/* * 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 <code>UCD</code> object holds the Collator-specific data needed to * compute the length of the shortest string that can * generate a partcular list of CEs. * * <code>UCD</code> objects are quite expensive to compute. Because * of this, they are cached. When you call <code>ucd_open</code> it * returns a reference counted cached object. When you call <code>ucd_close</code> * 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 * <code>ucd_flushCCache</code>. If you no longer need any <code>UCD</code> * objects, you can call <code>ucd_freeCache</code> * * @internal ICU 4.0.1 technology preview */ typedef void UCD; /** * Open a <code>UCD</code> object. * * @param coll - the collator * @param status - will be set if any errors occur. * * @return the <code>UCD</code> object. You must call * <code>ucd_close</code> 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 <code>ucd_close</code>. * * @internal ICU 4.0.1 technology preview */ U_INTERNAL UCD * U_EXPORT2 ucd_open(UCollator *coll, UErrorCode *status); /** * Release a <code>UCD</code> object. * * @param ucd - the object * * @internal ICU 4.0.1 technology preview */ U_INTERNAL void U_EXPORT2 ucd_close(UCD *ucd); /** * Get the <code>UCollator</code> object used to create a <code>UCD</code> object. * The <code>UCollator</code> 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 <code>UCD</code> object * * @return the <code>UCollator</code> used to create the given * <code>UCD</code> object. * * @internal ICU 4.0.1 technology preview */ U_INTERNAL UCollator * U_EXPORT2 ucd_getCollator(UCD *ucd); /** * <code>UCD</code> 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 <code>close</code> * for each <code>UCD</code> object that you have used. also, * DO NOT call this if another thread may be calling <code>ucd_flushCache</code> * at the same time. * * @internal ICU 4.0.1 technology preview */ U_INTERNAL void U_EXPORT2 ucd_freeCache(); /** * <code>UCD</code> objects are expensive to compute, and so * may be cached. This routine will remove any unused <code>UCD</code> * 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 <code>UCD</code> object by calling <code>ucd_open</code>. * Then you construct a <code>BMS</code> object from the <code>UCD</code> object, the pattern * string and the target string. Then you call the <code>search</code> method. Here's a code sample: * * <pre> * 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(); * } * </pre> * * 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 <code>MBS</code> object. * * @param ucd - A <code>UCD</code> 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 <code>BMS</code> object. * * Note: if on return status is set to an error, the only safe * thing to do with the returned object is to call * <code>bms_close</code>. * * @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 <code>BMS</code> object and release all the * storage associated with it. * * @param bms - the <code>BMS</code> 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 <code>BMS</code> object * @return <code>TRUE</code> 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 <code>UCD</code> object used to create * a given <code>BMS</code> object. * * @param bms - the <code>BMS</code> object * * @return - the <code>UCD</code> object used to create * the given <code>BMS</code> 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 <code>BMS</code> 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 <code>TRUE</code> if the match succeeds, <code>FALSE</code> 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 <code>BMS</code> 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 */