forked from mirrors/gecko-dev
226 lines
9 KiB
C++
226 lines
9 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef NSLINEBREAKER_H_
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#define NSLINEBREAKER_H_
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#include "mozilla/intl/LineBreaker.h"
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#include "nsString.h"
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#include "nsTArray.h"
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class nsAtom;
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class nsHyphenator;
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/**
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* A receiver of line break data.
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*/
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class nsILineBreakSink {
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public:
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/**
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* Sets the break data for a substring of the associated text chunk.
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* One or more of these calls will be performed; the union of all substrings
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* will cover the entire text chunk. Substrings may overlap (i.e., we may
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* set the break-before state of a character more than once).
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* @param aBreakBefore the break-before states for the characters in the substring.
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* These are enum values from gfxTextRun::CompressedGlyph:
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* FLAG_BREAK_TYPE_NONE - no linebreak is allowed here
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* FLAG_BREAK_TYPE_NORMAL - a normal (whitespace) linebreak
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* FLAG_BREAK_TYPE_HYPHEN - a hyphenation point
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*/
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virtual void SetBreaks(uint32_t aStart, uint32_t aLength, uint8_t* aBreakBefore) = 0;
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/**
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* Indicates which characters should be capitalized. Only called if
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* BREAK_NEED_CAPITALIZATION was requested.
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*/
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virtual void SetCapitalization(uint32_t aStart, uint32_t aLength, bool* aCapitalize) = 0;
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};
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/**
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* A line-breaking state machine. You feed text into it via AppendText calls
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* and it computes the possible line breaks. Because break decisions can
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* require a lot of context, the breaks for a piece of text are sometimes not
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* known until later text has been seen (or all text ends). So breaks are
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* returned via a call to SetBreaks on the nsILineBreakSink object passed
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* with each text chunk, which might happen during the corresponding AppendText
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* call, or might happen during a later AppendText call or even a Reset()
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* call.
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*
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* The linebreak results MUST NOT depend on how the text is broken up
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* into AppendText calls.
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*
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* The current strategy is that we break the overall text into
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* whitespace-delimited "words". Then those words are passed to the LineBreaker
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* service for deeper analysis if they contain a "complex" character as described
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* below.
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*
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* This class also handles detection of which characters should be capitalized
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* for text-transform:capitalize. This is a good place to handle that because
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* we have all the context we need.
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*/
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class nsLineBreaker {
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public:
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nsLineBreaker();
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~nsLineBreaker();
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static inline bool IsSpace(char16_t u) { return mozilla::intl::NS_IsSpace(u); }
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static inline bool IsComplexASCIIChar(char16_t u)
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{
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return !((0x0030 <= u && u <= 0x0039) ||
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(0x0041 <= u && u <= 0x005A) ||
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(0x0061 <= u && u <= 0x007A) ||
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(0x000a == u));
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}
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static inline bool IsComplexChar(char16_t u)
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{
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return IsComplexASCIIChar(u) ||
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mozilla::intl::NS_NeedsPlatformNativeHandling(u) ||
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(0x1100 <= u && u <= 0x11ff) || // Hangul Jamo
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(0x2000 <= u && u <= 0x21ff) || // Punctuations and Symbols
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(0x2e80 <= u && u <= 0xd7ff) || // several CJK blocks
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(0xf900 <= u && u <= 0xfaff) || // CJK Compatibility Idographs
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(0xff00 <= u && u <= 0xffef); // Halfwidth and Fullwidth Forms
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}
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// Break opportunities exist at the end of each run of breakable whitespace
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// (see IsSpace above). Break opportunities can also exist between pairs of
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// non-whitespace characters, as determined by mozilla::intl::LineBreaker.
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// We pass a whitespace-
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// delimited word to LineBreaker if it contains at least one character
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// matching IsComplexChar.
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// We provide flags to control on a per-chunk basis where breaks are allowed.
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// At any character boundary, exactly one text chunk governs whether a
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// break is allowed at that boundary.
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//
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// We operate on text after whitespace processing has been applied, so
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// other characters (e.g. tabs and newlines) may have been converted to
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// spaces.
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/**
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* Flags passed with each chunk of text.
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*/
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enum {
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/*
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* Do not introduce a break opportunity at the start of this chunk of text.
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*/
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BREAK_SUPPRESS_INITIAL = 0x01,
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/**
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* Do not introduce a break opportunity in the interior of this chunk of text.
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* Also, whitespace in this chunk is treated as non-breakable.
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*/
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BREAK_SUPPRESS_INSIDE = 0x02,
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/**
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* The sink currently is already set up to have no breaks in it;
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* if no breaks are possible, nsLineBreaker does not need to call
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* SetBreaks on it. This is useful when handling large quantities of
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* preformatted text; the textruns will never have any breaks set on them,
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* and there is no need to ever actually scan the text for breaks, except
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* at the end of textruns in case context is needed for following breakable
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* text.
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*/
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BREAK_SKIP_SETTING_NO_BREAKS = 0x04,
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/**
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* We need to be notified of characters that should be capitalized
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* (as in text-transform:capitalize) in this chunk of text.
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*/
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BREAK_NEED_CAPITALIZATION = 0x08,
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/**
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* Auto-hyphenation is enabled, so we need to get a hyphenator
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* (if available) and use it to find breakpoints.
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*/
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BREAK_USE_AUTO_HYPHENATION = 0x10
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};
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/**
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* Append "invisible whitespace". This acts like whitespace, but there is
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* no actual text associated with it. Only the BREAK_SUPPRESS_INSIDE flag
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* is relevant here.
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*/
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nsresult AppendInvisibleWhitespace(uint32_t aFlags);
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/**
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* Feed Unicode text into the linebreaker for analysis. aLength must be
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* nonzero.
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* @param aSink can be null if the breaks are not actually needed (we may
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* still be setting up state for later breaks)
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*/
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nsresult AppendText(nsAtom* aHyphenationLanguage, const char16_t* aText, uint32_t aLength,
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uint32_t aFlags, nsILineBreakSink* aSink);
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/**
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* Feed 8-bit text into the linebreaker for analysis. aLength must be nonzero.
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* @param aSink can be null if the breaks are not actually needed (we may
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* still be setting up state for later breaks)
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*/
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nsresult AppendText(nsAtom* aHyphenationLanguage, const uint8_t* aText, uint32_t aLength,
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uint32_t aFlags, nsILineBreakSink* aSink);
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/**
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* Reset all state. This means the current run has ended; any outstanding
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* calls through nsILineBreakSink are made, and all outstanding references to
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* nsILineBreakSink objects are dropped.
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* After this call, this linebreaker can be reused.
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* This must be called at least once between any call to AppendText() and
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* destroying the object.
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* @param aTrailingBreak this is set to true when there is a break opportunity
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* at the end of the text. This will normally only be declared true when there
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* is breakable whitespace at the end.
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*/
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nsresult Reset(bool* aTrailingBreak);
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/*
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* Set word-break mode for linebreaker. This is set by word-break property.
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* @param aMode is LineBreaker::kWordBreak_* value.
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*/
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void SetWordBreak(uint8_t aMode) { mWordBreak = aMode; }
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private:
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// This is a list of text sources that make up the "current word" (i.e.,
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// run of text which does not contain any whitespace). All the mLengths
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// are are nonzero, these cannot overlap.
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struct TextItem {
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TextItem(nsILineBreakSink* aSink, uint32_t aSinkOffset, uint32_t aLength,
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uint32_t aFlags)
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: mSink(aSink), mSinkOffset(aSinkOffset), mLength(aLength), mFlags(aFlags) {}
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nsILineBreakSink* mSink;
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uint32_t mSinkOffset;
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uint32_t mLength;
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uint32_t mFlags;
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};
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// State for the nonwhitespace "word" that started in previous text and hasn't
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// finished yet.
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// When the current word ends, this computes the linebreak opportunities
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// *inside* the word (excluding either end) and sets them through the
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// appropriate sink(s). Then we clear the current word state.
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nsresult FlushCurrentWord();
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void UpdateCurrentWordLanguage(nsAtom *aHyphenationLanguage);
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void FindHyphenationPoints(nsHyphenator *aHyphenator,
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const char16_t *aTextStart,
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const char16_t *aTextLimit,
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uint8_t *aBreakState);
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AutoTArray<char16_t,100> mCurrentWord;
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// All the items that contribute to mCurrentWord
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AutoTArray<TextItem,2> mTextItems;
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nsAtom* mCurrentWordLanguage;
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bool mCurrentWordContainsMixedLang;
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bool mCurrentWordContainsComplexChar;
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// True if the previous character was breakable whitespace
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bool mAfterBreakableSpace;
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// True if a break must be allowed at the current position because
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// a run of breakable whitespace ends here
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bool mBreakHere;
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// line break mode by "word-break" style
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uint8_t mWordBreak;
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};
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#endif /*NSLINEBREAKER_H_*/
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