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/*
* Copyright (C) 2006 Lars Knoll <lars@trolltech.com>
* Copyright (C) 2007, 2011, 2012 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.
*
*/
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_TEXT_CHARACTER_BREAK_ITERATOR_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_TEXT_CHARACTER_BREAK_ITERATOR_H_
#include <unicode/brkiter.h>
#include "third_party/blink/renderer/platform/platform_export.h"
#include "third_party/blink/renderer/platform/text/character.h"
#include "third_party/blink/renderer/platform/text/layout_locale.h"
#include "third_party/blink/renderer/platform/wtf/text/atomic_string.h"
#include "third_party/blink/renderer/platform/wtf/text/character_names.h"
#include "third_party/blink/renderer/platform/wtf/text/wtf_uchar.h"
namespace blink {
typedef icu::BreakIterator TextBreakIterator;
const int kTextBreakDone = -1;
// 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 PLATFORM_EXPORT CharacterBreakIterator final {
STACK_ALLOCATED();
public:
explicit CharacterBreakIterator(const StringView&);
explicit CharacterBreakIterator(base::span<const UChar>);
CharacterBreakIterator(const CharacterBreakIterator&) = delete;
CharacterBreakIterator& operator=(const CharacterBreakIterator&) = delete;
int Next();
int Current();
bool IsBreak(int offset) const;
int Preceding(int offset) const;
int Following(int offset) const;
bool operator!() const { return !is_8bit_ && !iterator_; }
private:
struct PLATFORM_EXPORT ReturnToPool {
void operator()(void* ptr) const;
};
using PooledIterator = std::unique_ptr<icu::BreakIterator, ReturnToPool>;
class Pool;
FRIEND_TEST_ALL_PREFIXES(TextBreakIteratorTest, PooledCharacterBreakIterator);
void CreateIteratorForBuffer(base::span<const UChar>);
unsigned ClusterLengthStartingAt(unsigned offset) const {
DCHECK(is_8bit_);
// The only Latin-1 Extended Grapheme Cluster is CR LF
return IsCRBeforeLF(offset) ? 2 : 1;
}
bool IsCRBeforeLF(unsigned offset) const {
DCHECK(is_8bit_);
// SAFTEY: second indexing is safe because of length check, but
// the first is not. Could be made safe by re-ordering.
return UNSAFE_TODO(charaters8_[offset]) == '\r' && offset + 1 < length_ &&
UNSAFE_BUFFERS(charaters8_[offset + 1]) == '\n';
}
bool IsLFAfterCR(unsigned offset) const {
DCHECK(is_8bit_);
return UNSAFE_TODO(charaters8_[offset]) == '\n' && offset >= 1 &&
UNSAFE_TODO(charaters8_[offset - 1]) == '\r';
}
bool is_8bit_ = false;
// For 8 bit strings, we implement the iterator ourselves.
const LChar* charaters8_ = nullptr;
unsigned offset_ = 0;
unsigned length_ = 0;
// For 16 bit strings, we use a TextBreakIterator.
PooledIterator 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.
PLATFORM_EXPORT unsigned NumGraphemeClusters(const String&);
// Returns the number of code units that the next grapheme cluster is made of.
PLATFORM_EXPORT unsigned LengthOfGraphemeCluster(const String&, unsigned = 0);
// Returns a list of graphemes cluster at each character using character break
// rules. The `graphemes` and `text` must have the same size.
PLATFORM_EXPORT void GraphemesClusterList(const StringView& text,
base::span<unsigned> graphemes);
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_TEXT_CHARACTER_BREAK_ITERATOR_H_
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