Adds a hy-phen-ator.

content/renderer/hyphenator/hyphenator.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/renderer/hyphenator/hyphenator.h"
+
+#include "base/file_util.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/string_util.h"
+#include "base/utf_string_conversions.h"
+#include "third_party/hyphen/hyphen.h"
+#include "unicode/uscript.h"
+
+namespace {
+
+// A class that converts a sequence of UTF-8 characters to UTF-16 ones and holds
+// only the length of converted UTF-16 characters. This class is used for
+// creating a mapping from the position of a UTF-8 string to a position of a
+// UTF-16 string without unnecessary conversions. Even though the following
+// snippet produces the same mapping, it needs to convert same characters many
+// times. This class incrementally counts the number of converted UTF-16
+// characters to avoid this problem.
+//
+//   scoped_array<size_t> position(new size_t[text.length()]);
+//   for (size_t i = 0; i < text.length(); ++i)
+//     position[i] = UTF8ToUTF16(text.substr(0, i)).length();
+//
+class UTF16TextLength {
+ public:
+  UTF16TextLength();
+  ~UTF16TextLength();
+
+  // Returns the current position.
+  int utf16_length() const { return utf16_length_; }
+
+  // Appends one UTF-8 character to this converter and advances the converted
+  // position. This converter increases the position by one when it finishes
+  // reading a BMP character and increases by two when it finish reading a
+  // non-BMP character.
+  void Append(char c);
+
+ private:
+  // The length of the converted UTF-16 text.
+  int utf16_length_;
+
+  // The buffer that stores UTF-8 characters being converted.
+  std::string utf8_text_;
+
+  DISALLOW_COPY_AND_ASSIGN(UTF16TextLength);
+};
+
+UTF16TextLength::UTF16TextLength()
+    : utf16_length_(0) {
+}
+
+UTF16TextLength::~UTF16TextLength() {
+}
+
+void UTF16TextLength::Append(char c) {
+  // Append the given character and try converting the UTF-8 characters in this
+  // buffer to Unicode codepoints. If this buffer includes a Unicode codepoint,
+  // get the number of UTF-16 characters representing this codepoint and advance
+  // the position.
+  int code = 0;
+  int index = 0;
+  utf8_text_.push_back(c);
+  U8_NEXT(utf8_text_.data(), index, static_cast<int>(utf8_text_.length()),
+          code);
+  if (code != U_SENTINEL) {
+    utf8_text_.clear();
+    utf16_length_ += U16_LENGTH(code);
+  }
+}
+
+// A class that encapsulates a hyphenation query. This class owns resources
+// temporarily needed for hyphenating one word, and deletes them when it is
+// deleted as listed in the following snippet.
+//
+//   std::vector<int> hyphens;
+//   QUery query(UTF8ToUTF16("hyphenate"));
+//   query.Hyphenate(dict, &hyphens);
+//
+class Query {
+ public:
+  explicit Query(const string16& word);
+  ~Query();
+
+  // Hyphenates a word with the specified dictionary. This function hyphenates
+  // the word provided to its constructor and returns a list of hyphenation
+  // points, positions where we can insert hyphens.
+  bool Hyphenate(HyphenDict* dictionary, std::vector<int>* hyphen_offsets);
+
+ private:
+  // A word to be hyphenated.
+  std::string word_utf8_;
+
+  // Return variables from the hyphen library.
+  scoped_array<char> hyphen_vector_;
+  char** rep_;
+  int* pos_;
+  int* cut_;
+
+  DISALLOW_COPY_AND_ASSIGN(Query);
+};
+
+Query::Query(const string16& word)
+    : rep_(NULL),
+      pos_(NULL),
+      cut_(NULL) {
+  // Remove trailing punctuation characters. WebKit does not remove these
+  // characters when it hyphenates a word. These characters prevent the hyphen
+  // library from applying some rules, i.e. they prevent the library from adding
+  // hyphens.
+  DCHECK(!word.empty());
+  const char16* data = word.data();
+  int length = static_cast<int>(word.length());
+  while (length > 0) {
+    int previous = length;
+    int code = 0;
+    U16_PREV(data, 0, previous, code);
+    UErrorCode error = U_ZERO_ERROR;
+    if (uscript_getScript(code, &error) != USCRIPT_COMMON)
+      break;
+    length = previous;
+  }
+  UTF16ToUTF8(word.c_str(), length, &word_utf8_);
+  // Create a hyphen vector used by hnj_hyphen_hyphenate2(). We allocate a
+  // buffer of |word_.length()| + 5 as written in Line 112 of
+  // <http://cs.chromium.org/src/third_party/hyphen/hyphen.h>.
+  hyphen_vector_.reset(new char[word_utf8_.length() + 5]);
+}
+
+Query::~Query() {
+  if (rep_) {
+    for (size_t i = 0; i < word_utf8_.length(); ++i) {
+      if (rep_[i])
+        free(rep_[i]);
+    }
+    free(rep_);
+  }
+  if (pos_)
+    free(pos_);
+  if (cut_)
+    free(cut_);
+}
+
+bool Query::Hyphenate(HyphenDict* dictionary,
+                      std::vector<int>* hyphen_offsets) {
+  DCHECK(dictionary);
+  DCHECK(hyphen_offsets);
+
+  int error_code = hnj_hyphen_hyphenate2(dictionary,
+                                         word_utf8_.data(),
+                                         static_cast<int>(word_utf8_.length()),
+                                         hyphen_vector_.get(),
+                                         NULL,
+                                         &rep_,
+                                         &pos_,
+                                         &cut_);
+  if (error_code)
+    return false;
+
+  // WebKit needs hyphenation points counted in UTF-16 characters. On the other
+  // hand, the hyphen library returns hyphenation points counted in UTF-8
+  // characters. We increamentally convert hyphenation points in UTF-8
+  // characters to hyphenation points in UTF-16 characters and write the
+  // converted hyphenation points to the output vector.
+  UTF16TextLength text_length;
+  hyphen_offsets->clear();
+  for (size_t i = 0; i < word_utf8_.length(); ++i) {
+    text_length.Append(word_utf8_[i]);
+    if (hyphen_vector_[i] & 1)
+      hyphen_offsets->push_back(text_length.utf16_length());
+  }
+  return !hyphen_offsets->empty();
+}
+
+}  // namespace
+
+namespace content {
+
+Hyphenator::Hyphenator(base::PlatformFile file)
+    : dictionary_(NULL),
+      rule_file_(file),
+      result_(0) {
+}
+
+Hyphenator::~Hyphenator() {
+  if (dictionary_)
+    hnj_hyphen_free(dictionary_);
+}
+
+bool Hyphenator::Initialize() {
+  if (dictionary_)
+    return true;
+
+  rule_map_.reset(new file_util::MemoryMappedFile);
+  if (!rule_map_->Initialize(rule_file_))
+    return false;
+
+  dictionary_ = hnj_hyphen_load(rule_map_->data(), rule_map_->length());
+  return !!dictionary_;
+}
+
+size_t Hyphenator::ComputeLastHyphenLocation(const string16& word,
+                                             size_t before_index) {
+  if (!dictionary_ || word.empty())
+    return 0;
+
+  // Call the hyphen library to get all hyphenation points, i.e. positions where
+  // we can insert hyphens. When WebKit finds a line-break, it calls this
+  // function twice or more with the same word to find the best hyphenation
+  // point. To avoid calling the hyphen library twice or more with the same
+  // word, we cache the last query.
+  if (word_ != word) {
+    word_ = word;
+    Query query(word);
+    result_ = query.Hyphenate(dictionary_, &hyphen_offsets_);
+  }
+  if (!result_)
+    return 0;
+  for (std::vector<int>::reverse_iterator it = hyphen_offsets_.rbegin();
+       it != hyphen_offsets_.rend(); ++it) {
+    if (static_cast<size_t>(*it) < before_index)
+      return *it;
+  }
+  return 0;
+}
+
+}  // namespace content