TextBreakIterator.cpp   [plain text]

/*
 * (C) 1999 Lars Knoll (knoll@kde.org)
 * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 * Copyright (C) 2007-2009 Torch Mobile, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include "config.h"
#include "TextBreakIterator.h"

#include "LineBreakIteratorPoolICU.h"
#include "UTextProviderLatin1.h"
#include "UTextProviderUTF16.h"
#include <mutex>
#include <wtf/Atomics.h>
#include <wtf/text/StringView.h>

namespace WebCore {

// Iterator initialization

static TextBreakIterator* initializeIterator(UBreakIteratorType type, const char* locale = currentTextBreakLocaleID())
{
    UErrorCode openStatus = U_ZERO_ERROR;
    TextBreakIterator* iterator = reinterpret_cast<TextBreakIterator*>(ubrk_open(type, locale, 0, 0, &openStatus));
    ASSERT_WITH_MESSAGE(U_SUCCESS(openStatus), "ICU could not open a break iterator: %s (%d)", u_errorName(openStatus), openStatus);
    return iterator;
}

#if !PLATFORM(IOS)

static TextBreakIterator* initializeIteratorWithRules(const char* breakRules)
{
    UParseError parseStatus;
    UErrorCode openStatus = U_ZERO_ERROR;
    unsigned length = strlen(breakRules);
    auto upconvertedCharacters = StringView(reinterpret_cast<const LChar*>(breakRules), length).upconvertedCharacters();
    TextBreakIterator* iterator = reinterpret_cast<TextBreakIterator*>(ubrk_openRules(upconvertedCharacters, length, 0, 0, &parseStatus, &openStatus));
    ASSERT_WITH_MESSAGE(U_SUCCESS(openStatus), "ICU could not open a break iterator: %s (%d)", u_errorName(openStatus), openStatus);
    return iterator;
}

#endif


// Iterator text setting

static TextBreakIterator* setTextForIterator(TextBreakIterator& iterator, StringView string)
{
    if (string.is8Bit()) {
        UTextWithBuffer textLocal;
        textLocal.text = UTEXT_INITIALIZER;
        textLocal.text.extraSize = sizeof(textLocal.buffer);
        textLocal.text.pExtra = textLocal.buffer;

        UErrorCode openStatus = U_ZERO_ERROR;
        UText* text = openLatin1UTextProvider(&textLocal, string.characters8(), string.length(), &openStatus);
        if (U_FAILURE(openStatus)) {
            LOG_ERROR("uTextOpenLatin1 failed with status %d", openStatus);
            return nullptr;
        }

        UErrorCode setTextStatus = U_ZERO_ERROR;
        ubrk_setUText(reinterpret_cast<UBreakIterator*>(&iterator), text, &setTextStatus);
        if (U_FAILURE(setTextStatus)) {
            LOG_ERROR("ubrk_setUText failed with status %d", setTextStatus);
            return nullptr;
        }

        utext_close(text);
    } else {
        UErrorCode setTextStatus = U_ZERO_ERROR;
        ubrk_setText(reinterpret_cast<UBreakIterator*>(&iterator), string.characters16(), string.length(), &setTextStatus);
        if (U_FAILURE(setTextStatus))
            return nullptr;
    }

    return &iterator;
}

static TextBreakIterator* setContextAwareTextForIterator(TextBreakIterator& iterator, StringView string, const UChar* priorContext, unsigned priorContextLength)
{
    if (string.is8Bit()) {
        UTextWithBuffer textLocal;
        textLocal.text = UTEXT_INITIALIZER;
        textLocal.text.extraSize = sizeof(textLocal.buffer);
        textLocal.text.pExtra = textLocal.buffer;

        UErrorCode openStatus = U_ZERO_ERROR;
        UText* text = openLatin1ContextAwareUTextProvider(&textLocal, string.characters8(), string.length(), priorContext, priorContextLength, &openStatus);
        if (U_FAILURE(openStatus)) {
            LOG_ERROR("openLatin1ContextAwareUTextProvider failed with status %d", openStatus);
            return nullptr;
        }

        UErrorCode setTextStatus = U_ZERO_ERROR;
        ubrk_setUText(reinterpret_cast<UBreakIterator*>(&iterator), text, &setTextStatus);
        if (U_FAILURE(setTextStatus)) {
            LOG_ERROR("ubrk_setUText failed with status %d", setTextStatus);
            return nullptr;
        }

        utext_close(text);
    } else {
        UText textLocal = UTEXT_INITIALIZER;

        UErrorCode openStatus = U_ZERO_ERROR;
        UText* text = openUTF16ContextAwareUTextProvider(&textLocal, string.characters16(), string.length(), priorContext, priorContextLength, &openStatus);
        if (U_FAILURE(openStatus)) {
            LOG_ERROR("openUTF16ContextAwareUTextProvider failed with status %d", openStatus);
            return 0;
        }

        UErrorCode setTextStatus = U_ZERO_ERROR;
        ubrk_setUText(reinterpret_cast<UBreakIterator*>(&iterator), text, &setTextStatus);
        if (U_FAILURE(setTextStatus)) {
            LOG_ERROR("ubrk_setUText failed with status %d", setTextStatus);
            return nullptr;
        }

        utext_close(text);
    }

    return &iterator;
}


// Static iterators

TextBreakIterator* wordBreakIterator(StringView string)
{
    static TextBreakIterator* staticWordBreakIterator = initializeIterator(UBRK_WORD);
    if (!staticWordBreakIterator)
        return nullptr;

    return setTextForIterator(*staticWordBreakIterator, string);
}

TextBreakIterator* sentenceBreakIterator(StringView string)
{
    static TextBreakIterator* staticSentenceBreakIterator = initializeIterator(UBRK_SENTENCE);
    if (!staticSentenceBreakIterator)
        return nullptr;

    return setTextForIterator(*staticSentenceBreakIterator, string);
}

TextBreakIterator* cursorMovementIterator(StringView string)
{
#if !PLATFORM(IOS)
    // This rule set is based on character-break iterator rules of ICU 4.0
    // <http://source.icu-project.org/repos/icu/icu/tags/release-4-0/source/data/brkitr/char.txt>.
    // The major differences from the original ones are listed below:
    // * Replaced '[\p{Grapheme_Cluster_Break = SpacingMark}]' with '[\p{General_Category = Spacing Mark} - $Extend]' for ICU 3.8 or earlier;
    // * Removed rules that prevent a cursor from moving after prepend characters (Bug 24342);
    // * Added rules that prevent a cursor from moving after virama signs of Indic languages except Tamil (Bug 15790), and;
    // * Added rules that prevent a cursor from moving before Japanese half-width katakara voiced marks.
    // * Added rules for regional indicator symbols.
    static const char* kRules =
        "$CR      = [\\p{Grapheme_Cluster_Break = CR}];"
        "$LF      = [\\p{Grapheme_Cluster_Break = LF}];"
        "$Control = [\\p{Grapheme_Cluster_Break = Control}];"
        "$VoiceMarks = [\\uFF9E\\uFF9F];"  // Japanese half-width katakana voiced marks
        "$Extend  = [\\p{Grapheme_Cluster_Break = Extend} $VoiceMarks - [\\u0E30 \\u0E32 \\u0E45 \\u0EB0 \\u0EB2]];"
        "$SpacingMark = [[\\p{General_Category = Spacing Mark}] - $Extend];"
        "$L       = [\\p{Grapheme_Cluster_Break = L}];"
        "$V       = [\\p{Grapheme_Cluster_Break = V}];"
        "$T       = [\\p{Grapheme_Cluster_Break = T}];"
        "$LV      = [\\p{Grapheme_Cluster_Break = LV}];"
        "$LVT     = [\\p{Grapheme_Cluster_Break = LVT}];"
        "$Hin0    = [\\u0905-\\u0939];"    // Devanagari Letter A,...,Ha
        "$HinV    = \\u094D;"              // Devanagari Sign Virama
        "$Hin1    = [\\u0915-\\u0939];"    // Devanagari Letter Ka,...,Ha
        "$Ben0    = [\\u0985-\\u09B9];"    // Bengali Letter A,...,Ha
        "$BenV    = \\u09CD;"              // Bengali Sign Virama
        "$Ben1    = [\\u0995-\\u09B9];"    // Bengali Letter Ka,...,Ha
        "$Pan0    = [\\u0A05-\\u0A39];"    // Gurmukhi Letter A,...,Ha
        "$PanV    = \\u0A4D;"              // Gurmukhi Sign Virama
        "$Pan1    = [\\u0A15-\\u0A39];"    // Gurmukhi Letter Ka,...,Ha
        "$Guj0    = [\\u0A85-\\u0AB9];"    // Gujarati Letter A,...,Ha
        "$GujV    = \\u0ACD;"              // Gujarati Sign Virama
        "$Guj1    = [\\u0A95-\\u0AB9];"    // Gujarati Letter Ka,...,Ha
        "$Ori0    = [\\u0B05-\\u0B39];"    // Oriya Letter A,...,Ha
        "$OriV    = \\u0B4D;"              // Oriya Sign Virama
        "$Ori1    = [\\u0B15-\\u0B39];"    // Oriya Letter Ka,...,Ha
        "$Tel0    = [\\u0C05-\\u0C39];"    // Telugu Letter A,...,Ha
        "$TelV    = \\u0C4D;"              // Telugu Sign Virama
        "$Tel1    = [\\u0C14-\\u0C39];"    // Telugu Letter Ka,...,Ha
        "$Kan0    = [\\u0C85-\\u0CB9];"    // Kannada Letter A,...,Ha
        "$KanV    = \\u0CCD;"              // Kannada Sign Virama
        "$Kan1    = [\\u0C95-\\u0CB9];"    // Kannada Letter A,...,Ha
        "$Mal0    = [\\u0D05-\\u0D39];"    // Malayalam Letter A,...,Ha
        "$MalV    = \\u0D4D;"              // Malayalam Sign Virama
        "$Mal1    = [\\u0D15-\\u0D39];"    // Malayalam Letter A,...,Ha
        "$RI      = [\\U0001F1E6-\\U0001F1FF];" // Emoji regional indicators
        "!!chain;"
        "!!forward;"
        "$CR $LF;"
        "$L ($L | $V | $LV | $LVT);"
        "($LV | $V) ($V | $T);"
        "($LVT | $T) $T;"
        "[^$Control $CR $LF] $Extend;"
        "[^$Control $CR $LF] $SpacingMark;"
        "$RI $RI / $RI;"
        "$RI $RI;"
        "$Hin0 $HinV $Hin1;"               // Devanagari Virama (forward)
        "$Ben0 $BenV $Ben1;"               // Bengali Virama (forward)
        "$Pan0 $PanV $Pan1;"               // Gurmukhi Virama (forward)
        "$Guj0 $GujV $Guj1;"               // Gujarati Virama (forward)
        "$Ori0 $OriV $Ori1;"               // Oriya Virama (forward)
        "$Tel0 $TelV $Tel1;"               // Telugu Virama (forward)
        "$Kan0 $KanV $Kan1;"               // Kannada Virama (forward)
        "$Mal0 $MalV $Mal1;"               // Malayalam Virama (forward)
        "!!reverse;"
        "$LF $CR;"
        "($L | $V | $LV | $LVT) $L;"
        "($V | $T) ($LV | $V);"
        "$T ($LVT | $T);"
        "$Extend      [^$Control $CR $LF];"
        "$SpacingMark [^$Control $CR $LF];"
        "$RI $RI / $RI $RI;"
        "$RI $RI;"
        "$Hin1 $HinV $Hin0;"               // Devanagari Virama (backward)
        "$Ben1 $BenV $Ben0;"               // Bengali Virama (backward)
        "$Pan1 $PanV $Pan0;"               // Gurmukhi Virama (backward)
        "$Guj1 $GujV $Guj0;"               // Gujarati Virama (backward)
        "$Ori1 $OriV $Ori0;"               // Gujarati Virama (backward)
        "$Tel1 $TelV $Tel0;"               // Telugu Virama (backward)
        "$Kan1 $KanV $Kan0;"               // Kannada Virama (backward)
        "$Mal1 $MalV $Mal0;"               // Malayalam Virama (backward)
        "!!safe_reverse;"
        "!!safe_forward;";
    static TextBreakIterator* staticCursorMovementIterator = initializeIteratorWithRules(kRules);
#else // PLATFORM(IOS)
    // Use the special Thai character break iterator for all locales
    static TextBreakIterator* staticCursorMovementIterator = initializeIterator(UBRK_CHARACTER, "th");
#endif // !PLATFORM(IOS)

    if (!staticCursorMovementIterator)
        return nullptr;

    return setTextForIterator(*staticCursorMovementIterator, string);
}

TextBreakIterator* acquireLineBreakIterator(StringView string, const AtomicString& locale, const UChar* priorContext, unsigned priorContextLength)
{
    TextBreakIterator* iterator = reinterpret_cast<TextBreakIterator*>(LineBreakIteratorPool::sharedPool().take(locale));
    if (!iterator)
        return nullptr;

    return setContextAwareTextForIterator(*iterator, string, priorContext, priorContextLength);
}

void releaseLineBreakIterator(TextBreakIterator* iterator)
{
    ASSERT_ARG(iterator, iterator);

    LineBreakIteratorPool::sharedPool().put(reinterpret_cast<UBreakIterator*>(iterator));
}

static TextBreakIterator* nonSharedCharacterBreakIterator;

static inline bool compareAndSwapNonSharedCharacterBreakIterator(TextBreakIterator* expected, TextBreakIterator* newValue)
{
#if ENABLE(COMPARE_AND_SWAP)
    return WTF::weakCompareAndSwap(reinterpret_cast<void**>(&nonSharedCharacterBreakIterator), expected, newValue);
#else
    DEPRECATED_DEFINE_STATIC_LOCAL(std::mutex, nonSharedCharacterBreakIteratorMutex, ());
    std::lock_guard<std::mutex> locker(nonSharedCharacterBreakIteratorMutex);
    if (nonSharedCharacterBreakIterator != expected)
        return false;
    nonSharedCharacterBreakIterator = newValue;
    return true;
#endif
}

NonSharedCharacterBreakIterator::NonSharedCharacterBreakIterator(StringView string)
{
    m_iterator = nonSharedCharacterBreakIterator;

    bool createdIterator = m_iterator && compareAndSwapNonSharedCharacterBreakIterator(m_iterator, 0);
    if (!createdIterator)
        m_iterator = initializeIterator(UBRK_CHARACTER);
    if (!m_iterator)
        return;

    m_iterator = setTextForIterator(*m_iterator, string);
}

NonSharedCharacterBreakIterator::~NonSharedCharacterBreakIterator()
{
    if (!compareAndSwapNonSharedCharacterBreakIterator(0, m_iterator))
        ubrk_close(reinterpret_cast<UBreakIterator*>(m_iterator));
}


// Iterator implemenation.

int textBreakFirst(TextBreakIterator* iterator)
{
    return ubrk_first(reinterpret_cast<UBreakIterator*>(iterator));
}

int textBreakLast(TextBreakIterator* iterator)
{
    return ubrk_last(reinterpret_cast<UBreakIterator*>(iterator));
}

int textBreakNext(TextBreakIterator* iterator)
{
    return ubrk_next(reinterpret_cast<UBreakIterator*>(iterator));
}

int textBreakPrevious(TextBreakIterator* iterator)
{
    return ubrk_previous(reinterpret_cast<UBreakIterator*>(iterator));
}

int textBreakPreceding(TextBreakIterator* iterator, int pos)
{
    return ubrk_preceding(reinterpret_cast<UBreakIterator*>(iterator), pos);
}

int textBreakFollowing(TextBreakIterator* iterator, int pos)
{
    return ubrk_following(reinterpret_cast<UBreakIterator*>(iterator), pos);
}

int textBreakCurrent(TextBreakIterator* iterator)
{
    return ubrk_current(reinterpret_cast<UBreakIterator*>(iterator));
}

bool isTextBreak(TextBreakIterator* iterator, int position)
{
    return ubrk_isBoundary(reinterpret_cast<UBreakIterator*>(iterator), position);
}

bool isWordTextBreak(TextBreakIterator* iterator)
{
    int ruleStatus = ubrk_getRuleStatus(reinterpret_cast<UBreakIterator*>(iterator));
    return ruleStatus != UBRK_WORD_NONE;
}

unsigned numGraphemeClusters(const String& s)
{
    unsigned stringLength = s.length();
    
    if (!stringLength)
        return 0;

    // The only Latin-1 Extended Grapheme Cluster is CR LF
    if (s.is8Bit() && !s.contains('\r'))
        return stringLength;

    NonSharedCharacterBreakIterator it(s);
    if (!it)
        return stringLength;

    unsigned num = 0;
    while (textBreakNext(it) != TextBreakDone)
        ++num;
    return num;
}

unsigned numCharactersInGraphemeClusters(const String& s, unsigned numGraphemeClusters)
{
    unsigned stringLength = s.length();

    if (!stringLength)
        return 0;

    // The only Latin-1 Extended Grapheme Cluster is CR LF
    if (s.is8Bit() && !s.contains('\r'))
        return std::min(stringLength, numGraphemeClusters);

    NonSharedCharacterBreakIterator it(s);
    if (!it)
        return std::min(stringLength, numGraphemeClusters);

    for (unsigned i = 0; i < numGraphemeClusters; ++i) {
        if (textBreakNext(it) == TextBreakDone)
            return stringLength;
    }
    return textBreakCurrent(it);
}

} // namespace WebCore