icuSources/layout/KhmerReordering.h

   1 /*
   2  * (C) Copyright IBM Corp. 1998-2005 - All Rights Reserved
   3  *
   4  * This file is a modification of the ICU file IndicReordering.h
   5  * by Jens Herden and Javier Sola for Khmer language
   6  *
   7  */
   8
   9 #ifndef __KHMERREORDERING_H
  10 #define __KHMERREORDERING_H
  11
  12 /**
  13  * \file
  14  * \internal
  15  */
  16
  17 #include "LETypes.h"
  18 #include "OpenTypeTables.h"
  19
  20 U_NAMESPACE_BEGIN
  21
  22 class LEGlyphStorage;
  23
  24 // Vocabulary
  25 //     Base ->         A consonant or an independent vowel in its full (not subscript) form. It is the
  26 //                     center of the syllable, it can be souranded by coeng (subscript) consonants, vowels,
  27 //                     split vowels, signs... but there is only one base in a syllable, it has to be coded as
  28 //                     the first character of the syllable.
  29 //     split vowel --> vowel that has two parts placed separately (e.g. Before and after the consonant).
  30 //                     Khmer language has five of them. Khmer split vowels either have one part before the
  31 //                     base and one after the base or they have a part before the base and a part above the base.
  32 //                     The first part of all Khmer split vowels is the same character, identical to
  33 //                     the glyph of Khmer dependent vowel SRA EI
  34 //     coeng -->  modifier used in Khmer to construct coeng (subscript) consonants
  35 //                Differently than indian languages, the coeng modifies the consonant that follows it,
  36 //                not the one preceding it  Each consonant has two forms, the base form and the subscript form
  37 //                the base form is the normal one (using the consonants code-point), the subscript form is
  38 //                displayed when the combination coeng + consonant is encountered.
  39 //     Consonant of type 1 -> A consonant which has subscript for that only occupies space under a base consonant
  40 //     Consonant of type 2.-> Its subscript form occupies space under and before the base (only one, RO)
  41 //     Consonant of Type 3 -> Its subscript form occupies space under and after the base (KHO, CHHO, THHO, BA, YO, SA)
  42 //     Consonant shifter -> Khmer has to series of consonants. The same dependent vowel has different sounds
  43 //                          if it is attached to a consonant of the first series or a consonant of the second series
  44 //                          Most consonants have an equivalent in the other series, but some of theme exist only in
  45 //                          one series (for example SA). If we want to use the consonant SA with a vowel sound that
  46 //                          can only be done with a vowel sound that corresponds to a vowel accompanying a consonant
  47 //                          of the other series, then we need to use a consonant shifter: TRIISAP or MUSIKATOAN
  48 //                          x17C9 y x17CA. TRIISAP changes a first series consonant to second series sound and
  49 //                          MUSIKATOAN a second series consonant to have a first series vowel sound.
  50 //                          Consonant shifter are both normally supercript marks, but, when they are followed by a
  51 //                          superscript, they change shape and take the form of subscript dependent vowel SRA U.
  52 //                          If they are in the same syllable as a coeng consonant, Unicode 3.0 says that they
  53 //                          should be typed before the coeng. Unicode 4.0 breaks the standard and says that it should
  54 //                          be placed after the coeng consonant.
  55 //     Dependent vowel ->   In khmer dependent vowels can be placed above, below, before or after the base
  56 //                          Each vowel has its own position. Only one vowel per syllable is allowed.
  57 //     Signs            ->  Khmer has above signs and post signs. Only one above sign and/or one post sign are
  58 //                          Allowed in a syllable.
  59 //
  60 //
  61
  62 struct KhmerClassTable    // This list must include all types of components that can be used inside a syllable
  63 {
  64     enum CharClassValues  // order is important here! This order must be the same that is found in each horizontal
  65                           // line in the statetable for Khmer (file KhmerReordering.cpp).
  66     {
  67         CC_RESERVED             =  0,
  68         CC_CONSONANT            =  1, // consonant of type 1 or independent vowel
  69         CC_CONSONANT2           =  2, // Consonant of type 2
  70         CC_CONSONANT3           =  3, // Consonant of type 3
  71         CC_ZERO_WIDTH_NJ_MARK   =  4, // Zero Width non joiner character (0x200C)
  72         CC_CONSONANT_SHIFTER    =  5,
  73         CC_ROBAT                =  6, // Khmer special diacritic accent -treated differently in state table
  74         CC_COENG                =  7, // Subscript consonant combining character
  75         CC_DEPENDENT_VOWEL      =  8,
  76         CC_SIGN_ABOVE           =  9,
  77         CC_SIGN_AFTER           = 10,
  78         CC_ZERO_WIDTH_J_MARK    = 11, // Zero width joiner character
  79         CC_COUNT                = 12  // This is the number of character classes
  80     };
  81
  82     enum CharClassFlags
  83     {
  84         CF_CLASS_MASK    = 0x0000FFFF,
  85
  86         CF_CONSONANT     = 0x01000000,  // flag to speed up comparing
  87         CF_SPLIT_VOWEL   = 0x02000000,  // flag for a split vowel -> the first part is added in front of the syllable
  88         CF_DOTTED_CIRCLE = 0x04000000,  // add a dotted circle if a character with this flag is the first in a syllable
  89         CF_COENG         = 0x08000000,  // flag to speed up comparing
  90         CF_SHIFTER       = 0x10000000,  // flag to speed up comparing
  91         CF_ABOVE_VOWEL   = 0x20000000,  // flag to speed up comparing
  92
  93         // position flags
  94         CF_POS_BEFORE    = 0x00080000,
  95         CF_POS_BELOW     = 0x00040000,
  96         CF_POS_ABOVE     = 0x00020000,
  97         CF_POS_AFTER     = 0x00010000,
  98         CF_POS_MASK      = 0x000f0000
  99     };
 100
 101     typedef le_uint32 CharClass;
 102
 103     typedef le_int32 ScriptFlags;
 104
 105     LEUnicode firstChar;   // for Khmer this will become x1780
 106     LEUnicode lastChar;    //  and this x17DF
 107     const CharClass *classTable;
 108
 109     CharClass getCharClass(LEUnicode ch) const;
 110
 111     static const KhmerClassTable *getKhmerClassTable();
 112 };
 113
 114
 115 class KhmerReordering /* not : public UObject because all methods are static */ {
 116 public:
 117     static le_int32 reorder(const LEUnicode *theChars, le_int32 charCount, le_int32 scriptCode,
 118         LEUnicode *outChars, LEGlyphStorage &glyphStorage);
 119
 120     static const FeatureMap *getFeatureMap(le_int32 &count);
 121
 122 private:
 123     // do not instantiate
 124     KhmerReordering();
 125
 126     static le_int32 findSyllable(const KhmerClassTable *classTable, const LEUnicode *chars, le_int32 prev, le_int32 charCount);
 127
 128 };
 129
 130
 131 U_NAMESPACE_END
 132 #endif