icuSources/layout/TibetanReordering.h

   1 /*
   2  *
   3  * (C) Copyright IBM Corp. 1998-2013 - All Rights Reserved
   4  *
   5  * Developed at DIT - Government of Bhutan
   6  *
   7  * Contact person: Pema Geyleg - <pema_geyleg@druknet.bt>
   8  *
   9  * This file is a modification of the ICU file KhmerReordering.h
  10  * by Jens Herden and Javier Sola who have given all their possible rights to IBM and the Governement of Bhutan
  11  * A first module for Dzongkha was developed by Karunakar under Panlocalisation funding.
  12  * Assistance for this module has been received from Namgay Thinley, Christopher Fynn and Javier Sola
  13  *
  14  */
  15
  16 #ifndef __TIBETANREORDERING_H
  17 #define __TIBETANREORDERING_H
  18
  19 /**
  20  * \file
  21  * \internal
  22  */
  23
  24 // #include "LETypes.h"
  25 // #include "OpenTypeTables.h"
  26
  27 U_NAMESPACE_BEGIN
  28
  29 class LEGlyphStorage;
  30
  31 // Vocabulary
  32 //     Base ->         A consonant in its full (not subscript) form. It is the
  33 //                     center of the syllable, it can be souranded by subjoined consonants, vowels,
  34 //                     signs... but there is only one base in a stack, it has to be coded as
  35 //                     the first character of the syllable.Included here are also groups of base + subjoined
  36 //                                                                               which are represented by one single code point in unicode (e.g. 0F43) Also other characters that might take
  37 //                     subjoined consonants or other combining characters.
  38 //     Subjoined ->    Subjoined consonants and groups of subjoined consonants which have a single code-point
  39 //                     to repersent the group (even if each subjoined consonant is represented independently
  40 //                     by anothe code-point
  41 //     Tsa Phru -->    Tsa Phru character, Bhutanese people will always place it right after the base, but sometimes, due to
  42 //                                                                              "normalization"
  43 //                                                                               is placed after all the subjoined consonants, and it is also permitted there.
  44 //     A Chung  Vowel lengthening mark --> . 0F71 It is placed after the base and any subjoined consonants but before any vowels
  45 //     Precomposed Sanskrit vowels --> The are combinations of subjoined consonants + vowels that have been assigned
  46 //                     a given code-point (in spite of each single part of them having also a code-point
  47 //                     They are avoided, and users are encouraged to use the combination of code-points that
  48 //                     represents the same sound instead of using this combined characters. This is included here
  49 //                     for compatibility with possible texts that use them (they are not in the Dzongkha keyboard).
  50 //     Halanta ->      The Halanta or Virama character 0F84 indicates that a consonant should not use its inheernt vowel,
  51 //                     in spite of not having other vowels present. It is usually placed immediatly after a base consonant,
  52 //                     but in some special cases it can also be placed after a subjoined consonant, so this is also
  53 //                     permitted in this algorithm. (Halanta is always displayed in Tibetan not used as a connecting char)
  54 //
  55 //     Subjoined vowels -> Dependent vowels (matras) placed below the base and below all subjoined consonants. There
  56 //                     might be as much as three subjoined vowels in a given stack (only one in general text, but up
  57 //                     to three for abreviations, they have to be permitted).
  58 //     Superscript vowels -> There are three superscript vowels, and they can be repeated or combined (up to three
  59 //                     times. They can combine with subjoined vowels, and are always coded after these.
  60 //     Anusvara -->    Nasalisation sign. Traditioinally placed in absence of vowels, but also after vowels. In some
  61 //                     special cases it can be placed before a vowel, so this is also permitted
  62 //     Candrabindu ->  Forms of the Anusvara with different glyphs (and different in identity) which can be placed
  63 //                     without vowel or after the vowel, but never before. Cannot combine with Anusvara.
  64 //     Stress marks -> Marks placed above or below a syllable, affecting the whole syllable. They are combining
  65 //                     marks, so they have to be attached to a specific stack. The are using to emphasise a syllable.
  66 //
  67 //     Digits ->       Digits are not considered as non-combining characters because there are a few characters which
  68 //                     combine with them, so they have to be considered independently.
  69 //     Digit combining marks -> dependent marks that combine with digits.
  70 //
  71 //     TODO
  72 //     There are a number of characters in the CJK block that are used in Tibetan script, two of these are symbols
  73 //     are used as bases for combining glyphs, and have not been encoded in Tibetan. As these characters are outside
  74 //     of the tibetan block, they have not been treated in this program.
  75
  76
  77 struct TibetanClassTable    // This list must include all types of components that can be used inside a syllable
  78 {
  79     enum CharClassValues  // order is important here! This order must be the same that is found in each horizontal
  80                           // line in the statetable for Tibetan (file TibetanReordering.cpp). It assigns one number
  81                           // to each type of character that has to be considered when analysing the order in which
  82                           // characters can be placed
  83     {
  84         CC_RESERVED             =  0, //Non Combining Characters
  85         CC_BASE                 =  1, // Base Consonants, Base Consonants with Subjoined attached in code point, Sanskrit base marks
  86         CC_SUBJOINED            =  2, // Subjoined Consonats, combination of more than Subjoined Consonants in the code point
  87         CC_TSA_PHRU             =  3, // Tsa-Phru character 0F39
  88         CC_A_CHUNG              =  4, // Vowel Lenthening a-chung mark 0F71
  89         CC_COMP_SANSKRIT        =  5, // Precomposed Sanskrit vowels including Subjoined characters and vowels
  90         CC_HALANTA              =  6, // Halanta Character 0F84
  91         CC_BELOW_VOWEL          =  7, // Subjoined vowels
  92         CC_ABOVE_VOWEL          =  8, // Superscript vowels
  93         CC_ANUSVARA             =  9, // Tibetan sign Rjes Su Nga Ro 0F7E
  94         CC_CANDRABINDU          = 10, // Tibetan sign Sna Ldan and Nyi Zla Naa Da 0F82, 0F83
  95         CC_VISARGA              = 11, // Tibetan sign Rnam Bcad (0F7F)
  96         CC_ABOVE_S_MARK         = 12, // Stress Marks placed above the text
  97         CC_BELOW_S_MARK         = 13, // Stress Marks placed below the text
  98         CC_DIGIT                = 14, // Dzongkha Digits
  99         CC_PRE_DIGIT_MARK       = 15, // Mark placed before the digit
 100         CC_POST_BELOW_DIGIT_M   = 16, // Mark placed below or after the digit
 101         CC_COUNT                = 17  // This is the number of character classes
 102     };
 103
 104     enum CharClassFlags
 105     {
 106         CF_CLASS_MASK    = 0x0000FFFF,
 107
 108         CF_DOTTED_CIRCLE = 0x04000000,  // add a dotted circle if a character with this flag is the first in a syllable
 109         CF_DIGIT         = 0x01000000,  // flag to speed up comparaisson
 110         CF_PREDIGIT      = 0x02000000,  // flag to detect pre-digit marks for reordering
 111
 112         // position flags
 113         CF_POS_BEFORE    = 0x00080000,
 114         CF_POS_BELOW     = 0x00040000,
 115         CF_POS_ABOVE     = 0x00020000,
 116         CF_POS_AFTER     = 0x00010000,
 117         CF_POS_MASK      = 0x000f0000
 118     };
 119
 120     typedef le_uint32 CharClass;
 121
 122     typedef le_int32 ScriptFlags;
 123
 124     LEUnicode firstChar;   // for Tibetan this will become xOF00
 125     LEUnicode lastChar;    //  and this x0FFF
 126     const CharClass *classTable;
 127
 128     CharClass getCharClass(LEUnicode ch) const;
 129
 130     static const TibetanClassTable *getTibetanClassTable();
 131 };
 132
 133
 134 class TibetanReordering /* not : public UObject because all methods are static */ {
 135 public:
 136     static le_int32 reorder(const LEUnicode *theChars, le_int32 charCount, le_int32 scriptCode,
 137         LEUnicode *outChars, LEGlyphStorage &glyphStorage);
 138
 139     static const FeatureMap *getFeatureMap(le_int32 &count);
 140
 141 private:
 142     // do not instantiate
 143     TibetanReordering();
 144
 145     static le_int32 findSyllable(const TibetanClassTable *classTable, const LEUnicode *chars, le_int32 prev, le_int32 charCount);
 146
 147 };
 148
 149
 150 U_NAMESPACE_END
 151 #endif