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/*
* Copyright (C) 2005-2023 Apple Inc. All rights reserved.
* Copyright (C) 2011 Google 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 <unicode/ubrk.h>
#include <wtf/ASCIICType.h>
#include <wtf/StdLibExtras.h>
#include <wtf/text/TextBreakIterator.h>
#include <wtf/unicode/CharacterNames.h>
namespace WebCore {
static const UChar lineBreakTableFirstCharacter = '!';
static const UChar lineBreakTableLastCharacter = 127;
static const unsigned lineBreakTableColumnCount = (lineBreakTableLastCharacter - lineBreakTableFirstCharacter) / 8 + 1;
WEBCORE_EXPORT extern const unsigned char lineBreakTable[][lineBreakTableColumnCount];
enum class NonBreakingSpaceBehavior {
IgnoreNonBreakingSpace,
TreatNonBreakingSpaceAsBreak,
};
enum class CanUseShortcut : bool { No, Yes };
template<NonBreakingSpaceBehavior nonBreakingSpaceBehavior>
static inline bool isBreakableSpace(UChar character)
{
switch (character) {
case ' ':
case '\n':
case '\t':
return true;
case noBreakSpace:
return nonBreakingSpaceBehavior == NonBreakingSpaceBehavior::TreatNonBreakingSpaceAsBreak;
default:
return false;
}
}
inline bool shouldBreakAfter(UChar lastCharacter, UChar character, UChar nextCharacter)
{
// Don't allow line breaking between '-' and a digit if the '-' may mean a minus sign in the context,
// while allow breaking in 'ABCD-1234' and '1234-5678' which may be in long URLs.
if (character == '-' && isASCIIDigit(nextCharacter))
return isASCIIAlphanumeric(lastCharacter);
// If both ch and nextCh are ASCII characters, use a lookup table for enhanced speed and for compatibility
// with other browsers (see comments for asciiLineBreakTable for details).
if (character >= lineBreakTableFirstCharacter && character <= lineBreakTableLastCharacter && nextCharacter >= lineBreakTableFirstCharacter && nextCharacter <= lineBreakTableLastCharacter) {
const unsigned char* tableRow = lineBreakTable[character - lineBreakTableFirstCharacter];
unsigned nextCharacterIndex = nextCharacter - lineBreakTableFirstCharacter;
return tableRow[nextCharacterIndex / 8] & (1 << (nextCharacterIndex % 8));
}
// Otherwise defer to the Unicode algorithm by returning false.
return false;
}
template<NonBreakingSpaceBehavior nonBreakingSpaceBehavior>
inline bool needsLineBreakIterator(UChar character)
{
if (nonBreakingSpaceBehavior == NonBreakingSpaceBehavior::TreatNonBreakingSpaceAsBreak)
return character > lineBreakTableLastCharacter;
return character > lineBreakTableLastCharacter && character != noBreakSpace;
}
// When in non-loose mode, we can use the ASCII shortcut table.
template<typename CharacterType, NonBreakingSpaceBehavior nonBreakingSpaceBehavior, CanUseShortcut canUseShortcut>
inline unsigned nextBreakablePosition(CachedLineBreakIteratorFactory& lineBreakIteratorFactory, const CharacterType* string, unsigned length, unsigned startPosition)
{
std::optional<unsigned> nextBreak;
CharacterType lastLastCharacter = startPosition > 1 ? string[startPosition - 2] : static_cast<CharacterType>(lineBreakIteratorFactory.priorContext().secondToLastCharacter());
CharacterType lastCharacter = startPosition > 0 ? string[startPosition - 1] : static_cast<CharacterType>(lineBreakIteratorFactory.priorContext().lastCharacter());
unsigned priorContextLength = lineBreakIteratorFactory.priorContext().length();
for (unsigned i = startPosition; i < length; i++) {
CharacterType character = string[i];
if (isBreakableSpace<nonBreakingSpaceBehavior>(character) || (canUseShortcut == CanUseShortcut::Yes && shouldBreakAfter(lastLastCharacter, lastCharacter, character)))
return i;
if (canUseShortcut == CanUseShortcut::No || needsLineBreakIterator<nonBreakingSpaceBehavior>(character) || needsLineBreakIterator<nonBreakingSpaceBehavior>(lastCharacter)) {
if (!nextBreak || nextBreak.value() < i) {
// Don't break if positioned at start of primary context and there is no prior context.
if (i || priorContextLength) {
auto& breakIterator = lineBreakIteratorFactory.get();
nextBreak = breakIterator.following(i - 1);
}
}
if (i == nextBreak && !isBreakableSpace<nonBreakingSpaceBehavior>(lastCharacter))
return i;
}
lastLastCharacter = lastCharacter;
lastCharacter = character;
}
return length;
}
template<typename CharacterType, NonBreakingSpaceBehavior nonBreakingSpaceBehavior>
inline unsigned nextBreakablePositionKeepingAllWords(const CharacterType* string, unsigned length, unsigned startPosition)
{
// FIXME: Use ICU instead.
for (unsigned i = startPosition; i < length; i++) {
if (isBreakableSpace<nonBreakingSpaceBehavior>(string[i]))
return i;
// FIXME: This should either be in isBreakableSpace (though previous attempts broke the world) or should use ICU instead.
if (string[i] == zeroWidthSpace)
return i;
if (string[i] == ideographicSpace)
return i + 1;
}
return length;
}
inline unsigned nextBreakablePositionKeepingAllWords(CachedLineBreakIteratorFactory& lineBreakIteratorFactory, unsigned startPosition)
{
auto stringView = lineBreakIteratorFactory.stringView();
if (stringView.is8Bit())
return nextBreakablePositionKeepingAllWords<LChar, NonBreakingSpaceBehavior::TreatNonBreakingSpaceAsBreak>(stringView.characters8(), stringView.length(), startPosition);
return nextBreakablePositionKeepingAllWords<UChar, NonBreakingSpaceBehavior::TreatNonBreakingSpaceAsBreak>(stringView.characters16(), stringView.length(), startPosition);
}
inline unsigned nextBreakablePositionKeepingAllWordsIgnoringNBSP(CachedLineBreakIteratorFactory& lineBreakIteratorFactory, unsigned startPosition)
{
auto stringView = lineBreakIteratorFactory.stringView();
if (stringView.is8Bit())
return nextBreakablePositionKeepingAllWords<LChar, NonBreakingSpaceBehavior::IgnoreNonBreakingSpace>(stringView.characters8(), stringView.length(), startPosition);
return nextBreakablePositionKeepingAllWords<UChar, NonBreakingSpaceBehavior::IgnoreNonBreakingSpace>(stringView.characters16(), stringView.length(), startPosition);
}
inline unsigned nextBreakablePosition(CachedLineBreakIteratorFactory& lineBreakIteratorFactory, unsigned startPosition)
{
auto stringView = lineBreakIteratorFactory.stringView();
if (stringView.is8Bit())
return nextBreakablePosition<LChar, NonBreakingSpaceBehavior::TreatNonBreakingSpaceAsBreak, CanUseShortcut::Yes>(lineBreakIteratorFactory, stringView.characters8(), stringView.length(), startPosition);
return nextBreakablePosition<UChar, NonBreakingSpaceBehavior::TreatNonBreakingSpaceAsBreak, CanUseShortcut::Yes>(lineBreakIteratorFactory, stringView.characters16(), stringView.length(), startPosition);
}
inline unsigned nextBreakablePositionIgnoringNBSP(CachedLineBreakIteratorFactory& lineBreakIteratorFactory, unsigned startPosition)
{
auto stringView = lineBreakIteratorFactory.stringView();
if (stringView.is8Bit())
return nextBreakablePosition<LChar, NonBreakingSpaceBehavior::IgnoreNonBreakingSpace, CanUseShortcut::Yes>(lineBreakIteratorFactory, stringView.characters8(), stringView.length(), startPosition);
return nextBreakablePosition<UChar, NonBreakingSpaceBehavior::IgnoreNonBreakingSpace, CanUseShortcut::Yes>(lineBreakIteratorFactory, stringView.characters16(), stringView.length(), startPosition);
}
inline unsigned nextBreakablePositionWithoutShortcut(CachedLineBreakIteratorFactory& lineBreakIteratorFactory, unsigned startPosition)
{
auto stringView = lineBreakIteratorFactory.stringView();
if (stringView.is8Bit())
return nextBreakablePosition<LChar, NonBreakingSpaceBehavior::TreatNonBreakingSpaceAsBreak, CanUseShortcut::No>(lineBreakIteratorFactory, stringView.characters8(), stringView.length(), startPosition);
return nextBreakablePosition<UChar, NonBreakingSpaceBehavior::TreatNonBreakingSpaceAsBreak, CanUseShortcut::No>(lineBreakIteratorFactory, stringView.characters16(), stringView.length(), startPosition);
}
inline unsigned nextBreakablePositionIgnoringNBSPWithoutShortcut(CachedLineBreakIteratorFactory& lineBreakIteratorFactory, unsigned startPosition)
{
auto stringView = lineBreakIteratorFactory.stringView();
if (stringView.is8Bit())
return nextBreakablePosition<LChar, NonBreakingSpaceBehavior::IgnoreNonBreakingSpace, CanUseShortcut::No>(lineBreakIteratorFactory, stringView.characters8(), stringView.length(), startPosition);
return nextBreakablePosition<UChar, NonBreakingSpaceBehavior::IgnoreNonBreakingSpace, CanUseShortcut::No>(lineBreakIteratorFactory, stringView.characters16(), stringView.length(), startPosition);
}
inline unsigned nextBreakablePositionBreakCharacter(CachedLineBreakIteratorFactory& lineBreakIteratorFactory, unsigned startPosition)
{
auto stringView = lineBreakIteratorFactory.stringView();
ASSERT(startPosition <= stringView.length());
// FIXME: Can/Should we implement this using a Shared Iterator (performance issue)
// https://bugs.webkit.org/show_bug.cgi?id=197876
NonSharedCharacterBreakIterator iterator(stringView);
std::optional<unsigned> next = ubrk_following(iterator, startPosition);
return next.value_or(stringView.length());
}
inline bool isBreakable(CachedLineBreakIteratorFactory& lineBreakIteratorFactory, unsigned startPosition, std::optional<unsigned>& nextBreakable, bool breakNBSP, bool canUseShortcut, bool keepAllWords, bool breakAnywhere)
{
if (nextBreakable && nextBreakable.value() >= startPosition)
return startPosition == nextBreakable;
if (breakAnywhere)
nextBreakable = nextBreakablePositionBreakCharacter(lineBreakIteratorFactory, startPosition);
else if (keepAllWords) {
if (breakNBSP)
nextBreakable = nextBreakablePositionKeepingAllWords(lineBreakIteratorFactory, startPosition);
else
nextBreakable = nextBreakablePositionKeepingAllWordsIgnoringNBSP(lineBreakIteratorFactory, startPosition);
} else if (!canUseShortcut) {
if (breakNBSP)
nextBreakable = nextBreakablePositionWithoutShortcut(lineBreakIteratorFactory, startPosition);
else
nextBreakable = nextBreakablePositionIgnoringNBSPWithoutShortcut(lineBreakIteratorFactory, startPosition);
} else {
if (breakNBSP)
nextBreakable = nextBreakablePosition(lineBreakIteratorFactory, startPosition);
else
nextBreakable = nextBreakablePositionIgnoringNBSP(lineBreakIteratorFactory, startPosition);
}
return startPosition == nextBreakable;
}
} // namespace WebCore
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