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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef NSLINEBREAKER_H_
+#define NSLINEBREAKER_H_
+
+#include "mozilla/intl/LineBreaker.h"
+#include "mozilla/intl/Segmenter.h"
+#include "nsString.h"
+#include "nsTArray.h"
+
+class nsAtom;
+class nsHyphenator;
+
+/**
+ * A receiver of line break data.
+ */
+class nsILineBreakSink {
+ public:
+ /**
+ * Sets the break data for a substring of the associated text chunk.
+ * One or more of these calls will be performed; the union of all substrings
+ * will cover the entire text chunk. Substrings may overlap (i.e., we may
+ * set the break-before state of a character more than once).
+ * @param aBreakBefore the break-before states for the characters in the
+ * substring. These are enum values from gfxTextRun::CompressedGlyph:
+ * FLAG_BREAK_TYPE_NONE - no linebreak is allowed here
+ * FLAG_BREAK_TYPE_NORMAL - a normal (whitespace) linebreak
+ * FLAG_BREAK_TYPE_HYPHEN - a hyphenation point
+ */
+ virtual void SetBreaks(uint32_t aStart, uint32_t aLength,
+ uint8_t* aBreakBefore) = 0;
+
+ /**
+ * Indicates which characters should be capitalized. Only called if
+ * BREAK_NEED_CAPITALIZATION was requested.
+ */
+ virtual void SetCapitalization(uint32_t aStart, uint32_t aLength,
+ bool* aCapitalize) = 0;
+};
+
+/**
+ * A line-breaking state machine. You feed text into it via AppendText calls
+ * and it computes the possible line breaks. Because break decisions can
+ * require a lot of context, the breaks for a piece of text are sometimes not
+ * known until later text has been seen (or all text ends). So breaks are
+ * returned via a call to SetBreaks on the nsILineBreakSink object passed
+ * with each text chunk, which might happen during the corresponding AppendText
+ * call, or might happen during a later AppendText call or even a Reset()
+ * call.
+ *
+ * The linebreak results MUST NOT depend on how the text is broken up
+ * into AppendText calls.
+ *
+ * The current strategy is that we break the overall text into
+ * whitespace-delimited "words". Then those words are passed to the LineBreaker
+ * service for deeper analysis if they contain a "complex" character as
+ * described below.
+ *
+ * This class also handles detection of which characters should be capitalized
+ * for text-transform:capitalize. This is a good place to handle that because
+ * we have all the context we need.
+ */
+class nsLineBreaker {
+ public:
+ nsLineBreaker();
+ ~nsLineBreaker();
+
+ static inline bool IsSpace(char16_t u) {
+ return mozilla::intl::NS_IsSpace(u);
+ }
+
+ static inline bool IsComplexASCIIChar(char16_t u) {
+ return !((0x0030 <= u && u <= 0x0039) || (0x0041 <= u && u <= 0x005A) ||
+ (0x0061 <= u && u <= 0x007A) || (0x000a == u));
+ }
+
+ static inline bool IsComplexChar(char16_t u) {
+ return IsComplexASCIIChar(u) ||
+ mozilla::intl::NS_NeedsPlatformNativeHandling(u) ||
+ (0x1100 <= u && u <= 0x11ff) || // Hangul Jamo
+ (0x2000 <= u && u <= 0x21ff) || // Punctuations and Symbols
+ (0x2e80 <= u && u <= 0xd7ff) || // several CJK blocks
+ (0xf900 <= u && u <= 0xfaff) || // CJK Compatibility Idographs
+ (0xff00 <= u && u <= 0xffef); // Halfwidth and Fullwidth Forms
+ }
+
+ // Break opportunities exist at the end of each run of breakable whitespace
+ // (see IsSpace above). Break opportunities can also exist between pairs of
+ // non-whitespace characters, as determined by mozilla::intl::LineBreaker.
+ // We pass a whitespace-
+ // delimited word to LineBreaker if it contains at least one character
+ // matching IsComplexChar.
+ // We provide flags to control on a per-chunk basis where breaks are allowed.
+ // At any character boundary, exactly one text chunk governs whether a
+ // break is allowed at that boundary.
+ //
+ // We operate on text after whitespace processing has been applied, so
+ // other characters (e.g. tabs and newlines) may have been converted to
+ // spaces.
+
+ /**
+ * Flags passed with each chunk of text.
+ */
+ enum {
+ /*
+ * Do not introduce a break opportunity at the start of this chunk of text.
+ */
+ BREAK_SUPPRESS_INITIAL = 0x01,
+ /**
+ * Do not introduce a break opportunity in the interior of this chunk of
+ * text. Also, whitespace in this chunk is treated as non-breakable.
+ */
+ BREAK_SUPPRESS_INSIDE = 0x02,
+ /**
+ * The sink currently is already set up to have no breaks in it;
+ * if no breaks are possible, nsLineBreaker does not need to call
+ * SetBreaks on it. This is useful when handling large quantities of
+ * preformatted text; the textruns will never have any breaks set on them,
+ * and there is no need to ever actually scan the text for breaks, except
+ * at the end of textruns in case context is needed for following breakable
+ * text.
+ */
+ BREAK_SKIP_SETTING_NO_BREAKS = 0x04,
+ /**
+ * We need to be notified of characters that should be capitalized
+ * (as in text-transform:capitalize) in this chunk of text.
+ */
+ BREAK_NEED_CAPITALIZATION = 0x08,
+ /**
+ * Auto-hyphenation is enabled, so we need to get a hyphenator
+ * (if available) and use it to find breakpoints.
+ */
+ BREAK_USE_AUTO_HYPHENATION = 0x10
+ };
+
+ /**
+ * Append "invisible whitespace". This acts like whitespace, but there is
+ * no actual text associated with it. Only the BREAK_SUPPRESS_INSIDE flag
+ * is relevant here.
+ */
+ nsresult AppendInvisibleWhitespace(uint32_t aFlags);
+
+ /**
+ * Feed Unicode text into the linebreaker for analysis. aLength must be
+ * nonzero.
+ * @param aSink can be null if the breaks are not actually needed (we may
+ * still be setting up state for later breaks)
+ */
+ nsresult AppendText(nsAtom* aHyphenationLanguage, const char16_t* aText,
+ uint32_t aLength, uint32_t aFlags,
+ nsILineBreakSink* aSink);
+ /**
+ * Feed 8-bit text into the linebreaker for analysis. aLength must be nonzero.
+ * @param aSink can be null if the breaks are not actually needed (we may
+ * still be setting up state for later breaks)
+ */
+ nsresult AppendText(nsAtom* aHyphenationLanguage, const uint8_t* aText,
+ uint32_t aLength, uint32_t aFlags,
+ nsILineBreakSink* aSink);
+ /**
+ * Reset all state. This means the current run has ended; any outstanding
+ * calls through nsILineBreakSink are made, and all outstanding references to
+ * nsILineBreakSink objects are dropped.
+ * After this call, this linebreaker can be reused.
+ * This must be called at least once between any call to AppendText() and
+ * destroying the object.
+ * @param aTrailingBreak this is set to true when there is a break opportunity
+ * at the end of the text. This will normally only be declared true when there
+ * is breakable whitespace at the end.
+ */
+ nsresult Reset(bool* aTrailingBreak);
+
+ /*
+ * Set word-break mode for line breaker. This is set by word-break property.
+ */
+ void SetWordBreak(mozilla::intl::WordBreakRule aMode) {
+ // If current word is non-empty and mode is changing, flush the breaker.
+ if (aMode != mWordBreak && !mCurrentWord.IsEmpty()) {
+ nsresult rv = FlushCurrentWord();
+ if (NS_FAILED(rv)) {
+ NS_WARNING("FlushCurrentWord failed, line-breaks may be wrong");
+ }
+ // If previous mode was break-all, we should allow a break here.
+ // XXX (jfkthame) css-text spec seems unclear on this, raised question in
+ // https://github.com/w3c/csswg-drafts/issues/3897
+ if (mWordBreak == mozilla::intl::WordBreakRule::BreakAll) {
+ mBreakHere = true;
+ }
+ }
+ mWordBreak = aMode;
+ }
+
+ /*
+ * Set line-break rule strictness mode for line breaker. This is set by the
+ * line-break property.
+ */
+ void SetStrictness(mozilla::intl::LineBreakRule aMode) {
+ if (aMode != mLineBreak && !mCurrentWord.IsEmpty()) {
+ nsresult rv = FlushCurrentWord();
+ if (NS_FAILED(rv)) {
+ NS_WARNING("FlushCurrentWord failed, line-breaks may be wrong");
+ }
+ // If previous mode was anywhere, we should allow a break here.
+ if (mLineBreak == mozilla::intl::LineBreakRule::Anywhere) {
+ mBreakHere = true;
+ }
+ }
+ mLineBreak = aMode;
+ }
+
+ /**
+ * Return whether the line-breaker has a buffered "current word" that may
+ * be extended with additional word-forming characters.
+ */
+ bool InWord() const { return !mCurrentWord.IsEmpty(); }
+
+ /**
+ * Set the word-continuation state, which will suppress capitalization of
+ * the next letter that might otherwise apply.
+ */
+ void SetWordContinuation(bool aContinuation) {
+ mWordContinuation = aContinuation;
+ }
+
+ private:
+ // This is a list of text sources that make up the "current word" (i.e.,
+ // run of text which does not contain any whitespace). All the mLengths
+ // are are nonzero, these cannot overlap.
+ struct TextItem {
+ TextItem(nsILineBreakSink* aSink, uint32_t aSinkOffset, uint32_t aLength,
+ uint32_t aFlags)
+ : mSink(aSink),
+ mSinkOffset(aSinkOffset),
+ mLength(aLength),
+ mFlags(aFlags) {}
+
+ nsILineBreakSink* mSink;
+ uint32_t mSinkOffset;
+ uint32_t mLength;
+ uint32_t mFlags;
+ };
+
+ // State for the nonwhitespace "word" that started in previous text and hasn't
+ // finished yet.
+
+ // When the current word ends, this computes the linebreak opportunities
+ // *inside* the word (excluding either end) and sets them through the
+ // appropriate sink(s). Then we clear the current word state.
+ nsresult FlushCurrentWord();
+
+ void UpdateCurrentWordLanguage(nsAtom* aHyphenationLanguage);
+
+ void FindHyphenationPoints(nsHyphenator* aHyphenator,
+ const char16_t* aTextStart,
+ const char16_t* aTextLimit, uint8_t* aBreakState);
+
+ AutoTArray<char16_t, 100> mCurrentWord;
+ // All the items that contribute to mCurrentWord
+ AutoTArray<TextItem, 2> mTextItems;
+ nsAtom* mCurrentWordLanguage;
+ bool mCurrentWordContainsMixedLang;
+ bool mCurrentWordContainsComplexChar;
+ bool mScriptIsChineseOrJapanese;
+
+ // True if the previous character was breakable whitespace
+ bool mAfterBreakableSpace;
+ // True if a break must be allowed at the current position because
+ // a run of breakable whitespace ends here
+ bool mBreakHere;
+ // Break rules for letters from the "word-break" property.
+ mozilla::intl::WordBreakRule mWordBreak;
+ // Line breaking strictness from the "line-break" property.
+ mozilla::intl::LineBreakRule mLineBreak;
+ // Should the text be treated as continuing a word-in-progress (for purposes
+ // of initial capitalization)? Normally this is set to false whenever we
+ // start using a linebreaker, but it may be set to true if the line-breaker
+ // has been explicitly flushed mid-word.
+ bool mWordContinuation;
+};
+
+#endif /*NSLINEBREAKER_H_*/
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