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/*
* Copyright (C) 2006 Lars Knoll <lars@trolltech.com>
* Copyright (C) 2007-2016 Apple Inc. All rights reserved.
*
* 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.
*
*/
#pragma once
#include <mutex>
#include <variant>
#include <wtf/NeverDestroyed.h>
#include <wtf/text/StringView.h>
#include <wtf/text/icu/TextBreakIteratorICU.h>
#if PLATFORM(COCOA)
#include <wtf/text/cf/TextBreakIteratorCF.h>
#else
#include <wtf/text/NullTextBreakIterator.h>
#endif
namespace WTF {
#if PLATFORM(COCOA)
typedef TextBreakIteratorCF TextBreakIteratorPlatform;
#else
typedef NullTextBreakIterator TextBreakIteratorPlatform;
#endif
class TextBreakIteratorCache;
class TextBreakIterator {
WTF_MAKE_FAST_ALLOCATED;
public:
enum class Mode {
Line,
Caret,
Delete
};
TextBreakIterator() = delete;
TextBreakIterator(const TextBreakIterator&) = delete;
TextBreakIterator(TextBreakIterator&&) = default;
TextBreakIterator& operator=(const TextBreakIterator&) = delete;
TextBreakIterator& operator=(TextBreakIterator&&) = default;
std::optional<unsigned> preceding(unsigned location) const
{
return switchOn(m_backing, [&](const auto& iterator) {
return iterator.preceding(location);
});
}
std::optional<unsigned> following(unsigned location) const
{
return switchOn(m_backing, [&](const auto& iterator) {
return iterator.following(location);
});
}
bool isBoundary(unsigned location) const
{
return switchOn(m_backing, [&](const auto& iterator) {
return iterator.isBoundary(location);
});
}
private:
friend class TextBreakIteratorCache;
// Use CachedTextBreakIterator instead of constructing one of these directly.
WTF_EXPORT_PRIVATE TextBreakIterator(StringView, Mode, const AtomString& locale);
void setText(StringView string)
{
return switchOn(m_backing, [&](auto& iterator) {
return iterator.setText(string);
});
}
Mode mode() const
{
return m_mode;
}
const AtomString& locale() const
{
return m_locale;
}
std::variant<TextBreakIteratorICU, TextBreakIteratorPlatform> m_backing;
Mode m_mode;
AtomString m_locale;
};
class CachedTextBreakIterator;
class TextBreakIteratorCache {
WTF_MAKE_FAST_ALLOCATED;
// Use CachedTextBreakIterator instead of dealing with the cache directly.
private:
friend class LazyNeverDestroyed<TextBreakIteratorCache>;
friend class CachedTextBreakIterator;
WTF_EXPORT_PRIVATE static TextBreakIteratorCache& singleton();
TextBreakIteratorCache(const TextBreakIteratorCache&) = delete;
TextBreakIteratorCache(TextBreakIteratorCache&&) = delete;
TextBreakIteratorCache& operator=(const TextBreakIteratorCache&) = delete;
TextBreakIteratorCache& operator=(TextBreakIteratorCache&&) = delete;
TextBreakIterator take(StringView string, TextBreakIterator::Mode mode, const AtomString& locale)
{
auto iter = std::find_if(m_unused.begin(), m_unused.end(), [&](TextBreakIterator& candidate) {
return candidate.mode() == mode && candidate.locale() == locale;
});
if (iter == m_unused.end())
return TextBreakIterator(string, mode, locale);
auto result = WTFMove(*iter);
m_unused.remove(iter - m_unused.begin());
result.setText(string);
return result;
}
void put(TextBreakIterator&& iterator)
{
m_unused.append(WTFMove(iterator));
if (m_unused.size() > capacity)
m_unused.remove(0);
}
TextBreakIteratorCache()
{
}
static constexpr int capacity = 2;
// FIXME: Break this up into different Vectors per mode.
Vector<TextBreakIterator, capacity> m_unused;
};
// RAII for TextBreakIterator and TextBreakIteratorCache.
class CachedTextBreakIterator {
WTF_MAKE_FAST_ALLOCATED;
public:
CachedTextBreakIterator(StringView string, TextBreakIterator::Mode mode, const AtomString& locale)
: m_backing(TextBreakIteratorCache::singleton().take(string, mode, locale))
{
}
~CachedTextBreakIterator()
{
TextBreakIteratorCache::singleton().put(WTFMove(m_backing));
}
CachedTextBreakIterator() = delete;
CachedTextBreakIterator(const CachedTextBreakIterator&) = delete;
CachedTextBreakIterator(CachedTextBreakIterator&&) = default;
CachedTextBreakIterator& operator=(const CachedTextBreakIterator&) = delete;
CachedTextBreakIterator& operator=(CachedTextBreakIterator&&) = default;
std::optional<unsigned> preceding(unsigned location) const
{
return m_backing.preceding(location);
}
std::optional<unsigned> following(unsigned location) const
{
return m_backing.following(location);
}
bool isBoundary(unsigned location) const
{
return m_backing.isBoundary(location);
}
private:
TextBreakIterator m_backing;
};
// Note: The returned iterator is good only until you get another iterator, with the exception of acquireLineBreakIterator.
enum class LineBreakIteratorMode { Default, Loose, Normal, Strict };
WTF_EXPORT_PRIVATE UBreakIterator* wordBreakIterator(StringView);
WTF_EXPORT_PRIVATE UBreakIterator* sentenceBreakIterator(StringView);
WTF_EXPORT_PRIVATE UBreakIterator* acquireLineBreakIterator(StringView, const AtomString& locale, const UChar* priorContext, unsigned priorContextLength, LineBreakIteratorMode);
WTF_EXPORT_PRIVATE void releaseLineBreakIterator(UBreakIterator*);
UBreakIterator* openLineBreakIterator(const AtomString& locale);
void closeLineBreakIterator(UBreakIterator*&);
WTF_EXPORT_PRIVATE bool isWordTextBreak(UBreakIterator*);
class LazyLineBreakIterator {
WTF_MAKE_FAST_ALLOCATED;
public:
LazyLineBreakIterator()
{
resetPriorContext();
}
explicit LazyLineBreakIterator(StringView stringView, const AtomString& locale = AtomString(), LineBreakIteratorMode mode = LineBreakIteratorMode::Default)
: m_stringView(stringView)
, m_locale(locale)
, m_mode(mode)
{
resetPriorContext();
}
~LazyLineBreakIterator()
{
if (m_iterator)
releaseLineBreakIterator(m_iterator);
}
StringView stringView() const { return m_stringView; }
LineBreakIteratorMode mode() const { return m_mode; }
UChar lastCharacter() const
{
static_assert(WTF_ARRAY_LENGTH(m_priorContext) == 2, "UBreakIterator unexpected prior context length");
return m_priorContext[1];
}
UChar secondToLastCharacter() const
{
static_assert(WTF_ARRAY_LENGTH(m_priorContext) == 2, "UBreakIterator unexpected prior context length");
return m_priorContext[0];
}
void setPriorContext(UChar last, UChar secondToLast)
{
static_assert(WTF_ARRAY_LENGTH(m_priorContext) == 2, "UBreakIterator unexpected prior context length");
m_priorContext[0] = secondToLast;
m_priorContext[1] = last;
}
void updatePriorContext(UChar last)
{
static_assert(WTF_ARRAY_LENGTH(m_priorContext) == 2, "UBreakIterator unexpected prior context length");
m_priorContext[0] = m_priorContext[1];
m_priorContext[1] = last;
}
void resetPriorContext()
{
static_assert(WTF_ARRAY_LENGTH(m_priorContext) == 2, "UBreakIterator unexpected prior context length");
m_priorContext[0] = 0;
m_priorContext[1] = 0;
}
unsigned priorContextLength() const
{
unsigned priorContextLength = 0;
static_assert(WTF_ARRAY_LENGTH(m_priorContext) == 2, "UBreakIterator unexpected prior context length");
if (m_priorContext[1]) {
++priorContextLength;
if (m_priorContext[0])
++priorContextLength;
}
return priorContextLength;
}
// Obtain text break iterator, possibly previously cached, where this iterator is (or has been)
// initialized to use the previously stored string as the primary breaking context and using
// previously stored prior context if non-empty.
UBreakIterator* get(unsigned priorContextLength)
{
ASSERT(priorContextLength <= priorContextCapacity);
const UChar* priorContext = priorContextLength ? &m_priorContext[priorContextCapacity - priorContextLength] : nullptr;
if (!m_iterator) {
m_iterator = acquireLineBreakIterator(m_stringView, m_locale, priorContext, priorContextLength, m_mode);
m_cachedPriorContext = priorContext;
m_cachedPriorContextLength = priorContextLength;
} else if (priorContext != m_cachedPriorContext || priorContextLength != m_cachedPriorContextLength) {
resetStringAndReleaseIterator(m_stringView, m_locale, m_mode);
return this->get(priorContextLength);
}
return m_iterator;
}
void resetStringAndReleaseIterator(StringView stringView, const AtomString& locale, LineBreakIteratorMode mode)
{
if (m_iterator)
releaseLineBreakIterator(m_iterator);
m_stringView = stringView;
m_locale = locale;
m_iterator = nullptr;
m_cachedPriorContext = nullptr;
m_mode = mode;
m_cachedPriorContextLength = 0;
}
private:
static constexpr unsigned priorContextCapacity = 2;
StringView m_stringView;
AtomString m_locale;
UBreakIterator* m_iterator { nullptr };
const UChar* m_cachedPriorContext { nullptr };
LineBreakIteratorMode m_mode { LineBreakIteratorMode::Default };
unsigned m_cachedPriorContextLength { 0 };
UChar m_priorContext[priorContextCapacity];
};
// Iterates over "extended grapheme clusters", as defined in UAX #29.
// Note that platform implementations may be less sophisticated - e.g. ICU prior to
// version 4.0 only supports "legacy grapheme clusters".
// Use this for general text processing, e.g. string truncation.
class NonSharedCharacterBreakIterator {
WTF_MAKE_FAST_ALLOCATED;
WTF_MAKE_NONCOPYABLE(NonSharedCharacterBreakIterator);
public:
WTF_EXPORT_PRIVATE NonSharedCharacterBreakIterator(StringView);
WTF_EXPORT_PRIVATE ~NonSharedCharacterBreakIterator();
NonSharedCharacterBreakIterator(NonSharedCharacterBreakIterator&&);
operator UBreakIterator*() const { return m_iterator; }
private:
UBreakIterator* m_iterator;
};
// Counts the number of grapheme clusters. A surrogate pair or a sequence
// of a non-combining character and following combining characters is
// counted as 1 grapheme cluster.
WTF_EXPORT_PRIVATE unsigned numGraphemeClusters(StringView);
// Returns the number of code units that create the specified number of
// grapheme clusters. If there are fewer clusters in the string than specified,
// the length of the string is returned.
WTF_EXPORT_PRIVATE unsigned numCodeUnitsInGraphemeClusters(StringView, unsigned);
}
using WTF::CachedTextBreakIterator;
using WTF::LazyLineBreakIterator;
using WTF::LineBreakIteratorMode;
using WTF::NonSharedCharacterBreakIterator;
using WTF::TextBreakIterator;
using WTF::TextBreakIteratorCache;
using WTF::isWordTextBreak;