csr2022.cpp (6281B)
1 // © 2016 and later: Unicode, Inc. and others. 2 // License & terms of use: http://www.unicode.org/copyright.html 3 /* 4 ********************************************************************** 5 * Copyright (C) 2005-2016, International Business Machines 6 * Corporation and others. All Rights Reserved. 7 ********************************************************************** 8 */ 9 10 #include "unicode/utypes.h" 11 12 #if !UCONFIG_NO_CONVERSION 13 14 #include "cmemory.h" 15 #include "cstring.h" 16 17 #include "csr2022.h" 18 #include "csmatch.h" 19 20 U_NAMESPACE_BEGIN 21 22 /** 23 * Matching function shared among the 2022 detectors JP, CN and KR 24 * Counts up the number of legal and unrecognized escape sequences in 25 * the sample of text, and computes a score based on the total number & 26 * the proportion that fit the encoding. 27 * 28 * 29 * @param text the byte buffer containing text to analyse 30 * @param textLen the size of the text in the byte. 31 * @param escapeSequences the byte escape sequences to test for. 32 * @return match quality, in the range of 0-100. 33 */ 34 int32_t CharsetRecog_2022::match_2022(const uint8_t *text, int32_t textLen, const uint8_t escapeSequences[][5], int32_t escapeSequences_length) const 35 { 36 int32_t i, j; 37 int32_t escN; 38 int32_t hits = 0; 39 int32_t misses = 0; 40 int32_t shifts = 0; 41 int32_t quality; 42 43 i = 0; 44 while(i < textLen) { 45 if(text[i] == 0x1B) { 46 escN = 0; 47 while(escN < escapeSequences_length) { 48 const uint8_t *seq = escapeSequences[escN]; 49 int32_t seq_length = static_cast<int32_t>(uprv_strlen((const char*)seq)); 50 51 if (textLen-i >= seq_length) { 52 j = 1; 53 while(j < seq_length) { 54 if(seq[j] != text[i+j]) { 55 goto checkEscapes; 56 } 57 58 j += 1; 59 } 60 61 hits += 1; 62 i += seq_length-1; 63 goto scanInput; 64 } 65 // else we ran out of string to compare this time. 66 checkEscapes: 67 escN += 1; 68 } 69 70 misses += 1; 71 } 72 73 if( text[i]== 0x0e || text[i] == 0x0f){ 74 shifts += 1; 75 } 76 77 scanInput: 78 i += 1; 79 } 80 81 if (hits == 0) { 82 return 0; 83 } 84 85 // 86 // Initial quality is based on relative proportion of recognized vs. 87 // unrecognized escape sequences. 88 // All good: quality = 100; 89 // half or less good: quality = 0; 90 // linear inbetween. 91 quality = (100*hits - 100*misses) / (hits + misses); 92 93 // Back off quality if there were too few escape sequences seen. 94 // Include shifts in this computation, so that KR does not get penalized 95 // for having only a single Escape sequence, but many shifts. 96 if (hits+shifts < 5) { 97 quality -= (5-(hits+shifts))*10; 98 } 99 100 if (quality < 0) { 101 quality = 0; 102 } 103 104 return quality; 105 } 106 107 108 static const uint8_t escapeSequences_2022JP[][5] = { 109 {0x1b, 0x24, 0x28, 0x43, 0x00}, // KS X 1001:1992 110 {0x1b, 0x24, 0x28, 0x44, 0x00}, // JIS X 212-1990 111 {0x1b, 0x24, 0x40, 0x00, 0x00}, // JIS C 6226-1978 112 {0x1b, 0x24, 0x41, 0x00, 0x00}, // GB 2312-80 113 {0x1b, 0x24, 0x42, 0x00, 0x00}, // JIS X 208-1983 114 {0x1b, 0x26, 0x40, 0x00, 0x00}, // JIS X 208 1990, 1997 115 {0x1b, 0x28, 0x42, 0x00, 0x00}, // ASCII 116 {0x1b, 0x28, 0x48, 0x00, 0x00}, // JIS-Roman 117 {0x1b, 0x28, 0x49, 0x00, 0x00}, // Half-width katakana 118 {0x1b, 0x28, 0x4a, 0x00, 0x00}, // JIS-Roman 119 {0x1b, 0x2e, 0x41, 0x00, 0x00}, // ISO 8859-1 120 {0x1b, 0x2e, 0x46, 0x00, 0x00} // ISO 8859-7 121 }; 122 123 #if !UCONFIG_ONLY_HTML_CONVERSION 124 static const uint8_t escapeSequences_2022KR[][5] = { 125 {0x1b, 0x24, 0x29, 0x43, 0x00} 126 }; 127 128 static const uint8_t escapeSequences_2022CN[][5] = { 129 {0x1b, 0x24, 0x29, 0x41, 0x00}, // GB 2312-80 130 {0x1b, 0x24, 0x29, 0x47, 0x00}, // CNS 11643-1992 Plane 1 131 {0x1b, 0x24, 0x2A, 0x48, 0x00}, // CNS 11643-1992 Plane 2 132 {0x1b, 0x24, 0x29, 0x45, 0x00}, // ISO-IR-165 133 {0x1b, 0x24, 0x2B, 0x49, 0x00}, // CNS 11643-1992 Plane 3 134 {0x1b, 0x24, 0x2B, 0x4A, 0x00}, // CNS 11643-1992 Plane 4 135 {0x1b, 0x24, 0x2B, 0x4B, 0x00}, // CNS 11643-1992 Plane 5 136 {0x1b, 0x24, 0x2B, 0x4C, 0x00}, // CNS 11643-1992 Plane 6 137 {0x1b, 0x24, 0x2B, 0x4D, 0x00}, // CNS 11643-1992 Plane 7 138 {0x1b, 0x4e, 0x00, 0x00, 0x00}, // SS2 139 {0x1b, 0x4f, 0x00, 0x00, 0x00}, // SS3 140 }; 141 #endif 142 143 CharsetRecog_2022JP::~CharsetRecog_2022JP() {} 144 145 const char *CharsetRecog_2022JP::getName() const { 146 return "ISO-2022-JP"; 147 } 148 149 UBool CharsetRecog_2022JP::match(InputText *textIn, CharsetMatch *results) const { 150 int32_t confidence = match_2022(textIn->fInputBytes, 151 textIn->fInputLen, 152 escapeSequences_2022JP, 153 UPRV_LENGTHOF(escapeSequences_2022JP)); 154 results->set(textIn, this, confidence); 155 return (confidence > 0); 156 } 157 158 #if !UCONFIG_ONLY_HTML_CONVERSION 159 CharsetRecog_2022KR::~CharsetRecog_2022KR() {} 160 161 const char *CharsetRecog_2022KR::getName() const { 162 return "ISO-2022-KR"; 163 } 164 165 UBool CharsetRecog_2022KR::match(InputText *textIn, CharsetMatch *results) const { 166 int32_t confidence = match_2022(textIn->fInputBytes, 167 textIn->fInputLen, 168 escapeSequences_2022KR, 169 UPRV_LENGTHOF(escapeSequences_2022KR)); 170 results->set(textIn, this, confidence); 171 return (confidence > 0); 172 } 173 174 CharsetRecog_2022CN::~CharsetRecog_2022CN() {} 175 176 const char *CharsetRecog_2022CN::getName() const { 177 return "ISO-2022-CN"; 178 } 179 180 UBool CharsetRecog_2022CN::match(InputText *textIn, CharsetMatch *results) const { 181 int32_t confidence = match_2022(textIn->fInputBytes, 182 textIn->fInputLen, 183 escapeSequences_2022CN, 184 UPRV_LENGTHOF(escapeSequences_2022CN)); 185 results->set(textIn, this, confidence); 186 return (confidence > 0); 187 } 188 #endif 189 190 CharsetRecog_2022::~CharsetRecog_2022() { 191 // nothing to do 192 } 193 194 U_NAMESPACE_END 195 #endif