path: root/dom/base/nsLineBreaker.cpp

/* -*- 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/. */

#include "nsLineBreaker.h"
#include "nsContentUtils.h"
#include "gfxTextRun.h"  // for the gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_* values
#include "nsHyphenationManager.h"
#include "nsHyphenator.h"
#include "mozilla/AutoRestore.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/intl/LineBreaker.h"  // for LineBreaker::ComputeBreakPositions
#include "mozilla/intl/Locale.h"

using mozilla::AutoRestore;
using mozilla::intl::LineBreaker;
using mozilla::intl::LineBreakRule;
using mozilla::intl::Locale;
using mozilla::intl::LocaleParser;
using mozilla::intl::WordBreakRule;

nsLineBreaker::nsLineBreaker()
    : mCurrentWordLanguage(nullptr),
      mCurrentWordContainsMixedLang(false),
      mCurrentWordContainsComplexChar(false),
      mScriptIsChineseOrJapanese(false),
      mAfterBreakableSpace(false),
      mBreakHere(false),
      mWordBreak(WordBreakRule::Normal),
      mLineBreak(LineBreakRule::Auto),
      mWordContinuation(false) {}

nsLineBreaker::~nsLineBreaker() {
  NS_ASSERTION(mCurrentWord.Length() == 0,
               "Should have Reset() before destruction!");
}

static void SetupCapitalization(const char16_t* aWord, uint32_t aLength,
                                bool* aCapitalization) {
  // Capitalize the first alphanumeric character after a space or start
  // of the word.
  // The only space character a word can contain is NBSP.
  bool capitalizeNextChar = true;
  for (uint32_t i = 0; i < aLength; ++i) {
    uint32_t ch = aWord[i];
    if (capitalizeNextChar) {
      if (i + 1 < aLength && NS_IS_SURROGATE_PAIR(ch, aWord[i + 1])) {
        ch = SURROGATE_TO_UCS4(ch, aWord[i + 1]);
      }
      if (nsContentUtils::IsAlphanumeric(ch)) {
        aCapitalization[i] = true;
        capitalizeNextChar = false;
      }
      if (!IS_IN_BMP(ch)) {
        ++i;
      }
    }
    if (ch == 0xA0 /*NBSP*/) {
      capitalizeNextChar = true;
    }
  }
}

nsresult nsLineBreaker::FlushCurrentWord() {
  uint32_t length = mCurrentWord.Length();
  AutoTArray<uint8_t, 4000> breakState;
  if (!breakState.AppendElements(length, mozilla::fallible)) {
    return NS_ERROR_OUT_OF_MEMORY;
  }

  if (mLineBreak == LineBreakRule::Anywhere) {
    memset(breakState.Elements(),
           gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NORMAL,
           length * sizeof(uint8_t));
  } else if (!mCurrentWordContainsComplexChar) {
    // For break-strict set everything internal to "break", otherwise
    // to "no break"!
    memset(breakState.Elements(),
           mWordBreak == WordBreakRule::BreakAll
               ? gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NORMAL
               : gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NONE,
           length * sizeof(uint8_t));
  } else {
    LineBreaker::ComputeBreakPositions(
        mCurrentWord.Elements(), length, mWordBreak, mLineBreak,
        mScriptIsChineseOrJapanese, breakState.Elements());
  }

  bool autoHyphenate = mCurrentWordLanguage && !mCurrentWordContainsMixedLang;
  uint32_t i;
  for (i = 0; autoHyphenate && i < mTextItems.Length(); ++i) {
    TextItem* ti = &mTextItems[i];
    if (!(ti->mFlags & BREAK_USE_AUTO_HYPHENATION)) {
      autoHyphenate = false;
    }
  }
  if (autoHyphenate) {
    RefPtr<nsHyphenator> hyphenator =
        nsHyphenationManager::Instance()->GetHyphenator(mCurrentWordLanguage);
    if (hyphenator) {
      FindHyphenationPoints(hyphenator, mCurrentWord.Elements(),
                            mCurrentWord.Elements() + length,
                            breakState.Elements());
    }
  }

  nsTArray<bool> capitalizationState;
  uint32_t offset = 0;
  for (i = 0; i < mTextItems.Length(); ++i) {
    TextItem* ti = &mTextItems[i];
    NS_ASSERTION(ti->mLength > 0, "Zero length word contribution?");

    if ((ti->mFlags & BREAK_SUPPRESS_INITIAL) && ti->mSinkOffset == 0) {
      breakState[offset] = gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NONE;
    }
    if (ti->mFlags & BREAK_SUPPRESS_INSIDE) {
      uint32_t exclude = ti->mSinkOffset == 0 ? 1 : 0;
      memset(breakState.Elements() + offset + exclude,
             gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NONE,
             (ti->mLength - exclude) * sizeof(uint8_t));
    }

    // Don't set the break state for the first character of the word, because
    // it was already set correctly earlier and we don't know what the true
    // value should be.
    uint32_t skipSet = i == 0 ? 1 : 0;
    if (ti->mSink) {
      ti->mSink->SetBreaks(ti->mSinkOffset + skipSet, ti->mLength - skipSet,
                           breakState.Elements() + offset + skipSet);

      if (!mWordContinuation && (ti->mFlags & BREAK_NEED_CAPITALIZATION)) {
        if (capitalizationState.Length() == 0) {
          if (!capitalizationState.AppendElements(length, mozilla::fallible)) {
            return NS_ERROR_OUT_OF_MEMORY;
          };
          memset(capitalizationState.Elements(), false, length * sizeof(bool));
          SetupCapitalization(mCurrentWord.Elements(), length,
                              capitalizationState.Elements());
        }
        ti->mSink->SetCapitalization(ti->mSinkOffset, ti->mLength,
                                     capitalizationState.Elements() + offset);
      }
    }

    offset += ti->mLength;
  }

  mCurrentWord.Clear();
  mTextItems.Clear();
  mCurrentWordContainsComplexChar = false;
  mCurrentWordContainsMixedLang = false;
  mCurrentWordLanguage = nullptr;
  mWordContinuation = false;
  return NS_OK;
}

// If the aFlags parameter to AppendText has all these bits set,
// then we don't need to worry about finding break opportunities
// in the appended text.
#define NO_BREAKS_NEEDED_FLAGS                      \
  (BREAK_SUPPRESS_INITIAL | BREAK_SUPPRESS_INSIDE | \
   BREAK_SKIP_SETTING_NO_BREAKS)

nsresult nsLineBreaker::AppendText(nsAtom* aHyphenationLanguage,
                                   const char16_t* aText, uint32_t aLength,
                                   uint32_t aFlags, nsILineBreakSink* aSink) {
  NS_ASSERTION(aLength > 0, "Appending empty text...");

  uint32_t offset = 0;

  // Continue the current word
  if (mCurrentWord.Length() > 0) {
    NS_ASSERTION(!mAfterBreakableSpace && !mBreakHere,
                 "These should not be set");

    while (offset < aLength && !IsSpace(aText[offset])) {
      mCurrentWord.AppendElement(aText[offset]);
      if (!mCurrentWordContainsComplexChar && IsComplexChar(aText[offset])) {
        mCurrentWordContainsComplexChar = true;
      }
      UpdateCurrentWordLanguage(aHyphenationLanguage);
      ++offset;
    }

    if (offset > 0) {
      mTextItems.AppendElement(TextItem(aSink, 0, offset, aFlags));
    }

    if (offset == aLength) return NS_OK;

    // We encountered whitespace, so we're done with this word
    nsresult rv = FlushCurrentWord();
    if (NS_FAILED(rv)) return rv;
  }

  AutoTArray<uint8_t, 4000> breakState;
  if (aSink) {
    if (!breakState.AppendElements(aLength, mozilla::fallible)) {
      return NS_ERROR_OUT_OF_MEMORY;
    }
  }

  bool noCapitalizationNeeded = true;
  nsTArray<bool> capitalizationState;
  if (aSink && (aFlags & BREAK_NEED_CAPITALIZATION)) {
    if (!capitalizationState.AppendElements(aLength, mozilla::fallible)) {
      return NS_ERROR_OUT_OF_MEMORY;
    }
    memset(capitalizationState.Elements(), false, aLength * sizeof(bool));
    noCapitalizationNeeded = false;
  }

  uint32_t start = offset;
  bool noBreaksNeeded =
      !aSink || ((aFlags & NO_BREAKS_NEEDED_FLAGS) == NO_BREAKS_NEEDED_FLAGS &&
                 !mBreakHere && !mAfterBreakableSpace);
  if (noBreaksNeeded && noCapitalizationNeeded) {
    // Skip to the space before the last word, since either the break data
    // here is not needed, or no breaks are set in the sink and there cannot
    // be any breaks in this chunk; and we don't need to do word-initial
    // capitalization. All we need is the context for the next chunk (if any).
    offset = aLength;
    while (offset > start) {
      --offset;
      if (IsSpace(aText[offset])) break;
    }
  }
  uint32_t wordStart = offset;
  bool wordHasComplexChar = false;

  RefPtr<nsHyphenator> hyphenator;
  if ((aFlags & BREAK_USE_AUTO_HYPHENATION) &&
      !(aFlags & BREAK_SUPPRESS_INSIDE) && aHyphenationLanguage) {
    hyphenator =
        nsHyphenationManager::Instance()->GetHyphenator(aHyphenationLanguage);
  }

  for (;;) {
    char16_t ch = aText[offset];
    bool isSpace = IsSpace(ch);
    bool isBreakableSpace = isSpace && !(aFlags & BREAK_SUPPRESS_INSIDE);

    if (aSink && !noBreaksNeeded) {
      breakState[offset] =
          mBreakHere || (mAfterBreakableSpace && !isBreakableSpace) ||
                  mWordBreak == WordBreakRule::BreakAll ||
                  mLineBreak == LineBreakRule::Anywhere
              ? gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NORMAL
              : gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NONE;
    }
    mBreakHere = false;
    mAfterBreakableSpace = isBreakableSpace;

    if (isSpace || ch == '\n') {
      if (offset > wordStart && aSink) {
        if (!(aFlags & BREAK_SUPPRESS_INSIDE)) {
          if (mLineBreak == LineBreakRule::Anywhere) {
            memset(breakState.Elements() + wordStart,
                   gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NORMAL,
                   offset - wordStart);
          } else if (wordHasComplexChar) {
            // Save current start-of-word state because ComputeBreakPositions()
            // will set it to false.
            AutoRestore<uint8_t> saveWordStartBreakState(breakState[wordStart]);
            LineBreaker::ComputeBreakPositions(
                aText + wordStart, offset - wordStart, mWordBreak, mLineBreak,
                mScriptIsChineseOrJapanese, breakState.Elements() + wordStart);
          }
          if (hyphenator) {
            FindHyphenationPoints(hyphenator, aText + wordStart, aText + offset,
                                  breakState.Elements() + wordStart);
          }
        }
        if (!mWordContinuation && !noCapitalizationNeeded) {
          SetupCapitalization(aText + wordStart, offset - wordStart,
                              capitalizationState.Elements() + wordStart);
        }
      }
      wordHasComplexChar = false;
      mWordContinuation = false;
      ++offset;
      if (offset >= aLength) break;
      wordStart = offset;
    } else {
      if (!wordHasComplexChar && IsComplexChar(ch)) {
        wordHasComplexChar = true;
      }
      ++offset;
      if (offset >= aLength) {
        // Save this word
        mCurrentWordContainsComplexChar = wordHasComplexChar;
        uint32_t len = offset - wordStart;
        char16_t* elems = mCurrentWord.AppendElements(len);
        if (!elems) return NS_ERROR_OUT_OF_MEMORY;
        memcpy(elems, aText + wordStart, sizeof(char16_t) * len);
        mTextItems.AppendElement(TextItem(aSink, wordStart, len, aFlags));
        // Ensure that the break-before for this word is written out
        offset = wordStart + 1;
        UpdateCurrentWordLanguage(aHyphenationLanguage);
        break;
      }
    }
  }

  if (aSink) {
    if (!noBreaksNeeded) {
      aSink->SetBreaks(start, offset - start, breakState.Elements() + start);
    }
    if (!noCapitalizationNeeded) {
      aSink->SetCapitalization(start, offset - start,
                               capitalizationState.Elements() + start);
    }
  }
  return NS_OK;
}

void nsLineBreaker::FindHyphenationPoints(nsHyphenator* aHyphenator,
                                          const char16_t* aTextStart,
                                          const char16_t* aTextLimit,
                                          uint8_t* aBreakState) {
  nsDependentSubstring string(aTextStart, aTextLimit);
  AutoTArray<bool, 200> hyphens;
  if (NS_SUCCEEDED(aHyphenator->Hyphenate(string, hyphens))) {
    for (uint32_t i = 0; i + 1 < string.Length(); ++i) {
      if (hyphens[i]) {
        aBreakState[i + 1] =
            gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_HYPHEN;
      }
    }
  }
}

nsresult nsLineBreaker::AppendText(nsAtom* aHyphenationLanguage,
                                   const uint8_t* aText, uint32_t aLength,
                                   uint32_t aFlags, nsILineBreakSink* aSink) {
  NS_ASSERTION(aLength > 0, "Appending empty text...");

  if (aFlags & (BREAK_NEED_CAPITALIZATION | BREAK_USE_AUTO_HYPHENATION)) {
    // Defer to the Unicode path if capitalization or hyphenation is required
    nsAutoString str;
    const char* cp = reinterpret_cast<const char*>(aText);
    CopyASCIItoUTF16(nsDependentCSubstring(cp, cp + aLength), str);
    return AppendText(aHyphenationLanguage, str.get(), aLength, aFlags, aSink);
  }

  uint32_t offset = 0;

  // Continue the current word
  if (mCurrentWord.Length() > 0) {
    NS_ASSERTION(!mAfterBreakableSpace && !mBreakHere,
                 "These should not be set");

    while (offset < aLength && !IsSpace(aText[offset])) {
      mCurrentWord.AppendElement(aText[offset]);
      if (!mCurrentWordContainsComplexChar &&
          IsComplexASCIIChar(aText[offset])) {
        mCurrentWordContainsComplexChar = true;
      }
      ++offset;
    }

    if (offset > 0) {
      mTextItems.AppendElement(TextItem(aSink, 0, offset, aFlags));
    }

    if (offset == aLength) {
      // We did not encounter whitespace so the word hasn't finished yet.
      return NS_OK;
    }

    // We encountered whitespace, so we're done with this word
    nsresult rv = FlushCurrentWord();
    if (NS_FAILED(rv)) return rv;
  }

  AutoTArray<uint8_t, 4000> breakState;
  if (aSink) {
    if (!breakState.AppendElements(aLength, mozilla::fallible)) {
      return NS_ERROR_OUT_OF_MEMORY;
    }
  }

  uint32_t start = offset;
  bool noBreaksNeeded =
      !aSink || ((aFlags & NO_BREAKS_NEEDED_FLAGS) == NO_BREAKS_NEEDED_FLAGS &&
                 !mBreakHere && !mAfterBreakableSpace);
  if (noBreaksNeeded) {
    // Skip to the space before the last word, since either the break data
    // here is not needed, or no breaks are set in the sink and there cannot
    // be any breaks in this chunk; all we need is the context for the next
    // chunk (if any)
    offset = aLength;
    while (offset > start) {
      --offset;
      if (IsSpace(aText[offset])) break;
    }
  }
  uint32_t wordStart = offset;
  bool wordHasComplexChar = false;

  for (;;) {
    uint8_t ch = aText[offset];
    bool isSpace = IsSpace(ch);
    bool isBreakableSpace = isSpace && !(aFlags & BREAK_SUPPRESS_INSIDE);

    if (aSink) {
      // Consider word-break style.  Since the break position of CJK scripts
      // will be set by nsILineBreaker, we don't consider CJK at this point.
      breakState[offset] =
          mBreakHere || (mAfterBreakableSpace && !isBreakableSpace) ||
                  mWordBreak == WordBreakRule::BreakAll ||
                  mLineBreak == LineBreakRule::Anywhere
              ? gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NORMAL
              : gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NONE;
    }
    mBreakHere = false;
    mAfterBreakableSpace = isBreakableSpace;

    if (isSpace) {
      if (offset > wordStart && aSink && !(aFlags & BREAK_SUPPRESS_INSIDE)) {
        if (mLineBreak == LineBreakRule::Anywhere) {
          memset(breakState.Elements() + wordStart,
                 gfxTextRun::CompressedGlyph::FLAG_BREAK_TYPE_NORMAL,
                 offset - wordStart);
        } else if (wordHasComplexChar) {
          // Save current start-of-word state because ComputeBreakPositions()
          // will set it to false.
          AutoRestore<uint8_t> saveWordStartBreakState(breakState[wordStart]);
          LineBreaker::ComputeBreakPositions(
              aText + wordStart, offset - wordStart, mWordBreak, mLineBreak,
              mScriptIsChineseOrJapanese, breakState.Elements() + wordStart);
        }
      }

      wordHasComplexChar = false;
      ++offset;
      if (offset >= aLength) break;
      wordStart = offset;
    } else {
      if (!wordHasComplexChar && IsComplexASCIIChar(ch)) {
        wordHasComplexChar = true;
      }
      ++offset;
      if (offset >= aLength) {
        // Save this word
        mCurrentWordContainsComplexChar = wordHasComplexChar;
        uint32_t len = offset - wordStart;
        char16_t* elems = mCurrentWord.AppendElements(len);
        if (!elems) return NS_ERROR_OUT_OF_MEMORY;
        uint32_t i;
        for (i = wordStart; i < offset; ++i) {
          elems[i - wordStart] = aText[i];
        }
        mTextItems.AppendElement(TextItem(aSink, wordStart, len, aFlags));
        // Ensure that the break-before for this word is written out
        offset = wordStart + 1;
        break;
      }
    }
  }

  if (!noBreaksNeeded) {
    aSink->SetBreaks(start, offset - start, breakState.Elements() + start);
  }
  return NS_OK;
}

void nsLineBreaker::UpdateCurrentWordLanguage(nsAtom* aHyphenationLanguage) {
  if (mCurrentWordLanguage && mCurrentWordLanguage != aHyphenationLanguage) {
    mCurrentWordContainsMixedLang = true;
    mScriptIsChineseOrJapanese = false;
  } else {
    if (aHyphenationLanguage && !mCurrentWordLanguage) {
      Locale loc;
      auto result =
          LocaleParser::TryParse(nsAtomCString(aHyphenationLanguage), loc);

      if (result.isErr()) {
        return;
      }
      if (loc.Script().Missing() && loc.AddLikelySubtags().isErr()) {
        return;
      }
      mScriptIsChineseOrJapanese =
          loc.Script().EqualTo("Hans") || loc.Script().EqualTo("Hant") ||
          loc.Script().EqualTo("Jpan") || loc.Script().EqualTo("Hrkt");
    }
    mCurrentWordLanguage = aHyphenationLanguage;
  }
}

nsresult nsLineBreaker::AppendInvisibleWhitespace(uint32_t aFlags) {
  nsresult rv = FlushCurrentWord();
  if (NS_FAILED(rv)) return rv;

  bool isBreakableSpace = !(aFlags & BREAK_SUPPRESS_INSIDE);
  if (mAfterBreakableSpace && !isBreakableSpace) {
    mBreakHere = true;
  }
  mAfterBreakableSpace = isBreakableSpace;
  mWordContinuation = false;
  return NS_OK;
}

nsresult nsLineBreaker::Reset(bool* aTrailingBreak) {
  nsresult rv = FlushCurrentWord();
  if (NS_FAILED(rv)) return rv;

  *aTrailingBreak = mBreakHere || mAfterBreakableSpace;
  mBreakHere = false;
  mAfterBreakableSpace = false;
  return NS_OK;
}