96 lines
3.7 KiB
C
96 lines
3.7 KiB
C
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#pragma once
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#include <cstdint>
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/**
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* Thai Character Classification
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*
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* Thai Unicode block (U+0E00-U+0E7F) contains:
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* - Consonants (ก-ฮ): U+0E01-U+0E2E
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* - Vowels that can appear in various positions
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* - Tone marks that stack above consonants/vowels
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* - Thai digits and punctuation
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*
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* Thai text rendering requires special handling because:
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* 1. Leading vowels (เ แ โ ไ ใ) display BEFORE the consonant but
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* appear AFTER in Unicode codepoint order
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* 2. Above vowels (ิ ี ึ ื etc.) must be positioned above consonants
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* 3. Below vowels (ุ ู) must be positioned below consonants
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* 4. Tone marks must stack above vowels/consonants
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*/
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namespace ThaiShaper {
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// Thai character types for positioning and cluster formation
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enum class ThaiCharType : uint8_t {
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NON_THAI, // Not a Thai character
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CONSONANT, // Base consonant (ก-ฮ)
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LEADING_VOWEL, // Vowels that display before consonant (เ แ โ ไ ใ)
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ABOVE_VOWEL, // Vowels above consonant (ั ิ ี ึ ื ็)
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BELOW_VOWEL, // Vowels below consonant (ุ ู ฺ)
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FOLLOW_VOWEL, // Vowels that follow consonant (ะ า ำ)
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TONE_MARK, // Tone marks (่ ้ ๊ ๋)
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NIKHAHIT, // Nikhahit (ํ) - special combining mark
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YAMAKKAN, // Yamakkan (์) - cancellation mark
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THAI_DIGIT, // Thai digits (๐-๙)
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THAI_SYMBOL, // Thai punctuation and symbols
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};
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// Check if a codepoint is in the Thai Unicode block
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inline bool isThaiCodepoint(uint32_t cp) { return cp >= 0x0E00 && cp <= 0x0E7F; }
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// Get the character type for a Thai codepoint
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ThaiCharType getThaiCharType(uint32_t cp);
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// Check if codepoint is a Thai consonant (can be a cluster base)
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inline bool isThaiConsonant(uint32_t cp) { return cp >= 0x0E01 && cp <= 0x0E2E; }
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// Check if codepoint is a leading vowel (needs reordering)
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inline bool isThaiLeadingVowel(uint32_t cp) {
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return cp == 0x0E40 || // SARA E (เ)
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cp == 0x0E41 || // SARA AE (แ)
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cp == 0x0E42 || // SARA O (โ)
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cp == 0x0E43 || // SARA AI MAIMUAN (ใ)
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cp == 0x0E44; // SARA AI MAIMALAI (ไ)
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}
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// Check if codepoint is an above vowel/mark (positioned above base)
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inline bool isThaiAboveVowel(uint32_t cp) {
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return cp == 0x0E31 || // MAI HAN-AKAT (ั)
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cp == 0x0E34 || // SARA I (ิ)
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cp == 0x0E35 || // SARA II (ี)
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cp == 0x0E36 || // SARA UE (ึ)
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cp == 0x0E37 || // SARA UEE (ื)
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cp == 0x0E47; // MAITAIKHU (็)
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}
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// Check if codepoint is a below vowel (positioned below base)
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inline bool isThaibelowVowel(uint32_t cp) {
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return cp == 0x0E38 || // SARA U (ุ)
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cp == 0x0E39 || // SARA UU (ู)
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cp == 0x0E3A; // PHINTHU (ฺ)
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}
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// Check if codepoint is a tone mark (positioned above)
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inline bool isThaiToneMark(uint32_t cp) {
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return cp == 0x0E48 || // MAI EK (่)
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cp == 0x0E49 || // MAI THO (้)
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cp == 0x0E4A || // MAI TRI (๊)
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cp == 0x0E4B; // MAI CHATTAWA (๋)
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}
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// Check if codepoint is a Thai digit
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inline bool isThaiDigit(uint32_t cp) { return cp >= 0x0E50 && cp <= 0x0E59; }
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// Check if a codepoint is a combining character (needs to attach to base)
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inline bool isThaiCombining(uint32_t cp) {
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return isThaiAboveVowel(cp) || isThaibelowVowel(cp) || isThaiToneMark(cp) || cp == 0x0E4C || // THANTHAKHAT (์)
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cp == 0x0E4D || // NIKHAHIT (ํ)
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cp == 0x0E4E; // YAMAKKAN
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}
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// Check if text contains any Thai codepoints (for fast path detection)
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bool containsThai(const char* text);
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} // namespace ThaiShaper
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