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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 0 : 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 0 : int32_t hits = 0;
39 0 : int32_t misses = 0;
40 0 : int32_t shifts = 0;
41 : int32_t quality;
42 :
43 0 : i = 0;
44 0 : while(i < textLen) {
45 0 : if(text[i] == 0x1B) {
46 0 : escN = 0;
47 0 : while(escN < escapeSequences_length) {
48 0 : const uint8_t *seq = escapeSequences[escN];
49 0 : int32_t seq_length = (int32_t)uprv_strlen((const char *) seq);
50 :
51 0 : if (textLen-i >= seq_length) {
52 0 : j = 1;
53 0 : while(j < seq_length) {
54 0 : if(seq[j] != text[i+j]) {
55 0 : goto checkEscapes;
56 : }
57 :
58 0 : j += 1;
59 : }
60 :
61 0 : hits += 1;
62 0 : i += seq_length-1;
63 0 : goto scanInput;
64 : }
65 : // else we ran out of string to compare this time.
66 : checkEscapes:
67 0 : escN += 1;
68 : }
69 :
70 0 : misses += 1;
71 : }
72 :
73 0 : if( text[i]== 0x0e || text[i] == 0x0f){
74 0 : shifts += 1;
75 : }
76 :
77 : scanInput:
78 0 : i += 1;
79 : }
80 :
81 0 : if (hits == 0) {
82 0 : return 0;
83 : }
84 :
85 : //
86 : // Initial quality is based on relative proportion of recongized vs.
87 : // unrecognized escape sequences.
88 : // All good: quality = 100;
89 : // half or less good: quality = 0;
90 : // linear inbetween.
91 0 : 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 0 : if (hits+shifts < 5) {
97 0 : quality -= (5-(hits+shifts))*10;
98 : }
99 :
100 0 : if (quality < 0) {
101 0 : quality = 0;
102 : }
103 :
104 0 : 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 0 : CharsetRecog_2022JP::~CharsetRecog_2022JP() {}
144 :
145 0 : const char *CharsetRecog_2022JP::getName() const {
146 0 : return "ISO-2022-JP";
147 : }
148 :
149 0 : UBool CharsetRecog_2022JP::match(InputText *textIn, CharsetMatch *results) const {
150 0 : int32_t confidence = match_2022(textIn->fInputBytes,
151 : textIn->fInputLen,
152 : escapeSequences_2022JP,
153 0 : UPRV_LENGTHOF(escapeSequences_2022JP));
154 0 : results->set(textIn, this, confidence);
155 0 : return (confidence > 0);
156 : }
157 :
158 : #if !UCONFIG_ONLY_HTML_CONVERSION
159 0 : CharsetRecog_2022KR::~CharsetRecog_2022KR() {}
160 :
161 0 : const char *CharsetRecog_2022KR::getName() const {
162 0 : return "ISO-2022-KR";
163 : }
164 :
165 0 : UBool CharsetRecog_2022KR::match(InputText *textIn, CharsetMatch *results) const {
166 0 : int32_t confidence = match_2022(textIn->fInputBytes,
167 : textIn->fInputLen,
168 : escapeSequences_2022KR,
169 0 : UPRV_LENGTHOF(escapeSequences_2022KR));
170 0 : results->set(textIn, this, confidence);
171 0 : return (confidence > 0);
172 : }
173 :
174 0 : CharsetRecog_2022CN::~CharsetRecog_2022CN() {}
175 :
176 0 : const char *CharsetRecog_2022CN::getName() const {
177 0 : return "ISO-2022-CN";
178 : }
179 :
180 0 : UBool CharsetRecog_2022CN::match(InputText *textIn, CharsetMatch *results) const {
181 0 : int32_t confidence = match_2022(textIn->fInputBytes,
182 : textIn->fInputLen,
183 : escapeSequences_2022CN,
184 0 : UPRV_LENGTHOF(escapeSequences_2022CN));
185 0 : results->set(textIn, this, confidence);
186 0 : return (confidence > 0);
187 : }
188 : #endif
189 :
190 0 : CharsetRecog_2022::~CharsetRecog_2022() {
191 : // nothing to do
192 0 : }
193 :
194 : U_NAMESPACE_END
195 : #endif
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