ui/base/ime/chromeos/character_composer.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef UI_BASE_IME_CHROMEOS_CHARACTER_COMPOSER_H_
   6 #define UI_BASE_IME_CHROMEOS_CHARACTER_COMPOSER_H_
   7
   8 #include <vector>
   9
  10 #include "base/strings/string_util.h"
  11 #include "ui/base/ime/ui_base_ime_export.h"
  12 #include "ui/events/keycodes/dom/dom_key.h"
  13
  14 namespace ui {
  15 class KeyEvent;
  16
  17 // A class to recognize compose and dead key sequence.
  18 // Outputs composed character.
  19 class UI_BASE_IME_EXPORT CharacterComposer {
  20  public:
  21   using ComposeBuffer = std::vector<DomKey>;
  22
  23   CharacterComposer();
  24   ~CharacterComposer();
  25
  26   void Reset();
  27
  28   // Filters keypress.
  29   // Returns true if the keypress is recognized as a part of composition
  30   // sequence.
  31   // Fabricated events which don't have the native event, are not supported.
  32   bool FilterKeyPress(const ui::KeyEvent& event);
  33
  34   // Returns a string consisting of composed character.
  35   // Empty string is returned when there is no composition result.
  36   const base::string16& composed_character() const {
  37     return composed_character_;
  38   }
  39
  40   // Returns the preedit string.
  41   const base::string16& preedit_string() const { return preedit_string_; }
  42
  43  private:
  44   // An enum to describe composition mode.
  45   enum CompositionMode {
  46     // This is the initial state.
  47     // Composite a character with dead-keys and compose-key.
  48     KEY_SEQUENCE_MODE,
  49     // Composite a character with a hexadecimal unicode sequence.
  50     HEX_MODE,
  51   };
  52
  53   // Filters keypress in key sequence mode.
  54   bool FilterKeyPressSequenceMode(const ui::KeyEvent& event);
  55
  56   // Filters keypress in hexadecimal mode.
  57   bool FilterKeyPressHexMode(const ui::KeyEvent& event);
  58
  59   // Commit a character composed from hexadecimal uncode sequence
  60   void CommitHex();
  61
  62   // Updates preedit string in hexadecimal mode.
  63   void UpdatePreeditStringHexMode();
  64
  65   // Remembers keypresses previously filtered.
  66   std::vector<DomKey> compose_buffer_;
  67
  68   // Records hexadecimal digits previously filtered.
  69   std::vector<unsigned int> hex_buffer_;
  70
  71   // A string representing the composed character.
  72   base::string16 composed_character_;
  73
  74   // Preedit string.
  75   base::string16 preedit_string_;
  76
  77   // Composition mode which this instance is in.
  78   CompositionMode composition_mode_;
  79
  80   DISALLOW_COPY_AND_ASSIGN(CharacterComposer);
  81 };
  82
  83 // Abstract class for determining whether a ComposeBuffer forms a valid
  84 // character composition sequence.
  85 class ComposeChecker {
  86  public:
  87   enum class CheckSequenceResult {
  88     // The sequence is not a composition sequence or the prefix of any
  89     // composition sequence.
  90     NO_MATCH,
  91     // The sequence is a prefix of one or more composition sequences.
  92     PREFIX_MATCH,
  93     // The sequence matches a composition sequence.
  94     FULL_MATCH
  95   };
  96   ComposeChecker() {}
  97   virtual ~ComposeChecker() {}
  98   virtual CheckSequenceResult CheckSequence(
  99       const ui::CharacterComposer::ComposeBuffer& sequence,
 100       uint32_t* composed_character) const = 0;
 101  private:
 102   DISALLOW_COPY_AND_ASSIGN(ComposeChecker);
 103 };
 104
 105 // Implementation of |ComposeChecker| using a compact generated tree.
 106 class TreeComposeChecker : public ComposeChecker {
 107  public:
 108   struct CompositionData {
 109     size_t maximum_sequence_length;
 110     int tree_entries;
 111     const uint16_t* tree;
 112   };
 113
 114   TreeComposeChecker(const CompositionData& data) : data_(data) {}
 115   CheckSequenceResult CheckSequence(
 116       const ui::CharacterComposer::ComposeBuffer& sequence,
 117       uint32_t* composed_character) const override;
 118
 119  private:
 120   bool Find(uint16_t index, uint16_t size, uint16_t key, uint16_t* value) const;
 121   const CompositionData& data_;
 122 };
 123
 124 }  // namespace ui
 125
 126 #endif  // UI_BASE_IME_CHROMEOS_CHARACTER_COMPOSER_H_