third_party/WebKit/Source/platform/fonts/ScriptRunIterator.h

   1 // Copyright 2015 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 ScriptRunIterator_h
   6 #define ScriptRunIterator_h
   7
   8 #include "platform/PlatformExport.h"
   9 #include "wtf/Deque.h"
  10 #include "wtf/Vector.h"
  11 #include "wtf/dtoa/utils.h"
  12
  13 #include <unicode/uchar.h>
  14 #include <unicode/uscript.h>
  15
  16 namespace blink {
  17
  18 class ScriptData;
  19
  20 class PLATFORM_EXPORT ScriptRunIterator {
  21 public:
  22     ScriptRunIterator(const UChar* text, size_t length);
  23
  24     // This maintains a reference to data. It must exist for the lifetime of
  25     // this object. Typically data is a singleton that exists for the life of
  26     // the process.
  27     ScriptRunIterator(const UChar* text, size_t length, const ScriptData*);
  28
  29     bool consume(unsigned& limit, UScriptCode&);
  30
  31 private:
  32     struct BracketRec {
  33         UChar32 ch;
  34         UScriptCode script;
  35     };
  36     void openBracket(UChar32);
  37     void closeBracket(UChar32);
  38     bool mergeSets();
  39     void fixupStack(UScriptCode resolvedScript);
  40     bool fetch(size_t* pos, UChar32*);
  41
  42     UScriptCode resolveCurrentScript() const;
  43
  44     const UChar* m_text;
  45     const size_t m_length;
  46
  47     Deque<BracketRec> m_brackets;
  48     size_t m_bracketsFixupDepth;
  49     // Limit max brackets so that the bracket tracking buffer does not grow
  50     // excessively large when processing long runs of text.
  51     static const int kMaxBrackets = 32;
  52
  53     Vector<UScriptCode> m_currentSet;
  54     Vector<UScriptCode> m_nextSet;
  55     Vector<UScriptCode> m_aheadSet;
  56
  57     UChar32 m_aheadCharacter;
  58     size_t m_aheadPos;
  59
  60     UScriptCode m_commonPreferred;
  61
  62     const ScriptData* m_scriptData;
  63
  64     DISALLOW_COPY_AND_ASSIGN(ScriptRunIterator);
  65 };
  66
  67 // ScriptData is a wrapper which returns a set of scripts for a particular
  68 // character retrieved from the character's primary script and script extensions,
  69 // as per ICU / Unicode data. ScriptData maintains a certain priority order of
  70 // the returned values, which are essential for mergeSets method to work
  71 // correctly.
  72 class PLATFORM_EXPORT ScriptData {
  73 protected:
  74     ScriptData() = default;
  75
  76 public:
  77     virtual ~ScriptData();
  78
  79     enum PairedBracketType {
  80         BracketTypeNone,
  81         BracketTypeOpen,
  82         BracketTypeClose,
  83         BracketTypeCount
  84     };
  85
  86     static const int kMaxScriptCount;
  87
  88     virtual void getScripts(UChar32, Vector<UScriptCode>& dst) const = 0;
  89
  90     virtual UChar32 getPairedBracket(UChar32) const = 0;
  91
  92     virtual PairedBracketType getPairedBracketType(UChar32) const = 0;
  93
  94 private:
  95     DISALLOW_COPY_AND_ASSIGN(ScriptData);
  96 };
  97
  98 class PLATFORM_EXPORT ICUScriptData : public ScriptData {
  99 public:
 100     ~ICUScriptData() override
 101     {
 102     }
 103
 104     static const ICUScriptData* instance();
 105
 106     void getScripts(UChar32, Vector<UScriptCode>& dst) const override;
 107
 108     UChar32 getPairedBracket(UChar32) const override;
 109
 110     PairedBracketType getPairedBracketType(UChar32) const override;
 111
 112 private:
 113     ICUScriptData()
 114     {
 115     }
 116
 117     DISALLOW_COPY_AND_ASSIGN(ICUScriptData);
 118 };
 119 }
 120
 121 #endif