "    ", -1, &status);
        m.reset(&s);
        for (i=0; ; i++) {
            if (m.find() == FALSE) {
                break;
            }
            REGEX_ASSERT(m.start(status) == i);
            REGEX_ASSERT(m.end(status) == i);
        }
        REGEX_ASSERT(i==5);

        // Check that the bump goes over characters outside the BMP OK
        // "\\U00010001\\U00010002\\U00010003\\U00010004".unescape()...in UTF-8
        unsigned char aboveBMP[] = {0xF0, 0x90, 0x80, 0x81, 0xF0, 0x90, 0x80, 0x82, 0xF0, 0x90, 0x80, 0x83, 0xF0, 0x90, 0x80, 0x84, 0x00};
        utext_openUTF8(&s, (char *)aboveBMP, -1, &status);
        m.reset(&s);
        for (i=0; ; i+=2) {
            if (m.find() == FALSE) {
                break;
            }
            REGEX_ASSERT(m.start(status) == i);
            REGEX_ASSERT(m.end(status) == i);
        }
        REGEX_ASSERT(i==10);
        
        utext_close(&s);
    }
    {
        // find() loop breaking test.
        //        with pattern of /.?/, should see a series of one char matches, then a single
        //        match of zero length at the end of the input string.
        int32_t                 i;
        UErrorCode          status=U_ZERO_ERROR;
        RegexMatcher        m(".?", 0, status);
        REGEX_CHECK_STATUS;
        UText s = UTEXT_INITIALIZER;
        utext_openUTF8(&s, "    ", -1, &status);
        m.reset(&s);
        for (i=0; ; i++) {
            if (m.find() == FALSE) {
                break;
            }
            REGEX_ASSERT(m.start(status) == i);
            REGEX_ASSERT(m.end(status) == (i<4 ? i+1 : i));
        }
        REGEX_ASSERT(i==5);
        
        utext_close(&s);
    }


    //
    // Matchers with no input string behave as if they had an empty input string.
    //

    {
        UErrorCode status = U_ZERO_ERROR;
        RegexMatcher  m(".?", 0, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(m.find());
        REGEX_ASSERT(m.start(status) == 0);
        REGEX_ASSERT(m.input() == "");
    }
    {
        UErrorCode status = U_ZERO_ERROR;
        RegexPattern  *p = RegexPattern::compile(".", 0, status);
        RegexMatcher  *m = p->matcher(status);
        REGEX_CHECK_STATUS;

        REGEX_ASSERT(m->find() == FALSE);
        REGEX_ASSERT(utext_nativeLength(m->inputText()) == 0);
        delete m;
        delete p;
    }
    
    //
    // Regions
    //
    {
        UErrorCode status = U_ZERO_ERROR;
        UText testPattern = UTEXT_INITIALIZER;
        UText testText    = UTEXT_INITIALIZER;
        utext_openUTF8(&testPattern, ".*", -1, &status);
        utext_openUTF8(&testText, "This is test data", -1, &status);
        
        RegexMatcher m(&testPattern, &testText, 0, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(m.regionStart() == 0);
        REGEX_ASSERT(m.regionEnd() == (int32_t)strlen("This is test data"));
        REGEX_ASSERT(m.hasTransparentBounds() == FALSE);
        REGEX_ASSERT(m.hasAnchoringBounds() == TRUE);
        
        m.region(2,4, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(m.matches(status));
        REGEX_ASSERT(m.start(status)==2);
        REGEX_ASSERT(m.end(status)==4);
        REGEX_CHECK_STATUS;
        
        m.reset();
        REGEX_ASSERT(m.regionStart() == 0);
        REGEX_ASSERT(m.regionEnd() == (int32_t)strlen("This is test data"));
        
        utext_openUTF8(&testText, "short", -1, &status);
        m.reset(&testText);
        REGEX_ASSERT(m.regionStart() == 0);
        REGEX_ASSERT(m.regionEnd() == (int32_t)strlen("short"));
        
        REGEX_ASSERT(m.hasAnchoringBounds() == TRUE);
        REGEX_ASSERT(&m == &m.useAnchoringBounds(FALSE));
        REGEX_ASSERT(m.hasAnchoringBounds() == FALSE);
        REGEX_ASSERT(&m == &m.reset());
        REGEX_ASSERT(m.hasAnchoringBounds() == FALSE);
        
        REGEX_ASSERT(&m == &m.useAnchoringBounds(TRUE));
        REGEX_ASSERT(m.hasAnchoringBounds() == TRUE);
        REGEX_ASSERT(&m == &m.reset());
        REGEX_ASSERT(m.hasAnchoringBounds() == TRUE);
    
        REGEX_ASSERT(m.hasTransparentBounds() == FALSE);
        REGEX_ASSERT(&m == &m.useTransparentBounds(TRUE));
        REGEX_ASSERT(m.hasTransparentBounds() == TRUE);
        REGEX_ASSERT(&m == &m.reset());
        REGEX_ASSERT(m.hasTransparentBounds() == TRUE);

        REGEX_ASSERT(&m == &m.useTransparentBounds(FALSE));
        REGEX_ASSERT(m.hasTransparentBounds() == FALSE);
        REGEX_ASSERT(&m == &m.reset());
        REGEX_ASSERT(m.hasTransparentBounds() == FALSE);
        
        utext_close(&testText);
        utext_close(&testPattern);
    }
    
    //
    // hitEnd() and requireEnd()
    //
    {
        UErrorCode status = U_ZERO_ERROR;
        UText testPattern = UTEXT_INITIALIZER;
        UText testText    = UTEXT_INITIALIZER;
        utext_openUTF8(&testPattern, ".*", -1, &status);
        utext_openUTF8(&testText, "aabb", -1, &status);
        
        RegexMatcher m1(&testPattern, &testText,  0, status);
        REGEX_ASSERT(m1.lookingAt(status) == TRUE);
        REGEX_ASSERT(m1.hitEnd() == TRUE);
        REGEX_ASSERT(m1.requireEnd() == FALSE);
        REGEX_CHECK_STATUS;
        
        status = U_ZERO_ERROR;
        utext_openUTF8(&testPattern, "a*", -1, &status);
        RegexMatcher m2(&testPattern, &testText, 0, status);
        REGEX_ASSERT(m2.lookingAt(status) == TRUE);
        REGEX_ASSERT(m2.hitEnd() == FALSE);
        REGEX_ASSERT(m2.requireEnd() == FALSE);
        REGEX_CHECK_STATUS;

        status = U_ZERO_ERROR;
        utext_openUTF8(&testPattern, ".*$", -1, &status);
        RegexMatcher m3(&testPattern, &testText, 0, status);
        REGEX_ASSERT(m3.lookingAt(status) == TRUE);
        REGEX_ASSERT(m3.hitEnd() == TRUE);
        REGEX_ASSERT(m3.requireEnd() == TRUE);
        REGEX_CHECK_STATUS;
        
        utext_close(&testText);
        utext_close(&testPattern);
    }
}


//---------------------------------------------------------------------------
//
//      API_Replace_UTF8   API test for class RegexMatcher, testing the
//                         Replace family of functions.
//
//---------------------------------------------------------------------------
void RegexTest::API_Replace_UTF8() {
    //
    //  Replace
    //
    int32_t             flags=0;
    UParseError         pe;
    UErrorCode          status=U_ZERO_ERROR;

    UText               re=UTEXT_INITIALIZER;
    utext_openUTF8(&re, "abc", -1, &status);
    RegexPattern *pat = RegexPattern::compile(&re, flags, pe, status);
    REGEX_CHECK_STATUS;
    
    char data[] = ".abc..abc...abc..";
    //             012345678901234567
    UText dataText = UTEXT_INITIALIZER;
    utext_openUTF8(&dataText, data, -1, &status);
    RegexMatcher *matcher = pat->matcher(&dataText, RegexPattern::PATTERN_IS_UTEXT, status);

    //
    //  Plain vanilla matches.
    //
    UnicodeString  dest;
    UText destText = UTEXT_INITIALIZER;
    utext_openUnicodeString(&destText, &dest, &status);
    UText *result;
    
    UText replText = UTEXT_INITIALIZER;
    
    utext_openUTF8(&replText, "yz", -1, &status);
    result = matcher->replaceFirst(&replText, NULL, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT(".yz..abc...abc..", result);
    utext_close(result);
    result = matcher->replaceFirst(&replText, &destText, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(result == &destText);
    REGEX_ASSERT_UTEXT(".yz..abc...abc..", result);

    result = matcher->replaceAll(&replText, NULL, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT(".yz..yz...yz..", result);
    utext_close(result);

    utext_replace(&destText, 0, utext_nativeLength(&destText), NULL, 0, &status);
    result = matcher->replaceAll(&replText, &destText, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(result == &destText);
    REGEX_ASSERT_UTEXT(".yz..yz...yz..", result);

    //
    //  Plain vanilla non-matches.
    //
    utext_openUTF8(&dataText, ".abx..abx...abx..", -1, &status);
    matcher->reset(&dataText);
    
    result = matcher->replaceFirst(&replText, NULL, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT(".abx..abx...abx..", result);
    utext_close(result);
    result = matcher->replaceFirst(&replText, &destText, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(result == &destText);
    REGEX_ASSERT_UTEXT(".abx..abx...abx..", result);

    result = matcher->replaceAll(&replText, NULL, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT(".abx..abx...abx..", result);
    utext_close(result);
    utext_replace(&destText, 0, utext_nativeLength(&destText), NULL, 0, &status);
    result = matcher->replaceAll(&replText, &destText, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(result == &destText);
    REGEX_ASSERT_UTEXT(".abx..abx...abx..", result);

    //
    // Empty source string
    //
    utext_openUTF8(&dataText, NULL, 0, &status);
    matcher->reset(&dataText);
    
    result = matcher->replaceFirst(&replText, NULL, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT("", result);
    utext_close(result);
    result = matcher->replaceFirst(&replText, &destText, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(result == &destText);
    REGEX_ASSERT_UTEXT("", result);

    result = matcher->replaceAll(&replText, NULL, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT("", result);
    utext_close(result);
    result = matcher->replaceAll(&replText, &destText, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(result == &destText);
    REGEX_ASSERT_UTEXT("", result);

    //
    // Empty substitution string
    //
    utext_openUTF8(&dataText, data, -1, &status); // ".abc..abc...abc.."
    matcher->reset(&dataText);
    
    utext_openUTF8(&replText, NULL, 0, &status);
    result = matcher->replaceFirst(&replText, NULL, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT("...abc...abc..", result);
    utext_close(result);
    result = matcher->replaceFirst(&replText, &destText, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(result == &destText);
    REGEX_ASSERT_UTEXT("...abc...abc..", result);

    result = matcher->replaceAll(&replText, NULL, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT("........", result);
    utext_close(result);
    utext_replace(&destText, 0, utext_nativeLength(&destText), NULL, 0, &status);
    result = matcher->replaceAll(&replText, &destText, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(result == &destText);
    REGEX_ASSERT_UTEXT("........", result);

    //
    // match whole string
    //
    utext_openUTF8(&dataText, "abc", -1, &status);
    matcher->reset(&dataText);

    utext_openUTF8(&replText, "xyz", -1, &status);
    result = matcher->replaceFirst(&replText, NULL, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT("xyz", result);
    utext_close(result);
    utext_replace(&destText, 0, utext_nativeLength(&destText), NULL, 0, &status);
    result = matcher->replaceFirst(&replText, &destText, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(result == &destText);
    REGEX_ASSERT_UTEXT("xyz", result);

    result = matcher->replaceAll(&replText, NULL, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT("xyz", result);
    utext_close(result);
    utext_replace(&destText, 0, utext_nativeLength(&destText), NULL, 0, &status);
    result = matcher->replaceAll(&replText, &destText, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(result == &destText);
    REGEX_ASSERT_UTEXT("xyz", result);

    //
    // Capture Group, simple case
    //
    utext_openUTF8(&re, "a(..)", -1, &status);
    RegexPattern *pat2 = RegexPattern::compile(&re, flags, pe, status);
    REGEX_CHECK_STATUS;
    
    utext_openUTF8(&dataText, "abcdefg", -1, &status);
    RegexMatcher *matcher2 = pat2->matcher(&dataText, RegexPattern::PATTERN_IS_UTEXT, status);
    REGEX_CHECK_STATUS;
    
    utext_openUTF8(&replText, "$1$1", -1, &status);
    result = matcher2->replaceFirst(&replText, NULL, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT("bcbcdefg", result);
    utext_close(result);
    utext_replace(&destText, 0, utext_nativeLength(&destText), NULL, 0, &status);
    result = matcher2->replaceFirst(&replText, &destText, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(result == &destText);
    REGEX_ASSERT_UTEXT("bcbcdefg", result);
    
    utext_openUTF8(&replText, "The value of \\$1 is $1.", -1, &status);
    result = matcher2->replaceFirst(&replText, NULL, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT("The value of $1 is bc.defg", result);
    utext_close(result);
    utext_replace(&destText, 0, utext_nativeLength(&destText), NULL, 0, &status);
    result = matcher2->replaceFirst(&replText, &destText, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(result == &destText);
    REGEX_ASSERT_UTEXT("The value of $1 is bc.defg", result);
    
    utext_openUTF8(&replText, "$ by itself, no group number $$$", -1, &status);
    result = matcher2->replaceFirst(&replText, NULL, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT("$ by itself, no group number $$$defg", result);
    utext_close(result);
    utext_replace(&destText, 0, utext_nativeLength(&destText), NULL, 0, &status);
    result = matcher2->replaceFirst(&replText, &destText, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(result == &destText);
    REGEX_ASSERT_UTEXT("$ by itself, no group number $$$defg", result);

    unsigned char supplDigitChars[] = "Supplemental Digit 1 $xxxx."; // \U0001D7CF, MATHEMATICAL BOLD DIGIT ONE
    //                                 012345678901234567890123456
    supplDigitChars[22] = 0xF0;
    supplDigitChars[23] = 0x9D;
    supplDigitChars[24] = 0x9F;
    supplDigitChars[25] = 0x8F;
    utext_openUTF8(&replText, (char *)supplDigitChars, -1, &status);
    
    result = matcher2->replaceFirst(&replText, NULL, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT_UTEXT("Supplemental Digit 1 bc.defg", result);
    utext_close(result);
    utext_replace(&destText, 0, utext_nativeLength(&destText), NULL, 0, &status);
    result = matcher2->replaceFirst(&replText, &destText, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(result == &destText);
    REGEX_ASSERT_UTEXT("Supplemental Digit 1 bc.defg", result);

    utext_openUTF8(&replText, "bad capture group number $5...", -1, &status);
    REGEX_ASSERT_FAIL((result = matcher2->replaceFirst(&replText, NULL, status)), U_INDEX_OUTOFBOUNDS_ERROR);
//    REGEX_ASSERT_UTEXT("abcdefg", result);
    utext_close(result);
    utext_replace(&destText, 0, utext_nativeLength(&destText), NULL, 0, &status);
    REGEX_ASSERT_FAIL((result = matcher2->replaceFirst(&replText, &destText, status)), U_INDEX_OUTOFBOUNDS_ERROR);
    REGEX_ASSERT(result == &destText);
//    REGEX_ASSERT_UTEXT("abcdefg", result);

    //
    // Replacement String with \u hex escapes
    //
    {
        utext_openUTF8(&dataText, "abc 1 abc 2 abc 3", -1, &status);
        utext_openUTF8(&replText, "--\\u0043--", -1, &status);
        matcher->reset(&dataText);
        
        result = matcher->replaceAll(&replText, NULL, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT_UTEXT("--C-- 1 --C-- 2 --C-- 3", result);
        utext_close(result);
        utext_replace(&destText, 0, utext_nativeLength(&destText), NULL, 0, &status);
        result = matcher->replaceAll(&replText, &destText, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == &destText);
        REGEX_ASSERT_UTEXT("--C-- 1 --C-- 2 --C-- 3", result);
    }
    {
        utext_openUTF8(&dataText, "abc !", -1, &status);
        utext_openUTF8(&replText, "--\\U00010000--", -1, &status);
        matcher->reset(&dataText);

        unsigned char expected[] = "--xxxx-- !"; // \U00010000, "LINEAR B SYLLABLE B008 A"
        //                          0123456789     
        expected[2] = 0xF0;
        expected[3] = 0x90;
        expected[4] = 0x80;
        expected[5] = 0x80;

        result = matcher->replaceAll(&replText, NULL, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT_UTEXT((char *)expected, result);
        utext_close(result);
        utext_replace(&destText, 0, utext_nativeLength(&destText), NULL, 0, &status);
        result = matcher->replaceAll(&replText, &destText, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == &destText);
        REGEX_ASSERT_UTEXT((char *)expected, result);
    }
    // TODO:  need more through testing of capture substitutions.

    // Bug 4057
    //
    {
        status = U_ZERO_ERROR;
        utext_openUTF8(&re, "ss(.*?)ee", -1, &status);
        utext_openUTF8(&dataText, "The matches start with ss and end with ee ss stuff ee fin", -1, &status);
        utext_openUTF8(&replText, "ooh", -1, &status);
        
        RegexMatcher m(&re, 0, status);
        REGEX_CHECK_STATUS;
        
        UnicodeString result;
        UText resultText = UTEXT_INITIALIZER;
        utext_openUnicodeString(&resultText, &result, &status);

        // Multiple finds do NOT bump up the previous appendReplacement postion.
        m.reset(&dataText);
        m.find();
        m.find();
        m.appendReplacement(&resultText, &replText, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT_UTEXT("The matches start with ss and end with ee ooh", &resultText);

        // After a reset into the interior of a string, appendReplacement still starts at beginning.
        status = U_ZERO_ERROR;
        result.truncate(0);
        utext_openUnicodeString(&resultText, &result, &status);
        m.reset(10, status);
        m.find();
        m.find();
        m.appendReplacement(&resultText, &replText, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT_UTEXT("The matches start with ss and end with ee ooh", &resultText);

        // find() at interior of string, appendReplacement still starts at beginning.
        status = U_ZERO_ERROR;
        result.truncate(0);
        utext_openUnicodeString(&resultText, &result, &status);
        m.reset();
        m.find(10, status);
        m.find();
        m.appendReplacement(&resultText, &replText, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT_UTEXT("The matches start with ss and end with ee ooh", &resultText);

        m.appendTail(&resultText);
        REGEX_ASSERT_UTEXT("The matches start with ss and end with ee ooh fin", &resultText);
        
        utext_close(&resultText);
    }

    delete matcher2;
    delete pat2;
    delete matcher;
    delete pat;
    
    utext_close(&dataText);
    utext_close(&replText);
    utext_close(&destText);
    utext_close(&re);
}


//---------------------------------------------------------------------------
//
//      API_Pattern_UTF8  Test that the API for class RegexPattern is
//                        present and nominally working.
//
//---------------------------------------------------------------------------
void RegexTest::API_Pattern_UTF8() {
    RegexPattern        pata;    // Test default constructor to not crash.
    RegexPattern        patb;

    REGEX_ASSERT(pata == patb);
    REGEX_ASSERT(pata == pata);

    UText         re1 = UTEXT_INITIALIZER;
    UText         re2 = UTEXT_INITIALIZER;
    UErrorCode    status = U_ZERO_ERROR;
    UParseError   pe;
    
    utext_openUTF8(&re1, "abc[a-l][m-z]", -1, &status);
    utext_openUTF8(&re2, "def", -1, &status);

    RegexPattern        *pat1 = RegexPattern::compile(&re1, 0, pe, status);
    RegexPattern        *pat2 = RegexPattern::compile(&re2, 0, pe, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(*pat1 == *pat1);
    REGEX_ASSERT(*pat1 != pata);

    // Assign
    patb = *pat1;
    REGEX_ASSERT(patb == *pat1);

    // Copy Construct
    RegexPattern patc(*pat1);
    REGEX_ASSERT(patc == *pat1);
    REGEX_ASSERT(patb == patc);
    REGEX_ASSERT(pat1 != pat2);
    patb = *pat2;
    REGEX_ASSERT(patb != patc);
    REGEX_ASSERT(patb == *pat2);

    // Compile with no flags.
    RegexPattern         *pat1a = RegexPattern::compile(&re1, pe, status);
    REGEX_ASSERT(*pat1a == *pat1);

    REGEX_ASSERT(pat1a->flags() == 0);

    // Compile with different flags should be not equal
    RegexPattern        *pat1b = RegexPattern::compile(&re1, UREGEX_CASE_INSENSITIVE, pe, status);
    REGEX_CHECK_STATUS;

    REGEX_ASSERT(*pat1b != *pat1a);
    REGEX_ASSERT(pat1b->flags() == UREGEX_CASE_INSENSITIVE);
    REGEX_ASSERT(pat1a->flags() == 0);
    delete pat1b;

    // clone
    RegexPattern *pat1c = pat1->clone();
    REGEX_ASSERT(*pat1c == *pat1);
    REGEX_ASSERT(*pat1c != *pat2);

    delete pat1c;
    delete pat1a;
    delete pat1;
    delete pat2;
    
    utext_close(&re1);
    utext_close(&re2);


    //
    //   Verify that a matcher created from a cloned pattern works.
    //     (Jitterbug 3423)
    //
    {
        UErrorCode     status     = U_ZERO_ERROR;
        UText          pattern    = UTEXT_INITIALIZER;
        utext_openUTF8(&pattern, "\\p{L}+", -1, &status);
        
        RegexPattern  *pSource    = RegexPattern::compile(&pattern, 0, status);
        RegexPattern  *pClone     = pSource->clone();
        delete         pSource;
        RegexMatcher  *mFromClone = pClone->matcher(status);
        REGEX_CHECK_STATUS;
        
        UText          input      = UTEXT_INITIALIZER;
        utext_openUTF8(&input, "Hello World", -1, &status);
        mFromClone->reset(&input);
        REGEX_ASSERT(mFromClone->find() == TRUE);
        REGEX_ASSERT(mFromClone->group(status) == "Hello");
        REGEX_ASSERT(mFromClone->find() == TRUE);
        REGEX_ASSERT(mFromClone->group(status) == "World");
        REGEX_ASSERT(mFromClone->find() == FALSE);
        delete mFromClone;
        delete pClone;
        
        utext_close(&input);
        utext_close(&pattern);
    }

    //
    //   matches convenience API
    //
    {
        UErrorCode status  = U_ZERO_ERROR;
        UText      pattern = UTEXT_INITIALIZER;
        UText      input   = UTEXT_INITIALIZER;
        
        utext_openUTF8(&input, "random input", -1, &status);

        utext_openUTF8(&pattern, ".*", -1, &status);
        REGEX_ASSERT(RegexPattern::matches(&pattern, &input, pe, status) == TRUE);
        REGEX_CHECK_STATUS;
        
        utext_openUTF8(&pattern, "abc", -1, &status);
        REGEX_ASSERT(RegexPattern::matches("abc", "random input", pe, status) == FALSE);
        REGEX_CHECK_STATUS;
        
        utext_openUTF8(&pattern, ".*nput", -1, &status);
        REGEX_ASSERT(RegexPattern::matches(".*nput", "random input", pe, status) == TRUE);
        REGEX_CHECK_STATUS;
        
        utext_openUTF8(&pattern, "random input", -1, &status);
        REGEX_ASSERT(RegexPattern::matches("random input", "random input", pe, status) == TRUE);
        REGEX_CHECK_STATUS;

        utext_openUTF8(&pattern, ".*u", -1, &status);
        REGEX_ASSERT(RegexPattern::matches(".*u", "random input", pe, status) == FALSE);
        REGEX_CHECK_STATUS;
        
        utext_openUTF8(&input, "abc", -1, &status);
        utext_openUTF8(&pattern, "abc", -1, &status);
        status = U_INDEX_OUTOFBOUNDS_ERROR;
        REGEX_ASSERT(RegexPattern::matches("abc", "abc", pe, status) == FALSE);
        REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);
        
        utext_close(&input);
        utext_close(&pattern);
    }


    //
    // Split()
    //
    status = U_ZERO_ERROR;
    utext_openUTF8(&re1, " +", -1, &status);
    pat1 = RegexPattern::compile(&re1, pe, status);
    REGEX_CHECK_STATUS;
    UnicodeString  fields[10];

    int32_t n;
    n = pat1->split("Now is the time", fields, 10, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==4);
    REGEX_ASSERT(fields[0]=="Now");
    REGEX_ASSERT(fields[1]=="is");
    REGEX_ASSERT(fields[2]=="the");
    REGEX_ASSERT(fields[3]=="time");
    REGEX_ASSERT(fields[4]=="");

    n = pat1->split("Now is the time", fields, 2, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==2);
    REGEX_ASSERT(fields[0]=="Now");
    REGEX_ASSERT(fields[1]=="is the time");
    REGEX_ASSERT(fields[2]=="the");   // left over from previous test

    fields[1] = "*";
    status = U_ZERO_ERROR;
    n = pat1->split("Now is the time", fields, 1, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==1);
    REGEX_ASSERT(fields[0]=="Now is the time");
    REGEX_ASSERT(fields[1]=="*");
    status = U_ZERO_ERROR;

    n = pat1->split("    Now       is the time   ", fields, 10, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==5);
    REGEX_ASSERT(fields[0]=="");
    REGEX_ASSERT(fields[1]=="Now");
    REGEX_ASSERT(fields[2]=="is");
    REGEX_ASSERT(fields[3]=="the");
    REGEX_ASSERT(fields[4]=="time");
    REGEX_ASSERT(fields[5]=="");

    n = pat1->split("     ", fields, 10, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==1);
    REGEX_ASSERT(fields[0]=="");

    fields[0] = "foo";
    n = pat1->split("", fields, 10, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==0);
    REGEX_ASSERT(fields[0]=="foo");

    delete pat1;

    //  split, with a pattern with (capture)
    utext_openUTF8(&re1, "<(\\w*)>", -1, &status);
    pat1 = RegexPattern::compile(&re1,  pe, status);
    REGEX_CHECK_STATUS;

    status = U_ZERO_ERROR;
    n = pat1->split("<a>Now is <b>the time<c>", fields, 10, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==6);
    REGEX_ASSERT(fields[0]=="");
    REGEX_ASSERT(fields[1]=="a");
    REGEX_ASSERT(fields[2]=="Now is ");
    REGEX_ASSERT(fields[3]=="b");
    REGEX_ASSERT(fields[4]=="the time");
    REGEX_ASSERT(fields[5]=="c");
    REGEX_ASSERT(fields[6]=="");
    REGEX_ASSERT(status==U_ZERO_ERROR);

    n = pat1->split("  <a>Now is <b>the time<c>", fields, 10, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==6);
    REGEX_ASSERT(fields[0]=="  ");
    REGEX_ASSERT(fields[1]=="a");
    REGEX_ASSERT(fields[2]=="Now is ");
    REGEX_ASSERT(fields[3]=="b");
    REGEX_ASSERT(fields[4]=="the time");
    REGEX_ASSERT(fields[5]=="c");
    REGEX_ASSERT(fields[6]=="");

    status = U_ZERO_ERROR;
    fields[6] = "foo";
    n = pat1->split("  <a>Now is <b>the time<c>", fields, 6, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==6);
    REGEX_ASSERT(fields[0]=="  ");
    REGEX_ASSERT(fields[1]=="a");
    REGEX_ASSERT(fields[2]=="Now is ");
    REGEX_ASSERT(fields[3]=="b");
    REGEX_ASSERT(fields[4]=="the time");
    REGEX_ASSERT(fields[5]=="c");
    REGEX_ASSERT(fields[6]=="foo");

    status = U_ZERO_ERROR;
    fields[5] = "foo";
    n = pat1->split("  <a>Now is <b>the time<c>", fields, 5, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==5);
    REGEX_ASSERT(fields[0]=="  ");
    REGEX_ASSERT(fields[1]=="a");
    REGEX_ASSERT(fields[2]=="Now is ");
    REGEX_ASSERT(fields[3]=="b");
    REGEX_ASSERT(fields[4]=="the time<c>");
    REGEX_ASSERT(fields[5]=="foo");

    status = U_ZERO_ERROR;
    fields[5] = "foo";
    n = pat1->split("  <a>Now is <b>the time", fields, 5, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==5);
    REGEX_ASSERT(fields[0]=="  ");
    REGEX_ASSERT(fields[1]=="a");
    REGEX_ASSERT(fields[2]=="Now is ");
    REGEX_ASSERT(fields[3]=="b");
    REGEX_ASSERT(fields[4]=="the time");
    REGEX_ASSERT(fields[5]=="foo");

    status = U_ZERO_ERROR;
    n = pat1->split("  <a>Now is <b>the time<c>", fields, 4, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==4);
    REGEX_ASSERT(fields[0]=="  ");
    REGEX_ASSERT(fields[1]=="a");
    REGEX_ASSERT(fields[2]=="Now is ");
    REGEX_ASSERT(fields[3]=="the time<c>");
    status = U_ZERO_ERROR;
    delete pat1;

    utext_openUTF8(&re1, "([-,])", -1, &status);
    pat1 = RegexPattern::compile(&re1, pe, status);
    REGEX_CHECK_STATUS;
    n = pat1->split("1-10,20", fields, 10, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(n==5);
    REGEX_ASSERT(fields[0]=="1");
    REGEX_ASSERT(fields[1]=="-");
    REGEX_ASSERT(fields[2]=="10");
    REGEX_ASSERT(fields[3]==",");
    REGEX_ASSERT(fields[4]=="20");
    delete pat1;


    //
    // RegexPattern::pattern() and patternText()
    //
    pat1 = new RegexPattern();
    REGEX_ASSERT(pat1->pattern() == "");
    REGEX_ASSERT_UTEXT("", pat1->patternText());
    delete pat1;

    utext_openUTF8(&re1, "(Hello, world)*", -1, &status);
    pat1 = RegexPattern::compile(&re1, pe, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(pat1->pattern() == "(Hello, world)*");
    REGEX_ASSERT_UTEXT("(Hello, world)*", pat1->patternText());
    delete pat1;

    utext_close(&re1);
}


//---------------------------------------------------------------------------
//
//      Extended       A more thorough check for features of regex patterns
//                     The test cases are in a separate data file,
//                       source/tests/testdata/regextst.txt
//                     A description of the test data format is included in that file.
//
//---------------------------------------------------------------------------

const char *
RegexTest::getPath(char buffer[2048], const char *filename) {
    UErrorCode status=U_ZERO_ERROR;
    const char *testDataDirectory = IntlTest::getSourceTestData(status);
    if (U_FAILURE(status)) {
        errln("ERROR: loadTestData() failed - %s", u_errorName(status));
        return NULL;
    }

    strcpy(buffer, testDataDirectory);
    strcat(buffer, filename);
    return buffer;
}

void RegexTest::Extended() {
    char tdd[2048];
    const char *srcPath;
    UErrorCode  status  = U_ZERO_ERROR;
    int32_t     lineNum = 0;

    //
    //  Open and read the test data file.
    //
    srcPath=getPath(tdd, "regextst.txt");
    if(srcPath==NULL) {
        return; /* something went wrong, error already output */
    }

    int32_t    len;
    UChar *testData = ReadAndConvertFile(srcPath, len, "utf-8", status);
    if (U_FAILURE(status)) {
        return; /* something went wrong, error already output */
    }

    //
    //  Put the test data into a UnicodeString
    //
    UnicodeString testString(FALSE, testData, len);

    RegexMatcher    quotedStuffMat(UNICODE_STRING_SIMPLE("\\s*([\\'\\\"/])(.*?)\\1"), 0, status);
    RegexMatcher    commentMat    (UNICODE_STRING_SIMPLE("\\s*(#.*)?$"), 0, status);
    RegexMatcher    flagsMat      (UNICODE_STRING_SIMPLE("\\s*([ixsmdteDEGLMvabtyYzZ2-9]*)([:letter:]*)"), 0, status);

    RegexMatcher    lineMat(UNICODE_STRING_SIMPLE("(.*?)\\r?\\n"), testString, 0, status);
    UnicodeString   testPattern;   // The pattern for test from the test file.
    UnicodeString   testFlags;     // the flags   for a test.
    UnicodeString   matchString;   // The marked up string to be used as input

    if (U_FAILURE(status)){
        dataerrln("Construct RegexMatcher() error.");
        delete [] testData;
        return;
    }

    //
    //  Loop over the test data file, once per line.
    //
    while (lineMat.find()) {
        lineNum++;
        if (U_FAILURE(status)) {
            errln("line %d: ICU Error \"%s\"", lineNum, u_errorName(status));
        }

        status = U_ZERO_ERROR;
        UnicodeString testLine = lineMat.group(1, status);
        if (testLine.length() == 0) {
            continue;
        }

        //
        // Parse the test line.  Skip blank and comment only lines.
        // Separate out the three main fields - pattern, flags, target.
        //

        commentMat.reset(testLine);
        if (commentMat.lookingAt(status)) {
            // This line is a comment, or blank.
            continue;
        }

        //
        //  Pull out the pattern field, remove it from the test file line.
        //
        quotedStuffMat.reset(testLine);
        if (quotedStuffMat.lookingAt(status)) {
            testPattern = quotedStuffMat.group(2, status);
            testLine.remove(0, quotedStuffMat.end(0, status));
        } else {
            errln("Bad pattern (missing quotes?) at test file line %d", lineNum);
            continue;
        }


        //
        //  Pull out the flags from the test file line.
        //
        flagsMat.reset(testLine);
        flagsMat.lookingAt(status);                  // Will always match, possibly an empty string.
        testFlags = flagsMat.group(1, status);
        if (flagsMat.group(2, status).length() > 0) {
            errln("Bad Match flag at line %d. Scanning %c\n",
                lineNum, flagsMat.group(2, status).charAt(0));
            continue;
        }
        testLine.remove(0, flagsMat.end(0, status));

        //
        //  Pull out the match string, as a whole.
        //    We'll process the <tags> later.
        //
        quotedStuffMat.reset(testLine);
        if (quotedStuffMat.lookingAt(status)) {
            matchString = quotedStuffMat.group(2, status);
            testLine.remove(0, quotedStuffMat.end(0, status));
        } else {
            errln("Bad match string at test file line %d", lineNum);
            continue;
        }

        //
        //  The only thing left from the input line should be an optional trailing comment.
        //
        commentMat.reset(testLine);
        if (commentMat.lookingAt(status) == FALSE) {
            errln("Line %d: unexpected characters at end of test line.", lineNum);
            continue;
        }

        //
        //  Run the test
        //
        regex_find(testPattern, testFlags, matchString, lineNum);
    }

    delete [] testData;

}


//---------------------------------------------------------------------------
//
//    regex_find(pattern, flags, inputString, lineNumber)
//
//         Function to run a single test from the Extended (data driven) tests.
//         See file test/testdata/regextst.txt for a description of the
//         pattern and inputString fields, and the allowed flags.
//         lineNumber is the source line in regextst.txt of the test.
//
//---------------------------------------------------------------------------


//  Set a value into a UVector at position specified by a decimal number in
//   a UnicodeString.   This is a utility function needed by the actual test function,
//   which follows.
static void set(UVector &vec, int32_t val, UnicodeString index) {
    UErrorCode  status=U_ZERO_ERROR;
    int32_t  idx = 0;
    for (int32_t i=0; i<index.length(); i++) {
        int32_t d=u_charDigitValue(index.charAt(i));
        if (d<0) {return;}
        idx = idx*10 + d;
    }
    while (vec.size()<idx+1) {vec.addElement(-1, status);}
    vec.setElementAt(val, idx);
}

void RegexTest::regex_find(const UnicodeString &pattern,
                           const UnicodeString &flags,
                           const UnicodeString &inputString,
                           int32_t line) {
    UnicodeString       unEscapedInput;
    UnicodeString       deTaggedInput;
    
    int32_t             patternUTF8Length,      inputUTF8Length;
    char                *patternChars  = NULL, *inputChars = NULL;
    UText               patternText    = UTEXT_INITIALIZER;
    UText               inputText      = UTEXT_INITIALIZER;
    UConverter          *UTF8Converter = NULL;

    UErrorCode          status         = U_ZERO_ERROR;
    UParseError         pe;
    RegexPattern        *parsePat      = NULL;
    RegexMatcher        *parseMatcher  = NULL;
    RegexPattern        *callerPattern = NULL, *UTF8Pattern = NULL;
    RegexMatcher        *matcher       = NULL, *UTF8Matcher = NULL;
    UVector             groupStarts(status);
    UVector             groupEnds(status);
    UBool               isMatch        = FALSE, isUTF8Match = FALSE;
    UBool               failed         = FALSE;
    int32_t             numFinds;
    int32_t             i;
    UBool               useMatchesFunc   = FALSE;
    UBool               useLookingAtFunc = FALSE;
    int32_t             regionStart      = -1;
    int32_t             regionEnd        = -1;

    //
    //  Compile the caller's pattern
    //
    uint32_t bflags = 0;
    if (flags.indexOf((UChar)0x69) >= 0)  { // 'i' flag
        bflags |= UREGEX_CASE_INSENSITIVE;
    }
    if (flags.indexOf((UChar)0x78) >= 0)  { // 'x' flag
        bflags |= UREGEX_COMMENTS;
    }
    if (flags.indexOf((UChar)0x73) >= 0)  { // 's' flag
        bflags |= UREGEX_DOTALL;
    }
    if (flags.indexOf((UChar)0x6d) >= 0)  { // 'm' flag
        bflags |= UREGEX_MULTILINE;
    }
    
    if (flags.indexOf((UChar)0x65) >= 0) { // 'e' flag
        bflags |= UREGEX_ERROR_ON_UNKNOWN_ESCAPES;
    }
    if (flags.indexOf((UChar)0x44) >= 0) { // 'D' flag
        bflags |= UREGEX_UNIX_LINES;
    }


    callerPattern = RegexPattern::compile(pattern, bflags, pe, status);
    if (status != U_ZERO_ERROR) {
        #if UCONFIG_NO_BREAK_ITERATION==1
        // 'v' test flag means that the test pattern should not compile if ICU was configured
        //     to not include break iteration.  RBBI is needed for Unicode word boundaries.
        if (flags.indexOf((UChar)0x76) >= 0 /*'v'*/ && status == U_UNSUPPORTED_ERROR) {
            goto cleanupAndReturn;
        }
        #endif
        if (flags.indexOf((UChar)0x45) >= 0) {  //  flags contain 'E'
            // Expected pattern compilation error.
            if (flags.indexOf((UChar)0x64) >= 0) {   // flags contain 'd'
                logln("Pattern Compile returns \"%s\"", u_errorName(status));
            }
            goto cleanupAndReturn;
        } else {
            // Unexpected pattern compilation error.
            errln("Line %d: error %s compiling pattern.", line, u_errorName(status));
            goto cleanupAndReturn;
        }
    }

    UTF8Converter = ucnv_open("UTF8", &status);
    ucnv_setFromUCallBack(UTF8Converter, UCNV_FROM_U_CALLBACK_STOP, NULL, NULL, NULL, &status);
    
    patternUTF8Length = pattern.extract(NULL, 0, UTF8Converter, status);
    status = U_ZERO_ERROR; // buffer overflow
    patternChars = new char[patternUTF8Length+1];
    pattern.extract(patternChars, patternUTF8Length+1, UTF8Converter, status);
    utext_openUTF8(&patternText, patternChars, patternUTF8Length, &status);
    
    if (status == U_ZERO_ERROR) {
        UTF8Pattern = RegexPattern::compile(&patternText, bflags, pe, status);
        
        if (status != U_ZERO_ERROR) {
#if UCONFIG_NO_BREAK_ITERATION==1
            // 'v' test flag means that the test pattern should not compile if ICU was configured
            //     to not include break iteration.  RBBI is needed for Unicode word boundaries.
            if (flags.indexOf((UChar)0x76) >= 0 /*'v'*/ && status == U_UNSUPPORTED_ERROR) {
                goto cleanupAndReturn;
            }
#endif
            if (flags.indexOf((UChar)0x45) >= 0) {  //  flags contain 'E'
                // Expected pattern compilation error.
                if (flags.indexOf((UChar)0x64) >= 0) {   // flags contain 'd'
                    logln("Pattern Compile returns \"%s\" (UTF8)", u_errorName(status));
                }
                goto cleanupAndReturn;
            } else {
                // Unexpected pattern compilation error.
                errln("Line %d: error %s compiling pattern. (UTF8)", line, u_errorName(status));
                goto cleanupAndReturn;
            }
        }
    }
    
    if (UTF8Pattern == NULL) {
        // UTF-8 does not allow unpaired surrogates, so this could actually happen without being a failure of the engine
        logln("Unable to create UTF-8 pattern, skipping UTF-8 tests for line %d", line);
        status = U_ZERO_ERROR;
    }

    if (flags.indexOf((UChar)0x64) >= 0) {  // 'd' flag
        RegexPatternDump(callerPattern);
    }

    if (flags.indexOf((UChar)0x45) >= 0) {  // 'E' flag
        errln("Expected, but did not get, a pattern compilation error.");
        goto cleanupAndReturn;
    }


    //
    // Number of times find() should be called on the test string, default to 1
    //
    numFinds = 1;
    for (i=2; i<=9; i++) {
        if (flags.indexOf((UChar)(0x30 + i)) >= 0) {   // digit flag
            if (numFinds != 1) {
                errln("Line %d: more than one digit flag.  Scanning %d.", line, i);
                goto cleanupAndReturn;
            }
            numFinds = i;
        }
    }
    
    // 'M' flag.  Use matches() instead of find()
    if (flags.indexOf((UChar)0x4d) >= 0) {
        useMatchesFunc = TRUE;
    }
    if (flags.indexOf((UChar)0x4c) >= 0) {
        useLookingAtFunc = TRUE;
    }

    //
    //  Find the tags in the input data, remove them, and record the group boundary
    //    positions.
    //
    parsePat = RegexPattern::compile("<(/?)(r|[0-9]+)>", 0, pe, status);
    REGEX_CHECK_STATUS_L(line);

    unEscapedInput = inputString.unescape();
    parseMatcher = parsePat->matcher(unEscapedInput, status);
    REGEX_CHECK_STATUS_L(line);
    while(parseMatcher->find()) {
        parseMatcher->appendReplacement(deTaggedInput, "", status);
        REGEX_CHECK_STATUS;
        UnicodeString groupNum = parseMatcher->group(2, status);
        if (groupNum == "r") {
            // <r> or </r>, a region specification within the string
            if (parseMatcher->group(1, status) == "/") {
                regionEnd = deTaggedInput.length();
            } else {
                regionStart = deTaggedInput.length();
            }
        } else {
            // <digits> or </digits>, a group match boundary tag.
            if (parseMatcher->group(1, status) == "/") {
                set(groupEnds, deTaggedInput.length(), groupNum);
            } else {
                set(groupStarts, deTaggedInput.length(), groupNum);
            }
        }
    }
    parseMatcher->appendTail(deTaggedInput);
    REGEX_ASSERT_L(groupStarts.size() == groupEnds.size(), line);
    if ((regionStart>=0 || regionEnd>=0) && (regionStart<0 || regionStart>regionEnd)) {
      errln("mismatched <r> tags");
      failed = TRUE;
      goto cleanupAndReturn;
    }


    //
    //  Configure the matcher according to the flags specified with this test.
    //
    matcher = callerPattern->matcher(deTaggedInput, status);
    REGEX_CHECK_STATUS_L(line);
    if (flags.indexOf((UChar)0x74) >= 0) {   //  't' trace flag
        matcher->setTrace(TRUE);
    }
    
    if (UTF8Pattern != NULL) {
        inputUTF8Length = deTaggedInput.extract(NULL, 0, UTF8Converter, status);
        status = U_ZERO_ERROR; // buffer overflow
        inputChars = new char[inputUTF8Length+1];
        deTaggedInput.extract(inputChars, inputUTF8Length+1, UTF8Converter, status);
        utext_openUTF8(&inputText, inputChars, inputUTF8Length, &status);

        if (status == U_ZERO_ERROR) {
            UTF8Matcher = UTF8Pattern->matcher(&inputText, RegexPattern::PATTERN_IS_UTEXT, status);
            REGEX_CHECK_STATUS_L(line);
        }
        
        if (UTF8Matcher == NULL) {
            // UTF-8 does not allow unpaired surrogates, so this could actually happen without being a failure of the engine
            logln("Unable to create UTF-8 matcher, skipping UTF-8 tests for line %d", line);
            status = U_ZERO_ERROR;
        }
    }

    if (regionStart>=0) {
       matcher->region(regionStart, regionEnd, status);
       REGEX_CHECK_STATUS_L(line);
       if (UTF8Matcher != NULL) {
           UTF8Matcher->region(regionStart, regionEnd, status);
           REGEX_CHECK_STATUS_L(line);
       }
    }
    if (flags.indexOf((UChar)0x61) >= 0) {   //  'a' anchoring bounds flag
        matcher->useAnchoringBounds(FALSE);
        if (UTF8Matcher != NULL) {
            UTF8Matcher->useAnchoringBounds(FALSE);
        }
    }
    if (flags.indexOf((UChar)0x62) >= 0) {   //  'b' transparent bounds flag
        matcher->useTransparentBounds(TRUE);
        if (UTF8Matcher != NULL) {
            UTF8Matcher->useTransparentBounds(TRUE);
        }
    }
    
    
    //
    // Do a find on the de-tagged input using the caller's pattern
    //     TODO: error on count>1 and not find().
    //           error on both matches() and lookingAt().
    //
    for (i=0; i<numFinds; i++) {
        if (useMatchesFunc) {
            isMatch = matcher->matches(status);
            if (UTF8Matcher != NULL) {
               isUTF8Match = UTF8Matcher->matches(status);
            }
        } else  if (useLookingAtFunc) {
            isMatch = matcher->lookingAt(status);
            if (UTF8Matcher != NULL) {
                isUTF8Match = UTF8Matcher->lookingAt(status);
            }
        } else {
            isMatch = matcher->find();
            if (UTF8Matcher != NULL) {
                isUTF8Match = UTF8Matcher->find();
            }
        }
    }
    matcher->setTrace(FALSE);

    //
    // Match up the groups from the find() with the groups from the tags
    //

    // number of tags should match number of groups from find operation.
    // matcher->groupCount does not include group 0, the entire match, hence the +1.
    //   G option in test means that capture group data is not available in the
    //     expected results, so the check needs to be suppressed.
    if (isMatch == FALSE && groupStarts.size() != 0) {
        errln("Error at line %d:  Match expected, but none found.", line);
        failed = TRUE;
        goto cleanupAndReturn;
    } else if (UTF8Matcher != NULL && isUTF8Match == FALSE && groupStarts.size() != 0) {
        errln("Error at line %d:  Match expected, but none found. (UTF8)", line);
        failed = TRUE;
        goto cleanupAndReturn;
    }

    if (flags.indexOf((UChar)0x47 /*G*/) >= 0) {
        // Only check for match / no match.  Don't check capture groups.
        if (isMatch && groupStarts.size() == 0) {
            errln("Error at line %d:  No match expected, but one found.", line);
            failed = TRUE;
        } else if (UTF8Matcher != NULL && isUTF8Match && groupStarts.size() == 0) {
            errln("Error at line %d:  No match expected, but one found. (UTF8)", line);
            failed = TRUE;
        }
        goto cleanupAndReturn;
    }

    REGEX_CHECK_STATUS_L(line);
    for (i=0; i<=matcher->groupCount(); i++) {
        int32_t  expectedStart = (i >= groupStarts.size()? -1 : groupStarts.elementAti(i));
        if (matcher->start(i, status) != expectedStart) {
            errln("Error at line %d: incorrect start position for group %d.  Expected %d, got %d",
                line, i, expectedStart, matcher->start(i, status));
            failed = TRUE;
            goto cleanupAndReturn;  // Good chance of subsequent bogus errors.  Stop now.
        } else if (UTF8Matcher != NULL && UTF8Matcher->start(i, status) != expectedStart) {
            errln("Error at line %d: incorrect start position for group %d.  Expected %d, got %d (UTF8)",
                  line, i, expectedStart, UTF8Matcher->start(i, status));
            failed = TRUE;
            goto cleanupAndReturn;  // Good chance of subsequent bogus errors.  Stop now.
        }
        
        int32_t  expectedEnd = (i >= groupEnds.size()? -1 : groupEnds.elementAti(i));
        if (matcher->end(i, status) != expectedEnd) {
            errln("Error at line %d: incorrect end position for group %d.  Expected %d, got %d",
                line, i, expectedEnd, matcher->end(i, status));
            failed = TRUE;
            // Error on end position;  keep going; real error is probably yet to come as group
            //   end positions work from end of the input data towards the front.
        } else if (UTF8Matcher != NULL && UTF8Matcher->end(i, status) != expectedEnd) {
            errln("Error at line %d: incorrect end position for group %d.  Expected %d, got %d (UTF8)",
                  line, i, expectedEnd, UTF8Matcher->end(i, status));
            failed = TRUE;
            // Error on end position;  keep going; real error is probably yet to come as group
            //   end positions work from end of the input data towards the front.
        }
    }
    if ( matcher->groupCount()+1 < groupStarts.size()) {
        errln("Error at line %d: Expected %d capture groups, found %d.",
            line, groupStarts.size()-1, matcher->groupCount());
        failed = TRUE;
        }
    else if (UTF8Matcher != NULL && UTF8Matcher->groupCount()+1 < groupStarts.size()) {
        errln("Error at line %d: Expected %d capture groups, found %d. (UTF8)",
              line, groupStarts.size()-1, UTF8Matcher->groupCount());
        failed = TRUE;
    }

    if ((flags.indexOf((UChar)0x59) >= 0) &&   //  'Y' flag:  RequireEnd() == false
        matcher->requireEnd() == TRUE) {
        errln("Error at line %d: requireEnd() returned TRUE.  Expected FALSE", line);
        failed = TRUE;
    } else if (UTF8Matcher != NULL && (flags.indexOf((UChar)0x59) >= 0) &&   //  'Y' flag:  RequireEnd() == false
        UTF8Matcher->requireEnd() == TRUE) {
        errln("Error at line %d: requireEnd() returned TRUE.  Expected FALSE (UTF8)", line);
        failed = TRUE;
    }
    
    if ((flags.indexOf((UChar)0x79) >= 0) &&   //  'y' flag:  RequireEnd() == true
        matcher->requireEnd() == FALSE) {
        errln("Error at line %d: requireEnd() returned FALSE.  Expected TRUE", line);
        failed = TRUE;
    } else if (UTF8Matcher != NULL && (flags.indexOf((UChar)0x79) >= 0) &&   //  'Y' flag:  RequireEnd() == false
        UTF8Matcher->requireEnd() == FALSE) {
        errln("Error at line %d: requireEnd() returned FALSE.  Expected TRUE (UTF8)", line);
        failed = TRUE;
    }
    
    if ((flags.indexOf((UChar)0x5A) >= 0) &&   //  'Z' flag:  hitEnd() == false
        matcher->hitEnd() == TRUE) {
        errln("Error at line %d: hitEnd() returned TRUE.  Expected FALSE", line);
        failed = TRUE;
    } else if (UTF8Matcher != NULL && (flags.indexOf((UChar)0x5A) >= 0) &&   //  'Z' flag:  hitEnd() == false
               UTF8Matcher->hitEnd() == TRUE) {
        errln("Error at line %d: hitEnd() returned TRUE.  Expected FALSE (UTF8)", line);
        failed = TRUE;
    }
    
    if ((flags.indexOf((UChar)0x7A) >= 0) &&   //  'z' flag:  hitEnd() == true
        matcher->hitEnd() == FALSE) {
        errln("Error at line %d: hitEnd() returned FALSE.  Expected TRUE", line);
        failed = TRUE;
    } else if (UTF8Matcher != NULL && (flags.indexOf((UChar)0x7A) >= 0) &&   //  'z' flag:  hitEnd() == true
               UTF8Matcher->hitEnd() == FALSE) {
        errln("Error at line %d: hitEnd() returned FALSE.  Expected TRUE (UTF8)", line);
        failed = TRUE;
    }


cleanupAndReturn:
    if (failed) {
        infoln((UnicodeString)"\""+pattern+(UnicodeString)"\"  "
            +flags+(UnicodeString)"  \""+inputString+(UnicodeString)"\"");
        // callerPattern->dump();
    }
    delete parseMatcher;
    delete parsePat;
    delete UTF8Matcher;
    delete UTF8Pattern;
    delete matcher;
    delete callerPattern;
    
    utext_close(&inputText);
    delete[] inputChars;
    utext_close(&patternText);
    delete[] patternChars;
    ucnv_close(UTF8Converter);
}


//---------------------------------------------------------------------------
//
//      Errors     Check for error handling in patterns.
//
//---------------------------------------------------------------------------
void RegexTest::Errors() {
    // \escape sequences that aren't implemented yet.
    //REGEX_ERR("hex format \\x{abcd} not implemented", 1, 13, U_REGEX_UNIMPLEMENTED);

    // Missing close parentheses
    REGEX_ERR("Comment (?# with no close", 1, 25, U_REGEX_MISMATCHED_PAREN);
    REGEX_ERR("Capturing Parenthesis(...", 1, 25, U_REGEX_MISMATCHED_PAREN);
    REGEX_ERR("Grouping only parens (?: blah blah", 1, 34, U_REGEX_MISMATCHED_PAREN);

    // Extra close paren
    REGEX_ERR("Grouping only parens (?: blah)) blah", 1, 31, U_REGEX_MISMATCHED_PAREN);
    REGEX_ERR(")))))))", 1, 1, U_REGEX_MISMATCHED_PAREN);
    REGEX_ERR("(((((((", 1, 7, U_REGEX_MISMATCHED_PAREN);

    // Look-ahead, Look-behind
    //  TODO:  add tests for unbounded length look-behinds.
    REGEX_ERR("abc(?<@xyz).*", 1, 7, U_REGEX_RULE_SYNTAX);       // illegal construct

    // Attempt to use non-default flags
    {
        UParseError   pe;
        UErrorCode    status = U_ZERO_ERROR;
        int32_t       flags  = UREGEX_CANON_EQ |
                               UREGEX_COMMENTS         | UREGEX_DOTALL   |
                               UREGEX_MULTILINE;
        RegexPattern *pat1= RegexPattern::compile(".*", flags, pe, status);
        REGEX_ASSERT(status == U_REGEX_UNIMPLEMENTED);
        delete pat1;
    }


    // Quantifiers are allowed only after something that can be quantified.
    REGEX_ERR("+", 1, 1, U_REGEX_RULE_SYNTAX);
    REGEX_ERR("abc\ndef(*2)", 2, 5, U_REGEX_RULE_SYNTAX);
    REGEX_ERR("abc**", 1, 5, U_REGEX_RULE_SYNTAX);

    // Mal-formed {min,max} quantifiers
    REGEX_ERR("abc{a,2}",1,5, U_REGEX_BAD_INTERVAL);
    REGEX_ERR("abc{4,2}",1,8, U_REGEX_MAX_LT_MIN);
    REGEX_ERR("abc{1,b}",1,7, U_REGEX_BAD_INTERVAL);
    REGEX_ERR("abc{1,,2}",1,7, U_REGEX_BAD_INTERVAL);
    REGEX_ERR("abc{1,2a}",1,8, U_REGEX_BAD_INTERVAL);
    REGEX_ERR("abc{222222222222222222222}",1,14, U_REGEX_NUMBER_TOO_BIG);
    REGEX_ERR("abc{5,50000000000}", 1, 17, U_REGEX_NUMBER_TOO_BIG);        // Overflows int during scan
    REGEX_ERR("abc{5,687865858}", 1, 16, U_REGEX_NUMBER_TOO_BIG);          // Overflows regex binary format
    REGEX_ERR("abc{687865858,687865859}", 1, 24, U_REGEX_NUMBER_TOO_BIG);

    // Ticket 5389
    REGEX_ERR("*c", 1, 1, U_REGEX_RULE_SYNTAX);

    // Invalid Back Reference \0
    //    For ICU 3.8 and earlier
    //    For ICU versions newer than 3.8, \0 introduces an octal escape.
    //
    REGEX_ERR("(ab)\\0", 1, 6, U_REGEX_BAD_ESCAPE_SEQUENCE);

}


//-------------------------------------------------------------------------------
//      
//  Read a text data file, convert it to UChars, and return the data
//    in one big UChar * buffer, which the caller must delete.
//
//--------------------------------------------------------------------------------
UChar *RegexTest::ReadAndConvertFile(const char *fileName, int32_t &ulen,
                                     const char *defEncoding, UErrorCode &status) {
    UChar       *retPtr  = NULL;
    char        *fileBuf = NULL;
    UConverter* conv     = NULL;
    FILE        *f       = NULL;

    ulen = 0;
    if (U_FAILURE(status)) {
        return retPtr;
    }

    //
    //  Open the file.
    //
    f = fopen(fileName, "rb");
    if (f == 0) {
        dataerrln("Error opening test data file %s\n", fileName);
        status = U_FILE_ACCESS_ERROR;
        return NULL;
    }
    //
    //  Read it in
    //
    int32_t            fileSize;
    int32_t            amt_read;

    fseek( f, 0, SEEK_END);
    fileSize = ftell(f);
    fileBuf = new char[fileSize];
    fseek(f, 0, SEEK_SET);
    amt_read = fread(fileBuf, 1, fileSize, f);
    if (amt_read != fileSize || fileSize <= 0) {
        errln("Error reading test data file.");
        goto cleanUpAndReturn;
    }

    //
    // Look for a Unicode Signature (BOM) on the data just read
    //
    int32_t        signatureLength;
    const char *   fileBufC;
    const char*    encoding;

    fileBufC = fileBuf;
    encoding = ucnv_detectUnicodeSignature(
        fileBuf, fileSize, &signatureLength, &status);
    if(encoding!=NULL ){
        fileBufC  += signatureLength;
        fileSize  -= signatureLength;
    } else {
        encoding = defEncoding;
        if (strcmp(encoding, "utf-8") == 0) {
            errln("file %s is missing its BOM", fileName);
        }
    }

    //
    // Open a converter to take the rule file to UTF-16
    //
    conv = ucnv_open(encoding, &status);
    if (U_FAILURE(status)) {
        goto cleanUpAndReturn;
    }

    //
    // Convert the rules to UChar.
    //  Preflight first to determine required buffer size.
    //
    ulen = ucnv_toUChars(conv,
        NULL,           //  dest,
        0,              //  destCapacity,
        fileBufC,
        fileSize,
        &status);
    if (status == U_BUFFER_OVERFLOW_ERROR) {
        // Buffer Overflow is expected from the preflight operation.
        status = U_ZERO_ERROR;

        retPtr = new UChar[ulen+1];
        ucnv_toUChars(conv,
            retPtr,       //  dest,
            ulen+1,
            fileBufC,
            fileSize,
            &status);
    }

cleanUpAndReturn:
    fclose(f);
    delete[] fileBuf;
    ucnv_close(conv);
    if (U_FAILURE(status)) {
        errln("ucnv_toUChars: ICU Error \"%s\"\n", u_errorName(status));
        delete retPtr;
        retPtr = 0;
        ulen   = 0;
    };
    return retPtr;
}


//-------------------------------------------------------------------------------
//
//   PerlTests  - Run Perl's regular expression tests
//                The input file for this test is re_tests, the standard regular
//                expression test data distributed with the Perl source code.
//
//                Here is Perl's description of the test data file:
//
//        # The tests are in a separate file 't/op/re_tests'.
//        # Each line in that file is a separate test.
//        # There are five columns, separated by tabs.
//        #
//        # Column 1 contains the pattern, optionally enclosed in C<''>.
//        # Modifiers can be put after the closing C<'>.
//        #
//        # Column 2 contains the string to be matched.
//        #
//        # Column 3 contains the expected result:
//        #     y   expect a match
//        #     n   expect no match
//        #     c   expect an error
//        # B   test exposes a known bug in Perl, should be skipped
//        # b   test exposes a known bug in Perl, should be skipped if noamp
//        #
//        # Columns 4 and 5 are used only if column 3 contains C<y> or C<c>.
//        #
//        # Column 4 contains a string, usually C<$&>.
//        #
//        # Column 5 contains the expected result of double-quote
//        # interpolating that string after the match, or start of error message.
//        #
//        # Column 6, if present, contains a reason why the test is skipped.
//        # This is printed with "skipped", for harness to pick up.
//        #
//        # \n in the tests are interpolated, as are variables of the form ${\w+}.
//        #
//        # If you want to add a regular expression test that can't be expressed
//        # in this format, don't add it here: put it in op/pat.t instead.
//
//        For ICU, if field 3 contains an 'i', the test will be skipped.
//        The test exposes is some known incompatibility between ICU and Perl regexps.
//        (The i is in addition to whatever was there before.)
//
//-------------------------------------------------------------------------------
void RegexTest::PerlTests() {
    char tdd[2048];
    const char *srcPath;
    UErrorCode  status = U_ZERO_ERROR;
    UParseError pe;

    //
    //  Open and read the test data file.
    //
    srcPath=getPath(tdd, "re_tests.txt");
    if(srcPath==NULL) {
        return; /* something went wrong, error already output */
    }

    int32_t    len;
    UChar *testData = ReadAndConvertFile(srcPath, len, "iso-8859-1", status);
    if (U_FAILURE(status)) {
        return; /* something went wrong, error already output */
    }

    //
    //  Put the test data into a UnicodeString
    //
    UnicodeString testDataString(FALSE, testData, len);

    //
    //  Regex to break the input file into lines, and strip the new lines.
    //     One line per match, capture group one is the desired data.
    //
    RegexPattern* linePat = RegexPattern::compile(UNICODE_STRING_SIMPLE("(.+?)[\\r\\n]+"), 0, pe, status);
    if (U_FAILURE(status)) {
        dataerrln("RegexPattern::compile() error");
        return;
    }
    RegexMatcher* lineMat = linePat->matcher(testDataString, status);

    //
    //  Regex to split a test file line into fields.
    //    There are six fields, separated by tabs.
    //
    RegexPattern* fieldPat = RegexPattern::compile(UNICODE_STRING_SIMPLE("\\t"), 0, pe, status);

    //
    //  Regex to identify test patterns with flag settings, and to separate them.
    //    Test patterns with flags look like 'pattern'i
    //    Test patterns without flags are not quoted:   pattern
    //   Coming out, capture group 2 is the pattern, capture group 3 is the flags.
    //
    RegexPattern *flagPat = RegexPattern::compile(UNICODE_STRING_SIMPLE("('?)(.*)\\1(.*)"), 0, pe, status);
    RegexMatcher* flagMat = flagPat->matcher(status);

    //
    // The Perl tests reference several perl-isms, which are evaluated/substituted
    //   in the test data.  Not being perl, this must be done explicitly.  Here
    //   are string constants and REs for these constructs.
    //
    UnicodeString nulnulSrc("${nulnul}");
    UnicodeString nulnul("\\u0000\\u0000", -1, US_INV);
    nulnul = nulnul.unescape();

    UnicodeString ffffSrc("${ffff}");
    UnicodeString ffff("\\uffff", -1, US_INV);
    ffff = ffff.unescape();

    //  regexp for $-[0], $+[2], etc.
    RegexPattern *groupsPat = RegexPattern::compile(UNICODE_STRING_SIMPLE("\\$([+\\-])\\[(\\d+)\\]"), 0, pe, status);
    RegexMatcher *groupsMat = groupsPat->matcher(status);

    //  regexp for $0, $1, $2, etc.
    RegexPattern *cgPat = RegexPattern::compile(UNICODE_STRING_SIMPLE("\\$(\\d+)"), 0, pe, status);
    RegexMatcher *cgMat = cgPat->matcher(status);


    //
    // Main Loop for the Perl Tests, runs once per line from the
    //   test data file.
    //
    int32_t  lineNum = 0;
    int32_t  skippedUnimplementedCount = 0;
    while (lineMat->find()) {
        lineNum++;

        //
        //  Get a line, break it into its fields, do the Perl
        //    variable substitutions.
        //
        UnicodeString line = lineMat->group(1, status);
        UnicodeString fields[7];
        fieldPat->split(line, fields, 7, status);

        flagMat->reset(fields[0]);
        flagMat->matches(status);
        UnicodeString pattern  = flagMat->group(2, status);
        pattern.findAndReplace("${bang}", "!");
        pattern.findAndReplace(nulnulSrc, UNICODE_STRING_SIMPLE("\\u0000\\u0000"));
        pattern.findAndReplace(ffffSrc, ffff);

        //
        //  Identify patterns that include match flag settings,
        //    split off the flags, remove the extra quotes.
        //
        UnicodeString flagStr = flagMat->group(3, status);
        if (U_FAILURE(status)) {
            errln("ucnv_toUChars: ICU Error \"%s\"\n", u_errorName(status));
            return;
        }
        int32_t flags = 0;
        const UChar UChar_c = 0x63;  // Char constants for the flag letters.
        const UChar UChar_i = 0x69;  //   (Damn the lack of Unicode support in C)
        const UChar UChar_m = 0x6d;
        const UChar UChar_x = 0x78;
        const UChar UChar_y = 0x79;
        if (flagStr.indexOf(UChar_i) != -1) {
            flags |= UREGEX_CASE_INSENSITIVE;
        }
        if (flagStr.indexOf(UChar_m) != -1) {
            flags |= UREGEX_MULTILINE;
        }
        if (flagStr.indexOf(UChar_x) != -1) {
            flags |= UREGEX_COMMENTS;
        }

        //
        // Compile the test pattern.
        //
        status = U_ZERO_ERROR;
        RegexPattern *testPat = RegexPattern::compile(pattern, flags, pe, status);
        if (status == U_REGEX_UNIMPLEMENTED) {
            //
            // Test of a feature that is planned for ICU, but not yet implemented.
            //   skip the test.
            skippedUnimplementedCount++;
            delete testPat;
            status = U_ZERO_ERROR;
            continue;
        }

        if (U_FAILURE(status)) {
            // Some tests are supposed to generate errors.
            //   Only report an error for tests that are supposed to succeed.
            if (fields[2].indexOf(UChar_c) == -1  &&  // Compilation is not supposed to fail AND
                fields[2].indexOf(UChar_i) == -1)     //   it's not an accepted ICU incompatibility
            {
                errln("line %d: ICU Error \"%s\"\n", lineNum, u_errorName(status));
            }
            status = U_ZERO_ERROR;
            delete testPat;
            continue;
        }

        if (fields[2].indexOf(UChar_i) >= 0) {
            // ICU should skip this test.
            delete testPat;
            continue;
        }

        if (fields[2].indexOf(UChar_c) >= 0) {
            // This pattern should have caused a compilation error, but didn't/
            errln("line %d: Expected a pattern compile error, got success.", lineNum);
            delete testPat;
            continue;
        }

        //
        // replace the Perl variables that appear in some of the
        //   match data strings.
        //
        UnicodeString matchString = fields[1];
        matchString.findAndReplace(nulnulSrc, nulnul);
        matchString.findAndReplace(ffffSrc,   ffff);

        // Replace any \n in the match string with an actual new-line char.
        //  Don't do full unescape, as this unescapes more than Perl does, which
        //  causes other spurious failures in the tests.
        matchString.findAndReplace(UNICODE_STRING_SIMPLE("\\n"), "\n");


        //
        // Run the test, check for expected match/don't match result.
        //
        RegexMatcher *testMat = testPat->matcher(matchString, status);
        UBool found = testMat->find();
        UBool expected = FALSE;
        if (fields[2].indexOf(UChar_y) >=0) {
            expected = TRUE;
        }
        if (expected != found) {
            errln("line %d: Expected %smatch, got %smatch",
                lineNum, expected?"":"no ", found?"":"no " );
            continue;
        }
        
        // Don't try to check expected results if there is no match.
        //   (Some have stuff in the expected fields)
        if (!found) {
            delete testMat;
            delete testPat;
            continue;
        }

        //
        // Interpret the Perl expression from the fourth field of the data file,
        // building up an ICU string from the results of the ICU match.
        //   The Perl expression will contain references to the results of
        //     a regex match, including the matched string, capture group strings,
        //     group starting and ending indicies, etc.
        //
        UnicodeString resultString;
        UnicodeString perlExpr = fields[3];
#if SUPPORT_MUTATING_INPUT_STRING
        groupsMat->reset(perlExpr);
        cgMat->reset(perlExpr);
#endif

        while (perlExpr.length() > 0) {
#if !SUPPORT_MUTATING_INPUT_STRING
            //  Perferred usage.  Reset after any modification to input string.
            groupsMat->reset(perlExpr);
            cgMat->reset(perlExpr);
#endif

            if (perlExpr.startsWith("$&")) {
                resultString.append(testMat->group(status));
                perlExpr.remove(0, 2);
            }

            else if (groupsMat->lookingAt(status)) {
                // $-[0]   $+[2]  etc.
                UnicodeString digitString = groupsMat->group(2, status);
                int32_t t = 0;
                int32_t groupNum = ICU_Utility::parseNumber(digitString, t, 10);
                UnicodeString plusOrMinus = groupsMat->group(1, status);
                int32_t matchPosition;
                if (plusOrMinus.compare("+") == 0) {
                    matchPosition = testMat->end(groupNum, status);
                } else {
                    matchPosition = testMat->start(groupNum, status);
                }
                if (matchPosition != -1) {
                    ICU_Utility::appendNumber(resultString, matchPosition);
                }
                perlExpr.remove(0, groupsMat->end(status));
            }

            else if (cgMat->lookingAt(status)) {
                // $1, $2, $3, etc.
                UnicodeString digitString = cgMat->group(1, status);
                int32_t t = 0;
                int32_t groupNum = ICU_Utility::parseNumber(digitString, t, 10);
                if (U_SUCCESS(status)) {
                    resultString.append(testMat->group(groupNum, status));
                    status = U_ZERO_ERROR;
                }
                perlExpr.remove(0, cgMat->end(status));
            }

            else if (perlExpr.startsWith("@-")) {
                int32_t i;
                for (i=0; i<=testMat->groupCount(); i++) {
                    if (i>0) {
                        resultString.append(" ");
                    }
                    ICU_Utility::appendNumber(resultString, testMat->start(i, status));
                }
                perlExpr.remove(0, 2);
            }

            else if (perlExpr.startsWith("@+")) {
                int32_t i;
                for (i=0; i<=testMat->groupCount(); i++) {
                    if (i>0) {
                        resultString.append(" ");
                    }
                    ICU_Utility::appendNumber(resultString, testMat->end(i, status));
                }
                perlExpr.remove(0, 2);
            }

            else if (perlExpr.startsWith(UNICODE_STRING_SIMPLE("\\"))) {    // \Escape.  Take following char as a literal.
                                                     //           or as an escaped sequence (e.g. \n)
                if (perlExpr.length() > 1) {
                    perlExpr.remove(0, 1);  // Remove the '\', but only if not last char.
                }
                UChar c = perlExpr.charAt(0);
                switch (c) {
                case 'n':   c = '\n'; break;
                // add any other escape sequences that show up in the test expected results.
                }
                resultString.append(c);
                perlExpr.remove(0, 1);
            }

            else  {
                // Any characters from the perl expression that we don't explicitly
                //  recognize before here are assumed to be literals and copied
                //  as-is to the expected results.
                resultString.append(perlExpr.charAt(0));
                perlExpr.remove(0, 1);
            }

            if (U_FAILURE(status)) {
                errln("Line %d: ICU Error \"%s\"", lineNum, u_errorName(status));
                break;
            }
        }

        //
        // Expected Results Compare
        //
        UnicodeString expectedS(fields[4]);
        expectedS.findAndReplace(nulnulSrc, nulnul);
        expectedS.findAndReplace(ffffSrc,   ffff);
        expectedS.findAndReplace(UNICODE_STRING_SIMPLE("\\n"), "\n");


        if (expectedS.compare(resultString) != 0) {
            err("Line %d: Incorrect perl expression results.", lineNum);
            infoln((UnicodeString)"Expected \""+expectedS+(UnicodeString)"\"; got \""+resultString+(UnicodeString)"\"");
        }

        delete testMat;
        delete testPat;
    }

    //
    // All done.  Clean up allocated stuff.
    //
    delete cgMat;
    delete cgPat;

    delete groupsMat;
    delete groupsPat;

    delete flagMat;
    delete flagPat;

    delete lineMat;
    delete linePat;

    delete fieldPat;
    delete [] testData;


    logln("%d tests skipped because of unimplemented regexp features.", skippedUnimplementedCount);

}


//-------------------------------------------------------------------------------
//
//   PerlTestsUTF8  Run Perl's regular expression tests on UTF-8-based UTexts
//                  (instead of using UnicodeStrings) to test the alternate engine.
//                  The input file for this test is re_tests, the standard regular
//                  expression test data distributed with the Perl source code.
//                  See PerlTests() for more information.
//
//-------------------------------------------------------------------------------
void RegexTest::PerlTestsUTF8() {
    char tdd[2048];
    const char *srcPath;
    UErrorCode  status = U_ZERO_ERROR;
    UParseError pe;
    LocalUConverterPointer UTF8Converter(ucnv_open("UTF-8", &status));
    UText       patternText = UTEXT_INITIALIZER;
    char       *patternChars = NULL;
    int32_t     patternLength;
    int32_t     patternCapacity = 0;
    UText       inputText = UTEXT_INITIALIZER;
    char       *inputChars = NULL;
    int32_t     inputLength;
    int32_t     inputCapacity = 0;

    ucnv_setFromUCallBack(UTF8Converter.getAlias(), UCNV_FROM_U_CALLBACK_STOP, NULL, NULL, NULL, &status);

    //
    //  Open and read the test data file.
    //
    srcPath=getPath(tdd, "re_tests.txt");
    if(srcPath==NULL) {
        return; /* something went wrong, error already output */
    }

    int32_t    len;
    UChar *testData = ReadAndConvertFile(srcPath, len, "iso-8859-1", status);
    if (U_FAILURE(status)) {
        return; /* something went wrong, error already output */
    }

    //
    //  Put the test data into a UnicodeString
    //
    UnicodeString testDataString(FALSE, testData, len);

    //
    //  Regex to break the input file into lines, and strip the new lines.
    //     One line per match, capture group one is the desired data.
    //
    RegexPattern* linePat = RegexPattern::compile(UNICODE_STRING_SIMPLE("(.+?)[\\r\\n]+"), 0, pe, status);
    if (U_FAILURE(status)) {
        dataerrln("RegexPattern::compile() error");
        return;
    }
    RegexMatcher* lineMat = linePat->matcher(testDataString, status);

    //
    //  Regex to split a test file line into fields.
    //    There are six fields, separated by tabs.
    //
    RegexPattern* fieldPat = RegexPattern::compile(UNICODE_STRING_SIMPLE("\\t"), 0, pe, status);

    //
    //  Regex to identify test patterns with flag settings, and to separate them.
    //    Test patterns with flags look like 'pattern'i
    //    Test patterns without flags are not quoted:   pattern
    //   Coming out, capture group 2 is the pattern, capture group 3 is the flags.
    //
    RegexPattern *flagPat = RegexPattern::compile(UNICODE_STRING_SIMPLE("('?)(.*)\\1(.*)"), 0, pe, status);
    RegexMatcher* flagMat = flagPat->matcher(status);

    //
    // The Perl tests reference several perl-isms, which are evaluated/substituted
    //   in the test data.  Not being perl, this must be done explicitly.  Here
    //   are string constants and REs for these constructs.
    //
    UnicodeString nulnulSrc("${nulnul}");
    UnicodeString nulnul("\\u0000\\u0000", -1, US_INV);
    nulnul = nulnul.unescape();

    UnicodeString ffffSrc("${ffff}");
    UnicodeString ffff("\\uffff", -1, US_INV);
    ffff = ffff.unescape();

    //  regexp for $-[0], $+[2], etc.
    RegexPattern *groupsPat = RegexPattern::compile(UNICODE_STRING_SIMPLE("\\$([+\\-])\\[(\\d+)\\]"), 0, pe, status);
    RegexMatcher *groupsMat = groupsPat->matcher(status);

    //  regexp for $0, $1, $2, etc.
    RegexPattern *cgPat = RegexPattern::compile(UNICODE_STRING_SIMPLE("\\$(\\d+)"), 0, pe, status);
    RegexMatcher *cgMat = cgPat->matcher(status);


    //
    // Main Loop for the Perl Tests, runs once per line from the
    //   test data file.
    //
    int32_t  lineNum = 0;
    int32_t  skippedUnimplementedCount = 0;
    while (lineMat->find()) {
        lineNum++;

        //
        //  Get a line, break it into its fields, do the Perl
        //    variable substitutions.
        //
        UnicodeString line = lineMat->group(1, status);
        UnicodeString fields[7];
        fieldPat->split(line, fields, 7, status);

        flagMat->reset(fields[0]);
        flagMat->matches(status);
        UnicodeString pattern  = flagMat->group(2, status);
        pattern.findAndReplace("${bang}", "!");
        pattern.findAndReplace(nulnulSrc, UNICODE_STRING_SIMPLE("\\u0000\\u0000"));
        pattern.findAndReplace(ffffSrc, ffff);

        //
        //  Identify patterns that include match flag settings,
        //    split off the flags, remove the extra quotes.
        //
        UnicodeString flagStr = flagMat->group(3, status);
        if (U_FAILURE(status)) {
            errln("ucnv_toUChars: ICU Error \"%s\"\n", u_errorName(status));
            return;
        }
        int32_t flags = 0;
        const UChar UChar_c = 0x63;  // Char constants for the flag letters.
        const UChar UChar_i = 0x69;  //   (Damn the lack of Unicode support in C)
        const UChar UChar_m = 0x6d;
        const UChar UChar_x = 0x78;
        const UChar UChar_y = 0x79;
        if (flagStr.indexOf(UChar_i) != -1) {
            flags |= UREGEX_CASE_INSENSITIVE;
        }
        if (flagStr.indexOf(UChar_m) != -1) {
            flags |= UREGEX_MULTILINE;
        }
        if (flagStr.indexOf(UChar_x) != -1) {
            flags |= UREGEX_COMMENTS;
        }
        
        //
        // Put the pattern in a UTF-8 UText
        //
        status = U_ZERO_ERROR;
        patternLength = pattern.extract(patternChars, patternCapacity, UTF8Converter.getAlias(), status);
        if (status == U_BUFFER_OVERFLOW_ERROR) {
            status = U_ZERO_ERROR;
            delete[] patternChars;
            patternCapacity = patternLength + 1;
            patternChars = new char[patternCapacity];
            pattern.extract(patternChars, patternCapacity, UTF8Converter.getAlias(), status);
        }
        utext_openUTF8(&patternText, patternChars, patternLength, &status);

        //
        // Compile the test pattern.
        //
        RegexPattern *testPat = RegexPattern::compile(&patternText, flags, pe, status);
        if (status == U_REGEX_UNIMPLEMENTED) {
            //
            // Test of a feature that is planned for ICU, but not yet implemented.
            //   skip the test.
            skippedUnimplementedCount++;
            delete testPat;
            status = U_ZERO_ERROR;
            continue;
        }

        if (U_FAILURE(status)) {
            // Some tests are supposed to generate errors.
            //   Only report an error for tests that are supposed to succeed.
            if (fields[2].indexOf(UChar_c) == -1  &&  // Compilation is not supposed to fail AND
                fields[2].indexOf(UChar_i) == -1)     //   it's not an accepted ICU incompatibility
            {
                errln("line %d: ICU Error \"%s\"\n", lineNum, u_errorName(status));
            }
            status = U_ZERO_ERROR;
            delete testPat;
            continue;
        }

        if (fields[2].indexOf(UChar_i) >= 0) {
            // ICU should skip this test.
            delete testPat;
            continue;
        }

        if (fields[2].indexOf(UChar_c) >= 0) {
            // This pattern should have caused a compilation error, but didn't/
            errln("line %d: Expected a pattern compile error, got success.", lineNum);
            delete testPat;
            continue;
        }


        //
        // replace the Perl variables that appear in some of the
        //   match data strings.
        //
        UnicodeString matchString = fields[1];
        matchString.findAndReplace(nulnulSrc, nulnul);
        matchString.findAndReplace(ffffSrc,   ffff);

        // Replace any \n in the match string with an actual new-line char.
        //  Don't do full unescape, as this unescapes more than Perl does, which
        //  causes other spurious failures in the tests.
        matchString.findAndReplace(UNICODE_STRING_SIMPLE("\\n"), "\n");

        //
        // Put the input in a UTF-8 UText
        //
        status = U_ZERO_ERROR;
        inputLength = matchString.extract(inputChars, inputCapacity, UTF8Converter.getAlias(), status);
        if (status == U_BUFFER_OVERFLOW_ERROR) {
            status = U_ZERO_ERROR;
            delete[] inputChars;
            inputCapacity = inputLength + 1;
            inputChars = new char[inputCapacity];
            matchString.extract(inputChars, inputCapacity, UTF8Converter.getAlias(), status);
        }
        utext_openUTF8(&inputText, inputChars, inputLength, &status);

        //
        // Run the test, check for expected match/don't match result.
        //
        RegexMatcher *testMat = testPat->matcher(&inputText, RegexPattern::PATTERN_IS_UTEXT, status);
        UBool found = testMat->find();
        UBool expected = FALSE;
        if (fields[2].indexOf(UChar_y) >=0) {
            expected = TRUE;
        }
        if (expected != found) {
            errln("line %d: Expected %smatch, got %smatch",
                lineNum, expected?"":"no ", found?"":"no " );
            continue;
        }
        
        // Don't try to check expected results if there is no match.
        //   (Some have stuff in the expected fields)
        if (!found) {
            delete testMat;
            delete testPat;
            continue;
        }

        //
        // Interpret the Perl expression from the fourth field of the data file,
        // building up an ICU string from the results of the ICU match.
        //   The Perl expression will contain references to the results of
        //     a regex match, including the matched string, capture group strings,
        //     group starting and ending indicies, etc.
        //
        UnicodeString resultString;
        UnicodeString perlExpr = fields[3];

        while (perlExpr.length() > 0) {
            groupsMat->reset(perlExpr);
            cgMat->reset(perlExpr);

            if (perlExpr.startsWith("$&")) {
                resultString.append(testMat->group(status));
                perlExpr.remove(0, 2);
            }

            else if (groupsMat->lookingAt(status)) {
                // $-[0]   $+[2]  etc.
                UnicodeString digitString = groupsMat->group(2, status);
                int32_t t = 0;
                int32_t groupNum = ICU_Utility::parseNumber(digitString, t, 10);
                UnicodeString plusOrMinus = groupsMat->group(1, status);
                int32_t matchPosition;
                if (plusOrMinus.compare("+") == 0) {
                    matchPosition = testMat->end(groupNum, status);
                } else {
                    matchPosition = testMat->start(groupNum, status);
                }
                if (matchPosition != -1) {
                    ICU_Utility::appendNumber(resultString, matchPosition);
                }
                perlExpr.remove(0, groupsMat->end(status));
            }

            else if (cgMat->lookingAt(status)) {
                // $1, $2, $3, etc.
                UnicodeString digitString = cgMat->group(1, status);
                int32_t t = 0;
                int32_t groupNum = ICU_Utility::parseNumber(digitString, t, 10);
                if (U_SUCCESS(status)) {
                    resultString.append(testMat->group(groupNum, status));
                    status = U_ZERO_ERROR;
                }
                perlExpr.remove(0, cgMat->end(status));
            }

            else if (perlExpr.startsWith("@-")) {
                int32_t i;
                for (i=0; i<=testMat->groupCount(); i++) {
                    if (i>0) {
                        resultString.append(" ");
                    }
                    ICU_Utility::appendNumber(resultString, testMat->start(i, status));
                }
                perlExpr.remove(0, 2);
            }

            else if (perlExpr.startsWith("@+")) {
                int32_t i;
                for (i=0; i<=testMat->groupCount(); i++) {
                    if (i>0) {
                        resultString.append(" ");
                    }
                    ICU_Utility::appendNumber(resultString, testMat->end(i, status));
                }
                perlExpr.remove(0, 2);
            }

            else if (perlExpr.startsWith(UNICODE_STRING_SIMPLE("\\"))) {    // \Escape.  Take following char as a literal.
                                                     //           or as an escaped sequence (e.g. \n)
                if (perlExpr.length() > 1) {
                    perlExpr.remove(0, 1);  // Remove the '\', but only if not last char.
                }
                UChar c = perlExpr.charAt(0);
                switch (c) {
                case 'n':   c = '\n'; break;
                // add any other escape sequences that show up in the test expected results.
                }
                resultString.append(c);
                perlExpr.remove(0, 1);
            }

            else  {
                // Any characters from the perl expression that we don't explicitly
                //  recognize before here are assumed to be literals and copied
                //  as-is to the expected results.
                resultString.append(perlExpr.charAt(0));
                perlExpr.remove(0, 1);
            }

            if (U_FAILURE(status)) {
                errln("Line %d: ICU Error \"%s\"", lineNum, u_errorName(status));
                break;
            }
        }

        //
        // Expected Results Compare
        //
        UnicodeString expectedS(fields[4]);
        expectedS.findAndReplace(nulnulSrc, nulnul);
        expectedS.findAndReplace(ffffSrc,   ffff);
        expectedS.findAndReplace(UNICODE_STRING_SIMPLE("\\n"), "\n");


        if (expectedS.compare(resultString) != 0) {
            err("Line %d: Incorrect perl expression results.", lineNum);
            infoln((UnicodeString)"Expected \""+expectedS+(UnicodeString)"\"; got \""+resultString+(UnicodeString)"\"");
        }

        delete testMat;
        delete testPat;
    }

    //
    // All done.  Clean up allocated stuff.
    //
    delete cgMat;
    delete cgPat;

    delete groupsMat;
    delete groupsPat;

    delete flagMat;
    delete flagPat;

    delete lineMat;
    delete linePat;

    delete fieldPat;
    delete [] testData;
    
    utext_close(&patternText);
    utext_close(&inputText);
    
    delete [] patternChars;
    delete [] inputChars;


    logln("%d tests skipped because of unimplemented regexp features.", skippedUnimplementedCount);

}


//--------------------------------------------------------------
//
//  Bug6149   Verify limits to heap expansion for backtrack stack.
//             Use this pattern,
//                 "(a?){1,}"
//             The zero-length match will repeat forever.
//                (That this goes into a loop is another bug)
//
//---------------------------------------------------------------
void RegexTest::Bug6149() {
    UnicodeString pattern("(a?){1,}");
    UnicodeString s("xyz");
    uint32_t flags = 0;
    UErrorCode status = U_ZERO_ERROR;

    RegexMatcher  matcher(pattern, s, flags, status);
    UBool result = false;
    REGEX_ASSERT_FAIL(result=matcher.matches(status), U_REGEX_STACK_OVERFLOW);
    REGEX_ASSERT(result == FALSE);
 }


//
//   Callbacks()    Test the callback function.
//                  When set, callbacks occur periodically during matching operations,
//                  giving the application code the ability to abort the operation
//                  before it's normal completion.
//

struct callBackContext {
    RegexTest        *test;
    int32_t          maxCalls;
    int32_t          numCalls;
    int32_t          lastSteps;
    void reset(int32_t max) {maxCalls=max; numCalls=0; lastSteps=0;};
};

U_CDECL_BEGIN
static UBool U_CALLCONV
testCallBackFn(const void *context, int32_t steps) {
    callBackContext  *info = (callBackContext *)context;
    if (info->lastSteps+1 != steps) {
        info->test->errln("incorrect steps in callback.  Expected %d, got %d\n", info->lastSteps+1, steps);
    }
    info->lastSteps = steps;
    info->numCalls++;
    return (info->numCalls < info->maxCalls);
}
U_CDECL_END

void RegexTest::Callbacks() {
   {
        // Getter returns NULLs if no callback has been set
        
        //   The variables that the getter will fill in.
        //   Init to non-null values so that the action of the getter can be seen.
        const void          *returnedContext = &returnedContext;
        URegexMatchCallback *returnedFn = &testCallBackFn;
        
        UErrorCode status = U_ZERO_ERROR;
        RegexMatcher matcher("x", 0, status);
        REGEX_CHECK_STATUS;
        matcher.getMatchCallback(returnedFn, returnedContext, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(returnedFn == NULL);
        REGEX_ASSERT(returnedContext == NULL);
    }
    
   {
        // Set and Get work
        callBackContext cbInfo = {this, 0, 0, 0};
        const void          *returnedContext;
        URegexMatchCallback *returnedFn;
        UErrorCode status = U_ZERO_ERROR;
        RegexMatcher matcher(UNICODE_STRING_SIMPLE("((.)+\\2)+x"), 0, status);  // A pattern that can run long.
        REGEX_CHECK_STATUS;
        matcher.setMatchCallback(testCallBackFn, &cbInfo, status);
        REGEX_CHECK_STATUS;
        matcher.getMatchCallback(returnedFn, returnedContext, status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(returnedFn == testCallBackFn);
        REGEX_ASSERT(returnedContext == &cbInfo);
        
        // A short-running match shouldn't invoke the callback
        status = U_ZERO_ERROR;
        cbInfo.reset(1);
        UnicodeString s = "xxx";
        matcher.reset(s);
        REGEX_ASSERT(matcher.matches(status));
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(cbInfo.numCalls == 0);
        
        // A medium-length match that runs long enough to invoke the
        //   callback, but not so long that the callback aborts it.
        status = U_ZERO_ERROR;
        cbInfo.reset(4);
        s = "aaaaaaaaaaaaaaaaaaab";
        matcher.reset(s);
        REGEX_ASSERT(matcher.matches(status)==FALSE);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(cbInfo.numCalls > 0);
        
        // A longer running match that the callback function will abort.
        status = U_ZERO_ERROR;
        cbInfo.reset(4);
        s = "aaaaaaaaaaaaaaaaaaaaaaab";
        matcher.reset(s);
        REGEX_ASSERT(matcher.matches(status)==FALSE);
        REGEX_ASSERT(status == U_REGEX_STOPPED_BY_CALLER);
        REGEX_ASSERT(cbInfo.numCalls == 4);
    }
 

}


//---------------------------------------------------------------------------
//
//    PreAllocatedUTextCAPI    Check the C API with pre-allocated mutable
//                             UTexts. The pure-C implementation of UText
//                             has no mutable backing stores, but we can
//                             use UnicodeString here to test the functionality.
//
//---------------------------------------------------------------------------
void RegexTest::PreAllocatedUTextCAPI () {
    UErrorCode           status = U_ZERO_ERROR;
    URegularExpression  *re;
    UText                patternText = UTEXT_INITIALIZER;
    UnicodeString        buffer;
    UText                bufferText = UTEXT_INITIALIZER;
    
    utext_openUnicodeString(&bufferText, &buffer, &status);

    /*
     *  getText() and getUText()
     */
    {
        UText  text1 = UTEXT_INITIALIZER;
        UText  text2 = UTEXT_INITIALIZER;
        UChar  text2Chars[20];
        UText  *resultText;

        status = U_ZERO_ERROR;
        utext_openUTF8(&text1, "abcccd", -1, &status);
        utext_openUTF8(&text2, "abcccxd", -1, &status);
        u_uastrncpy(text2Chars, "abcccxd", sizeof(text2)/2);
        utext_openUChars(&text2, text2Chars, -1, &status);
        
        utext_openUTF8(&patternText, "abc*d", -1, &status);
        re = uregex_openUText(&patternText, 0, NULL, &status);

        /* First set a UText */
        uregex_setUText(re, &text1, &status);
        resultText = uregex_getUText(re, &bufferText, &status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(resultText == &bufferText);
        utext_setNativeIndex(resultText, 0);
        utext_setNativeIndex(&text1, 0);
        REGEX_ASSERT(utext_compare(resultText, -1, &text1, -1) == 0);
        
        resultText = uregex_getUText(re, &bufferText, &status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(resultText == &bufferText);
        utext_setNativeIndex(resultText, 0);
        utext_setNativeIndex(&text1, 0);
        REGEX_ASSERT(utext_compare(resultText, -1, &text1, -1) == 0);

        /* Then set a UChar * */
        uregex_setText(re, text2Chars, 7, &status);
        resultText = uregex_getUText(re, &bufferText, &status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(resultText == &bufferText);
        utext_setNativeIndex(resultText, 0);
        utext_setNativeIndex(&text2, 0);
        REGEX_ASSERT(utext_compare(resultText, -1, &text2, -1) == 0);
        
        uregex_close(re);
        utext_close(&text1);
        utext_close(&text2);
    }

    /*
     *  group()
     */
    {
        UChar    text1[80];
        UText   *actual;
        UBool    result;
        u_uastrncpy(text1, "noise abc interior def, and this is off the end",  sizeof(text1)/2);

        status = U_ZERO_ERROR;
        re = uregex_openC("abc(.*?)def", 0, NULL, &status);
        REGEX_CHECK_STATUS;

        uregex_setText(re, text1, -1, &status);
        result = uregex_find(re, 0, &status);
        REGEX_ASSERT(result==TRUE);

        /*  Capture Group 0, the full match.  Should succeed.  */
        status = U_ZERO_ERROR;
        actual = uregex_groupUText(re, 0, &bufferText, &status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(actual == &bufferText);
        REGEX_ASSERT_UTEXT("abc interior def", actual);

        /*  Capture group #1.  Should succeed. */
        status = U_ZERO_ERROR;
        actual = uregex_groupUText(re, 1, &bufferText, &status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(actual == &bufferText);
        REGEX_ASSERT_UTEXT(" interior ", actual);

        /*  Capture group out of range.  Error. */
        status = U_ZERO_ERROR;
        actual = uregex_groupUText(re, 2, &bufferText, &status);
        REGEX_ASSERT(status == U_INDEX_OUTOFBOUNDS_ERROR);
        REGEX_ASSERT(actual == &bufferText);

        uregex_close(re);

    }
    
    /*
     *  replaceFirst()
     */
    {
        UChar    text1[80];
        UChar    text2[80];
        UText    replText = UTEXT_INITIALIZER;
        UText   *result;
        
        status = U_ZERO_ERROR;
        u_uastrncpy(text1, "Replace xaax x1x x...x.",  sizeof(text1)/2);
        u_uastrncpy(text2, "No match here.",  sizeof(text2)/2);
        utext_openUTF8(&replText, "<$1>", -1, &status);

        re = uregex_openC("x(.*?)x", 0, NULL, &status);
        REGEX_CHECK_STATUS;

        /*  Normal case, with match */
        uregex_setText(re, text1, -1, &status);
        utext_replace(&bufferText, 0, utext_nativeLength(&bufferText), NULL, 0, &status);
        result = uregex_replaceFirstUText(re, &replText, &bufferText, &status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == &bufferText);
        REGEX_ASSERT_UTEXT("Replace <aa> x1x x...x.", result);

        /* No match.  Text should copy to output with no changes.  */
        uregex_setText(re, text2, -1, &status);
        utext_replace(&bufferText, 0, utext_nativeLength(&bufferText), NULL, 0, &status);
        result = uregex_replaceFirstUText(re, &replText, &bufferText, &status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == &bufferText);
        REGEX_ASSERT_UTEXT("No match here.", result);
        
        /* Unicode escapes */
        uregex_setText(re, text1, -1, &status);
        utext_openUTF8(&replText, "\\\\\\u0041$1\\U00000042$\\a", -1, &status);
        utext_replace(&bufferText, 0, utext_nativeLength(&bufferText), NULL, 0, &status);
        result = uregex_replaceFirstUText(re, &replText, &bufferText, &status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == &bufferText);
        REGEX_ASSERT_UTEXT("Replace \\AaaB$a x1x x...x.", result);

        uregex_close(re);
        utext_close(&replText);
    }


    /*
     *  replaceAll()
     */
    {
        UChar    text1[80];
        UChar    text2[80];
        UText    replText = UTEXT_INITIALIZER;
        UText   *result;

        status = U_ZERO_ERROR;
        u_uastrncpy(text1, "Replace xaax x1x x...x.",  sizeof(text1)/2);
        u_uastrncpy(text2, "No match here.",  sizeof(text2)/2);
        utext_openUTF8(&replText, "<$1>", -1, &status);

        re = uregex_openC("x(.*?)x", 0, NULL, &status);
        REGEX_CHECK_STATUS;

        /*  Normal case, with match */
        uregex_setText(re, text1, -1, &status);
        utext_replace(&bufferText, 0, utext_nativeLength(&bufferText), NULL, 0, &status);
        result = uregex_replaceAllUText(re, &replText, &bufferText, &status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == &bufferText);
        REGEX_ASSERT_UTEXT("Replace <aa> <1> <...>.", result);

        /* No match.  Text should copy to output with no changes.  */
        uregex_setText(re, text2, -1, &status);
        utext_replace(&bufferText, 0, utext_nativeLength(&bufferText), NULL, 0, &status);
        result = uregex_replaceAllUText(re, &replText, &bufferText, &status);
        REGEX_CHECK_STATUS;
        REGEX_ASSERT(result == &bufferText);
        REGEX_ASSERT_UTEXT("No match here.", result);

        uregex_close(re);
        utext_close(&replText);
    }


    /*
     *  splitUText() uses the C++ API directly, and the UnicodeString version uses mutable UTexts,
     *   so we don't need to test it here.
     */
    
    utext_close(&bufferText);
    utext_close(&patternText);
}

//--------------------------------------------------------------
//
//  Bug7651   Regex pattern that exceeds default operator stack depth in matcher.
//
//---------------------------------------------------------------
void RegexTest::Bug7651() {
    UnicodeString pattern1("((?<![A-Za-z0-9])[#\\uff03][A-Za-z0-9_][A-Za-z0-9_\\u00c0-\\u00d6\\u00c8-\\u00f6\\u00f8-\\u00ff]*|(?<![A-Za-z0-9_])[@\\uff20][A-Za-z0-9_]+(?:\\/[\\w-]+)?|(https?\\:\\/\\/|www\\.)\\S+(?<![\\!\\),\\.:;\\]\\u0080-\\uFFFF])|\\$[A-Za-z]+)");
    //  The following should exceed the default operator stack depth in the matcher, i.e. force the matcher to malloc instead of using fSmallData.
    UnicodeString pattern2("((https?\\:\\/\\/|www\\.)\\S+(?<![\\!\\),\\.:;\\]\\u0080-\\uFFFF])|(?<![A-Za-z0-9_])[\\@\\uff20][A-Za-z0-9_]+(?:\\/[\\w\\-]+)?|(?<![A-Za-z0-9])[\\#\\uff03][A-Za-z0-9_][A-Za-z0-9_\\u00c0-\\u00d6\\u00c8-\\u00f6\\u00f8-\\u00ff]*|\\$[A-Za-z]+)");
    UnicodeString s("#ff @abcd This is test");
    RegexPattern  *REPattern = NULL;
    RegexMatcher  *REMatcher = NULL;
    UErrorCode status = U_ZERO_ERROR;
    UParseError pe;

    REPattern = RegexPattern::compile(pattern1, 0, pe, status);
    REGEX_CHECK_STATUS;
    REMatcher = REPattern->matcher(s, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(REMatcher->find());
    REGEX_ASSERT(REMatcher->start(status) == 0);
    delete REPattern;
    delete REMatcher;
    status = U_ZERO_ERROR;

    REPattern = RegexPattern::compile(pattern2, 0, pe, status);
    REGEX_CHECK_STATUS;
    REMatcher = REPattern->matcher(s, status);
    REGEX_CHECK_STATUS;
    REGEX_ASSERT(REMatcher->find());
    REGEX_ASSERT(REMatcher->start(status) == 0);
    delete REPattern;
    delete REMatcher;
    status = U_ZERO_ERROR;
 }

#endif  /* !UCONFIG_NO_REGULAR_EXPRESSIONS  */