/* * Copyright (C) 1996-2012, International Business Machines Corporation and Others. * All rights reserved. */ /** * \file * \brief C API: Boyer-Moore StringSearch prototype. * \internal */ #ifndef _BMS_H #define _BMS_H #include "unicode/utypes.h" #if !UCONFIG_NO_COLLATION && !UCONFIG_NO_BREAK_ITERATION #include "unicode/ucol.h" #ifndef U_HIDE_INTERNAL_API /** * A UCD object holds the Collator-specific data needed to * compute the length of the shortest string that can * generate a partcular list of CEs. * * UCD objects are quite expensive to compute. Because * of this, they are cached. When you call ucd_open it * returns a reference counted cached object. When you call ucd_close * the reference count on the object is decremented but the object is not deleted. * * If you do not need to reuse any unreferenced objects in the cache, you can call * ucd_flushCCache. If you no longer need any UCD * objects, you can call ucd_freeCache * * @internal ICU 4.0.1 technology preview */ typedef void UCD; /** * Open a UCD object. * * @param coll - the collator * @param status - will be set if any errors occur. * * @return the UCD object. You must call * ucd_close when you are done using the object. * * Note: if on return status is set to an error, the only safe * thing to do with the returned object is to call ucd_close. * * @internal ICU 4.0.1 technology preview */ U_INTERNAL UCD * U_EXPORT2 ucd_open(UCollator *coll, UErrorCode *status); /** * Release a UCD object. * * @param ucd - the object * * @internal ICU 4.0.1 technology preview */ U_INTERNAL void U_EXPORT2 ucd_close(UCD *ucd); /** * Get the UCollator object used to create a UCD object. * The UCollator object returned may not be the exact * object that was used to create this object, but it will have the * same behavior. * * @param ucd - the UCD object * * @return the UCollator used to create the given * UCD object. * * @internal ICU 4.0.1 technology preview */ U_INTERNAL UCollator * U_EXPORT2 ucd_getCollator(UCD *ucd); /** * UCD objects are expensive to compute, and so * may be cached. This routine will free the cached objects and delete * the cache. * * WARNING: Don't call this until you are have called close * for each UCD object that you have used. also, * DO NOT call this if another thread may be calling ucd_flushCache * at the same time. * * @internal ICU 4.0.1 technology preview */ U_INTERNAL void U_EXPORT2 ucd_freeCache(); /** * UCD objects are expensive to compute, and so * may be cached. This routine will remove any unused UCD * objects from the cache. * * @internal 4.0.1 technology preview */ U_INTERNAL void U_EXPORT2 ucd_flushCache(); /** * BMS * * This object holds the information needed to do a Collation sensitive Boyer-Moore search. It encapulates * the pattern, the "bad character" and "good suffix" tables, the Collator-based data needed to compute them, * and a reference to the text being searched. * * To do a search, you first need to get a UCD object by calling ucd_open. * Then you construct a BMS object from the UCD object, the pattern * string and the target string. Then you call the search method. Here's a code sample: * * 
 * void boyerMooreExample(UCollator *collator, UChar *pattern, int32_t patternLen, UChar *target, int32_t targetLength)
 * {
 *     UErrorCode status = U_ZERO_ERROR;
 *     int32_t offset = 0, start = -1, end = -1;
 *     UCD *ucd = NULL);
 *     BMS *bms = NULL;
 *
 *     ucd = ucd_open(collator, &status);
 *     if (U_FAILURE(status)) {
 *         // could not create a UCD object
 *         return;
 *     }
 *
 *     BMS *bms = bms_open(ucd, pattern, patternLength, target, targetlength, &status);
 *     if (U_FAILURE(status)) {
 *         // could not create a BMS object
 *         ucd_close(ucd);
 *         return;
 *     }
 *
 *
 *     // Find all matches
 *     while (bms_search(bms, offset, &start, &end)) {
 *         // process the match between start and end
 *         ...
 *
 *         // advance past the match
 *         offset = end; 
 *     }
 *
 *     // at this point, if offset == 0, there were no matches
 *     if (offset == 0) {
 *         // handle the case of no matches
 *     }
 *
 *     bms_close(bms);
 *     ucd_close(ucd);
 *
 *     // UCD objects are cached, so the call to
 *     // ucd_close doesn't delete the object.
 *     // Call this if you don't need the object any more.
 *     ucd_flushCache();
 * }
 *
* * NOTE: This is a technology preview. The final version of this API may not bear any resenblence to this API. * * Knows linitations: * 1) Backwards searching has not been implemented. * * 2) For Han and Hangul characters, this code ignores any Collation tailorings. In general, * this isn't a problem, but in Korean locals, at strength 1, Hangul characters are tailored * to be equal to Han characters with the same pronounciation. Because this code ignroes * tailorings, searching for a Hangul character will not find a Han character and visa-versa. * * 3) In some cases, searching for a pattern that needs to be normalized and ends * in a discontiguous contraction may fail. The only known cases of this are with * the Tibetan script. For example searching for the pattern * "\u0F7F\u0F80\u0F81\u0F82\u0F83\u0F84\u0F85" will fail. (This case is artificial. We've * been unable to find a pratical, real-world example of this failure.) * * NOTE: This is a technology preview. The final version of this API may not bear any resenblence to this API. * * @internal ICU 4.0.1 technology preview */ struct BMS; typedef struct BMS BMS; /**< @see BMS */ /** * Construct a MBS object. * * @param ucd - A UCD object holding the Collator-sensitive data * @param pattern - the string for which to search * @param patternLength - the length of the string for which to search * @param target - the string in which to search * @param targetLength - the length of the string in which to search * @param status - will be set if any errors occur. * * @return the BMS object. * * Note: if on return status is set to an error, the only safe * thing to do with the returned object is to call * bms_close. * * @internal ICU 4.0.1 technology preview */ U_INTERNAL BMS * U_EXPORT2 bms_open(UCD *ucd, const UChar *pattern, int32_t patternLength, const UChar *target, int32_t targetLength, UErrorCode *status); /** * Close a BMS object and release all the * storage associated with it. * * @param bms - the BMS object to close. * @internal ICU 4.0.1 technology preview */ U_INTERNAL void U_EXPORT2 bms_close(BMS *bms); /** * Test the pattern to see if it generates any CEs. * * @param bms - the BMS object * @return TRUE if the pattern string did not generate any CEs * * @internal ICU 4.0.1 technology preview */ U_INTERNAL UBool U_EXPORT2 bms_empty(BMS *bms); /** * Get the UCD object used to create * a given BMS object. * * @param bms - the BMS object * * @return - the UCD object used to create * the given BMS object. * * @internal ICU 4.0.1 technology preview */ U_INTERNAL UCD * U_EXPORT2 bms_getData(BMS *bms); /** * Search for the pattern string in the target string. * * @param bms - the BMS object * @param offset - the offset in the target string at which to begin the search * @param start - will be set to the starting offset of the match, or -1 if there's no match * @param end - will be set to the ending offset of the match, or -1 if there's no match * * @return TRUE if the match succeeds, FALSE otherwise. * * @internal ICU 4.0.1 technology preview */ U_INTERNAL UBool U_EXPORT2 bms_search(BMS *bms, int32_t offset, int32_t *start, int32_t *end); /** * Set the target string for the match. * * @param bms - the BMS object * @param target - the new target string * @param targetLength - the length of the new target string * @param status - will be set if any errors occur. * * @internal ICU 4.0.1 technology preview */ U_INTERNAL void U_EXPORT2 bms_setTargetString(BMS *bms, const UChar *target, int32_t targetLength, UErrorCode *status); #endif /* U_HIDE_INTERNAL_API */ #endif #endif /* _BMS_H */