275 lines
8.5 KiB
C
275 lines
8.5 KiB
C
/*
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* Copyright (C) 1996-2010, International Business Machines Corporation and Others.
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* All rights reserved.
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*/
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/**
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* \file
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* \brief C API: Boyer-Moore StringSearch prototype.
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* \internal
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*/
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#ifndef _BMS_H
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#define _BMS_H
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#include "unicode/utypes.h"
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#if !UCONFIG_NO_COLLATION && !UCONFIG_NO_BREAK_ITERATION
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#include "unicode/ucol.h"
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/**
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* A <code>UCD</code> object holds the Collator-specific data needed to
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* compute the length of the shortest string that can
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* generate a partcular list of CEs.
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*
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* <code>UCD</code> objects are quite expensive to compute. Because
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* of this, they are cached. When you call <code>ucd_open</code> it
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* returns a reference counted cached object. When you call <code>ucd_close</code>
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* the reference count on the object is decremented but the object is not deleted.
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*
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* If you do not need to reuse any unreferenced objects in the cache, you can call
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* <code>ucd_flushCCache</code>. If you no longer need any <code>UCD</code>
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* objects, you can call <code>ucd_freeCache</code>
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*/
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typedef void UCD;
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/**
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* Open a <code>UCD</code> object.
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*
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* @param coll - the collator
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* @param status - will be set if any errors occur.
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*
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* @return the <code>UCD</code> object. You must call
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* <code>ucd_close</code> when you are done using the object.
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*
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* Note: if on return status is set to an error, the only safe
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* thing to do with the returned object is to call <code>ucd_close</code>.
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*
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* @internal ICU 4.0.1 technology preview
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*/
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U_CAPI UCD * U_EXPORT2
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ucd_open(UCollator *coll, UErrorCode *status);
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/**
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* Release a <code>UCD</code> object.
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*
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* @param ucd - the object
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*
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* @internal ICU 4.0.1 technology preview
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*/
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U_CAPI void U_EXPORT2
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ucd_close(UCD *ucd);
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/**
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* Get the <code>UCollator</code> object used to create a <code>UCD</code> object.
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* The <code>UCollator</code> object returned may not be the exact
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* object that was used to create this object, but it will have the
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* same behavior.
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*
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* @param ucd - the <code>UCD</code> object
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*
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* @return the <code>UCollator</code> used to create the given
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* <code>UCD</code> object.
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*
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* @internal ICU 4.0.1 technology preview
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*/
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U_CAPI UCollator * U_EXPORT2
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ucd_getCollator(UCD *ucd);
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/**
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* <code>UCD</code> objects are expensive to compute, and so
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* may be cached. This routine will free the cached objects and delete
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* the cache.
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*
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* WARNING: Don't call this until you are have called <code>close</code>
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* for each <code>UCD</code> object that you have used. also,
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* DO NOT call this if another thread may be calling <code>ucd_flushCache</code>
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* at the same time.
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*
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* @internal ICU 4.0.1 technology preview
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*/
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U_CAPI void U_EXPORT2
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ucd_freeCache();
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/**
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* <code>UCD</code> objects are expensive to compute, and so
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* may be cached. This routine will remove any unused <code>UCD</code>
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* objects from the cache.
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*
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* @internal 4.0.1 technology preview
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*/
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U_CAPI void U_EXPORT2
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ucd_flushCache();
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/**
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* BMS
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*
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* This object holds the information needed to do a Collation sensitive Boyer-Moore search. It encapulates
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* the pattern, the "bad character" and "good suffix" tables, the Collator-based data needed to compute them,
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* and a reference to the text being searched.
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*
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* To do a search, you first need to get a <code>UCD</code> object by calling <code>ucd_open</code>.
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* Then you construct a <code>BMS</code> object from the <code>UCD</code> object, the pattern
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* string and the target string. Then you call the <code>search</code> method. Here's a code sample:
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*
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* <pre>
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* void boyerMooreExample(UCollator *collator, UChar *pattern, int32_t patternLen, UChar *target, int32_t targetLength)
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* {
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* UErrorCode status = U_ZERO_ERROR;
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* int32_t offset = 0, start = -1, end = -1;
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* UCD *ucd = NULL);
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* BMS *bms = NULL;
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*
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* ucd = ucd_open(collator, &status);
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* if (U_FAILURE(status)) {
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* // could not create a UCD object
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* return;
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* }
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*
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* BMS *bms = bms_open(ucd, pattern, patternLength, target, targetlength, &status);
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* if (U_FAILURE(status)) {
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* // could not create a BMS object
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* ucd_close(ucd);
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* return;
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* }
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*
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*
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* // Find all matches
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* while (bms_search(bms, offset, &start, &end)) {
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* // process the match between start and end
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* ...
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*
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* // advance past the match
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* offset = end;
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* }
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*
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* // at this point, if offset == 0, there were no matches
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* if (offset == 0) {
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* // handle the case of no matches
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* }
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*
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* bms_close(bms);
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* ucd_close(ucd);
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*
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* // UCD objects are cached, so the call to
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* // ucd_close doesn't delete the object.
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* // Call this if you don't need the object any more.
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* ucd_flushCache();
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* }
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* </pre>
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*
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* NOTE: This is a technology preview. The final version of this API may not bear any resenblence to this API.
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*
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* Knows linitations:
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* 1) Backwards searching has not been implemented.
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*
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* 2) For Han and Hangul characters, this code ignores any Collation tailorings. In general,
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* this isn't a problem, but in Korean locals, at strength 1, Hangul characters are tailored
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* to be equal to Han characters with the same pronounciation. Because this code ignroes
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* tailorings, searching for a Hangul character will not find a Han character and visa-versa.
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*
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* 3) In some cases, searching for a pattern that needs to be normalized and ends
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* in a discontiguous contraction may fail. The only known cases of this are with
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* the Tibetan script. For example searching for the pattern
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* "\u0F7F\u0F80\u0F81\u0F82\u0F83\u0F84\u0F85" will fail. (This case is artificial. We've
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* been unable to find a pratical, real-world example of this failure.)
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*
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* NOTE: This is a technology preview. The final version of this API may not bear any resenblence to this API.
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*
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* @internal ICU 4.0.1 technology preview
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*/
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struct BMS;
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typedef struct BMS BMS; /**< @see BMS */
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/**
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* Construct a <code>MBS</code> object.
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*
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* @param ucd - A <code>UCD</code> object holding the Collator-sensitive data
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* @param pattern - the string for which to search
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* @param patternLength - the length of the string for which to search
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* @param target - the string in which to search
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* @param targetLength - the length of the string in which to search
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* @param status - will be set if any errors occur.
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*
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* @return the <code>BMS</code> object.
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*
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* Note: if on return status is set to an error, the only safe
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* thing to do with the returned object is to call
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* <code>bms_close</code>.
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*
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* @internal ICU 4.0.1 technology preview
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*/
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U_CAPI BMS * U_EXPORT2
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bms_open(UCD *ucd,
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const UChar *pattern, int32_t patternLength,
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const UChar *target, int32_t targetLength,
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UErrorCode *status);
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/**
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* Close a <code>BMS</code> object and release all the
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* storage associated with it.
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*
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* @param bms - the <code>BMS</code> object to close.
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* @internal ICU 4.0.1 technology preview
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*/
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U_CAPI void U_EXPORT2
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bms_close(BMS *bms);
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/**
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* Test the pattern to see if it generates any CEs.
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*
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* @param bms - the <code>BMS</code> object
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* @return <code>TRUE</code> if the pattern string did not generate any CEs
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*
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* @internal ICU 4.0.1 technology preview
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*/
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U_CAPI UBool U_EXPORT2
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bms_empty(BMS *bms);
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/**
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* Get the <code>UCD</code> object used to create
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* a given <code>BMS</code> object.
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*
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* @param bms - the <code>BMS</code> object
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*
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* @return - the <code>UCD</code> object used to create
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* the given <code>BMS</code> object.
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*
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* @internal ICU 4.0.1 technology preview
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*/
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U_CAPI UCD * U_EXPORT2
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bms_getData(BMS *bms);
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/**
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* Search for the pattern string in the target string.
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*
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* @param bms - the <code>BMS</code> object
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* @param offset - the offset in the target string at which to begin the search
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* @param start - will be set to the starting offset of the match, or -1 if there's no match
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* @param end - will be set to the ending offset of the match, or -1 if there's no match
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*
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* @return <code>TRUE</code> if the match succeeds, <code>FALSE</code> otherwise.
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*
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* @internal ICU 4.0.1 technology preview
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*/
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U_CAPI UBool U_EXPORT2
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bms_search(BMS *bms, int32_t offset, int32_t *start, int32_t *end);
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/**
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* Set the target string for the match.
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*
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* @param bms - the <code>BMS</code> object
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* @param target - the new target string
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* @param targetLength - the length of the new target string
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* @param status - will be set if any errors occur.
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*
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* @internal ICU 4.0.1 technology preview
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*/
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U_CAPI void U_EXPORT2
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bms_setTargetString(BMS *bms, const UChar *target, int32_t targetLength, UErrorCode *status);
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#endif
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#endif /* _BMS_H */
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