Google Git
Sign in
skia / external / github.com / unicode-org / icu / icu-release-2-1-d02 / . / source / i18n / rbbi_bld.cpp
blob: 8538b40a9f952fb640f9dccc226b1ec01b533961 [file] [log] [blame]
/*
**********************************************************************
* Copyright (C) 1999 International Business Machines Corporation *
* and others. All rights reserved. *
**********************************************************************
* Date Name Description
* 12/9/99 rgillam Ported from Java
**********************************************************************
*/
#include "unicode/rbbi.h"
#include "rbbi_bld.h"
#include "cmemory.h"
#include "unicode/uchar.h"
//=======================================================================
// RuleBasedBreakIterator.Builder
//=======================================================================
/**
* The Builder class has the job of constructing a RuleBasedBreakIterator from a
* textual description. A Builder is constructed by RuleBasedBreakIterator's
* constructor, which uses it to construct the iterator itself and then throws it
* away.
* <p>The construction logic is separated out into its own class for two primary
* reasons:
* <ul><li>The construction logic is quite complicated and large. Separating it
* out into its own class means the code must only be loaded into memory while a
* RuleBasedBreakIterator is being constructed, and can be purged after that.
* <li>There is a fair amount of state that must be maintained throughout the
* construction process that is not needed by the iterator after construction.
* Separating this state out into another class prevents all of the functions that
* construct the iterator from having to have really long parameter lists,
* (hopefully) contributing to readability and maintainability.</ul>
* <p>It'd be really nice if this could be an independent class rather than an
* inner class, because that would shorten the source file considerably, but
* making Builder an inner class of RuleBasedBreakIterator allows it direct access
* to RuleBasedBreakIterator's private members, which saves us from having to
* provide some kind of "back door" to the Builder class that could then also be
* used by other classes.
*/
const int32_t
RuleBasedBreakIteratorBuilder::END_STATE_FLAG = 0x8000;
const int32_t
RuleBasedBreakIteratorBuilder::DONT_LOOP_FLAG = 0x4000;
const int32_t
RuleBasedBreakIteratorBuilder::LOOKAHEAD_STATE_FLAG = 0x2000;
const int32_t
RuleBasedBreakIteratorBuilder::ALL_FLAGS = END_STATE_FLAG
| DONT_LOOP_FLAG | LOOKAHEAD_STATE_FLAG;
// constants for various characters
const UChar NULL_CHAR = 0x0000;
const UChar OPEN_PAREN = 0x28;
const UChar CLOSE_PAREN = 0x29;
const UChar OPEN_BRACKET = 0x5b;
const UChar CLOSE_BRACKET = 0x5d;
const UChar OPEN_BRACE = 0x7b;
const UChar CLOSE_BRACE = 0x7d;
const UChar SEMICOLON = 0x3b;
const UChar EQUAL_SIGN = 0x3d;
const UChar MINUS = 0x2d;
const UChar CARET = 0x5e;
const UChar AMPERSAND = 0x26;
const UChar COLON = 0x3a;
const UChar ASTERISK = 0x2a;
const UChar PLUS = 0x2b;
const UChar QUESTION = 0x3f;
const UChar PERIOD = 0x2e;
const UChar PIPE = 0x7c;
const UChar BANG = 0x21;
const UChar SLASH = 0x2f;
const UChar BACKSLASH = 0x5c;
const UChar ASCII_LOW = 0x20;
const UChar ASCII_HI = 0x7f;
const UnicodeString IGNORE_NAME = UnicodeString("$ignore");
//============================================================================
/**
* This class is a completely non-general quick-and-dirty class to make up
* for the fact that at the time of this writing (12/20/99) there was no
* general hash table class in the ICU. When one is created, this class should
* be removed and the code that depends on this class should be altered to use
* the regular hash-table class. This class is just here as a temporary measure
* until that happens. --rtg 12/20/99
*/
class ExpressionList {
private:
UVector keys;
UVector sets;
UVector strings;
public:
static const UnicodeSet setNotThere; // an empty UnicodeSet we can use as a return value
// in get() when the key isn't found
static const UnicodeString stringNotThere;
ExpressionList();
~ExpressionList();
const UnicodeSet& getSet(const UnicodeString& key) const;
void putSet(const UnicodeString& key, UnicodeSet* valueToAdopt);
const UnicodeString& getString(const UnicodeString& key) const;
void putString(const UnicodeString& key, UnicodeString* valueToAdopt);
const UnicodeString& getKeyAt(int32_t x) const { return *((UnicodeString*)keys[x]); }
const UnicodeSet& operator[](int32_t x) const { return *((UnicodeSet*)sets[x]); }
int32_t size() const { return keys.size(); }
};
const UnicodeSet
ExpressionList::setNotThere;
const UnicodeString
ExpressionList::stringNotThere;
ExpressionList::ExpressionList()
{
}
ExpressionList::~ExpressionList()
{
for (int32_t i = 0; i < keys.size(); i++) {
delete (UnicodeString*)keys[i];
delete (UnicodeSet*)sets[i];
delete (UnicodeString*)strings[i];
}
}
const UnicodeSet&
ExpressionList::getSet(const UnicodeString& key) const
{
for (int32_t i = 0; i < keys.size(); i++) {
if (key == *((UnicodeString*)keys[i])) {
return *((UnicodeSet*)sets[i]);
}
}
return setNotThere;
}
void
ExpressionList::putSet(const UnicodeString& key, UnicodeSet* valueToAdopt)
{
const UnicodeSet& theSet = getSet(key);
if (&theSet != &setNotThere) {
UnicodeSet* value = (UnicodeSet*)(&theSet);
value->clear();
value->addAll(*valueToAdopt);
delete valueToAdopt;
}
else {
keys.addElement(new UnicodeString(key));
sets.addElement(valueToAdopt);
strings.addElement(new UnicodeString);
}
}
const UnicodeString&
ExpressionList::getString(const UnicodeString& key) const
{
for (int32_t i = 0; i < keys.size(); i++) {
if (key == *((UnicodeString*)keys[i])) {
return *((UnicodeString*)strings[i]);
}
}
return stringNotThere;
}
void
ExpressionList::putString(const UnicodeString& key, UnicodeString* valueToAdopt)
{
const UnicodeString& theString = getString(key);
if (&theString != &stringNotThere) {
UnicodeString* value = (UnicodeString*)(&theString);
*value = *valueToAdopt;
delete valueToAdopt;
}
else {
keys.addElement(new UnicodeString(key));
sets.addElement(new UnicodeSet);
strings.addElement(valueToAdopt);
}
}
//============================================================================
#define error(message, position, context) \
setUpErrorMessage(message, position, context); \
err = U_PARSE_ERROR; \
return
void
stringDeleter(void* o) {
delete (UnicodeString*)o;
}
void
usetDeleter(void* o) {
delete (UnicodeSet*)o;
}
void
tableRowDeleter(void* o) {
delete [] (int16_t*)o;
}
void
vectorDeleter(void* o) {
delete (UVector*)o;
}
void
mergeRowDeleter(void* o) {
delete [] (int32_t*)o;
}
/**
* No special construction is required for the Builder.
*/
RuleBasedBreakIteratorBuilder::RuleBasedBreakIteratorBuilder(
RuleBasedBreakIterator& iteratorToBuild)
: iterator(iteratorToBuild),
tables(new RuleBasedBreakIteratorTables)
{
iterator.tables = tables;
tempRuleList.setDeleter(&stringDeleter);
categories.setDeleter(&usetDeleter);
tempStateTable.setDeleter(&tableRowDeleter);
decisionPointStack.setDeleter(&vectorDeleter);
// decisionPointList, loopingStates, and statesToBackfill (as well as the
// individual elements in decisionPointStack) don't need deleters--
// their element type is int32_t
mergeList.setDeleter(&mergeRowDeleter);
}
RuleBasedBreakIteratorBuilder::~RuleBasedBreakIteratorBuilder()
{
delete expressions;
}
/**
* This is the main function for setting up the BreakIterator's tables. It
* just vectors different parts of the job off to other functions.
*/
void
RuleBasedBreakIteratorBuilder::buildBreakIterator(const UnicodeString& description,
UErrorCode& err)
{
if (U_FAILURE(err))
return;
UnicodeString tempDesc(description);
buildRuleList(tempDesc, err);
buildCharCategories(err);
buildStateTable(err);
buildBackwardsStateTable(err);
}
/**
* Thus function has three main purposes:
* <ul><li>Perform general syntax checking on the description, so the rest of the
* build code can assume that it's parsing a legal description.
* <li>Split the description into separate rules
* <li>Perform variable-name substitutions (so that no one else sees variable names)
* </ul>
*/
void
RuleBasedBreakIteratorBuilder::buildRuleList(UnicodeString& description,
UErrorCode& err)
{
if (U_FAILURE(err))
return;
// invariants:
// - parentheses must be balanced: ()[]{}
// - nothing can be nested inside {}
// - nothing can be nested inside [] except more []s
// - pairs of ()[]{} must not be empty
// - ; can only occur at the outer level
// - | can only appear inside ()
// - only one = or / can occur in a single rule
// - = and / cannot both occur in the same rule
// - the right-hand side of a = expression must be enclosed in [] or ()
// - *. ?, and + may not occur at the beginning of a rule, nor may they follow
// =, /, (, (, |, }, ;, +, ?, or * (except that ? can follow *)
// - the rule list must contain at least one / rule (which may or may not
// actually contain a /
// - no rule may be empty
// - all printing characters in the ASCII range except letters and digits
// are reserved and must be preceded by \
// - ! may only occur at the beginning of a rule
// set up a vector to contain the broken-up description (each entry in the
// vector is a separate rule) and a stack for keeping track of opening
// punctuation
UStack parenStack;
int32_t p = 0;
int32_t ruleStart = 0;
UChar c = 0x0000;
UChar lastC = 0x0000;
UChar lastOpen = 0x0000;
UBool haveEquals = FALSE;
UBool haveSlash = FALSE;
UBool sawVarName = FALSE;
UBool sawIllegalChar = FALSE;
int32_t illegalCharPos = 0;
UChar expectedClose = 0x0000;
// if the description doesn't end with a semicolon, tack a semicolon onto the end
if (description.length() != 0 && description[description.length() - 1] != SEMICOLON) {
description += SEMICOLON;
}
// for each character, do...
while (p < description.length()) {
c = description[p];
switch (c) {
// if the character is opening punctuation, verify that no nesting
// rules are broken, and push the character onto the stack
case OPEN_BRACE:
case OPEN_BRACKET:
case OPEN_PAREN:
if (lastOpen == OPEN_BRACE) {
error("Can't nest brackets inside {}", p, description);
}
if (lastOpen == OPEN_BRACKET && c != OPEN_BRACKET) {
error("Can't nest anything in [] but []", p, description);
}
// if we see { anywhere except on the left-hand side of =,
// we must be seeing a variable name that was never defined
if (c == OPEN_BRACE && (haveEquals || haveSlash)) {
error("Unknown variable name", p, description);
}
lastOpen = c;
parenStack.push((void*)c);
if (c == OPEN_BRACE) {
sawVarName = TRUE;
}
break;
// if the character is closing punctuation, verify that it matches the
// last opening punctuation we saw, and that the brackets contain
// something, then pop the stack
case CLOSE_BRACE:
case CLOSE_BRACKET:
case CLOSE_PAREN:
expectedClose = NULL_CHAR;
switch (lastOpen) {
case OPEN_BRACE:
expectedClose = CLOSE_BRACE;
break;
case OPEN_BRACKET:
expectedClose = CLOSE_BRACKET;
break;
case OPEN_PAREN:
expectedClose = CLOSE_PAREN;
break;
}
if (c != expectedClose) {
error("Unbalanced parentheses", p, description);
}
if (lastC == lastOpen) {
error("Parens don't contain anything", p, description);
}
parenStack.pop();
if (!parenStack.empty()) {
lastOpen = (UChar)(int32_t)parenStack.peek();
}
else {
lastOpen = NULL_CHAR;
}
break;
// if the character is an asterisk, make sure it occurs in a place
// where an asterisk can legally go
case ASTERISK:
case PLUS:
case QUESTION:
switch (lastC) {
case EQUAL_SIGN: case SLASH: case OPEN_PAREN: case PIPE:
case ASTERISK: case PLUS: case QUESTION: case SEMICOLON:
case NULL_CHAR:
error("Misplaced *, +, or ?", p, description);
default:
break;
}
break;
// if the character is an equals sign, make sure we haven't seen another
// equals sign or a slash yet
case EQUAL_SIGN:
if (haveEquals || haveSlash) {
error("More than one = or / in rule", p, description);
}
haveEquals = TRUE;
sawIllegalChar = FALSE;
break;
// if the character is a slash, make sure we haven't seen another slash
// or an equals sign yet
case SLASH:
if (haveEquals || haveSlash) {
error("More than one = or / in rule", p, description);
}
if (sawVarName) {
error("Unknown variable name", p, description);
}
haveSlash = TRUE;
break;
// if the character is an exclamation point, make sure it occurs only
// at the beginning of a rule
case BANG:
if (lastC != SEMICOLON && lastC != NULL_CHAR) {
error("! can only occur at the beginning of a rule", p, description);
}
break;
// if the character is a backslash, skip the character that follows it
// (it'll get treated as a literal character)
case BACKSLASH:
++p;
break;
// we don't have to do anything special on a period
case PERIOD:
break;
// if the character is a syntax character that can only occur
// inside [], make sure that it does in fact only occur inside []
// (or in a variable name)
case CARET:
case MINUS:
case COLON:
case AMPERSAND:
if (lastOpen != OPEN_BRACKET && lastOpen != OPEN_BRACE && !sawIllegalChar) {
sawIllegalChar = TRUE;
illegalCharPos = p;
}
break;
// if the character is a semicolon, do the following...
case SEMICOLON:
// if we saw any illegal characters along the way, throw
// an error
if (sawIllegalChar) {
error("Illegal character", illegalCharPos, description);
}
// make sure the rule contains something and that there are no
// unbalanced parentheses or brackets
if (lastC == SEMICOLON || lastC == NULL_CHAR) {
error("Empty rule", p, description);
}
if (!parenStack.empty()) {
error("Unbalanced parenheses", p, description);
}
if (parenStack.empty()) {
// if the rule contained an = sign, call processSubstitution()
// to replace the substitution name with the substitution text
// wherever it appears in the description
if (haveEquals) {
processSubstitution(description, ruleStart, p + 1, p + 1, err);
}
else {
// otherwise, check to make sure the rule doesn't reference
// any undefined substitutions
if (sawVarName) {
error("Unknown variable name", p, description);
}
// then add it to tempRuleList
UnicodeString* newRule = new UnicodeString();
description.extractBetween(ruleStart, p, *newRule);
tempRuleList.addElement(newRule);
}
// and reset everything to process the next rule
ruleStart = p + 1;
haveEquals = haveSlash = sawVarName = sawIllegalChar = FALSE;
}
break;
// if the character is a vertical bar, check to make sure that it
// occurs inside a () expression and that the character that precedes
// it isn't also a vertical bar
case PIPE:
if (lastC == PIPE) {
error("Empty alternative", p, description);
}
if (parenStack.empty() || lastOpen != OPEN_PAREN) {
error("Misplaced |", p, description);
}
break;
// if the character is anything else (escaped characters are
// skipped and don't make it here), it's an error
default:
if (c >= ASCII_LOW && c < ASCII_HI && !u_isalpha(c)
&& !u_isdigit(c) && !sawIllegalChar) {
sawIllegalChar = TRUE;
illegalCharPos = p;
}
break;
}
lastC = c;
++p;
}
if (tempRuleList.size() == 0) {
error("No valid rules in description", p, description);
}
}
/**
* This function performs variable-name substitutions. First it does syntax
* checking on the variable-name definition. If it's syntactically valid, it
* then goes through the remainder of the description and does a simple
* find-and-replace of the variable name with its text. (The variable text
* must be enclosed in either [] or () for this to work.)
*/
void
RuleBasedBreakIteratorBuilder::processSubstitution(UnicodeString& description,
int32_t ruleStart,
int32_t ruleEnd,
int32_t startPos,
UErrorCode& err)
{
if (U_FAILURE(err))
return;
// isolate out the text on either side of the equals sign
UnicodeString substitutionRule;
UnicodeString replace;
UnicodeString replaceWith;
description.extractBetween(ruleStart, ruleEnd, substitutionRule);
int32_t equalPos = substitutionRule.indexOf(EQUAL_SIGN);
substitutionRule.extractBetween(0, equalPos, replace);
substitutionRule.extractBetween(equalPos + 1, substitutionRule.length() - 1, replaceWith);
// check to see whether the substitution name is something we've declared
// to be "special". For RuleBasedBreakIterator itself, this is "$ignore".
// This function takes care of any extra processing that has to be done
// with "special" substitution names.
handleSpecialSubstitution(replace, replaceWith, startPos, description, err);
// perform various other syntax checks on the rule
if (replaceWith.length() == 0) {
error("Nothing on right-hand side of =", startPos, description);
}
if (replace.length() == 0) {
error("Nothing on left-hand side of =", startPos, description);
}
if (!(replaceWith[0] == OPEN_BRACKET
&& replaceWith[replaceWith.length() - 1] == CLOSE_BRACKET)
&& !(replaceWith[0] == OPEN_PAREN
&& replaceWith[replaceWith.length() - 1] == CLOSE_PAREN)) {
error("Illegal right-hand side for =", startPos, description);
}
// now go through the rest of the description (which hasn't been broken up
// into separate rules yet) and replace every occurrence of the
// substitution name with the substitution body
if (replace[0] != OPEN_BRACE) {
replace.insert(0, OPEN_BRACE);
replace += CLOSE_BRACE;
}
description.removeBetween(ruleStart, ruleEnd);
int32_t lastPos = startPos;
int32_t pos = description.indexOf(replace, lastPos);
while (pos != -1) {
description.replaceBetween(pos, pos + replace.length(), replaceWith);
lastPos = pos + replace.length();
pos = description.indexOf(replace, lastPos);
}
}
/**
* This function defines a protocol for handling substitution names that
* are "special," i.e., that have some property beyond just being
* substitutions. At the RuleBasedBreakIterator level, we have one
* special substitution name, "$ignore". Subclasses can override this
* function to add more. Any special processing that has to go on beyond
* that which is done by the normal substitution-processing code is done
* here.
*/
void
RuleBasedBreakIteratorBuilder::handleSpecialSubstitution(const UnicodeString& replace,
const UnicodeString& replaceWith,
int32_t startPos,
const UnicodeString& description,
UErrorCode& err)
{
if (U_FAILURE(err))
return;
// if we get a definition for a substitution called "$ignore", it defines
// the ignore characters for the iterator. Check to make sure the expression
// is a [] expression, and if it is, parse it and store the characters off
// to the side.
if (replace == IGNORE_NAME) {
if (replaceWith.charAt(0) == OPEN_PAREN) {
error("Ignore group can't be enclosed in (", startPos, description);
}
ignoreChars = UnicodeSet(replaceWith, err);
}
}
/**
* This function provides a hook for subclasses to mess with the character
* category table.
*/
void
RuleBasedBreakIteratorBuilder::mungeExpressionList()
{
// base class doesn't do anything-- this is here
// for subclasses
}
/**
* This function builds the character category table. On entry,
* tempRuleList is a vector of break rules that has had variable names substituted.
* On exit, the charCategoryTable data member has been initialized to hold the
* character category table, and tempRuleList's rules have been munged to contain
* character category numbers everywhere a literal character or a [] expression
* originally occurred.
*/
void
RuleBasedBreakIteratorBuilder::buildCharCategories(UErrorCode& err)
{
if (U_FAILURE(err))
return;
int32_t bracketLevel = 0;
int32_t p = 0;
int32_t lineNum = 0;
// build hash table of every literal character or [] expression in the rule list
// and derive a UnicodeSet object representing the characters each refers to
while (lineNum < tempRuleList.size()) {
UnicodeString* line = (UnicodeString*)(tempRuleList[lineNum]);
p = 0;
while (p < line->length()) {
UChar c = (*line)[p];
switch (c) {
// skip over all syntax characters except [
case OPEN_PAREN: case CLOSE_PAREN: case ASTERISK: case PERIOD: case SLASH:
case PIPE: case SEMICOLON: case QUESTION: case BANG: case PLUS:
break;
// for [, find the matching ] (taking nested [] pairs into account)
// and add the whole expression to the expression list
case OPEN_BRACKET:
{
int32_t q = p + 1;
++bracketLevel;
while (q < line->length() && bracketLevel != 0) {
c = (*line)[q];
if (c == OPEN_BRACKET) {
++bracketLevel;
}
else if (c == CLOSE_BRACKET) {
--bracketLevel;
}
++q;
}
UnicodeString temp;
line->extractBetween(p, q, temp);
if (&expressions->getSet(temp) == &ExpressionList::setNotThere) {
expressions->putSet(temp, new UnicodeSet(temp, err));
}
p = q - 1;
}
break;
// for \ sequences, just move to the next character and treat
// it as a single character
case BACKSLASH:
++p;
c = (*line)[p];
// DON'T break; fall through into "default" clause
// for an isolated single character, add it to the expression list
default:
{
UnicodeString temp;
line->extractBetween(p, p + 1, temp);
expressions->putSet(temp, new UnicodeSet(temp, err));
}
break;
}
++p;
}
++lineNum;
}
// create the temporary category table (which is a vector of UnicodeSet objects)
if (ignoreChars.isEmpty()) {
categories.addElement(new UnicodeSet(ignoreChars));
}
else {
categories.addElement(new UnicodeSet());
}
ignoreChars.clear();
// this is a hook to allow subclasses to add categories on their own
mungeExpressionList();
// Derive the character categories. Go through the existing character categories
// looking for overlap. Any time there's overlap, we create a new character
// category for the characters that overlapped and remove them from their original
// category. At the end, any characters that are left in the expression haven't
// been mentioned in any category, so another new category is created for them.
// For example, if the first expression is [abc], then a, b, and c will be placed
// into a single character category. If the next expression is [bcd], we will first
// remove b and c from their existing category (leaving a behind), create a new
// category for b and c, and then create another new category for d (which hadn't
// been mentioned in the previous expression).
// At no time should a character ever occur in more than one character category.
// for each expression in the expressions list, do...
for (int32_t i = 0; i < expressions->size(); i++) {
// initialize the working char set to the chars in the current expression
UnicodeSet e = UnicodeSet((*expressions)[i]);
// for each category in the category list, do...
for (int32_t j = categories.size() - 1; !e.isEmpty() && j > 0; j--) {
// if there's overlap between the current working set of chars
// and the current category...
UnicodeSet* that = (UnicodeSet*)(categories[j]);
UnicodeSet temp = UnicodeSet(e);
temp.retainAll(*that);
if (!temp.isEmpty()) {
// if the current category is not a subset of the current
// working set of characters, then remove the overlapping
// characters from the current category and create a new
// category for them
if (temp != *that) {
that->removeAll(temp);
categories.addElement(new UnicodeSet(temp));
}
// and always remove the overlapping characters from the current
// working set of characters
e.removeAll(temp);
}
}
// if there are still characters left in the working char set,
// add a new category containing them
if (!e.isEmpty()) {
categories.addElement(new UnicodeSet(e));
}
}
// we have the ignore characters stored in position 0. Make an extra pass through
// the character category list and remove anything from the ignore list that shows
// up in some other category
UnicodeSet allChars;
for (int32_t i = 1; i < categories.size(); i++)
allChars.addAll(*(UnicodeSet*)(categories[i]));
UnicodeSet* ignoreChars = (UnicodeSet*)(categories[0]);
ignoreChars->removeAll(allChars);
// now that we've derived the character categories, go back through the expression
// list and replace each UnicodeSet object with a String that represents the
// character categories that expression refers to. The String is encoded: each
// character is a character category number (plus 0x100 to avoid confusing them
// with syntax characters in the rule grammar)
for (int32_t i = 0; i < expressions->size(); i++) {
const UnicodeSet& cs = (*expressions)[i];
UnicodeString* cats = new UnicodeString;
// for each category...
for (int32_t j = 1; j < categories.size(); j++) {
// if the current expression contains characters in that category...
if (cs.containsAll(*(UnicodeSet*)(categories[j]))) {
// then add the encoded category number to the String for this
// expression
*cats += (UChar)(0x100 + j);
if (cs == *(UnicodeSet*)(categories[j])) {
break;
}
}
}
// once we've finished building the encoded String for this expression,
// replace the UnicodeSet object with it
expressions->putString(expressions->getKeyAt(i), cats);
}
// and finally, we turn the temporary category table into a permanent category
// table, which is a CompactByteArray. (we skip category 0, which by definition
// refers to all characters not mentioned specifically in the rules)
tables->charCategoryTable = ucmp8_open((int8_t)0);
// for each category...
for (int32_t i = 0; i < categories.size(); i++) {
UnicodeSet& chars = *(UnicodeSet*)(categories[i]);
const UnicodeString& pairs = chars.getPairs();
// go through the character ranges in the category one by one...
for (int32_t j = 0; j < pairs.length(); j += 2) {
// and set the corresponding elements in the CompactArray accordingly
if (i != 0) {
ucmp8_setRange(tables->charCategoryTable, pairs[j], pairs[j + 1],
(int8_t)i);
}
// (category 0 is special-- it's the hiding place for the ignore
// characters, whose real category number in the CompactArray is
// -1 [this is because category 0 contains all characters not
// specifically mentioned anywhere in the rules] )
else {
ucmp8_setRange(tables->charCategoryTable, pairs[j], pairs[j + 1],
RuleBasedBreakIterator::IGNORE);
}
}
}
// once we've populated the CompactArray, compact it
ucmp8_compact(tables->charCategoryTable, 32);
// initialize numCategories
numCategories = categories.size();
tables->numCategories = numCategories;
}
/**
* This is the function that builds the forward state table. Most of the real
* work is done in parseRule(), which is called once for each rule in the
* description.
*/
void
RuleBasedBreakIteratorBuilder::buildStateTable(UErrorCode& err)
{
if (U_FAILURE(err))
return;
// initialize our temporary state table, and fill it with two states:
// state 0 is a dummy state that allows state 1 to be the starting state
// and 0 to represent "stop". State 1 is added here to seed things
// before we start parsing
tempStateTable.addElement(new int16_t[tables->numCategories + 1]);
tempStateTable.addElement(new int16_t[tables->numCategories + 1]);
// call parseRule() for every rule in the rule list (except those which
// start with !, which are actually backwards-iteration rules)
for (int32_t i = 0; i < tempRuleList.size(); i++) {
UnicodeString* rule = (UnicodeString*)tempRuleList[i];
if ((*rule)[0] != BANG) {
parseRule(*rule, TRUE);
}
}
// finally, use finishBuildingStateTable() to minimize the number of
// states in the table and perform some other cleanup work
finishBuildingStateTable(TRUE);
}
/**
* This is where most of the work really happens. This routine parses a single
* rule in the rule description, adding and modifying states in the state
* table according to the new expression. The state table is kept deterministic
* throughout the whole operation, although some ugly postprocessing is needed
* to handle the *? token.
*/
void
RuleBasedBreakIteratorBuilder::parseRule(const UnicodeString& rule,
UBool forward)
{
// algorithm notes:
// - The basic idea here is to read successive character-category groups
// from the input string. For each group, you create a state and point
// the appropriate entries in the previous state to it. This produces a
// straight line from the start state to the end state. The {}, *, and (|)
// idioms produce branches in this straight line. These branches (states
// that can transition to more than one other state) are called "decision
// points." A list of decision points is kept. This contains a list of
// all states that can transition to the next state to be created. For a
// straight line progression, the only thing in the decision-point list is
// the current state. But if there's a branch, the decision-point list
// will contain all of the beginning points of the branch when the next
// state to be created represents the end point of the branch. A stack is
// used to save decision point lists in the presence of nested parentheses
// and the like. For example, when a { is encountered, the current decision
// point list is saved on the stack and restored when the corresponding }
// is encountered. This way, after the } is read, the decision point list
// will contain both the state right before the } _and_ the state before
// the whole {} expression. Both of these states can transition to the next
// state after the {} expression.
// - one complication arises when we have to stamp a transition value into
// an array cell that already contains one. The updateStateTable() and
// mergeStates() functions handle this case. Their basic approach is to
// create a new state that combines the two states that conflict and point
// at it when necessary. This happens recursively, so if the merged states
// also conflict, they're resolved in the same way, and so on. There are
// a number of tests aimed at preventing infinite recursion.
// - another complication arises with repeating characters. It's somewhat
// ambiguous whether the user wants a greedy or non-greedy match in these cases.
// (e.g., whether "[a-z]*abc" means the SHORTEST sequence of letters ending in
// "abc" or the LONGEST sequence of letters ending in "abc". We've adopted
// the *? to mean "shortest" and * by itself to mean "longest". (You get the
// same result with both if there's no overlap between the repeating character
// group and the group immediately following it.) Handling the *? token is
// rather complicated and involves keeping track of whether a state needs to
// be merged (as described above) or merely overwritten when you update one of
// its cells, and copying the contents of a state that loops with a *? token
// into some of the states that follow it after the rest of the table-building
// process is complete ("backfilling").
// implementation notes:
// - This function assumes syntax checking has been performed on the input string
// prior to its being passed in here. It assumes that parentheses are
// balanced, all literal characters are enclosed in [] and turned into category
// numbers, that there are no illegal characters or character sequences, and so
// on. Violation of these invariants will lead to undefined behavior.
// - It'd probably be better to use linked lists rather than UVector and UStack
// to maintain the decision point list and stack. I went for simplicity in
// this initial implementation. If performance is critical enough, we can go
// back and fix this later.
// -There are a number of important limitations on the *? token. It does not work
// right when followed by a repeating character sequence (e.g., ".*?(abc)*")
// (although it does work right when followed by a single repeating character).
// It will not always work right when nested in parentheses or braces (although
// sometimes it will). It also will not work right if the group of repeating
// characters and the group of characters that follows overlap partially
// (e.g., "[a-g]*?[e-j]"). None of these capabilites was deemed necessary for
// describing breaking rules we know about, so we left them out for
// expeditiousness.
// - Rules such as "[a-z]*?abc;" will be treated the same as "[a-z]*?aa*bc;"--
// that is, if the string ends in "aaaabc", the break will go before the first
// "a" rather than the last one. Both of these are limitations in the design
// of RuleBasedBreakIterator and not limitations of the rule parser.
int32_t p = 0;
int32_t currentState = 1; // don't use state number 0; 0 means "stop"
int32_t lastState = currentState;
UnicodeString pendingChars;
UnicodeString temp;
int16_t* state;
UBool sawEarlyBreak = FALSE;
// if we're adding rules to the backward state table, mark the initial state
// as a looping state
if (!forward) {
loopingStates.addElement((void*)1);
}
// put the current state on the decision point list before we start
decisionPointList.addElement((void*)currentState); // we want currentState to
// be 1 here...
currentState = tempStateTable.size() - 1; // but after that, we want it to be
// 1 less than the state number of the next state
while (p < rule.length()) {
UChar c = rule[p];
clearLoopingStates = FALSE;
// this section handles literal characters, escaped characters (which are
// effectively literal characters too), the . token, and [] expressions
if (c == OPEN_BRACKET
|| c == BACKSLASH
|| u_isalpha(c)
|| u_isdigit(c)
|| c < ASCII_LOW
|| c == PERIOD
|| c >= ASCII_HI) {
// if we're not on a period, isolate the expression and look up
// the corresponding category list
if (c != PERIOD) {
int32_t q = p;
// if we're on a backslash, the expression is the character
// after the backslash
if (c == BACKSLASH) {
q = p + 2;
++p;
}
// if we're on an opening bracket, scan to the closing bracket
// to isolate the expression
else if (c == OPEN_BRACKET) {
int32_t bracketLevel = 1;
while (bracketLevel > 0) {
++q;
c = rule[q];
if (c == OPEN_BRACKET) {
++bracketLevel;
}
else if (c == CLOSE_BRACKET) {
--bracketLevel;
}
else if (c == BACKSLASH) {
++q;
}
}
++q;
}
// otherwise, the expression is just the character itself
else {
q = p + 1;
}
// look up the category list for the expression and store it
// in pendingChars
rule.extractBetween(p, q, temp);
pendingChars = expressions->getString(temp);
// advance the current position past the expression
p = q - 1;
}
// if the character we're on is a period, we end up down here
else {
int32_t rowNum = (int32_t)decisionPointList.lastElement();
state = (int16_t*)tempStateTable[rowNum];
// if the period is followed by an asterisk, then just set the current
// state to loop back on itself
if (p + 1 < rule.length() && rule[p + 1] == ASTERISK && state[0] != 0) {
decisionPointList.addElement((void*)state[0]);
pendingChars.remove();
++p;
if (p + 1 < rule.length() && rule[p + 1] == QUESTION) {
//System.out.println("Saw *?");
setLoopingStates(&decisionPointList, decisionPointList);
++p;
}
//System.out.println("Saw .*");
}
// otherwise, fabricate a category list ("pendingChars") with
// every category in it
else {
pendingChars.remove();
for (int32_t i = 0; i < numCategories; i++)
pendingChars += (UChar)(i + 0x100);
}
}
// we'll end up in here for all expressions except for .*, which is
// special-cased above
if (pendingChars.length() != 0) {
// if the expression is followed by an asterisk, then push a copy
// of the current decision point list onto the stack
if (p + 1 < rule.length() && (
rule[p + 1] == ASTERISK ||
rule[p + 1] == QUESTION
)) {
UVector* clone = new UVector;
for (int32_t i = 0; i < decisionPointList.size(); i++) {
clone->addElement(decisionPointList[i]);
// (there's no ownership issue here because the vector
// elements are all integers)
}
decisionPointStack.push(clone);
}
// create a new state, add it to the list of states to backfill
// if we have looping states to worry about, set its "don't make
// me an accepting state" flag if we've seen a slash, and add
// it to the end of the state table
int32_t newState = tempStateTable.size();
if (loopingStates.size() != 0) {
statesToBackfill.addElement((void*)newState);
}
state = new int16_t[numCategories + 1];
if (sawEarlyBreak) {
state[numCategories] = DONT_LOOP_FLAG;
}
tempStateTable.addElement(state);
// update everybody in the decision point list to point to
// the new state (this also performs all the reconciliation
// needed to make the table deterministic), then clear the
// decision point list
updateStateTable(decisionPointList, pendingChars, (int16_t)newState);
decisionPointList.removeAllElements();
// add all states created since the last literal character we've
// seen to the decision point list
lastState = currentState;
do {
++currentState;
decisionPointList.addElement((void*)currentState);
} while (currentState + 1 < tempStateTable.size());
}
}
// a * denotes a repeating character or group (* after () is handled separately
// below). In addition to restoring the decision point list, modify the
// current state to point to itself on the appropriate character categories.
if (c == PLUS || c == ASTERISK || c == QUESTION) {
// when there's a *, update the current state to loop back on itself
// on the character categories that caused us to enter this state
if (c == ASTERISK || c == PLUS) {
for (int32_t i = lastState + 1; i < tempStateTable.size(); i++) {
UVector temp2;
temp2.addElement((void*)i);
updateStateTable(temp2, pendingChars, (int16_t)(lastState + 1));
}
}
// pop the top element off the decision point stack and merge
// it with the current decision point list (this causes the divergent
// paths through the state table to come together again on the next
// new state)
if (c == ASTERISK || c == QUESTION) {
UVector* temp2 = (UVector*)decisionPointStack.pop();
for (int32_t i = 0; i < temp2->size(); i++)
decisionPointList.addElement((*temp2)[i]);
delete temp2;
// a ? after a * modifies the behavior of * in cases where there is overlap
// between the set of characters that repeat and the characters which follow.
// Without the ?, all states following the repeating state, up to a state which
// is reached by a character that doesn't overlap, will loop back into the
// repeating state. With the ?, the mark states following the *? DON'T loop
// back into the repeating state. Thus, "[a-z]*xyz" will match the longest
// sequence of letters that ends in "xyz," while "[a-z]*? will match the
// _shortest_ sequence of letters that ends in "xyz".
// We use extra bookkeeping to achieve this effect, since everything else works
// according to the "longest possible match" principle. The basic principle
// is that transitions out of a looping state are written in over the looping
// value instead of being reconciled, and that we copy the contents of the
// looping state into empty cells of all non-terminal states that follow the
// looping state.
//System.out.println("c = " + c + ", p = " + p + ", rule.length() = " + rule.length());
if (c == ASTERISK && p + 1 < rule.length() && rule[p + 1] == QUESTION) {
//System.out.println("Saw *?");
setLoopingStates(&decisionPointList, decisionPointList);
++p;
}
}
}
// a ( marks the beginning of a sequence of characters. Parentheses can either
// contain several alternative character sequences (i.e., "(ab|cd|ef)"), or
// they can contain a sequence of characters that can repeat (i.e., "(abc)*"). Thus,
// A () group can have multiple entry and exit points. To keep track of this,
// we reserve TWO spots on the decision-point stack. The top of the stack is
// the list of exit points, which becomes the current decision point list when
// the ) is reached. The next entry down is the decision point list at the
// beginning of the (), which becomes the current decision point list at every
// entry point.
// In addition to keeping track of the exit points and the active decision
// points before the ( (i.e., the places from which the () can be entered),
// we need to keep track of the entry points in case the expression loops
// (i.e., is followed by *). We do that by creating a dummy state in the
// state table and adding it to the decision point list (BEFORE it's duplicated
// on the stack). Nobody points to this state, so it'll get optimized out
// at the end. It exists only to hold the entry points in case the ()
// expression loops.
if (c == OPEN_PAREN) {
// add a new state to the state table to hold the entry points into
// the () expression
tempStateTable.addElement(new int16_t[numCategories + 1]);
// we have to adjust lastState and currentState to account for the
// new dummy state
lastState = currentState;
++currentState;
// add the current state to the decision point list (add it at the
// BEGINNING so we can find it later)
decisionPointList.insertElementAt((void*)currentState, 0);
// finally, push a copy of the current decision point list onto the
// stack (this keeps track of the active decision point list before
// the () expression), followed by an empty decision point list
// (this will hold the exit points)
UVector* clone = new UVector;
for (int32_t i = 0; i < decisionPointList.size(); i++) {
clone->addElement(decisionPointList[i]);
}
decisionPointStack.push(clone);
decisionPointStack.push(new UVector());
}
// a | separates alternative character sequences in a () expression. When
// a | is encountered, we add the current decision point list to the exit-point
// list, and restore the decision point list to its state prior to the (.
if (c == PIPE) {
// pick out the top two decision point lists on the stack
UVector* oneDown = (UVector*)decisionPointStack.pop();
UVector* twoDown = (UVector*)decisionPointStack.peek();
decisionPointStack.push(oneDown);
// append the current decision point list to the list below it
// on the stack (the list of exit points), and restore the
// current decision point list to its state before the () expression
for (int32_t i = 0; i < decisionPointList.size(); i++)
oneDown->addElement(decisionPointList[i]);
decisionPointList.removeAllElements();
for (int32_t i = 0; i < twoDown->size(); i++)
decisionPointList.addElement((*twoDown)[i]);
}
// a ) marks the end of a sequence of characters. We do one of two things
// depending on whether the sequence repeats (i.e., whether the ) is followed
// by *): If the sequence doesn't repeat, then the exit-point list is merged
// with the current decision point list and the decision point list from before
// the () is thrown away. If the sequence does repeat, then we fish out the
// state we were in before the ( and copy all of its forward transitions
// (i.e., every transition added by the () expression) into every state in the
// exit-point list and the current decision point list. The current decision
// point list is then merged with both the exit-point list AND the saved version
// of the decision point list from before the (). Then we throw out the *.
if (c == CLOSE_PAREN) {
// pull the exit point list off the stack, merge it with the current
// decision point list, and make the merged version the current
// decision point list
UVector* exitPoints = (UVector*)decisionPointStack.pop();
for (int32_t i = 0; i < exitPoints->size(); i++)
decisionPointList.addElement((*exitPoints)[i]);
delete exitPoints;
// if the ) isn't followed by a *, then all we have to do is throw
// away the other list on the decision point stack, and we're done
if (p + 1 >= rule.length() || (
rule[p + 1] != ASTERISK &&
rule[p + 1] != PLUS &&
rule[p + 1] != QUESTION)
) {
delete (UVector*)decisionPointStack.pop();
}
// but if the sequence repeats, we have a lot more work to do...
else {
// now exitPoints and decisionPointList have to point to equivalent
// vectors, but not the SAME vector
exitPoints = new UVector;
for (int32_t i = 0; i < decisionPointList.size(); i++)
exitPoints->addElement(decisionPointList[i]);
// pop the original decision point list off the stack
UVector* temp2 = (UVector*)decisionPointStack.pop();
// we squirreled away the row number of our entry point list
// at the beginning of the original decision point list. Fish
// that state number out and retrieve the entry point list
int32_t tempStateNum = (int32_t)temp2->firstElement();
int16_t* tempState = (int16_t*)tempStateTable.elementAt(tempStateNum);
// merge the original decision point list with the current
// decision point list
if (rule.charAt(p + 1) == QUESTION || rule.charAt(p + 1) == ASTERISK) {
for (int32_t i = 0; i < temp2->size(); i++)
decisionPointList.addElement((*temp2)[i]);
delete temp2;
}
// finally, copy every forward reference from the entry point
// list into every state in the new decision point list
if (rule[p + 1] == PLUS || rule[p + 1] == ASTERISK) {
for (int32_t i = 0; i < numCategories; i++) {
if (tempState[i] > tempStateNum) {
updateStateTable(*exitPoints,
UnicodeString((UChar)(i + 0x100)),
tempState[i]);
}
}
}
// update lastState and currentState, and throw away the *
lastState = currentState;
currentState = tempStateTable.size() - 1;
++p;
delete exitPoints;
}
}
// a / marks the position where the break is to go if the character sequence
// matches this rule. We update the flag word of every state on the decision
// point list to mark them as ending states, and take note of the fact that
// we've seen the slash
if (c == SLASH) {
sawEarlyBreak = TRUE;
for (int32_t i = 0; i < decisionPointList.size(); i++) {
state = (int16_t*)tempStateTable.elementAt((int32_t)decisionPointList[i]);
state[numCategories] |= LOOKAHEAD_STATE_FLAG;
}
}
// if we get here without executing any of the above clauses, we have a
// syntax error. However, for now we just ignore the offending character
// and move on
/*
debugPrintln("====Parsed \"" + rule.substring(0, p + 1) + "\"...");
System.out.println(" currentState = " + currentState);
debugPrintVectorOfVectors(" decisionPointStack:", " ", decisionPointStack);
debugPrintVector(" ", decisionPointList);
debugPrintVector(" loopingStates = ", loopingStates);
debugPrintVector(" statesToBackfill = ", statesToBackfill);
System.out.println(" sawEarlyBreak = " + sawEarlyBreak);
debugPrintTempStateTable();
*/
// clearLoopingStates is a signal back from updateStateTable() that we've
// transitioned to a state that won't loop back to the current looping
// state. (In other words, we've gotten to a point where we can no longer
// go back into a *? we saw earlier.) Clear out the list of looping states
// and backfill any states that need to be backfilled.
if (clearLoopingStates) {
setLoopingStates(0, decisionPointList);
}
// advance to the next character, now that we've processed the current
// character
++p;
}
// this takes care of backfilling any states that still need to be backfilled
setLoopingStates(0, decisionPointList);
// when we reach the end of the string, we do a postprocessing step to mark the
// end states. The decision point list contains every state that can transition
// to the end state-- that is, every state that is the last state in a sequence
// that matches the rule. All of these states are considered "mark states"
// or "accepting states"-- that is, states that cause the position returned from
// next() to be updated. A mark state represents a possible break position.
// This allows us to look ahead and remember how far the rule matched
// before following the new branch (see next() for more information).
// The temporary state table has an extra "flag column" at the end where this
// information is stored. We mark the end states by setting a flag in their
// flag column.
// Now if we saw the / in the rule, then everything after it is lookahead
// material and the break really goes where the slash is. In this case,
// we mark these states as BOTH accepting states and lookahead states. This
// signals that these states cause the break position to be updated to the
// position of the slash rather than the current break position.
for (int32_t i = 0; i < decisionPointList.size(); i++) {
int32_t rowNum = (int32_t)decisionPointList[i];
state = (int16_t*)tempStateTable[rowNum];
state[numCategories] |= END_STATE_FLAG;
if (sawEarlyBreak) {
state[numCategories] |= LOOKAHEAD_STATE_FLAG;
}
}
/*
debugPrintln("====Parsed \"" + rule + ";");
System.out.println();
System.out.println(" currentState = " + currentState);
debugPrintVectorOfVectors(" decisionPointStack:", " ", decisionPointStack);
debugPrintVector(" ", decisionPointList);
debugPrintVector(" loopingStates = ", loopingStates);
debugPrintVector(" statesToBackfill = ", statesToBackfill);
System.out.println(" sawEarlyBreak = " + sawEarlyBreak);
debugPrintTempStateTable();
*/
}
/**
* Update entries in the state table, and merge states when necessary to keep
* the table deterministic.
* @param rows The list of rows that need updating (the decision point list)
* @param pendingChars A character category list, encoded in a String. This is the
* list of the columns that need updating.
* @param newValue Update the cells specfied above to contain this value
*/
void
RuleBasedBreakIteratorBuilder::updateStateTable(const UVector& rows,
const UnicodeString& pendingChars,
int16_t newValue)
{
// create a dummy state that has the specified row number (newValue) in
// the cells that need to be updated (those specified by pendingChars)
// and 0 in the other cells
int16_t* newValues = new int16_t[numCategories + 1];
for (int32_t i = 0; i < pendingChars.length(); i++)
newValues[(int32_t)(pendingChars[i]) - 0x100] = newValue;
// go through the list of rows to update, and update them by calling
// mergeStates() to merge them the the dummy state we created
for (int32_t i = 0; i < rows.size(); i++) {
mergeStates((int32_t)rows[i], newValues, rows);
}
}
/**
* The real work of making the state table deterministic happens here. This function
* merges a state in the state table (specified by rowNum) with a state that is
* passed in (newValues). The basic process is to copy the nonzero cells in newStates
* into the state in the state table (we'll call that oldValues). If there's a
* collision (i.e., if the same cell has a nonzero value in both states, and it's
* not the SAME value), then we have to reconcile the collision. We do this by
* creating a new state, adding it to the end of the state table, and using this
* function recursively to merge the original two states into a single, combined
* state. This process may happen recursively (i.e., each successive level may
* involve collisions). To prevent infinite recursion, we keep a log of merge
* operations. Any time we're merging two states we've merged before, we can just
* supply the row number for the result of that merge operation rather than creating
* a new state just like it.
* @param rowNum The row number in the state table of the state to be updated
* @param newValues The state to merge it with.
* @param rowsBeingUpdated A copy of the list of rows passed to updateStateTable()
* (itself a copy of the decision point list from parseRule()). Newly-created
* states get added to the decision point list if their "parents" were on it.
*/
void
RuleBasedBreakIteratorBuilder::mergeStates(int32_t rowNum,
int16_t* newValues,
const UVector& rowsBeingUpdated)
{
int16_t* oldValues = (int16_t*)(tempStateTable[rowNum]);
/*
System.out.print("***Merging " + rowNum + ":");
for (int32_t i = 0; i < oldValues.length; i++) System.out.print("\t" + oldValues[i]);
System.out.println();
System.out.print(" with \t");
for (int32_t i = 0; i < newValues.length; i++) System.out.print("\t" + newValues[i]);
System.out.println();
*/
UBool isLoopingState = loopingStates.contains((void*)rowNum);
// for each of the cells in the rows we're reconciling, do...
for (int32_t i = 0; i < numCategories; i++) {
// if they contain the same value, we don't have to do anything
if (oldValues[i] == newValues[i]) {
continue;
}
// if oldValues is a looping state and the state the current cell points to
// is too, then we can just stomp over the current value of that cell (and
// set the clear-looping-states flag if necessary)
else if (isLoopingState && loopingStates.contains((void*)oldValues[i])) {
if (newValues[i] != 0) {
if (oldValues[i] == 0) {
clearLoopingStates = TRUE;
}
oldValues[i] = newValues[i];
}
}
// if the current cell in oldValues is 0, copy in the corresponding value
// from newValues
else if (oldValues[i] == 0) {
oldValues[i] = newValues[i];
}
// the last column of each row is the flag column. Take care to merge the
// flag words correctly
else if (i == numCategories) {
oldValues[i] = (int16_t)((newValues[i] & ALL_FLAGS) | oldValues[i]);
}
// if both newValues and oldValues have a nonzero value in the current
// cell, and it isn't the same value both places...
else if (oldValues[i] != 0 && newValues[i] != 0) {
// look up this pair of cell values in the merge list. If it's
// found, update the cell in oldValues to point to the merged state
int32_t combinedRowNum = searchMergeList(oldValues[i], newValues[i]);
if (combinedRowNum != 0) {
oldValues[i] = (int16_t)combinedRowNum;
}
// otherwise, we have to reconcile them...
else {
// copy our row numbers into variables to make things easier
int32_t oldRowNum = oldValues[i];
int32_t newRowNum = newValues[i];
combinedRowNum = tempStateTable.size();
// add this pair of row numbers to the merge list (create it first
// if we haven't created the merge list yet)
int32_t* entry = new int32_t[3];
entry[0] = oldRowNum;
entry[1] = newRowNum;
entry[2] = combinedRowNum;
mergeList.addElement(entry);
//System.out.println("***At " + rowNum + ", merging " + oldRowNum + " and " + newRowNum + " into " + combinedRowNum);
// create a new row to represent the merged state, and copy the
// contents of oldRow into it, then add it to the end of the
// state table and update the original row (oldValues) to point
// to the new, merged, state
int16_t* newRow = new int16_t[numCategories + 1];
int16_t* oldRow = (int16_t*)(tempStateTable[oldRowNum]);
uprv_memcpy(newRow, oldRow, (numCategories + 1) * sizeof int16_t);
tempStateTable.addElement(newRow);
oldValues[i] = (int16_t)combinedRowNum;
//System.out.println("lastOldRowNum = " + lastOldRowNum);
//System.out.println("lastCombinedRowNum = " + lastCombinedRowNum);
//System.out.println("decisionPointList.contains(lastOldRowNum) = " + decisionPointList.contains(new Integer(lastOldRowNum)));
//System.out.println("decisionPointList.contains(lastCombinedRowNum) = " + decisionPointList.contains(new Integer(lastCombinedRowNum)));
// if the decision point list contains either of the parent rows,
// update it to include the new row as well
if ((decisionPointList.contains((void*)oldRowNum)
|| decisionPointList.contains((void*)newRowNum))
&& !decisionPointList.contains((void*)combinedRowNum)
) {
decisionPointList.addElement((void*)combinedRowNum);
}
// do the same thing with the list of rows being updated
if ((rowsBeingUpdated.contains((void*)oldRowNum)
|| rowsBeingUpdated.contains((void*)newRowNum))
&& !rowsBeingUpdated.contains((void*)combinedRowNum)
) {
decisionPointList.addElement((void*)combinedRowNum);
}
// now (groan) do the same thing for all the entries on the
// decision point stack
for (int32_t k = 0; k < decisionPointStack.size(); k++) {
UVector* dpl = (UVector*)decisionPointStack[k];
if ((dpl->contains((void*)oldRowNum)
|| dpl->contains((void*)newRowNum))
&& !dpl->contains((void*)combinedRowNum)
) {
dpl->addElement((void*)combinedRowNum);
}
}
// FINALLY (puff puff puff), call mergeStates() recursively to copy
// the row referred to by newValues into the new row and resolve any
// conflicts that come up at that level
mergeStates(combinedRowNum, (int16_t*)(tempStateTable.elementAt(
newValues[i])), rowsBeingUpdated);
}
}
}
}
/**
* The merge list is a list of pairs of rows that have been merged somewhere in
* the process of building this state table, along with the row number of the
* row containing the merged state. This function looks up a pair of row numbers
* and returns the row number of the row they combine into. (It returns 0 if
* this pair of rows isn't in the merge list.)
*/
int32_t
RuleBasedBreakIteratorBuilder::searchMergeList(int32_t a, int32_t b)
{
int32_t* entry;
for (int32_t i = 0; i < mergeList.size(); i++) {
entry = (int32_t*)(mergeList[i]);
// we have a hit if the two row numbers match the two row numbers
// in the beginning of the entry (the two that combine), in either
// order
if ((entry[0] == a && entry[1] == b) || (entry[0] == b && entry[1] == a)) {
return entry[2];
}
// we also have a hit if one of the two row numbers matches the marged
// row number and the other one matches one of the original row numbers
if ((entry[2] == a && (entry[0] == b || entry[1] == b))) {
return entry[2];
}
if ((entry[2] == b && (entry[0] == a || entry[1] == a))) {
return entry[2];
}
}
return 0;
}
/**
* This function is used to update the list of current loooping states (i.e.,
* states that are controlled by a *? construct). It backfills values from
* the looping states into unpopulated cells of the states that are currently
* marked for backfilling, and then updates the list of looping states to be
* the new list
* @param newLoopingStates The list of new looping states
* @param endStates The list of states to treat as end states (states that
* can exit the loop).
*/
void
RuleBasedBreakIteratorBuilder::setLoopingStates(const UVector* newLoopingStates,
const UVector& endStates)
{
// if the current list of looping states isn't empty, we have to backfill
// values from the looping states into the states that are waiting to be
// backfilled
if (!loopingStates.isEmpty()) {
int32_t loopingState = (int32_t)loopingStates.lastElement();
int32_t rowNum;
// don't backfill into an end state OR any state reachable from an end state
// (since the search for reachable states is recursive, it's split out into
// a separate function, eliminateBackfillStates(), below)
for (int32_t i = 0; i < endStates.size(); i++) {
eliminateBackfillStates((int32_t)endStates[i]);
}
// we DON'T actually backfill the states that need to be backfilled here.
// Instead, we MARK them for backfilling. The reason for this is that if
// there are multiple rules in the state-table description, the looping
// states may have some of their values changed by a succeeding rule, and
// this wouldn't be reflected in the backfilled states. We mark a state
// for backfilling by putting the row number of the state to copy from
// into the flag cell at the end of the row
for (int32_t i = 0; i < statesToBackfill.size(); i++) {
rowNum = (int32_t)statesToBackfill.elementAt(i);
int16_t* state = (int16_t*)tempStateTable[rowNum];
state[numCategories] =
(int16_t)((state[numCategories] & ALL_FLAGS) | loopingState);
}
statesToBackfill.removeAllElements();
loopingStates.removeAllElements();
}
if (newLoopingStates != 0) {
for (int32_t i = 0; i < newLoopingStates->size(); i++) {
loopingStates.addElement((*newLoopingStates)[i]);
}
}
}
/**
* This removes "ending states" and states reachable from them from the
* list of states to backfill.
* @param The row number of the state to remove from the backfill list
*/
void
RuleBasedBreakIteratorBuilder::eliminateBackfillStates(int32_t baseState)
{
// don't do anything unless this state is actually in the backfill list...
if (statesToBackfill.contains((void*)baseState)) {
// if it is, take it out
statesToBackfill.removeElement((void*)baseState);
// then go through and recursively call this function for every
// state that the base state points to
int16_t* state = (int16_t*)tempStateTable[baseState];
for (int32_t i = 0; i < numCategories; i++) {
if (state[i] != 0) {
eliminateBackfillStates(state[i]);
}
}
}
}
/**
* This function completes the backfilling process by actually doing the
* backfilling on the states that are marked for it
*/
void
RuleBasedBreakIteratorBuilder::backfillLoopingStates(void)
{
int16_t* state;
int16_t* loopingState = 0;
int32_t loopingStateRowNum = 0;
int32_t fromState;
// for each state in the state table...
for (int32_t i = 0; i < tempStateTable.size(); i++) {
state = (int16_t*)tempStateTable[i];
// check the state's flag word to see if it's marked for backfilling
// (it's marked for backfilling if any bits other than the two high-order
// bits are set-- if they are, then the flag word, minus the two high bits,
// is the row number to copy from)
fromState = state[numCategories] & ~ALL_FLAGS;
if (fromState > 0) {
// load up the state to copy from (if we haven't already)
if (fromState != loopingStateRowNum) {
loopingStateRowNum = fromState;
loopingState = (int16_t*)tempStateTable[loopingStateRowNum];
}
// clear out the backfill part of the flag word
state[numCategories] &= ALL_FLAGS;
// then fill all zero cells in the current state with values
// from the corresponding cells of the fromState
for (int32_t j = 0; j < numCategories + 1; j++) {
if (state[j] == 0) {
state[j] = loopingState[j];
}
else if (state[j] == DONT_LOOP_FLAG) {
state[j] = 0;
}
}
}
}
}
/**
* This function completes the state-table-building process by doing several
* postprocessing steps and copying everything into its final resting place
* in the iterator itself
* @param forward TRUE if we're working on the forward state table
*/
void
RuleBasedBreakIteratorBuilder::finishBuildingStateTable(UBool forward)
{
//debugPrintTempStateTable();
// start by backfilling the looping states
backfillLoopingStates();
//debugPrintTempStateTable();
int32_t* rowNumMap = new int32_t[tempStateTable.size()];
int32_t rowNumMapSize = tempStateTable.size();
UStack rowsToFollow;
rowsToFollow.push((void*)1);
rowNumMap[1] = 1;
// determine which states are no longer reachable from the start state
// (the reachable states will have their row numbers in the row number
// map, and the nonreachable states will have zero in the row number map)
while (rowsToFollow.size() != 0) {
int32_t rowNum = (int32_t)rowsToFollow.pop();
int16_t* row = (int16_t*)(tempStateTable[rowNum]);
for (int32_t i = 0; i < numCategories; i++) {
if (row[i] != 0) {
if (rowNumMap[row[i]] == 0) {
rowNumMap[row[i]] = row[i];
rowsToFollow.push((void*)row[i]);
}
}
}
}
/*
System.out.println("The following rows are not reachable:");
for (int32_t i = 1; i < rowNumMap.length; i++)
if (rowNumMap[i] == 0) System.out.print("\t" + i);
System.out.println();
*/
int32_t newRowNum;
// algorithm for minimizing the number of states in the table adapted from
// Aho & Ullman, "Principles of Compiler Design"
// The basic idea here is to organize the states into classes. When we're done,
// all states in the same class can be considered identical and all but one eliminated.
// initially assign states to classes based on the number of populated cells they
// contain (the class number is the number of populated cells)
int32_t* stateClasses = new int32_t[tempStateTable.size()];
int32_t nextClass = numCategories + 1;
int16_t* state1 = 0;
int16_t* state2 = 0;
for (int32_t i = 1; i < tempStateTable.size(); i++) {
if (rowNumMap[i] == 0) {
continue;
}
state1 = (int16_t*)tempStateTable[i];
for (int32_t j = 0; j < numCategories; j++) {
if (state1[j] != 0) {
++stateClasses[i];
}
}
if (stateClasses[i] == 0) {
stateClasses[i] = nextClass;
}
}
++nextClass;
// then, for each class, elect the first member of that class as that class's
// "representative". For each member of the class, compare it to the "representative."
// If there's a column position where the state being tested transitions to a
// state in a DIFFERENT class from the class where the "representative" transitions,
// then move the state into a new class. Repeat this process until no new classes
// are created.
int32_t currentClass;
int32_t lastClass;
UBool split;
do {
//System.out.println("Making a pass...");
currentClass = 1;
lastClass = nextClass;
while (currentClass < nextClass) {
//System.out.print("States in class #" + currentClass +":");
split = FALSE;
state1 = state2 = 0;
for (int32_t i = 0; i < tempStateTable.size(); i++) {
if (stateClasses[i] == currentClass) {
//System.out.print("\t" + i);
if (state1 == 0) {
state1 = (int16_t*)tempStateTable[i];
}
else {
state2 = (int16_t*)tempStateTable[i];
for (int32_t j = 0; j < numCategories + 1; j++) {
if ((j == numCategories && state1[j] != state2[j] && forward)
|| (j != numCategories && stateClasses[state1[j]]
!= stateClasses[state2[j]])) {
stateClasses[i] = nextClass;
split = TRUE;
break;
}
}
}
}
}
if (split) {
++nextClass;
}
++currentClass;
//System.out.println();
}
} while (lastClass != nextClass);
// at this point, all of the states in a class except the first one (the
//"representative") can be eliminated, so update the row-number map accordingly
int32_t* representatives = new int32_t[nextClass];
for (int32_t i = 1; i < tempStateTable.size(); i++) {
if (representatives[stateClasses[i]] == 0) {
representatives[stateClasses[i]] = i;
}
else {
rowNumMap[i] = representatives[stateClasses[i]];
}
}
delete [] stateClasses;
delete [] representatives;
//System.out.println("Renumbering...");
// renumber all remaining rows...
// first drop all that are either unreferenced or not a class representative
for (int32_t i = 1; i < rowNumMapSize; i++) {
if (rowNumMap[i] != i) {
delete [] tempStateTable[i];
tempStateTable.setElementAt(0, i);
}
}
// then calculate everybody's new row number and update the row
// number map appropriately (the first pass updates the row numbers
// of all the class representatives [the rows we're keeping], and the
// second pass updates the cross references for all the rows that
// are being deleted)
newRowNum = 1;
for (int32_t i = 1; i < rowNumMapSize; i++) {
if (tempStateTable[i] != 0) {
rowNumMap[i] = newRowNum++;
}
}
for (int32_t i = 1; i < rowNumMapSize; i++) {
if (tempStateTable[i] == 0) {
rowNumMap[i] = rowNumMap[rowNumMap[i]];
}
}
//for (int32_t i = 1; i < rowNumMap.length; i++) rowNumMap[i] = i; int32_t newRowNum = rowNumMap.length;
// allocate the permanent state table, and copy the remaining rows into it
// (adjusting all the cell values, of course)
// this section does that for the forward state table
if (forward) {
tables->endStates = new UBool[newRowNum];
tables->lookaheadStates = new UBool[newRowNum];
tables->stateTable = new int16_t[newRowNum * numCategories];
int32_t p = 0;
int32_t p2 = 0;
for (int32_t i = 0; i < tempStateTable.size(); i++) {
int16_t* row = (int16_t*)(tempStateTable[i]);
if (row == 0) {
continue;
}
for (int32_t j = 0; j < numCategories; j++) {
tables->stateTable[p] = (int16_t)(rowNumMap[row[j]]);
++p;
}
tables->endStates[p2] = ((row[numCategories] & END_STATE_FLAG) != 0);
tables->lookaheadStates[p2] = ((row[numCategories] & LOOKAHEAD_STATE_FLAG) != 0);
++p2;
}
}
// and this section does it for the backward state table
else {
tables->backwardsStateTable = new int16_t[newRowNum * numCategories];
int32_t p = 0;
for (int32_t i = 0; i < tempStateTable.size(); i++) {
int16_t* row = (int16_t*)(tempStateTable[i]);
if (row == 0) {
continue;
}
for (int32_t j = 0; j < numCategories; j++) {
tables->backwardsStateTable[p] = (int16_t)(rowNumMap[row[j]]);
++p;
}
}
}
delete [] rowNumMap;
}
/**
* This function builds the backward state table from the forward state
* table and any additional rules (identified by the ! on the front)
* supplied in the description
*/
void
RuleBasedBreakIteratorBuilder::buildBackwardsStateTable(UErrorCode& err)
{
if (U_FAILURE(err))
return;
// create the temporary state table and seed it with two rows (row 0
// isn't used for anything, and we have to create row 1 (the initial
// state) before we can do anything else
tempStateTable.removeAllElements();
tempStateTable.addElement(new int16_t[numCategories + 1]);
tempStateTable.addElement(new int16_t[numCategories + 1]);
// although the backwards state table is built automatically from the forward
// state table, there are some situations (the default sentence-break rules,
// for example) where this doesn't yield enough stop states, causing a dramatic
// drop in performance. To help with these cases, the user may supply
// supplemental rules that are added to the backward state table. These have
// the same syntax as the normal break rules, but begin with BANG to distinguish
// them from normal break rules
for (int32_t i = 0; i < tempRuleList.size(); i++) {
UnicodeString* rule = (UnicodeString*)tempRuleList[i];
if ((*rule)[0] == BANG) {
rule->remove(0, 1);
parseRule(*rule, FALSE);
}
}
backfillLoopingStates();
// Backwards iteration is qualitatively different from forwards iteration.
// This is because backwards iteration has to be made to operate from no context
// at all-- the user should be able to ask BreakIterator for the break position
// immediately on either side of some arbitrary offset in the text. The
// forward iteration table doesn't let us do that-- it assumes complete
// information on the context, which means starting from the beginning of the
// document.
// The way we do backward and random-access iteration is to back up from the
// current (or user-specified) position until we see something we're sure is
// a break position (it may not be the last break position immediately
// preceding our starting point, however). Then we roll forward from there to
// locate the actual break position we're after.
// This means that the backwards state table doesn't have to identify every
// break position, allowing the building algorithm to be much simpler. Here,
// we use a "pairs" approach, scanning the forward-iteration state table for
// pairs of character categories we ALWAYS break between, and building a state
// table from that information. No context is required-- all this state table
// looks at is a pair of adjacent characters.
// It's possible that the user has supplied supplementary rules (see above).
// This has to be done first to keep parseRule() and friends from becoming
// EVEN MORE complicated. The automatically-generated states are appended
// onto the end of the state table, and then the two sets of rules are
// stitched together at the end. Take note of the row number of the
// first row of the auromatically-generated part.
int32_t backTableOffset = tempStateTable.size();
if (backTableOffset > 2) {
++backTableOffset;
}
// the automatically-generated part of the table models a two-dimensional
// array where the two dimensions represent the two characters we're currently
// looking at. To model this as a state table, we actually need one additional
// row to represent the initial state. It gets populated with the row numbers
// of the other rows (in order).
for (int32_t i = 0; i < numCategories + 1; i++)
tempStateTable.addElement(new int16_t[numCategories + 1]);
int16_t* state = (int16_t*)tempStateTable[backTableOffset - 1];
for (int32_t i = 0; i < numCategories; i++)
state[i] = (int16_t)(i + backTableOffset);
// scavenge the forward state table for pairs of character categories
// that always have a break between them. The algorithm is as follows:
// Look down each column in the state table. For each nonzero cell in
// that column, look up the row it points to. For each nonzero cell in
// that row, populate a cell in the backwards state table: the row number
// of that cell is the number of the column we were scanning (plus the
// offset that locates this sub-table), and the column number of that cell
// is the column number of the nonzero cell we just found. This cell is
// populated with its own column number (adjusted according to the actual
// location of the sub-table). This process will produce a state table
// whose behavior is the same as looking up successive pairs of characters
// in an array of Booleans to determine whether there is a break.
int32_t numRows = tempStateTable.size() / numCategories;
for (int32_t column = 0; column < numCategories; column++) {
for (int32_t row = 0; row < numRows; row++) {
int32_t nextRow = tables->lookupState(row, column);
if (nextRow != 0) {
for (int32_t nextColumn = 0; nextColumn < numCategories; nextColumn++) {
int32_t cellValue = tables->lookupState(nextRow, nextColumn);
if (cellValue != 0) {
state = (int16_t*)tempStateTable[nextColumn + backTableOffset];
state[column] = (int16_t)(column + backTableOffset);
}
}
}
}
}
//debugPrintTempStateTable();
// if the user specified some backward-iteration rules with the ! token,
// we have to merge the resulting state table with the auto-generated one
// above. First copy the populated cells from row 1 over the populated
// cells in the auto-generated table. Then copy values from row 1 of the
// auto-generated table into all of the the unpopulated cells of the
// rule-based table.
if (backTableOffset > 1) {
// for every row in the auto-generated sub-table, if a cell is
// populated that is also populated in row 1 of the rule-based
// sub-table, copy the value from row 1 over the value in the
// auto-generated sub-table
state = (int16_t*)tempStateTable[1];
for (int32_t i = backTableOffset - 1; i < tempStateTable.size(); i++) {
int16_t* state2 = (int16_t*)tempStateTable[i];
for (int32_t j = 0; j < numCategories; j++) {
if (state[j] != 0 && state2[j] != 0) {
state2[j] = state[j];
}
}
}
// now, for every row in the rule-based sub-table that is not
// an end state, fill in all unpopulated cells with the values
// of the corresponding cells in the first row of the auto-
// generated sub-table.
state = (int16_t*)tempStateTable[backTableOffset - 1];
for (int32_t i = 1; i < backTableOffset - 1; i++) {
int16_t* state2 = (int16_t*)tempStateTable[i];
if ((state2[numCategories] & END_STATE_FLAG) == 0) {
for (int32_t j = 0; j < numCategories; j++) {
if (state2[j] == 0) {
state2[j] = state[j];
}
}
}
}
}
//debugPrintTempStateTable();
// finally, clean everything up and copy it into the actual BreakIterator
// by calling finishBuildingStateTable()
finishBuildingStateTable(FALSE);
/*
System.out.print("C:\t");
for (int32_t i = 0; i < numCategories; i++)
System.out.print(Integer.toString(i) + "\t");
System.out.println(); System.out.print("=================================================");
for (int32_t i = 0; i < backwardsStateTable.length; i++) {
if (i % numCategories == 0) {
System.out.println();
System.out.print(Integer.toString(i / numCategories) + ":\t");
}
if (backwardsStateTable[i] == 0) System.out.print(".\t"); else System.out.print(Integer.toString(backwardsStateTable[i]) + "\t");
}
System.out.println();
*/
}
void
RuleBasedBreakIteratorBuilder::setUpErrorMessage(const UnicodeString& message,
int32_t position,
const UnicodeString& context)
{
static UChar lbrks[] = { 0x000a, 0x000a };
errorMessage = context;
errorMessage.insert(position, lbrks, 2);
errorMessage.insert(0, lbrks, 1);
errorMessage.insert(0, message);
}