modules/skunicode/src/SkUnicode_icu.cpp

/*
* 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 "modules/skunicode/src/SkUnicode_icu.h"

#include "include/core/SkString.h"
#include "include/core/SkTypes.h"
#include "include/private/SkBitmaskEnum.h"
#include "include/private/SkMutex.h"
#include "include/private/SkOnce.h"
#include "include/private/SkTArray.h"
#include "include/private/SkTFitsIn.h"
#include "include/private/SkTHash.h"
#include "include/private/SkTemplates.h"
#include "include/private/SkTo.h"
#include "modules/skunicode/include/SkUnicode.h"
#include "src/utils/SkUTF.h"

#include <functional>
#include <string>
#include <unicode/umachine.h>
#include <utility>
#include <vector>

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

static const SkICULib* ICULib() {
    static const auto gICU = SkLoadICULib();

    return gICU.get();
}

// sk_* wrappers for ICU funcs
#define SKICU_FUNC(funcname)                                                                \
    template <typename... Args>                                                             \
    auto sk_##funcname(Args&&... args) -> decltype(funcname(std::forward<Args>(args)...)) { \
        return ICULib()->f_##funcname(std::forward<Args>(args)...);                         \
    }                                                                                       \

SKICU_EMIT_FUNCS
#undef SKICU_FUNC

static inline UBreakIterator* sk_ubrk_clone(const UBreakIterator* bi, UErrorCode* status) {
    const auto* icu = ICULib();
    SkASSERT(icu->f_ubrk_clone_ || icu->f_ubrk_safeClone_);
    return icu->f_ubrk_clone_
        ? icu->f_ubrk_clone_(bi, status)
        : icu->f_ubrk_safeClone_(bi, nullptr, nullptr, status);
}

static void ubidi_close_wrapper(UBiDi* bidi) {
    sk_ubidi_close(bidi);
}
static UText* utext_close_wrapper(UText* ut) {
    return sk_utext_close(ut);
}
static void ubrk_close_wrapper(UBreakIterator* bi) {
    sk_ubrk_close(bi);
}

using SkUnicodeBidi = std::unique_ptr<UBiDi, SkFunctionWrapper<decltype(ubidi_close),
                                                               ubidi_close_wrapper>>;
using ICUUText = std::unique_ptr<UText, SkFunctionWrapper<decltype(utext_close),
                                                         utext_close_wrapper>>;
using ICUBreakIterator = std::unique_ptr<UBreakIterator, SkFunctionWrapper<decltype(ubrk_close),
                                                                           ubrk_close_wrapper>>;
/** 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 sk_ubidi_getLength(fBidi.get()); }
    Level getLevelAt(Position pos) override { return sk_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(sk_ubidi_openSized(utf16Units, 0, &status));
        if (U_FAILURE(status)) {
            SkDEBUGF("Bidi error: %s", sk_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.
        sk_ubidi_setPara(bidi.get(), (const UChar*)utf16, utf16Units, bidiLevel, nullptr, &status);
        if (U_FAILURE(status)) {
            SkDEBUGF("Bidi error: %s", sk_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);
    }
};

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 = sk_ubrk_first(fBreakIterator.get()); }
    Position current() override { return fLastResult = sk_ubrk_current(fBreakIterator.get()); }
    Position next() override { return fLastResult = sk_ubrk_next(fBreakIterator.get()); }
    Status status() override { return sk_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(sk_utext_openUTF8(nullptr, &utftext8[0], utf8Units, &status));

        if (U_FAILURE(status)) {
            SkDEBUGF("Break error: %s", sk_u_errorName(status));
            return false;
        }
        SkASSERT(text);
        sk_ubrk_setUText(fBreakIterator.get(), text.get(), &status);
        if (U_FAILURE(status)) {
            SkDEBUGF("Break error: %s", sk_u_errorName(status));
            return false;
        }
        fLastResult = 0;
        return true;
    }
    bool setText(const char16_t utftext16[], int utf16Units) override {
        UErrorCode status = U_ZERO_ERROR;
        ICUUText text(sk_utext_openUChars(nullptr, reinterpret_cast<const UChar*>(&utftext16[0]),
                                          utf16Units, &status));

        if (U_FAILURE(status)) {
            SkDEBUGF("Break error: %s", sk_u_errorName(status));
            return false;
        }
        SkASSERT(text);
        sk_ubrk_setUText(fBreakIterator.get(), text.get(), &status);
        if (U_FAILURE(status)) {
            SkDEBUGF("Break error: %s", sk_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(sk_ubrk_open(convertType(type), sk_uloc_getDefault(),
                                                          nullptr, 0, &status));
                if (U_FAILURE(status)) {
                    SkDEBUGF("Break error: %s", sk_u_errorName(status));
                } else {
                    cachedIterator = fBreakCache.set(type, std::move(newIterator));
                }
            }
        }
        ICUBreakIterator iterator;
        if (cachedIterator) {
            iterator.reset(sk_ubrk_clone(cachedIterator->get(), &status));
            if (U_FAILURE(status)) {
                SkDEBUGF("Break error: %s", sk_u_errorName(status));
            }
        }
        return iterator;
    }
};

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
        auto utf16 = convertUtf8ToUtf16(utf8, utf8Units);

        // Create bidi iterator
        UErrorCode status = U_ZERO_ERROR;
        SkUnicodeBidi bidi(sk_ubidi_openSized(utf16.size(), 0, &status));
        if (U_FAILURE(status)) {
            SkDEBUGF("Bidi error: %s", sk_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.
        sk_ubidi_setPara(bidi.get(), (const UChar*)utf16.c_str(), utf16.size(), bidiLevel, nullptr,
                         &status);
        if (U_FAILURE(status)) {
            SkDEBUGF("Bidi error: %s", sk_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 = sk_ubidi_getLength(bidi.get());

        if (end16 == 0) {
            return true;
        }
        if (sk_ubidi_getDirection(bidi.get()) != UBIDI_MIXED) {
            // The entire paragraph is unidirectional.
            bidiRegions->emplace_back(0, utf8Units, sk_ubidi_getLevelAt(bidi.get(), 0));
            return true;
        }

        while (pos16 < end16) {
            auto level = sk_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", sk_u_errorName(status));
            return false;
        }
        SkASSERT(iterator);

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

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

        // Get the words
        int32_t pos = sk_ubrk_first(iterator.get());
        while (pos != UBRK_DONE) {
            words->emplace_back(pos);
            pos = sk_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(sk_utext_openUTF8(nullptr, &utf8[0], utf8Units, &status));

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

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

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

        auto iter = iterator.get();
        int32_t pos = sk_ubrk_first(iter);
        while (pos != UBRK_DONE) {
            int s = type == SkUnicode::BreakType::kLines
                        ? UBRK_LINE_SOFT
                        : sk_ubrk_getRuleStatus(iter);
            setBreak(pos, s);
            pos = sk_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 bool isControl(SkUnichar utf8) {
        return sk_u_iscntrl(utf8);
    }

    static bool isWhitespace(SkUnichar utf8) {
        return sk_u_isWhitespace(utf8);
    }

    static bool isSpace(SkUnichar utf8) {
        return sk_u_isspace(utf8);
    }

    static bool isTabulation(SkUnichar utf8) {
        return utf8 == '\t';
    }

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

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(sk_ubrk_open(convertType(breakType), locale, nullptr, 0,
                                               &status));
        if (U_FAILURE(status)) {
            SkDEBUGF("Break error: %s", sk_u_errorName(status));
            return nullptr;
        }
        return std::unique_ptr<SkBreakIterator>(new SkBreakIterator_icu(std::move(iterator)));
    }
    std::unique_ptr<SkBreakIterator> makeBreakIterator(BreakType breakType) override {
        return makeBreakIterator(sk_uloc_getDefault(), breakType);
    }

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

    SkString toUpper(const SkString& str) override {
        // Convert to UTF16 since that's what ICU wants.
        auto str16 = convertUtf8ToUtf16(str.c_str(), str.size());

        UErrorCode icu_err = U_ZERO_ERROR;
        const auto upper16len = sk_u_strToUpper(nullptr, 0, (UChar*)(str16.c_str()), str16.size(),
                                                nullptr, &icu_err);
        if (icu_err != U_BUFFER_OVERFLOW_ERROR || upper16len <= 0) {
            return SkString();
        }

        SkAutoSTArray<128, uint16_t> upper16(upper16len);
        icu_err = U_ZERO_ERROR;
        sk_u_strToUpper((UChar*)(upper16.get()), SkToS32(upper16.size()),
                        (UChar*)(str16.c_str()), str16.size(),
                        nullptr, &icu_err);
        SkASSERT(!U_FAILURE(icu_err));

        // ... and back to utf8 'cause that's what we want.
        return convertUtf16ToUtf8((char16_t*)upper16.get(), upper16.size());
    }

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

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

        // Convert to UTF16 since we want the results in utf16
        auto utf16 = convertUtf8ToUtf16(utf8, utf8Units);
        return SkUnicode_icu::extractWords((uint16_t*)utf16.c_str(), utf16.size(), results);
    }

    bool computeCodeUnitFlags(char utf8[], int utf8Units, bool replaceTabs,
                          SkTArray<SkUnicode::CodeUnitFlags, true>* results) override {
        results->reset();
        results->push_back_n(utf8Units + 1, CodeUnitFlags::kNoCodeUnitFlag);

        SkUnicode_icu::extractPositions(utf8, utf8Units, BreakType::kLines, [&](int pos,
                                                                       int status) {
            (*results)[pos] |= status == UBRK_LINE_HARD
                                    ? CodeUnitFlags::kHardLineBreakBefore
                                    : CodeUnitFlags::kSoftLineBreakBefore;
        });

        SkUnicode_icu::extractPositions(utf8, utf8Units, BreakType::kGraphemes, [&](int pos,
                                                                       int status) {
            (*results)[pos] |= CodeUnitFlags::kGraphemeStart;
        });

        const char* current = utf8;
        const char* end = utf8 + utf8Units;
        while (current < end) {
            auto before = current - utf8;
            SkUnichar unichar = SkUTF::NextUTF8(&current, end);
            if (unichar < 0) unichar = 0xFFFD;
            auto after = current - utf8;
            if (replaceTabs && SkUnicode_icu::isTabulation(unichar)) {
                results->at(before) |= SkUnicode::kTabulation;
                if (replaceTabs) {
                    unichar = ' ';
                    utf8[before] = ' ';
                }
            }
            for (auto i = before; i < after; ++i) {
                if (SkUnicode_icu::isSpace(unichar)) {
                    results->at(i) |= SkUnicode::kPartOfIntraWordBreak;
                }
                if (SkUnicode_icu::isWhitespace(unichar)) {
                    results->at(i) |= SkUnicode::kPartOfWhiteSpaceBreak;
                }
                if (SkUnicode_icu::isControl(unichar)) {
                    results->at(i) |= SkUnicode::kControl;
                }
            }
        }

        return true;
    }

    bool computeCodeUnitFlags(char16_t utf16[], int utf16Units, bool replaceTabs,
                          SkTArray<SkUnicode::CodeUnitFlags, true>* results) override {
        results->reset();
        results->push_back_n(utf16Units + 1, CodeUnitFlags::kNoCodeUnitFlag);

        // Get white spaces
        this->forEachCodepoint((char16_t*)&utf16[0], utf16Units,
           [results, replaceTabs, &utf16](SkUnichar unichar, int32_t start, int32_t end) {
                for (auto i = start; i < end; ++i) {
                    if (replaceTabs && SkUnicode_icu::isTabulation(unichar)) {
                        results->at(i) |= SkUnicode::kTabulation;
                    if (replaceTabs) {
                            unichar = ' ';
                            utf16[start] = ' ';
                        }
                    }
                    if (SkUnicode_icu::isSpace(unichar)) {
                        results->at(i) |= SkUnicode::kPartOfIntraWordBreak;
                    }
                    if (SkUnicode_icu::isWhitespace(unichar)) {
                        results->at(i) |= SkUnicode::kPartOfWhiteSpaceBreak;
                    }
                    if (SkUnicode_icu::isControl(unichar)) {
                        results->at(i) |= SkUnicode::kControl;
                    }
                }
           });
        // Get graphemes
        this->forEachBreak((char16_t*)&utf16[0],
                           utf16Units,
                           SkUnicode::BreakType::kGraphemes,
                           [results](SkBreakIterator::Position pos, SkBreakIterator::Status) {
                               (*results)[pos] |= CodeUnitFlags::kGraphemeStart;
                           });
        // Get line breaks
        this->forEachBreak(
                (char16_t*)&utf16[0],
                utf16Units,
                SkUnicode::BreakType::kLines,
                [results](SkBreakIterator::Position pos, SkBreakIterator::Status status) {
                    if (status ==
                        (SkBreakIterator::Status)SkUnicode::LineBreakType::kHardLineBreak) {
                        // Hard line breaks clears off all the other flags
                        // TODO: Treat \n as a formatting mark and do not pass it to SkShaper
                        (*results)[pos-1] = CodeUnitFlags::kHardLineBreakBefore;
                    } else {
                        (*results)[pos] |= CodeUnitFlags::kSoftLineBreakBefore;
                    }
                });

        return true;
    }

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

std::unique_ptr<SkUnicode> SkUnicode::Make() {
    #if defined(SK_USING_THIRD_PARTY_ICU)
    if (!SkLoadICU()) {
        static SkOnce once;
        once([] { SkDEBUGF("SkLoadICU() failed!\n"); });
        return nullptr;
    }
    #endif

    return ICULib()
        ? std::make_unique<SkUnicode_icu>()
        : nullptr;
}