modules/skshaper/src/SkUnicode_icu.cpp - skia - Git at Google

 /*
 * Copyright 2020 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 #include "include/core/SkString.h"
 #include "include/private/SkMutex.h"
 #include "include/private/SkTFitsIn.h"
 #include "include/private/SkTHash.h"
 #include "include/private/SkTemplates.h"
 #include "modules/skshaper/src/SkUnicode.h"
 #include "src/utils/SkUTF.h"
 #include <unicode/ubidi.h>
 #include <unicode/ubrk.h>
 #include <unicode/uscript.h>
 #include <unicode/ustring.h>
 #include <unicode/utext.h>
 #include <unicode/utypes.h>
 #include <vector>
 #include <functional>

 #if defined(SK_USING_THIRD_PARTY_ICU)
 #include "SkLoadICU.h"
 #endif

 // ubrk_clone added as draft in ICU69 and Android API 31 (first ICU NDK).
 // ubrk_safeClone deprecated in ICU69 and not exposed by Android.
 template<typename...> using void_t = void;
 template<typename T, typename = void>
 struct SkUbrkClone {
     UBreakIterator* operator()(T bi, UErrorCode* status) {
         return ubrk_safeClone(bi, nullptr, nullptr, status);
     }
 };
 template<typename T>
 struct SkUbrkClone<T, void_t<decltype(ubrk_clone(std::declval<T>(), nullptr))>> {
     UBreakIterator* operator()(T bi, UErrorCode* status) {
         return ubrk_clone(bi, status);
     }
 };

 using SkUnicodeBidi = std::unique_ptr<UBiDi, SkFunctionWrapper<decltype(ubidi_close), ubidi_close>>;
 using ICUUText = std::unique_ptr<UText, SkFunctionWrapper<decltype(utext_close), utext_close>>;
 using ICUBreakIterator = std::unique_ptr<UBreakIterator, SkFunctionWrapper<decltype(ubrk_close), ubrk_close>>;

 /** Replaces invalid utf-8 sequences with REPLACEMENT CHARACTER U+FFFD. */
 static inline SkUnichar utf8_next(const char** ptr, const char* end) {
     SkUnichar val = SkUTF::NextUTF8(ptr, end);
     return val < 0 ? 0xFFFD : val;
 }

 static UBreakIteratorType convertType(SkUnicode::BreakType type) {
     switch (type) {
         case SkUnicode::BreakType::kLines: return UBRK_LINE;
         case SkUnicode::BreakType::kGraphemes: return UBRK_CHARACTER;
         case SkUnicode::BreakType::kWords: return UBRK_WORD;
         default:
             return UBRK_CHARACTER;
     }
 }

 class SkBidiIterator_icu : public SkBidiIterator {
     SkUnicodeBidi fBidi;
 public:
     explicit SkBidiIterator_icu(SkUnicodeBidi bidi) : fBidi(std::move(bidi)) {}
     Position getLength() override { return ubidi_getLength(fBidi.get()); }
     Level getLevelAt(Position pos) override { return ubidi_getLevelAt(fBidi.get(), pos); }

     static std::unique_ptr<SkBidiIterator> makeBidiIterator(const uint16_t utf16[], int utf16Units, Direction dir) {
         UErrorCode status = U_ZERO_ERROR;
         SkUnicodeBidi bidi(ubidi_openSized(utf16Units, 0, &status));
         if (U_FAILURE(status)) {
             SkDEBUGF("Bidi error: %s", u_errorName(status));
             return nullptr;
         }
         SkASSERT(bidi);
         uint8_t bidiLevel = (dir == SkBidiIterator::kLTR) ? UBIDI_LTR : UBIDI_RTL;
         // The required lifetime of utf16 isn't well documented.
         // It appears it isn't used after ubidi_setPara except through ubidi_getText.
         ubidi_setPara(bidi.get(), (const UChar*)utf16, utf16Units, bidiLevel, nullptr, &status);
         if (U_FAILURE(status)) {
             SkDEBUGF("Bidi error: %s", u_errorName(status));
             return nullptr;
         }
         return std::unique_ptr<SkBidiIterator>(new SkBidiIterator_icu(std::move(bidi)));
     }

     // ICU bidi iterator works with utf16 but clients (Flutter for instance) may work with utf8
     // This method allows the clients not to think about all these details
     static std::unique_ptr<SkBidiIterator> makeBidiIterator(const char utf8[], int utf8Units, Direction dir) {
         // Convert utf8 into utf16 since ubidi only accepts utf16
         if (!SkTFitsIn<int32_t>(utf8Units)) {
             SkDEBUGF("Bidi error: text too long");
             return nullptr;
         }

         // Getting the length like this seems to always set U_BUFFER_OVERFLOW_ERROR
         int utf16Units = SkUTF::UTF8ToUTF16(nullptr, 0, utf8, utf8Units);
         if (utf16Units < 0) {
             SkDEBUGF("Bidi error: Invalid utf8 input");
             return nullptr;
         }
         std::unique_ptr<uint16_t[]> utf16(new uint16_t[utf16Units]);
         SkDEBUGCODE(int dstLen =) SkUTF::UTF8ToUTF16(utf16.get(), utf16Units, utf8, utf8Units);
         SkASSERT(dstLen == utf16Units);

         return makeBidiIterator(utf16.get(), utf16Units, dir);
     }

     // This method returns the final results only: a list of bidi regions
     // (this is all SkParagraph really needs; SkShaper however uses the iterator itself)
     static std::vector<Region> getBidiRegions(const char utf8[], int utf8Units, Direction dir) {

         auto bidiIterator = makeBidiIterator(utf8, utf8Units, dir);
         std::vector<Region> bidiRegions;
         const char* start8 = utf8;
         const char* end8 = utf8 + utf8Units;
         SkBidiIterator::Level currentLevel = 0;

         Position pos8 = 0;
         Position pos16 = 0;
         Position end16 = bidiIterator->getLength();
         while (pos16 < end16) {
             auto level = bidiIterator->getLevelAt(pos16);
             if (pos16 == 0) {
                 currentLevel = level;
             } else if (level != currentLevel) {
                 auto end = start8 - utf8;
                 bidiRegions.emplace_back(pos8, end, currentLevel);
                 currentLevel = level;
                 pos8 = end;
             }
             SkUnichar u = utf8_next(&start8, end8);
             pos16 += SkUTF::ToUTF16(u);
         }
         auto end = start8 - utf8;
         if (end != pos8) {
             bidiRegions.emplace_back(pos8, end, currentLevel);
         }
         return bidiRegions;
     }
 };

 void SkBidiIterator::ReorderVisual(const Level runLevels[], int levelsCount,
                                    int32_t logicalFromVisual[]) {
     ubidi_reorderVisual(runLevels, levelsCount, logicalFromVisual);
 }

 class SkBreakIterator_icu : public SkBreakIterator {
     ICUBreakIterator fBreakIterator;
     Position fLastResult;
  public:
     explicit SkBreakIterator_icu(ICUBreakIterator iter)
         : fBreakIterator(std::move(iter)), fLastResult(0) {}
     Position first() override
       { return fLastResult = ubrk_first(fBreakIterator.get()); }
     Position current() override
       { return fLastResult = ubrk_current(fBreakIterator.get()); }
     Position next() override
       { return fLastResult = ubrk_next(fBreakIterator.get()); }
     Position preceding(Position offset) override
         { return fLastResult = ubrk_preceding(fBreakIterator.get(), offset); }
     Position following(Position offset) override
         { return fLastResult = ubrk_following(fBreakIterator.get(), offset);}
     Status status() override { return ubrk_getRuleStatus(fBreakIterator.get()); }
     bool isDone() override { return fLastResult == UBRK_DONE; }

     bool setText(const char utftext8[], int utf8Units) override {
         UErrorCode status = U_ZERO_ERROR;
         ICUUText text(utext_openUTF8(nullptr, &utftext8[0], utf8Units, &status));

         if (U_FAILURE(status)) {
             SkDEBUGF("Break error: %s", u_errorName(status));
             return false;
         }
         SkASSERT(text);
         ubrk_setUText(fBreakIterator.get(), text.get(), &status);
         if (U_FAILURE(status)) {
             SkDEBUGF("Break error: %s", u_errorName(status));
             return false;
         }
         fLastResult = 0;
         return true;
     }
 };

 class SkIcuBreakIteratorCache {
     SkTHashMap<SkUnicode::BreakType, ICUBreakIterator> fBreakCache;
     SkMutex fBreakCacheMutex;

  public:
     static SkIcuBreakIteratorCache& get() {
         static SkIcuBreakIteratorCache instance;
         return instance;
     }

     ICUBreakIterator makeBreakIterator(SkUnicode::BreakType type) {
         UErrorCode status = U_ZERO_ERROR;
         ICUBreakIterator* cachedIterator;
         {
             SkAutoMutexExclusive lock(fBreakCacheMutex);
             cachedIterator = fBreakCache.find(type);
             if (!cachedIterator) {
                 ICUBreakIterator newIterator(ubrk_open(convertType(type), uloc_getDefault(), nullptr, 0, &status));
                 if (U_FAILURE(status)) {
                     SkDEBUGF("Break error: %s", u_errorName(status));
                 } else {
                     cachedIterator = fBreakCache.set(type, std::move(newIterator));
                 }
             }
         }
         ICUBreakIterator iterator;
         if (cachedIterator) {
             iterator.reset(SkUbrkClone<const UBreakIterator*>()(cachedIterator->get(), &status));
             if (U_FAILURE(status)) {
                 SkDEBUGF("Break error: %s", u_errorName(status));
             }
         }
         return iterator;
     }
 };

 class SkScriptIterator_icu : public SkScriptIterator {
  public:
    bool getScript(SkUnichar u, ScriptID* script) override {
         UErrorCode status = U_ZERO_ERROR;
         UScriptCode scriptCode = uscript_getScript(u, &status);
         if (U_FAILURE (status)) {
             return false;
         }
         if (script) {
             *script = (ScriptID)scriptCode;
         }
         return true;
    }

    static std::unique_ptr<SkScriptIterator> makeScriptIterator() {
         return std::unique_ptr<SkScriptIterator>(new SkScriptIterator_icu());
    }
 };

 class SkUnicode_icu : public SkUnicode {
     static bool extractBidi(const char utf8[],
                             int utf8Units,
                             TextDirection dir,
                             std::vector<BidiRegion>* bidiRegions) {

         // Convert to UTF16 since for now bidi iterator only operates on utf16
         std::unique_ptr<uint16_t[]> utf16;
         auto utf16Units = utf8ToUtf16(utf8, utf8Units, &utf16);
         if (utf16Units < 0) {
             return false;
         }

         // Create bidi iterator
         UErrorCode status = U_ZERO_ERROR;
         SkUnicodeBidi bidi(ubidi_openSized(utf16Units, 0, &status));
         if (U_FAILURE(status)) {
             SkDEBUGF("Bidi error: %s", u_errorName(status));
             return false;
         }
         SkASSERT(bidi);
         uint8_t bidiLevel = (dir == TextDirection::kLTR) ? UBIDI_LTR : UBIDI_RTL;
         // The required lifetime of utf16 isn't well documented.
         // It appears it isn't used after ubidi_setPara except through ubidi_getText.
         ubidi_setPara(bidi.get(), (const UChar*)utf16.get(), utf16Units, bidiLevel, nullptr, &status);
         if (U_FAILURE(status)) {
             SkDEBUGF("Bidi error: %s", u_errorName(status));
             return false;
         }

         // Iterate through bidi regions and the result positions into utf8
         const char* start8 = utf8;
         const char* end8 = utf8 + utf8Units;
         BidiLevel currentLevel = 0;

         Position pos8 = 0;
         Position pos16 = 0;
         Position end16 = ubidi_getLength(bidi.get());
         while (pos16 < end16) {
             auto level = ubidi_getLevelAt(bidi.get(), pos16);
             if (pos16 == 0) {
                 currentLevel = level;
             } else if (level != currentLevel) {
                 Position end = start8 - utf8;
                 bidiRegions->emplace_back(pos8, end, currentLevel);
                 currentLevel = level;
                 pos8 = end;
             }
             SkUnichar u = utf8_next(&start8, end8);
             pos16 += SkUTF::ToUTF16(u);
         }
         Position end = start8 - utf8;
         if (end != pos8) {
             bidiRegions->emplace_back(pos8, end, currentLevel);
         }
         return true;
     }

     static bool extractWords(uint16_t utf16[], int utf16Units, std::vector<Position>* words) {

         UErrorCode status = U_ZERO_ERROR;

         ICUBreakIterator iterator = SkIcuBreakIteratorCache::get().makeBreakIterator(BreakType::kWords);
         if (!iterator) {
             SkDEBUGF("Break error: %s", u_errorName(status));
             return false;
         }
         SkASSERT(iterator);

         ICUUText utf16UText(utext_openUChars(nullptr, (UChar*)utf16, utf16Units, &status));
         if (U_FAILURE(status)) {
             SkDEBUGF("Break error: %s", u_errorName(status));
             return false;
         }

         ubrk_setUText(iterator.get(), utf16UText.get(), &status);
         if (U_FAILURE(status)) {
             SkDEBUGF("Break error: %s", u_errorName(status));
             return false;
         }

         // Get the words
         int32_t pos = ubrk_first(iterator.get());
         while (pos != UBRK_DONE) {
             words->emplace_back(pos);
             pos = ubrk_next(iterator.get());
         }

         return true;
     }

     static bool extractPositions
         (const char utf8[], int utf8Units, BreakType type, std::function<void(int, int)> setBreak) {

         UErrorCode status = U_ZERO_ERROR;
         ICUUText text(utext_openUTF8(nullptr, &utf8[0], utf8Units, &status));

         if (U_FAILURE(status)) {
             SkDEBUGF("Break error: %s", u_errorName(status));
             return false;
         }
         SkASSERT(text);

         ICUBreakIterator iterator = SkIcuBreakIteratorCache::get().makeBreakIterator(type);
         if (!iterator) {
             return false;
         }

         ubrk_setUText(iterator.get(), text.get(), &status);
         if (U_FAILURE(status)) {
             SkDEBUGF("Break error: %s", u_errorName(status));
             return false;
         }

         auto iter = iterator.get();
         int32_t pos = ubrk_first(iter);
         while (pos != UBRK_DONE) {
             auto status = type == SkUnicode::BreakType::kLines
                               ? UBRK_LINE_SOFT
                               : ubrk_getRuleStatus(iter);
             setBreak(pos, status);
             pos = ubrk_next(iter);
         }

         if (type == SkUnicode::BreakType::kLines) {
             // This is a workaround for https://bugs.chromium.org/p/skia/issues/detail?id=10715
             // (ICU line break iterator does not work correctly on Thai text with new lines)
             // So, we only use the iterator to collect soft line breaks and
             // scan the text for all hard line breaks ourselves
             const char* end = utf8 + utf8Units;
             const char* ch = utf8;
             while (ch < end) {
                 auto unichar = utf8_next(&ch, end);
                 if (isHardLineBreak(unichar)) {
                     setBreak(ch - utf8, UBRK_LINE_HARD);
                 }
             }
         }
         return true;
     }

     static int utf8ToUtf16(const char* utf8, size_t utf8Units, std::unique_ptr<uint16_t[]>* utf16) {
         int utf16Units = SkUTF::UTF8ToUTF16(nullptr, 0, utf8, utf8Units);
         if (utf16Units < 0) {
             SkDEBUGF("Convert error: Invalid utf8 input");
             return utf16Units;
         }
         *utf16 = std::unique_ptr<uint16_t[]>(new uint16_t[utf16Units]);
         SkDEBUGCODE(int dstLen =) SkUTF::UTF8ToUTF16(utf16->get(), utf16Units, utf8, utf8Units);
         SkASSERT(dstLen == utf16Units);
         return utf16Units;
    }

     static int utf16ToUtf8(const uint16_t* utf16, size_t utf16Units, std::unique_ptr<char[]>* utf8) {
         int utf8Units = SkUTF::UTF16ToUTF8(nullptr, 0, utf16, utf16Units);
         if (utf8Units < 0) {
             SkDEBUGF("Convert error: Invalid utf16 input");
             return utf8Units;
         }
         *utf8 = std::unique_ptr<char[]>(new char[utf8Units]);
         SkDEBUGCODE(int dstLen =) SkUTF::UTF16ToUTF8(utf8->get(), utf8Units, utf16, utf16Units);
         SkASSERT(dstLen == utf8Units);
         return utf8Units;
    }

 public:
     ~SkUnicode_icu() override { }
     std::unique_ptr<SkBidiIterator> makeBidiIterator(const uint16_t text[], int count,
                                                      SkBidiIterator::Direction dir) override {
         return SkBidiIterator_icu::makeBidiIterator(text, count, dir);
     }
     std::unique_ptr<SkBidiIterator> makeBidiIterator(const char text[],
                                                      int count,
                                                      SkBidiIterator::Direction dir) override {
         return SkBidiIterator_icu::makeBidiIterator(text, count, dir);
     }
     std::unique_ptr<SkBreakIterator> makeBreakIterator(const char locale[],
                                                        BreakType breakType) override {
         UErrorCode status = U_ZERO_ERROR;
         ICUBreakIterator iterator(ubrk_open(convertType(breakType), locale, nullptr, 0, &status));
         if (U_FAILURE(status)) {
             SkDEBUGF("Break error: %s", u_errorName(status));
             return nullptr;
         }
         return std::unique_ptr<SkBreakIterator>(new SkBreakIterator_icu(std::move(iterator)));
     }
     std::unique_ptr<SkScriptIterator> makeScriptIterator() override {
         return SkScriptIterator_icu::makeScriptIterator();
     }

     // TODO: Use ICU data file to detect controls and whitespaces
     bool isControl(SkUnichar utf8) override {
         return u_iscntrl(utf8);
     }

     bool isWhitespace(SkUnichar utf8) override {
         return u_isWhitespace(utf8);
     }

     bool isSpace(SkUnichar utf8) override {
         return u_isspace(utf8);
     }

     static bool isHardLineBreak(SkUnichar utf8) {
         auto property = u_getIntPropertyValue(utf8, UCHAR_LINE_BREAK);
         return property == U_LB_LINE_FEED || property == U_LB_MANDATORY_BREAK;
     }

     SkString convertUtf16ToUtf8(const std::u16string& utf16) override {
         std::unique_ptr<char[]> utf8;
         auto utf8Units = SkUnicode_icu::utf16ToUtf8((uint16_t*)utf16.data(), utf16.size(), &utf8);
         if (utf8Units >= 0) {
             return SkString(utf8.get(), utf8Units);
         } else {
             return SkString();
         }
     }

     bool getBidiRegions(const char utf8[],
                         int utf8Units,
                         TextDirection dir,
                         std::vector<BidiRegion>* results) override {
         return extractBidi(utf8, utf8Units, dir, results);
     }

     bool getLineBreaks(const char utf8[],
                        int utf8Units,
                        std::vector<LineBreakBefore>* results) override {

         return extractPositions(utf8, utf8Units, BreakType::kLines,
             [results](int pos, int status) {
                     results->emplace_back(pos, status == UBRK_LINE_HARD
                                                         ? LineBreakType::kHardLineBreak
                                                         : LineBreakType::kSoftLineBreak);
         });
     }

     bool getWords(const char utf8[], int utf8Units, std::vector<Position>* results) override {

         // Convert to UTF16 since we want the results in utf16
         std::unique_ptr<uint16_t[]> utf16;
         auto utf16Units = utf8ToUtf16(utf8, utf8Units, &utf16);
         if (utf16Units < 0) {
             return false;
         }

         return extractWords(utf16.get(), utf16Units, results);
     }

     bool getGraphemes(const char utf8[], int utf8Units, std::vector<Position>* results) override {

         return extractPositions(utf8, utf8Units, BreakType::kGraphemes,
             [results](int pos, int status) { results->emplace_back(pos);
         });
     }

     void reorderVisual(const BidiLevel runLevels[],
                        int levelsCount,
                        int32_t logicalFromVisual[]) override {
         ubidi_reorderVisual(runLevels, levelsCount, logicalFromVisual);
     }
 };

 std::unique_ptr<SkUnicode> SkUnicode::Make() {
     #if defined(SK_USING_THIRD_PARTY_ICU)
     if (!SkLoadICU()) {
         SkDEBUGF("SkLoadICU() failed!\n");
         return nullptr;
     }
     #endif
     return std::make_unique<SkUnicode_icu>();
 }
	/*
	* Copyright 2020 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/
	#include "include/core/SkString.h"
	#include "include/private/SkMutex.h"
	#include "include/private/SkTFitsIn.h"
	#include "include/private/SkTHash.h"
	#include "include/private/SkTemplates.h"
	#include "modules/skshaper/src/SkUnicode.h"
	#include "src/utils/SkUTF.h"
	#include <unicode/ubidi.h>
	#include <unicode/ubrk.h>
	#include <unicode/uscript.h>
	#include <unicode/ustring.h>
	#include <unicode/utext.h>
	#include <unicode/utypes.h>
	#include <vector>
	#include <functional>

	#if defined(SK_USING_THIRD_PARTY_ICU)
	#include "SkLoadICU.h"
	#endif

	// ubrk_clone added as draft in ICU69 and Android API 31 (first ICU NDK).
	// ubrk_safeClone deprecated in ICU69 and not exposed by Android.
	template<typename...> using void_t = void;
	template<typename T, typename = void>
	struct SkUbrkClone {
	UBreakIterator* operator()(T bi, UErrorCode* status) {
	return ubrk_safeClone(bi, nullptr, nullptr, status);
	}
	};
	template<typename T>
	struct SkUbrkClone<T, void_t<decltype(ubrk_clone(std::declval<T>(), nullptr))>> {
	UBreakIterator* operator()(T bi, UErrorCode* status) {
	return ubrk_clone(bi, status);
	}
	};

	using SkUnicodeBidi = std::unique_ptr<UBiDi, SkFunctionWrapper<decltype(ubidi_close), ubidi_close>>;
	using ICUUText = std::unique_ptr<UText, SkFunctionWrapper<decltype(utext_close), utext_close>>;
	using ICUBreakIterator = std::unique_ptr<UBreakIterator, SkFunctionWrapper<decltype(ubrk_close), ubrk_close>>;

	/** Replaces invalid utf-8 sequences with REPLACEMENT CHARACTER U+FFFD. */
	static inline SkUnichar utf8_next(const char** ptr, const char* end) {
	SkUnichar val = SkUTF::NextUTF8(ptr, end);
	return val < 0 ? 0xFFFD : val;
	}

	static UBreakIteratorType convertType(SkUnicode::BreakType type) {
	switch (type) {
	case SkUnicode::BreakType::kLines: return UBRK_LINE;
	case SkUnicode::BreakType::kGraphemes: return UBRK_CHARACTER;
	case SkUnicode::BreakType::kWords: return UBRK_WORD;
	default:
	return UBRK_CHARACTER;
	}
	}

	class SkBidiIterator_icu : public SkBidiIterator {
	SkUnicodeBidi fBidi;
	public:
	explicit SkBidiIterator_icu(SkUnicodeBidi bidi) : fBidi(std::move(bidi)) {}
	Position getLength() override { return ubidi_getLength(fBidi.get()); }
	Level getLevelAt(Position pos) override { return ubidi_getLevelAt(fBidi.get(), pos); }

	static std::unique_ptr<SkBidiIterator> makeBidiIterator(const uint16_t utf16[], int utf16Units, Direction dir) {
	UErrorCode status = U_ZERO_ERROR;
	SkUnicodeBidi bidi(ubidi_openSized(utf16Units, 0, &status));
	if (U_FAILURE(status)) {
	SkDEBUGF("Bidi error: %s", u_errorName(status));
	return nullptr;
	}
	SkASSERT(bidi);
	uint8_t bidiLevel = (dir == SkBidiIterator::kLTR) ? UBIDI_LTR : UBIDI_RTL;
	// The required lifetime of utf16 isn't well documented.
	// It appears it isn't used after ubidi_setPara except through ubidi_getText.
	ubidi_setPara(bidi.get(), (const UChar*)utf16, utf16Units, bidiLevel, nullptr, &status);
	if (U_FAILURE(status)) {
	SkDEBUGF("Bidi error: %s", u_errorName(status));
	return nullptr;
	}
	return std::unique_ptr<SkBidiIterator>(new SkBidiIterator_icu(std::move(bidi)));
	}

	// ICU bidi iterator works with utf16 but clients (Flutter for instance) may work with utf8
	// This method allows the clients not to think about all these details
	static std::unique_ptr<SkBidiIterator> makeBidiIterator(const char utf8[], int utf8Units, Direction dir) {
	// Convert utf8 into utf16 since ubidi only accepts utf16
	if (!SkTFitsIn<int32_t>(utf8Units)) {
	SkDEBUGF("Bidi error: text too long");
	return nullptr;
	}

	// Getting the length like this seems to always set U_BUFFER_OVERFLOW_ERROR
	int utf16Units = SkUTF::UTF8ToUTF16(nullptr, 0, utf8, utf8Units);
	if (utf16Units < 0) {
	SkDEBUGF("Bidi error: Invalid utf8 input");
	return nullptr;
	}
	std::unique_ptr<uint16_t[]> utf16(new uint16_t[utf16Units]);
	SkDEBUGCODE(int dstLen =) SkUTF::UTF8ToUTF16(utf16.get(), utf16Units, utf8, utf8Units);
	SkASSERT(dstLen == utf16Units);

	return makeBidiIterator(utf16.get(), utf16Units, dir);
	}

	// This method returns the final results only: a list of bidi regions
	// (this is all SkParagraph really needs; SkShaper however uses the iterator itself)
	static std::vector<Region> getBidiRegions(const char utf8[], int utf8Units, Direction dir) {

	auto bidiIterator = makeBidiIterator(utf8, utf8Units, dir);
	std::vector<Region> bidiRegions;
	const char* start8 = utf8;
	const char* end8 = utf8 + utf8Units;
	SkBidiIterator::Level currentLevel = 0;

	Position pos8 = 0;
	Position pos16 = 0;
	Position end16 = bidiIterator->getLength();
	while (pos16 < end16) {
	auto level = bidiIterator->getLevelAt(pos16);
	if (pos16 == 0) {
	currentLevel = level;
	} else if (level != currentLevel) {
	auto end = start8 - utf8;
	bidiRegions.emplace_back(pos8, end, currentLevel);
	currentLevel = level;
	pos8 = end;
	}
	SkUnichar u = utf8_next(&start8, end8);
	pos16 += SkUTF::ToUTF16(u);
	}
	auto end = start8 - utf8;
	if (end != pos8) {
	bidiRegions.emplace_back(pos8, end, currentLevel);
	}
	return bidiRegions;
	}
	};

	void SkBidiIterator::ReorderVisual(const Level runLevels[], int levelsCount,
	int32_t logicalFromVisual[]) {
	ubidi_reorderVisual(runLevels, levelsCount, logicalFromVisual);
	}

	class SkBreakIterator_icu : public SkBreakIterator {
	ICUBreakIterator fBreakIterator;
	Position fLastResult;
	public:
	explicit SkBreakIterator_icu(ICUBreakIterator iter)
	: fBreakIterator(std::move(iter)), fLastResult(0) {}
	Position first() override
	{ return fLastResult = ubrk_first(fBreakIterator.get()); }
	Position current() override
	{ return fLastResult = ubrk_current(fBreakIterator.get()); }
	Position next() override
	{ return fLastResult = ubrk_next(fBreakIterator.get()); }
	Position preceding(Position offset) override
	{ return fLastResult = ubrk_preceding(fBreakIterator.get(), offset); }
	Position following(Position offset) override
	{ return fLastResult = ubrk_following(fBreakIterator.get(), offset);}
	Status status() override { return ubrk_getRuleStatus(fBreakIterator.get()); }
	bool isDone() override { return fLastResult == UBRK_DONE; }

	bool setText(const char utftext8[], int utf8Units) override {
	UErrorCode status = U_ZERO_ERROR;
	ICUUText text(utext_openUTF8(nullptr, &utftext8[0], utf8Units, &status));

	if (U_FAILURE(status)) {
	SkDEBUGF("Break error: %s", u_errorName(status));
	return false;
	}
	SkASSERT(text);
	ubrk_setUText(fBreakIterator.get(), text.get(), &status);
	if (U_FAILURE(status)) {
	SkDEBUGF("Break error: %s", u_errorName(status));
	return false;
	}
	fLastResult = 0;
	return true;
	}
	};

	class SkIcuBreakIteratorCache {
	SkTHashMap<SkUnicode::BreakType, ICUBreakIterator> fBreakCache;
	SkMutex fBreakCacheMutex;

	public:
	static SkIcuBreakIteratorCache& get() {
	static SkIcuBreakIteratorCache instance;
	return instance;
	}

	ICUBreakIterator makeBreakIterator(SkUnicode::BreakType type) {
	UErrorCode status = U_ZERO_ERROR;
	ICUBreakIterator* cachedIterator;
	{
	SkAutoMutexExclusive lock(fBreakCacheMutex);
	cachedIterator = fBreakCache.find(type);
	if (!cachedIterator) {
	ICUBreakIterator newIterator(ubrk_open(convertType(type), uloc_getDefault(), nullptr, 0, &status));
	if (U_FAILURE(status)) {
	SkDEBUGF("Break error: %s", u_errorName(status));
	} else {
	cachedIterator = fBreakCache.set(type, std::move(newIterator));
	}
	}
	}
	ICUBreakIterator iterator;
	if (cachedIterator) {
	iterator.reset(SkUbrkClone<const UBreakIterator*>()(cachedIterator->get(), &status));
	if (U_FAILURE(status)) {
	SkDEBUGF("Break error: %s", u_errorName(status));
	}
	}
	return iterator;
	}
	};

	class SkScriptIterator_icu : public SkScriptIterator {
	public:
	bool getScript(SkUnichar u, ScriptID* script) override {
	UErrorCode status = U_ZERO_ERROR;
	UScriptCode scriptCode = uscript_getScript(u, &status);
	if (U_FAILURE (status)) {
	return false;
	}
	if (script) {
	*script = (ScriptID)scriptCode;
	}
	return true;
	}

	static std::unique_ptr<SkScriptIterator> makeScriptIterator() {
	return std::unique_ptr<SkScriptIterator>(new SkScriptIterator_icu());
	}
	};

	class SkUnicode_icu : public SkUnicode {
	static bool extractBidi(const char utf8[],
	int utf8Units,
	TextDirection dir,
	std::vector<BidiRegion>* bidiRegions) {

	// Convert to UTF16 since for now bidi iterator only operates on utf16
	std::unique_ptr<uint16_t[]> utf16;
	auto utf16Units = utf8ToUtf16(utf8, utf8Units, &utf16);
	if (utf16Units < 0) {
	return false;
	}

	// Create bidi iterator
	UErrorCode status = U_ZERO_ERROR;
	SkUnicodeBidi bidi(ubidi_openSized(utf16Units, 0, &status));
	if (U_FAILURE(status)) {
	SkDEBUGF("Bidi error: %s", u_errorName(status));
	return false;
	}
	SkASSERT(bidi);
	uint8_t bidiLevel = (dir == TextDirection::kLTR) ? UBIDI_LTR : UBIDI_RTL;
	// The required lifetime of utf16 isn't well documented.
	// It appears it isn't used after ubidi_setPara except through ubidi_getText.
	ubidi_setPara(bidi.get(), (const UChar*)utf16.get(), utf16Units, bidiLevel, nullptr, &status);
	if (U_FAILURE(status)) {
	SkDEBUGF("Bidi error: %s", u_errorName(status));
	return false;
	}

	// Iterate through bidi regions and the result positions into utf8
	const char* start8 = utf8;
	const char* end8 = utf8 + utf8Units;
	BidiLevel currentLevel = 0;

	Position pos8 = 0;
	Position pos16 = 0;
	Position end16 = ubidi_getLength(bidi.get());
	while (pos16 < end16) {
	auto level = ubidi_getLevelAt(bidi.get(), pos16);
	if (pos16 == 0) {
	currentLevel = level;
	} else if (level != currentLevel) {
	Position end = start8 - utf8;
	bidiRegions->emplace_back(pos8, end, currentLevel);
	currentLevel = level;
	pos8 = end;
	}
	SkUnichar u = utf8_next(&start8, end8);
	pos16 += SkUTF::ToUTF16(u);
	}
	Position end = start8 - utf8;
	if (end != pos8) {
	bidiRegions->emplace_back(pos8, end, currentLevel);
	}
	return true;
	}

	static bool extractWords(uint16_t utf16[], int utf16Units, std::vector<Position>* words) {

	UErrorCode status = U_ZERO_ERROR;

	ICUBreakIterator iterator = SkIcuBreakIteratorCache::get().makeBreakIterator(BreakType::kWords);
	if (!iterator) {
	SkDEBUGF("Break error: %s", u_errorName(status));
	return false;
	}
	SkASSERT(iterator);

	ICUUText utf16UText(utext_openUChars(nullptr, (UChar*)utf16, utf16Units, &status));
	if (U_FAILURE(status)) {
	SkDEBUGF("Break error: %s", u_errorName(status));
	return false;
	}

	ubrk_setUText(iterator.get(), utf16UText.get(), &status);
	if (U_FAILURE(status)) {
	SkDEBUGF("Break error: %s", u_errorName(status));
	return false;
	}

	// Get the words
	int32_t pos = ubrk_first(iterator.get());
	while (pos != UBRK_DONE) {
	words->emplace_back(pos);
	pos = ubrk_next(iterator.get());
	}

	return true;
	}

	static bool extractPositions
	(const char utf8[], int utf8Units, BreakType type, std::function<void(int, int)> setBreak) {

	UErrorCode status = U_ZERO_ERROR;
	ICUUText text(utext_openUTF8(nullptr, &utf8[0], utf8Units, &status));

	if (U_FAILURE(status)) {
	SkDEBUGF("Break error: %s", u_errorName(status));
	return false;
	}
	SkASSERT(text);

	ICUBreakIterator iterator = SkIcuBreakIteratorCache::get().makeBreakIterator(type);
	if (!iterator) {
	return false;
	}

	ubrk_setUText(iterator.get(), text.get(), &status);
	if (U_FAILURE(status)) {
	SkDEBUGF("Break error: %s", u_errorName(status));
	return false;
	}

	auto iter = iterator.get();
	int32_t pos = ubrk_first(iter);
	while (pos != UBRK_DONE) {
	auto status = type == SkUnicode::BreakType::kLines
	? UBRK_LINE_SOFT
	: ubrk_getRuleStatus(iter);
	setBreak(pos, status);
	pos = ubrk_next(iter);
	}

	if (type == SkUnicode::BreakType::kLines) {
	// This is a workaround for https://bugs.chromium.org/p/skia/issues/detail?id=10715
	// (ICU line break iterator does not work correctly on Thai text with new lines)
	// So, we only use the iterator to collect soft line breaks and
	// scan the text for all hard line breaks ourselves
	const char* end = utf8 + utf8Units;
	const char* ch = utf8;
	while (ch < end) {
	auto unichar = utf8_next(&ch, end);
	if (isHardLineBreak(unichar)) {
	setBreak(ch - utf8, UBRK_LINE_HARD);
	}
	}
	}
	return true;
	}

	static int utf8ToUtf16(const char* utf8, size_t utf8Units, std::unique_ptr<uint16_t[]>* utf16) {
	int utf16Units = SkUTF::UTF8ToUTF16(nullptr, 0, utf8, utf8Units);
	if (utf16Units < 0) {
	SkDEBUGF("Convert error: Invalid utf8 input");
	return utf16Units;
	}
	*utf16 = std::unique_ptr<uint16_t[]>(new uint16_t[utf16Units]);
	SkDEBUGCODE(int dstLen =) SkUTF::UTF8ToUTF16(utf16->get(), utf16Units, utf8, utf8Units);
	SkASSERT(dstLen == utf16Units);
	return utf16Units;
	}

	static int utf16ToUtf8(const uint16_t* utf16, size_t utf16Units, std::unique_ptr<char[]>* utf8) {
	int utf8Units = SkUTF::UTF16ToUTF8(nullptr, 0, utf16, utf16Units);
	if (utf8Units < 0) {
	SkDEBUGF("Convert error: Invalid utf16 input");
	return utf8Units;
	}
	*utf8 = std::unique_ptr<char[]>(new char[utf8Units]);
	SkDEBUGCODE(int dstLen =) SkUTF::UTF16ToUTF8(utf8->get(), utf8Units, utf16, utf16Units);
	SkASSERT(dstLen == utf8Units);
	return utf8Units;
	}

	public:
	~SkUnicode_icu() override { }
	std::unique_ptr<SkBidiIterator> makeBidiIterator(const uint16_t text[], int count,
	SkBidiIterator::Direction dir) override {
	return SkBidiIterator_icu::makeBidiIterator(text, count, dir);
	}
	std::unique_ptr<SkBidiIterator> makeBidiIterator(const char text[],
	int count,
	SkBidiIterator::Direction dir) override {
	return SkBidiIterator_icu::makeBidiIterator(text, count, dir);
	}
	std::unique_ptr<SkBreakIterator> makeBreakIterator(const char locale[],
	BreakType breakType) override {
	UErrorCode status = U_ZERO_ERROR;
	ICUBreakIterator iterator(ubrk_open(convertType(breakType), locale, nullptr, 0, &status));
	if (U_FAILURE(status)) {
	SkDEBUGF("Break error: %s", u_errorName(status));
	return nullptr;
	}
	return std::unique_ptr<SkBreakIterator>(new SkBreakIterator_icu(std::move(iterator)));
	}
	std::unique_ptr<SkScriptIterator> makeScriptIterator() override {
	return SkScriptIterator_icu::makeScriptIterator();
	}

	// TODO: Use ICU data file to detect controls and whitespaces
	bool isControl(SkUnichar utf8) override {
	return u_iscntrl(utf8);
	}

	bool isWhitespace(SkUnichar utf8) override {
	return u_isWhitespace(utf8);
	}

	bool isSpace(SkUnichar utf8) override {
	return u_isspace(utf8);
	}

	static bool isHardLineBreak(SkUnichar utf8) {
	auto property = u_getIntPropertyValue(utf8, UCHAR_LINE_BREAK);
	return property == U_LB_LINE_FEED \|\| property == U_LB_MANDATORY_BREAK;
	}

	SkString convertUtf16ToUtf8(const std::u16string& utf16) override {
	std::unique_ptr<char[]> utf8;
	auto utf8Units = SkUnicode_icu::utf16ToUtf8((uint16_t*)utf16.data(), utf16.size(), &utf8);
	if (utf8Units >= 0) {
	return SkString(utf8.get(), utf8Units);
	} else {
	return SkString();
	}
	}

	bool getBidiRegions(const char utf8[],
	int utf8Units,
	TextDirection dir,
	std::vector<BidiRegion>* results) override {
	return extractBidi(utf8, utf8Units, dir, results);
	}

	bool getLineBreaks(const char utf8[],
	int utf8Units,
	std::vector<LineBreakBefore>* results) override {

	return extractPositions(utf8, utf8Units, BreakType::kLines,
	[results](int pos, int status) {
	results->emplace_back(pos, status == UBRK_LINE_HARD
	? LineBreakType::kHardLineBreak
	: LineBreakType::kSoftLineBreak);
	});
	}

	bool getWords(const char utf8[], int utf8Units, std::vector<Position>* results) override {

	// Convert to UTF16 since we want the results in utf16
	std::unique_ptr<uint16_t[]> utf16;
	auto utf16Units = utf8ToUtf16(utf8, utf8Units, &utf16);
	if (utf16Units < 0) {
	return false;
	}

	return extractWords(utf16.get(), utf16Units, results);
	}

	bool getGraphemes(const char utf8[], int utf8Units, std::vector<Position>* results) override {

	return extractPositions(utf8, utf8Units, BreakType::kGraphemes,
	[results](int pos, int status) { results->emplace_back(pos);
	});
	}

	void reorderVisual(const BidiLevel runLevels[],
	int levelsCount,
	int32_t logicalFromVisual[]) override {
	ubidi_reorderVisual(runLevels, levelsCount, logicalFromVisual);
	}
	};

	std::unique_ptr<SkUnicode> SkUnicode::Make() {
	#if defined(SK_USING_THIRD_PARTY_ICU)
	if (!SkLoadICU()) {
	SkDEBUGF("SkLoadICU() failed!\n");
	return nullptr;
	}
	#endif
	return std::make_unique<SkUnicode_icu>();
	}