/*
* Copyright (C) 1996-2010, 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"
/**
* 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>
*/
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_CAPI 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_CAPI 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_CAPI 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_CAPI 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_CAPI 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_CAPI 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_CAPI 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_CAPI 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_CAPI 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_CAPI 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_CAPI void U_EXPORT2
bms_setTargetString(BMS *bms, const UChar *target, int32_t targetLength, UErrorCode *status);
#endif
#endif /* _BMS_H */