176 lines
5.1 KiB
C++
176 lines
5.1 KiB
C++
/*
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**********************************************************************
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* Copyright (C) 2005-2009, International Business Machines
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* Corporation and others. All Rights Reserved.
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**********************************************************************
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*/
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#include "unicode/utypes.h"
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#if !UCONFIG_NO_CONVERSION
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#include "cstring.h"
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#include "csr2022.h"
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U_NAMESPACE_BEGIN
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#define ARRAY_SIZE(array) (sizeof array / sizeof array[0])
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/**
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* Matching function shared among the 2022 detectors JP, CN and KR
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* Counts up the number of legal an unrecognized escape sequences in
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* the sample of text, and computes a score based on the total number &
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* the proportion that fit the encoding.
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*
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*
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* @param text the byte buffer containing text to analyse
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* @param textLen the size of the text in the byte.
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* @param escapeSequences the byte escape sequences to test for.
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* @return match quality, in the range of 0-100.
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*/
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int32_t CharsetRecog_2022::match_2022(const uint8_t *text, int32_t textLen, const uint8_t escapeSequences[][5], int32_t escapeSequences_length)
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{
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int32_t i, j;
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int32_t escN;
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int32_t hits = 0;
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int32_t misses = 0;
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int32_t shifts = 0;
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int32_t quality;
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i = 0;
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while(i < textLen) {
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if(text[i] == 0x1B) {
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escN = 0;
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while(escN < escapeSequences_length) {
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const uint8_t *seq = escapeSequences[escN];
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int32_t seq_length = (int32_t)uprv_strlen((const char *) seq);
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if (textLen-i >= seq_length) {
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j = 1;
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while(j < seq_length) {
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if(seq[j] != text[i+j]) {
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goto checkEscapes;
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}
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j += 1;
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}
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hits += 1;
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i += seq_length-1;
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goto scanInput;
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}
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// else we ran out of string to compare this time.
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checkEscapes:
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escN += 1;
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}
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misses += 1;
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}
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if( text[i]== 0x0e || text[i] == 0x0f){
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shifts += 1;
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}
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scanInput:
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i += 1;
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}
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if (hits == 0) {
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return 0;
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}
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//
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// Initial quality is based on relative proportion of recongized vs.
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// unrecognized escape sequences.
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// All good: quality = 100;
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// half or less good: quality = 0;
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// linear inbetween.
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quality = (100*hits - 100*misses) / (hits + misses);
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// Back off quality if there were too few escape sequences seen.
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// Include shifts in this computation, so that KR does not get penalized
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// for having only a single Escape sequence, but many shifts.
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if (hits+shifts < 5) {
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quality -= (5-(hits+shifts))*10;
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}
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if (quality < 0) {
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quality = 0;
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}
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return quality;
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}
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static const uint8_t escapeSequences_2022JP[][5] = {
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{0x1b, 0x24, 0x28, 0x43, 0x00}, // KS X 1001:1992
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{0x1b, 0x24, 0x28, 0x44, 0x00}, // JIS X 212-1990
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{0x1b, 0x24, 0x40, 0x00, 0x00}, // JIS C 6226-1978
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{0x1b, 0x24, 0x41, 0x00, 0x00}, // GB 2312-80
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{0x1b, 0x24, 0x42, 0x00, 0x00}, // JIS X 208-1983
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{0x1b, 0x26, 0x40, 0x00, 0x00}, // JIS X 208 1990, 1997
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{0x1b, 0x28, 0x42, 0x00, 0x00}, // ASCII
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{0x1b, 0x28, 0x48, 0x00, 0x00}, // JIS-Roman
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{0x1b, 0x28, 0x49, 0x00, 0x00}, // Half-width katakana
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{0x1b, 0x28, 0x4a, 0x00, 0x00}, // JIS-Roman
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{0x1b, 0x2e, 0x41, 0x00, 0x00}, // ISO 8859-1
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{0x1b, 0x2e, 0x46, 0x00, 0x00} // ISO 8859-7
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};
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static const uint8_t escapeSequences_2022KR[][5] = {
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{0x1b, 0x24, 0x29, 0x43, 0x00}
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};
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static const uint8_t escapeSequences_2022CN[][5] = {
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{0x1b, 0x24, 0x29, 0x41, 0x00}, // GB 2312-80
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{0x1b, 0x24, 0x29, 0x47, 0x00}, // CNS 11643-1992 Plane 1
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{0x1b, 0x24, 0x2A, 0x48, 0x00}, // CNS 11643-1992 Plane 2
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{0x1b, 0x24, 0x29, 0x45, 0x00}, // ISO-IR-165
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{0x1b, 0x24, 0x2B, 0x49, 0x00}, // CNS 11643-1992 Plane 3
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{0x1b, 0x24, 0x2B, 0x4A, 0x00}, // CNS 11643-1992 Plane 4
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{0x1b, 0x24, 0x2B, 0x4B, 0x00}, // CNS 11643-1992 Plane 5
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{0x1b, 0x24, 0x2B, 0x4C, 0x00}, // CNS 11643-1992 Plane 6
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{0x1b, 0x24, 0x2B, 0x4D, 0x00}, // CNS 11643-1992 Plane 7
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{0x1b, 0x4e, 0x00, 0x00, 0x00}, // SS2
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{0x1b, 0x4f, 0x00, 0x00, 0x00}, // SS3
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};
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const char *CharsetRecog_2022JP::getName() const
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{
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return "ISO-2022-JP";
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}
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int32_t CharsetRecog_2022JP::match(InputText *textIn)
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{
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return match_2022(textIn->fInputBytes, textIn->fInputLen, escapeSequences_2022JP, ARRAY_SIZE(escapeSequences_2022JP));
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}
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const char *CharsetRecog_2022KR::getName() const
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{
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return "ISO-2022-KR";
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}
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int32_t CharsetRecog_2022KR::match(InputText *textIn)
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{
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return match_2022(textIn->fInputBytes, textIn->fInputLen, escapeSequences_2022KR, ARRAY_SIZE(escapeSequences_2022KR));
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}
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const char *CharsetRecog_2022CN::getName() const
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{
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return "ISO-2022-CN";
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}
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int32_t CharsetRecog_2022CN::match(InputText *textIn)
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{
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return match_2022(textIn->fInputBytes, textIn->fInputLen, escapeSequences_2022CN, ARRAY_SIZE(escapeSequences_2022CN));
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}
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CharsetRecog_2022::~CharsetRecog_2022()
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{
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// nothing to do
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}
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U_NAMESPACE_END
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#endif
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