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Diffstat (limited to 'intl/icu/source/i18n/csr2022.cpp')
| -rw-r--r-- | intl/icu/source/i18n/csr2022.cpp | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/intl/icu/source/i18n/csr2022.cpp b/intl/icu/source/i18n/csr2022.cpp new file mode 100644 index 000000000..66289ee6f --- /dev/null +++ b/intl/icu/source/i18n/csr2022.cpp @@ -0,0 +1,195 @@ +// Copyright (C) 2016 and later: Unicode, Inc. and others. +// License & terms of use: http://www.unicode.org/copyright.html +/* + ********************************************************************** + * Copyright (C) 2005-2016, International Business Machines + * Corporation and others. All Rights Reserved. + ********************************************************************** + */ + +#include "unicode/utypes.h" + +#if !UCONFIG_NO_CONVERSION + +#include "cmemory.h" +#include "cstring.h" + +#include "csr2022.h" +#include "csmatch.h" + +U_NAMESPACE_BEGIN + +/** + * Matching function shared among the 2022 detectors JP, CN and KR + * Counts up the number of legal and unrecognized escape sequences in + * the sample of text, and computes a score based on the total number & + * the proportion that fit the encoding. + * + * + * @param text the byte buffer containing text to analyse + * @param textLen the size of the text in the byte. + * @param escapeSequences the byte escape sequences to test for. + * @return match quality, in the range of 0-100. + */ +int32_t CharsetRecog_2022::match_2022(const uint8_t *text, int32_t textLen, const uint8_t escapeSequences[][5], int32_t escapeSequences_length) const +{ + int32_t i, j; + int32_t escN; + int32_t hits = 0; + int32_t misses = 0; + int32_t shifts = 0; + int32_t quality; + + i = 0; + while(i < textLen) { + if(text[i] == 0x1B) { + escN = 0; + while(escN < escapeSequences_length) { + const uint8_t *seq = escapeSequences[escN]; + int32_t seq_length = (int32_t)uprv_strlen((const char *) seq); + + if (textLen-i >= seq_length) { + j = 1; + while(j < seq_length) { + if(seq[j] != text[i+j]) { + goto checkEscapes; + } + + j += 1; + } + + hits += 1; + i += seq_length-1; + goto scanInput; + } + // else we ran out of string to compare this time. +checkEscapes: + escN += 1; + } + + misses += 1; + } + + if( text[i]== 0x0e || text[i] == 0x0f){ + shifts += 1; + } + +scanInput: + i += 1; + } + + if (hits == 0) { + return 0; + } + + // + // Initial quality is based on relative proportion of recongized vs. + // unrecognized escape sequences. + // All good: quality = 100; + // half or less good: quality = 0; + // linear inbetween. + quality = (100*hits - 100*misses) / (hits + misses); + + // Back off quality if there were too few escape sequences seen. + // Include shifts in this computation, so that KR does not get penalized + // for having only a single Escape sequence, but many shifts. + if (hits+shifts < 5) { + quality -= (5-(hits+shifts))*10; + } + + if (quality < 0) { + quality = 0; + } + + return quality; +} + + +static const uint8_t escapeSequences_2022JP[][5] = { + {0x1b, 0x24, 0x28, 0x43, 0x00}, // KS X 1001:1992 + {0x1b, 0x24, 0x28, 0x44, 0x00}, // JIS X 212-1990 + {0x1b, 0x24, 0x40, 0x00, 0x00}, // JIS C 6226-1978 + {0x1b, 0x24, 0x41, 0x00, 0x00}, // GB 2312-80 + {0x1b, 0x24, 0x42, 0x00, 0x00}, // JIS X 208-1983 + {0x1b, 0x26, 0x40, 0x00, 0x00}, // JIS X 208 1990, 1997 + {0x1b, 0x28, 0x42, 0x00, 0x00}, // ASCII + {0x1b, 0x28, 0x48, 0x00, 0x00}, // JIS-Roman + {0x1b, 0x28, 0x49, 0x00, 0x00}, // Half-width katakana + {0x1b, 0x28, 0x4a, 0x00, 0x00}, // JIS-Roman + {0x1b, 0x2e, 0x41, 0x00, 0x00}, // ISO 8859-1 + {0x1b, 0x2e, 0x46, 0x00, 0x00} // ISO 8859-7 +}; + +#if !UCONFIG_ONLY_HTML_CONVERSION +static const uint8_t escapeSequences_2022KR[][5] = { + {0x1b, 0x24, 0x29, 0x43, 0x00} +}; + +static const uint8_t escapeSequences_2022CN[][5] = { + {0x1b, 0x24, 0x29, 0x41, 0x00}, // GB 2312-80 + {0x1b, 0x24, 0x29, 0x47, 0x00}, // CNS 11643-1992 Plane 1 + {0x1b, 0x24, 0x2A, 0x48, 0x00}, // CNS 11643-1992 Plane 2 + {0x1b, 0x24, 0x29, 0x45, 0x00}, // ISO-IR-165 + {0x1b, 0x24, 0x2B, 0x49, 0x00}, // CNS 11643-1992 Plane 3 + {0x1b, 0x24, 0x2B, 0x4A, 0x00}, // CNS 11643-1992 Plane 4 + {0x1b, 0x24, 0x2B, 0x4B, 0x00}, // CNS 11643-1992 Plane 5 + {0x1b, 0x24, 0x2B, 0x4C, 0x00}, // CNS 11643-1992 Plane 6 + {0x1b, 0x24, 0x2B, 0x4D, 0x00}, // CNS 11643-1992 Plane 7 + {0x1b, 0x4e, 0x00, 0x00, 0x00}, // SS2 + {0x1b, 0x4f, 0x00, 0x00, 0x00}, // SS3 +}; +#endif + +CharsetRecog_2022JP::~CharsetRecog_2022JP() {} + +const char *CharsetRecog_2022JP::getName() const { + return "ISO-2022-JP"; +} + +UBool CharsetRecog_2022JP::match(InputText *textIn, CharsetMatch *results) const { + int32_t confidence = match_2022(textIn->fInputBytes, + textIn->fInputLen, + escapeSequences_2022JP, + UPRV_LENGTHOF(escapeSequences_2022JP)); + results->set(textIn, this, confidence); + return (confidence > 0); +} + +#if !UCONFIG_ONLY_HTML_CONVERSION +CharsetRecog_2022KR::~CharsetRecog_2022KR() {} + +const char *CharsetRecog_2022KR::getName() const { + return "ISO-2022-KR"; +} + +UBool CharsetRecog_2022KR::match(InputText *textIn, CharsetMatch *results) const { + int32_t confidence = match_2022(textIn->fInputBytes, + textIn->fInputLen, + escapeSequences_2022KR, + UPRV_LENGTHOF(escapeSequences_2022KR)); + results->set(textIn, this, confidence); + return (confidence > 0); +} + +CharsetRecog_2022CN::~CharsetRecog_2022CN() {} + +const char *CharsetRecog_2022CN::getName() const { + return "ISO-2022-CN"; +} + +UBool CharsetRecog_2022CN::match(InputText *textIn, CharsetMatch *results) const { + int32_t confidence = match_2022(textIn->fInputBytes, + textIn->fInputLen, + escapeSequences_2022CN, + UPRV_LENGTHOF(escapeSequences_2022CN)); + results->set(textIn, this, confidence); + return (confidence > 0); +} +#endif + +CharsetRecog_2022::~CharsetRecog_2022() { + // nothing to do +} + +U_NAMESPACE_END +#endif |