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Bug 1856267 - Consider incompatible breaking rules for old line segmenteri vs new line segmenter. r=TYLin

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Even if ASCII, old line segmenter rules aren't compatible with UAX#14.
`layout/reftests/line-breaking/markup-src-1.html` runs on old segmenter prefs,
so we should use old non-breaking conditions for it with old segmenter.

Also, if word-break is break-all, we might have break opportunity for AL, NU,
IS, and QU combinations. So we should use ICU4X segmenter if break-all.

Differential Revision: https://phabricator.services.mozilla.com/D191144
This commit is contained in:
Makoto Kato 2023-10-18 13:21:58 +00:00
parent dccb39dd6d
commit a9331c503a
2 changed files with 24 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
dom/base/nsLineBreaker.cpp
View File

@ -14,6 +14,7 @@
#include "mozilla/intl/LineBreaker.h" // for LineBreaker::ComputeBreakPositions
#include "mozilla/intl/Locale.h"
#include "mozilla/intl/UnicodeProperties.h"
#include "mozilla/StaticPrefs_intl.h"
using mozilla::AutoRestore;
using mozilla::intl::LineBreaker;
@ -46,7 +47,14 @@ static constexpr uint8_t kNonBreakableASCII[] = {
};
template <typename T>
static constexpr bool IsNonBreakableChar(T aChar) {
static constexpr bool IsNonBreakableChar(T aChar, bool aLegacyBehavior) {
if (aLegacyBehavior) {
// If not using ICU4X, line break rules aren't compatible with UAX#14. Use
// old way.
return (0x0030 <= aChar && aChar <= 0x0039) ||
(0x0041 <= aChar && aChar <= 0x005A) ||
(0x0061 <= aChar && aChar <= 0x007A) || (0x000a == aChar);
}
if (aChar < 0x20 || aChar > 0x7f) {
return false;
}
@ -61,7 +69,8 @@ nsLineBreaker::nsLineBreaker()
mBreakHere(false),
mWordBreak(WordBreakRule::Normal),
mLineBreak(LineBreakRule::Auto),
mWordContinuation(false) {}
mWordContinuation(false),
mLegacyBehavior(!mozilla::StaticPrefs::intl_icu4x_segmenter_enabled()) {}
nsLineBreaker::~nsLineBreaker() {
NS_ASSERTION(mCurrentWord.Length() == 0,
@ -142,13 +151,12 @@ nsresult nsLineBreaker::FlushCurrentWord() {
memset(breakState.Elements(),
gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NORMAL,
length * sizeof(uint8_t));
} else if (!mCurrentWordMightBeBreakable) {
// For break-strict set everything internal to "break", otherwise
// to "no break"!
} else if (!mCurrentWordMightBeBreakable &&
mWordBreak != WordBreakRule::BreakAll) {
// word-break: normal or keep-all has no break opportunity if the word
// is non-breakable. (See the comment of kNonBreakableASCII).
memset(breakState.Elements(),
mWordBreak == WordBreakRule::BreakAll
? gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NORMAL
: gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NONE,
gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NONE,
length * sizeof(uint8_t));
} else {
LineBreaker::ComputeBreakPositions(
@ -246,7 +254,7 @@ nsresult nsLineBreaker::AppendText(nsAtom* aHyphenationLanguage,
while (offset < aLength && !IsSpace(aText[offset])) {
mCurrentWord.AppendElement(aText[offset]);
if (!mCurrentWordMightBeBreakable &&
!IsNonBreakableChar<char16_t>(aText[offset])) {
!IsNonBreakableChar<char16_t>(aText[offset], mLegacyBehavior)) {
mCurrentWordMightBeBreakable = true;
}
UpdateCurrentWordLanguage(aHyphenationLanguage);
@ -363,7 +371,8 @@ nsresult nsLineBreaker::AppendText(nsAtom* aHyphenationLanguage,
continue;
}
if (!wordMightBeBreakable && !IsNonBreakableChar<char16_t>(ch)) {
if (!wordMightBeBreakable &&
!IsNonBreakableChar<char16_t>(ch, mLegacyBehavior)) {
wordMightBeBreakable = true;
}
++offset;
@ -435,7 +444,7 @@ nsresult nsLineBreaker::AppendText(nsAtom* aHyphenationLanguage,
while (offset < aLength && !IsSpace(aText[offset])) {
mCurrentWord.AppendElement(aText[offset]);
if (!mCurrentWordMightBeBreakable &&
!IsNonBreakableChar<uint8_t>(aText[offset])) {
!IsNonBreakableChar<uint8_t>(aText[offset], mLegacyBehavior)) {
mCurrentWordMightBeBreakable = true;
}
++offset;
@ -528,7 +537,8 @@ nsresult nsLineBreaker::AppendText(nsAtom* aHyphenationLanguage,
continue;
}
if (!wordMightBeBreakable && !IsNonBreakableChar<uint8_t>(ch)) {
if (!wordMightBeBreakable &&
!IsNonBreakableChar<uint8_t>(ch, mLegacyBehavior)) {
wordMightBeBreakable = true;
}
++offset;

2
dom/base/nsLineBreaker.h
View File

@ -264,6 +264,8 @@ class nsLineBreaker {
// start using a linebreaker, but it may be set to true if the line-breaker
// has been explicitly flushed mid-word.
bool mWordContinuation;
// True if using old line segmenter.
const bool mLegacyBehavior;
};
#endif /*NSLINEBREAKER_H_*/