135 lines
6.7 KiB
C++
135 lines
6.7 KiB
C++
// Copyright (C) 2016 and later: Unicode, Inc. and others.
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// License & terms of use: http://www.unicode.org/copyright.html
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/*
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* (C) Copyright IBM Corp. 1998-2005 - All Rights Reserved
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*
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* This file is a modification of the ICU file IndicReordering.h
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* by Jens Herden and Javier Sola for Khmer language
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*
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*/
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#ifndef __KHMERREORDERING_H
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#define __KHMERREORDERING_H
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/**
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* \file
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* \internal
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*/
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#include "LETypes.h"
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#include "OpenTypeTables.h"
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U_NAMESPACE_BEGIN
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class LEGlyphStorage;
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// Vocabulary
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// Base -> A consonant or an independent vowel in its full (not subscript) form. It is the
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// center of the syllable, it can be souranded by coeng (subscript) consonants, vowels,
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// split vowels, signs... but there is only one base in a syllable, it has to be coded as
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// the first character of the syllable.
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// split vowel --> vowel that has two parts placed separately (e.g. Before and after the consonant).
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// Khmer language has five of them. Khmer split vowels either have one part before the
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// base and one after the base or they have a part before the base and a part above the base.
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// The first part of all Khmer split vowels is the same character, identical to
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// the glyph of Khmer dependent vowel SRA EI
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// coeng --> modifier used in Khmer to construct coeng (subscript) consonants
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// Differently than indian languages, the coeng modifies the consonant that follows it,
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// not the one preceding it Each consonant has two forms, the base form and the subscript form
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// the base form is the normal one (using the consonants code-point), the subscript form is
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// displayed when the combination coeng + consonant is encountered.
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// Consonant of type 1 -> A consonant which has subscript for that only occupies space under a base consonant
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// Consonant of type 2.-> Its subscript form occupies space under and before the base (only one, RO)
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// Consonant of Type 3 -> Its subscript form occupies space under and after the base (KHO, CHHO, THHO, BA, YO, SA)
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// Consonant shifter -> Khmer has to series of consonants. The same dependent vowel has different sounds
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// if it is attached to a consonant of the first series or a consonant of the second series
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// Most consonants have an equivalent in the other series, but some of theme exist only in
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// one series (for example SA). If we want to use the consonant SA with a vowel sound that
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// can only be done with a vowel sound that corresponds to a vowel accompanying a consonant
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// of the other series, then we need to use a consonant shifter: TRIISAP or MUSIKATOAN
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// x17C9 y x17CA. TRIISAP changes a first series consonant to second series sound and
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// MUSIKATOAN a second series consonant to have a first series vowel sound.
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// Consonant shifter are both normally supercript marks, but, when they are followed by a
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// superscript, they change shape and take the form of subscript dependent vowel SRA U.
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// If they are in the same syllable as a coeng consonant, Unicode 3.0 says that they
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// should be typed before the coeng. Unicode 4.0 breaks the standard and says that it should
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// be placed after the coeng consonant.
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// Dependent vowel -> In khmer dependent vowels can be placed above, below, before or after the base
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// Each vowel has its own position. Only one vowel per syllable is allowed.
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// Signs -> Khmer has above signs and post signs. Only one above sign and/or one post sign are
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// Allowed in a syllable.
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//
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//
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struct KhmerClassTable // This list must include all types of components that can be used inside a syllable
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{
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enum CharClassValues // order is important here! This order must be the same that is found in each horizontal
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// line in the statetable for Khmer (file KhmerReordering.cpp).
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{
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CC_RESERVED = 0,
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CC_CONSONANT = 1, // consonant of type 1 or independent vowel
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CC_CONSONANT2 = 2, // Consonant of type 2
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CC_CONSONANT3 = 3, // Consonant of type 3
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CC_ZERO_WIDTH_NJ_MARK = 4, // Zero Width non joiner character (0x200C)
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CC_CONSONANT_SHIFTER = 5,
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CC_ROBAT = 6, // Khmer special diacritic accent -treated differently in state table
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CC_COENG = 7, // Subscript consonant combining character
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CC_DEPENDENT_VOWEL = 8,
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CC_SIGN_ABOVE = 9,
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CC_SIGN_AFTER = 10,
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CC_ZERO_WIDTH_J_MARK = 11, // Zero width joiner character
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CC_COUNT = 12 // This is the number of character classes
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};
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enum CharClassFlags
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{
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CF_CLASS_MASK = 0x0000FFFF,
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CF_CONSONANT = 0x01000000, // flag to speed up comparing
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CF_SPLIT_VOWEL = 0x02000000, // flag for a split vowel -> the first part is added in front of the syllable
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CF_DOTTED_CIRCLE = 0x04000000, // add a dotted circle if a character with this flag is the first in a syllable
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CF_COENG = 0x08000000, // flag to speed up comparing
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CF_SHIFTER = 0x10000000, // flag to speed up comparing
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CF_ABOVE_VOWEL = 0x20000000, // flag to speed up comparing
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// position flags
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CF_POS_BEFORE = 0x00080000,
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CF_POS_BELOW = 0x00040000,
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CF_POS_ABOVE = 0x00020000,
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CF_POS_AFTER = 0x00010000,
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CF_POS_MASK = 0x000f0000
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};
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typedef le_uint32 CharClass;
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typedef le_int32 ScriptFlags;
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LEUnicode firstChar; // for Khmer this will become x1780
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LEUnicode lastChar; // and this x17DF
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const CharClass *classTable;
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CharClass getCharClass(LEUnicode ch) const;
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static const KhmerClassTable *getKhmerClassTable();
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};
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class KhmerReordering /* not : public UObject because all methods are static */ {
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public:
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static le_int32 reorder(const LEUnicode *theChars, le_int32 charCount, le_int32 scriptCode,
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LEUnicode *outChars, LEGlyphStorage &glyphStorage);
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static const FeatureMap *getFeatureMap(le_int32 &count);
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private:
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// do not instantiate
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KhmerReordering();
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static le_int32 findSyllable(const KhmerClassTable *classTable, const LEUnicode *chars, le_int32 prev, le_int32 charCount);
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};
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U_NAMESPACE_END
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#endif
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