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| 1 /* | |
| 2 ********************************************************************** | |
| 3 * Copyright (C) 2005-2010, International Business Machines | |
| 4 * Corporation and others. All Rights Reserved. | |
| 5 ********************************************************************** | |
| 6 * file name: ucsdet.h | |
| 7 * encoding: US-ASCII | |
| 8 * indentation:4 | |
| 9 * | |
| 10 * created on: 2005Aug04 | |
| 11 * created by: Andy Heninger | |
| 12 * | |
| 13 * ICU Character Set Detection, API for C | |
| 14 * | |
| 15 * Draft version 18 Oct 2005 | |
| 16 * | |
| 17 */ | |
| 18 | |
| 19 #ifndef __UCSDET_H | |
| 20 #define __UCSDET_H | |
| 21 | |
| 22 #include "unicode/utypes.h" | |
| 23 | |
| 24 #if !UCONFIG_NO_CONVERSION | |
| 25 | |
| 26 #include "unicode/localpointer.h" | |
| 27 #include "unicode/uenum.h" | |
| 28 | |
| 29 /** | |
| 30 * \file | |
| 31 * \brief C API: Charset Detection API | |
| 32 * | |
| 33 * This API provides a facility for detecting the | |
| 34 * charset or encoding of character data in an unknown text format. | |
| 35 * The input data can be from an array of bytes. | |
| 36 * <p> | |
| 37 * Character set detection is at best an imprecise operation. The detection | |
| 38 * process will attempt to identify the charset that best matches the characteri
stics | |
| 39 * of the byte data, but the process is partly statistical in nature, and | |
| 40 * the results can not be guaranteed to always be correct. | |
| 41 * <p> | |
| 42 * For best accuracy in charset detection, the input data should be primarily | |
| 43 * in a single language, and a minimum of a few hundred bytes worth of plain tex
t | |
| 44 * in the language are needed. The detection process will attempt to | |
| 45 * ignore html or xml style markup that could otherwise obscure the content. | |
| 46 */ | |
| 47 | |
| 48 | |
| 49 struct UCharsetDetector; | |
| 50 /** | |
| 51 * Structure representing a charset detector | |
| 52 * @stable ICU 3.6 | |
| 53 */ | |
| 54 typedef struct UCharsetDetector UCharsetDetector; | |
| 55 | |
| 56 struct UCharsetMatch; | |
| 57 /** | |
| 58 * Opaque structure representing a match that was identified | |
| 59 * from a charset detection operation. | |
| 60 * @stable ICU 3.6 | |
| 61 */ | |
| 62 typedef struct UCharsetMatch UCharsetMatch; | |
| 63 | |
| 64 /** | |
| 65 * Open a charset detector. | |
| 66 * | |
| 67 * @param status Any error conditions occurring during the open | |
| 68 * operation are reported back in this variable. | |
| 69 * @return the newly opened charset detector. | |
| 70 * @stable ICU 3.6 | |
| 71 */ | |
| 72 U_STABLE UCharsetDetector * U_EXPORT2 | |
| 73 ucsdet_open(UErrorCode *status); | |
| 74 | |
| 75 /** | |
| 76 * Close a charset detector. All storage and any other resources | |
| 77 * owned by this charset detector will be released. Failure to | |
| 78 * close a charset detector when finished with it can result in | |
| 79 * memory leaks in the application. | |
| 80 * | |
| 81 * @param ucsd The charset detector to be closed. | |
| 82 * @stable ICU 3.6 | |
| 83 */ | |
| 84 U_STABLE void U_EXPORT2 | |
| 85 ucsdet_close(UCharsetDetector *ucsd); | |
| 86 | |
| 87 #if U_SHOW_CPLUSPLUS_API | |
| 88 | |
| 89 U_NAMESPACE_BEGIN | |
| 90 | |
| 91 /** | |
| 92 * \class LocalUCharsetDetectorPointer | |
| 93 * "Smart pointer" class, closes a UCharsetDetector via ucsdet_close(). | |
| 94 * For most methods see the LocalPointerBase base class. | |
| 95 * | |
| 96 * @see LocalPointerBase | |
| 97 * @see LocalPointer | |
| 98 * @stable ICU 4.4 | |
| 99 */ | |
| 100 U_DEFINE_LOCAL_OPEN_POINTER(LocalUCharsetDetectorPointer, UCharsetDetector, ucsd
et_close); | |
| 101 | |
| 102 U_NAMESPACE_END | |
| 103 | |
| 104 #endif | |
| 105 | |
| 106 /** | |
| 107 * Set the input byte data whose charset is to detected. | |
| 108 * | |
| 109 * Ownership of the input text byte array remains with the caller. | |
| 110 * The input string must not be altered or deleted until the charset | |
| 111 * detector is either closed or reset to refer to different input text. | |
| 112 * | |
| 113 * @param ucsd the charset detector to be used. | |
| 114 * @param textIn the input text of unknown encoding. . | |
| 115 * @param len the length of the input text, or -1 if the text | |
| 116 * is NUL terminated. | |
| 117 * @param status any error conditions are reported back in this variable. | |
| 118 * | |
| 119 * @stable ICU 3.6 | |
| 120 */ | |
| 121 U_STABLE void U_EXPORT2 | |
| 122 ucsdet_setText(UCharsetDetector *ucsd, const char *textIn, int32_t len, UErrorCo
de *status); | |
| 123 | |
| 124 | |
| 125 /** Set the declared encoding for charset detection. | |
| 126 * The declared encoding of an input text is an encoding obtained | |
| 127 * by the user from an http header or xml declaration or similar source that | |
| 128 * can be provided as an additional hint to the charset detector. | |
| 129 * | |
| 130 * How and whether the declared encoding will be used during the | |
| 131 * detection process is TBD. | |
| 132 * | |
| 133 * @param ucsd the charset detector to be used. | |
| 134 * @param encoding an encoding for the current data obtained from | |
| 135 * a header or declaration or other source outside | |
| 136 * of the byte data itself. | |
| 137 * @param length the length of the encoding name, or -1 if the name string | |
| 138 * is NUL terminated. | |
| 139 * @param status any error conditions are reported back in this variable. | |
| 140 * | |
| 141 * @stable ICU 3.6 | |
| 142 */ | |
| 143 U_STABLE void U_EXPORT2 | |
| 144 ucsdet_setDeclaredEncoding(UCharsetDetector *ucsd, const char *encoding, int32_t
length, UErrorCode *status); | |
| 145 | |
| 146 | |
| 147 /** | |
| 148 * Return the charset that best matches the supplied input data. | |
| 149 * | |
| 150 * Note though, that because the detection | |
| 151 * only looks at the start of the input data, | |
| 152 * there is a possibility that the returned charset will fail to handle | |
| 153 * the full set of input data. | |
| 154 * <p> | |
| 155 * The returned UCharsetMatch object is owned by the UCharsetDetector. | |
| 156 * It will remain valid until the detector input is reset, or until | |
| 157 * the detector is closed. | |
| 158 * <p> | |
| 159 * The function will fail if | |
| 160 * <ul> | |
| 161 * <li>no charset appears to match the data.</li> | |
| 162 * <li>no input text has been provided</li> | |
| 163 * </ul> | |
| 164 * | |
| 165 * @param ucsd the charset detector to be used. | |
| 166 * @param status any error conditions are reported back in this variable. | |
| 167 * @return a UCharsetMatch representing the best matching charset, | |
| 168 * or NULL if no charset matches the byte data. | |
| 169 * | |
| 170 * @stable ICU 3.6 | |
| 171 */ | |
| 172 U_STABLE const UCharsetMatch * U_EXPORT2 | |
| 173 ucsdet_detect(UCharsetDetector *ucsd, UErrorCode *status); | |
| 174 | |
| 175 | |
| 176 /** | |
| 177 * Find all charset matches that appear to be consistent with the input, | |
| 178 * returning an array of results. The results are ordered with the | |
| 179 * best quality match first. | |
| 180 * | |
| 181 * Because the detection only looks at a limited amount of the | |
| 182 * input byte data, some of the returned charsets may fail to handle | |
| 183 * the all of input data. | |
| 184 * <p> | |
| 185 * The returned UCharsetMatch objects are owned by the UCharsetDetector. | |
| 186 * They will remain valid until the detector is closed or modified | |
| 187 * | |
| 188 * <p> | |
| 189 * Return an error if | |
| 190 * <ul> | |
| 191 * <li>no charsets appear to match the input data.</li> | |
| 192 * <li>no input text has been provided</li> | |
| 193 * </ul> | |
| 194 * | |
| 195 * @param ucsd the charset detector to be used. | |
| 196 * @param matchesFound pointer to a variable that will be set to the | |
| 197 * number of charsets identified that are consistent with | |
| 198 * the input data. Output only. | |
| 199 * @param status any error conditions are reported back in this variable. | |
| 200 * @return A pointer to an array of pointers to UCharSetMatch objec
ts. | |
| 201 * This array, and the UCharSetMatch instances to which it
refers, | |
| 202 * are owned by the UCharsetDetector, and will remain valid
until | |
| 203 * the detector is closed or modified. | |
| 204 * @stable ICU 3.6 | |
| 205 */ | |
| 206 U_STABLE const UCharsetMatch ** U_EXPORT2 | |
| 207 ucsdet_detectAll(UCharsetDetector *ucsd, int32_t *matchesFound, UErrorCode *stat
us); | |
| 208 | |
| 209 | |
| 210 | |
| 211 /** | |
| 212 * Get the name of the charset represented by a UCharsetMatch. | |
| 213 * | |
| 214 * The storage for the returned name string is owned by the | |
| 215 * UCharsetMatch, and will remain valid while the UCharsetMatch | |
| 216 * is valid. | |
| 217 * | |
| 218 * The name returned is suitable for use with the ICU conversion APIs. | |
| 219 * | |
| 220 * @param ucsm The charset match object. | |
| 221 * @param status Any error conditions are reported back in this variable. | |
| 222 * @return The name of the matching charset. | |
| 223 * | |
| 224 * @stable ICU 3.6 | |
| 225 */ | |
| 226 U_STABLE const char * U_EXPORT2 | |
| 227 ucsdet_getName(const UCharsetMatch *ucsm, UErrorCode *status); | |
| 228 | |
| 229 /** | |
| 230 * Get a confidence number for the quality of the match of the byte | |
| 231 * data with the charset. Confidence numbers range from zero to 100, | |
| 232 * with 100 representing complete confidence and zero representing | |
| 233 * no confidence. | |
| 234 * | |
| 235 * The confidence values are somewhat arbitrary. They define an | |
| 236 * an ordering within the results for any single detection operation | |
| 237 * but are not generally comparable between the results for different input. | |
| 238 * | |
| 239 * A confidence value of ten does have a general meaning - it is used | |
| 240 * for charsets that can represent the input data, but for which there | |
| 241 * is no other indication that suggests that the charset is the correct one. | |
| 242 * Pure 7 bit ASCII data, for example, is compatible with a | |
| 243 * great many charsets, most of which will appear as possible matches | |
| 244 * with a confidence of 10. | |
| 245 * | |
| 246 * @param ucsm The charset match object. | |
| 247 * @param status Any error conditions are reported back in this variable. | |
| 248 * @return A confidence number for the charset match. | |
| 249 * | |
| 250 * @stable ICU 3.6 | |
| 251 */ | |
| 252 U_STABLE int32_t U_EXPORT2 | |
| 253 ucsdet_getConfidence(const UCharsetMatch *ucsm, UErrorCode *status); | |
| 254 | |
| 255 /** | |
| 256 * Get the RFC 3066 code for the language of the input data. | |
| 257 * | |
| 258 * The Charset Detection service is intended primarily for detecting | |
| 259 * charsets, not language. For some, but not all, charsets, a language is | |
| 260 * identified as a byproduct of the detection process, and that is what | |
| 261 * is returned by this function. | |
| 262 * | |
| 263 * CAUTION: | |
| 264 * 1. Language information is not available for input data encoded in | |
| 265 * all charsets. In particular, no language is identified | |
| 266 * for UTF-8 input data. | |
| 267 * | |
| 268 * 2. Closely related languages may sometimes be confused. | |
| 269 * | |
| 270 * If more accurate language detection is required, a linguistic | |
| 271 * analysis package should be used. | |
| 272 * | |
| 273 * The storage for the returned name string is owned by the | |
| 274 * UCharsetMatch, and will remain valid while the UCharsetMatch | |
| 275 * is valid. | |
| 276 * | |
| 277 * @param ucsm The charset match object. | |
| 278 * @param status Any error conditions are reported back in this variable. | |
| 279 * @return The RFC 3066 code for the language of the input data, or | |
| 280 * an empty string if the language could not be determined. | |
| 281 * | |
| 282 * @stable ICU 3.6 | |
| 283 */ | |
| 284 U_STABLE const char * U_EXPORT2 | |
| 285 ucsdet_getLanguage(const UCharsetMatch *ucsm, UErrorCode *status); | |
| 286 | |
| 287 | |
| 288 /** | |
| 289 * Get the entire input text as a UChar string, placing it into | |
| 290 * a caller-supplied buffer. A terminating | |
| 291 * NUL character will be appended to the buffer if space is available. | |
| 292 * | |
| 293 * The number of UChars in the output string, not including the terminating | |
| 294 * NUL, is returned. | |
| 295 * | |
| 296 * If the supplied buffer is smaller than required to hold the output, | |
| 297 * the contents of the buffer are undefined. The full output string length | |
| 298 * (in UChars) is returned as always, and can be used to allocate a buffer | |
| 299 * of the correct size. | |
| 300 * | |
| 301 * | |
| 302 * @param ucsm The charset match object. | |
| 303 * @param buf A UChar buffer to be filled with the converted text data. | |
| 304 * @param cap The capacity of the buffer in UChars. | |
| 305 * @param status Any error conditions are reported back in this variable. | |
| 306 * @return The number of UChars in the output string. | |
| 307 * | |
| 308 * @stable ICU 3.6 | |
| 309 */ | |
| 310 U_STABLE int32_t U_EXPORT2 | |
| 311 ucsdet_getUChars(const UCharsetMatch *ucsm, | |
| 312 UChar *buf, int32_t cap, UErrorCode *status); | |
| 313 | |
| 314 | |
| 315 | |
| 316 /** | |
| 317 * Get an iterator over the set of all detectable charsets - | |
| 318 * over the charsets that are known to the charset detection | |
| 319 * service. | |
| 320 * | |
| 321 * The returned UEnumeration provides access to the names of | |
| 322 * the charsets. | |
| 323 * | |
| 324 * The state of the Charset detector that is passed in does not | |
| 325 * affect the result of this function, but requiring a valid, open | |
| 326 * charset detector as a parameter insures that the charset detection | |
| 327 * service has been safely initialized and that the required detection | |
| 328 * data is available. | |
| 329 * | |
| 330 * @param ucsd a Charset detector. | |
| 331 * @param status Any error conditions are reported back in this variable. | |
| 332 * @return an iterator providing access to the detectable charset names. | |
| 333 * @stable ICU 3.6 | |
| 334 */ | |
| 335 U_STABLE UEnumeration * U_EXPORT2 | |
| 336 ucsdet_getAllDetectableCharsets(const UCharsetDetector *ucsd, UErrorCode *statu
s); | |
| 337 | |
| 338 | |
| 339 /** | |
| 340 * Test whether input filtering is enabled for this charset detector. | |
| 341 * Input filtering removes text that appears to be HTML or xml | |
| 342 * markup from the input before applying the code page detection | |
| 343 * heuristics. | |
| 344 * | |
| 345 * @param ucsd The charset detector to check. | |
| 346 * @return TRUE if filtering is enabled. | |
| 347 * @stable ICU 3.6 | |
| 348 */ | |
| 349 U_STABLE UBool U_EXPORT2 | |
| 350 ucsdet_isInputFilterEnabled(const UCharsetDetector *ucsd); | |
| 351 | |
| 352 | |
| 353 /** | |
| 354 * Enable filtering of input text. If filtering is enabled, | |
| 355 * text within angle brackets ("<" and ">") will be removed | |
| 356 * before detection, which will remove most HTML or xml markup. | |
| 357 * | |
| 358 * @param ucsd the charset detector to be modified. | |
| 359 * @param filter <code>true</code> to enable input text filtering. | |
| 360 * @return The previous setting. | |
| 361 * | |
| 362 * @stable ICU 3.6 | |
| 363 */ | |
| 364 U_STABLE UBool U_EXPORT2 | |
| 365 ucsdet_enableInputFilter(UCharsetDetector *ucsd, UBool filter); | |
| 366 | |
| 367 #endif | |
| 368 #endif /* __UCSDET_H */ | |
| 369 | |
| 370 | |
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