626 lines
27 KiB
C
626 lines
27 KiB
C
/*
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**********************************************************************
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* Copyright (C) 2001 IBM and others. All rights reserved.
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**********************************************************************
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* Date Name Description
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* 06/28/2001 synwee Creation.
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**********************************************************************
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*/
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#ifndef USEARCH_H
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#define USEARCH_H
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#include "unicode/utypes.h"
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#include "unicode/ucol.h"
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#include "unicode/ucoleitr.h"
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#include "unicode/ubrk.h"
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/**
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* \file
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* \brief C API: StringSearch
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*
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* C Apis for an engine that provides language-sensitive text searching based
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* on the comparison rules defined in a <tt>UCollator</tt> data struct,
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* see <tt>ucol.h</tt>. This ensures that language eccentricity can be
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* handled, e.g. for the German collator, characters ß and SS will be matched
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* if case is chosen to be ignored.
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* See the <a href=http://oss.software.ibm.com/icu/develop/collation/ICU_collation_design.htm>
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* "ICU Collation Design Document"</a> for more information.
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* <p>
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* The algorithm implemented is a modified form of the Boyer Moore's search.
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* For more information see
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* <a href=http://oss.software.ibm.com/icu/docs/papers/text-search.html>
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* "Efficient Text Searching in Java"</a>, published in <i>Java Report</i>
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* in February, 1999, for further information on the algorithm.
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* <p>
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* There are 2 match options for selection:<br>
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* Let S' be the sub-string of a text string S between the offsets start and
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* end <start, end>.
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* <br>
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* A pattern string P matches a text string S at the offsets <start, end>
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* if
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* <pre>
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* option 1. Some canonical equivalent of P matches some canonical equivalent
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* of S'
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* option 2. P matches S' and if P starts or ends with a combining mark,
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* there exists no non-ignorable combining mark before or after S’
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* in S respectively.
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* </pre>
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* Option 2. will be the default·
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* <p>
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* This search has APIs similar to that of other text iteration mechanisms
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* such as the break iterators in <tt>ubrk.h</tt>. Using these
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* APIs, it is easy to scan through text looking for all occurances of
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* a given pattern. This search iterator allows changing of direction by
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* calling a <tt>reset</tt> followed by a <tt>next</tt> or <tt>previous</tt>.
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* Though a direction change can occur without calling <tt>reset</tt> first,
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* this operation comes with some speed penalty.
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* Generally, match results in the forward direction will match the result
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* matches in the backwards direction in the reverse order
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* <p>
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* <tt>usearch.h</tt> provides APIs to specify the starting position
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* within the text string to be searched, e.g. <tt>usearch_setOffset</tt>,
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* <tt>usearch_preceding</tt> and <tt>usearch_following</tt>. Since the
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* starting position will be set as it is specified, please take note that
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* there are some dangerous positions which the search may render incorrect
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* results:
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* <ul>
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* <li> The midst of a substring that requires normalization.
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* <li> If the following match is to be found, the position should not be the
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* second character which requires to be swapped with the preceding
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* character. Vice versa, if the preceding match is to be found,
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* position to search from should not be the first character which
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* requires to be swapped with the next character. E.g certain Thai and
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* Lao characters require swapping.
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* <li> If a following pattern match is to be found, any position within a
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* contracting sequence except the first will fail. Vice versa if a
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* preceding pattern match is to be found, a invalid starting point
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* would be any character within a contracting sequence except the last.
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* </ul>
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* <p>
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* A breakiterator can be used if only matches at logical breaks are desired.
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* Using a breakiterator will only give you results that exactly matches the
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* boundaries given by the breakiterator. For instance the pattern "e" will
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* not be found in the string "\u00e9" if a character break iterator is used.
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* <p>
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* Options are provided to handle overlapping matches.
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* E.g. In English, overlapping matches produces the result 0 and 2
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* for the pattern "abab" in the text "ababab", where else mutually
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* exclusive matches only produce the result of 0.
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* <p>
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* Though collator attributes will be taken into consideration while
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* performing matches, there are no APIs here for setting and getting the
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* attributes. These attributes can be set by getting the collator
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* from <tt>usearch_getCollator</tt> and using the APIs in <tt>ucol.h</tt>.
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* Lastly to update String Search to the new collator attributes,
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* usearch_reset() has to be called.
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* <p>
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* Restriction: <br>
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* Currently there are no composite characters that consists of a
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* character with combining class > 0 before a character with combining
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* class == 0. However, if such a character exists in the future, the
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* search mechanism does not guarantee the results for option 1.
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*
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* <p>
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* Example of use:<br>
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* <pre><code>
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* char *tgtstr = "The quick brown fox jumped over the lazy fox";
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* char *patstr = "fox";
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* UChar target[64];
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* UChar pattern[16];
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* UErrorCode status = U_ZERO_ERROR;
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* u_uastrcpy(target, tgtstr);
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* u_uastrcpy(pattern, patstr);
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*
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* UStringSearch *search = usearch_open(pattern, -1, target, -1, "en_US",
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* &status);
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* if (U_SUCCESS(status)) {
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* for (int pos = usearch_first(search, &status);
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* pos != USEARCH_DONE;
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* pos = usearch_next(search, &status)) {
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* printf("Found match at %d pos, length is %d\n", pos,
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* usearch_getMatchLength(search));
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* }
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* }
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* </code></pre>
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* @since ICU 2.0
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*/
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/**
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* DONE is returned by previous() and next() after all valid matches have
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* been returned, and by first() and last() if there are no matches at all.
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*/
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#define USEARCH_DONE -1
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/**
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* Data structure for searching
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*/
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struct UStringSearch;
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/**
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* Data structure for searching
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*/
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typedef struct UStringSearch UStringSearch;
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typedef enum {
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/** Option for overlapping matches */
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USEARCH_OVERLAP,
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/**
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Option for canonical matches. option 1 in header documentation.
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The default value will be USEARCH_OFF
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*/
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USEARCH_CANONICAL_MATCH,
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USEARCH_ATTRIBUTE_COUNT
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} USearchAttribute;
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typedef enum {
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/** default value for any USearchAttribute */
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USEARCH_DEFAULT = -1,
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/** value for USEARCH_OVERLAP and USEARCH_CANONICAL_MATCH */
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USEARCH_OFF,
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/** value for USEARCH_OVERLAP and USEARCH_CANONICAL_MATCH */
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USEARCH_ON,
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USEARCH_ATTRIBUTE_VALUE_COUNT
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} USearchAttributeValue;
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/* open and close ------------------------------------------------------ */
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/**
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* Creating a search iterator data struct using the argument locale language
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* rule set. A collator will be created in the process, which will be owned by
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* this search and will be deleted in <tt>usearch_close</tt>.
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* @param pattern for matching
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* @param patternlength length of the pattern, -1 for null-termination
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* @param text text string
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* @param textlength length of the text string, -1 for null-termination
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* @param locale name of locale for the rules to be used
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* @param breakiter A BreakIterator that will be used to restrict the points
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* at which matches are detected. If a match is found, but
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* the match's start or end index is not a boundary as
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* determined by the <tt>BreakIterator</tt>, the match will
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* be rejected and another will be searched for.
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* If this parameter is <tt>NULL</tt>, no break detection is
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* attempted.
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* @param status for errors if it occurs. If pattern or text is NULL, or if
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* patternlength or textlength is 0 then an
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* U_ILLEGAL_ARGUMENT_ERROR is returned.
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* @return search iterator data structure, or NULL if there is an error.
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* @draft ICU 2.0
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*/
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U_CAPI UStringSearch * U_EXPORT2 usearch_open(const UChar *pattern,
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int32_t patternlength,
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const UChar *text,
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int32_t textlength,
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const char *locale,
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UBreakIterator *breakiter,
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UErrorCode *status);
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/**
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* Creating a search iterator data struct using the argument collator language
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* rule set. Note, user retains the ownership of this collator, thus the
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* responsibility of deletion lies with the user.
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* @param pattern for matching
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* @param patternlength length of the pattern, -1 for null-termination
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* @param text text string
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* @param textlength length of the text string, -1 for null-termination
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* @param collator used for the language rules
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* @param breakiter A BreakIterator that will be used to restrict the points
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* at which matches are detected. If a match is found, but
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* the match's start or end index is not a boundary as
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* determined by the <tt>BreakIterator</tt>, the match will
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* be rejected and another will be searched for.
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* If this parameter is <tt>NULL</tt>, no break detection is
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* attempted.
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* @param status for errors if it occurs. If collator, pattern or text is NULL,
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* or if patternlength or textlength is 0 then an
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* U_ILLEGAL_ARGUMENT_ERROR is returned.
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* @return search iterator data structure, or NULL if there is an error.
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* @draft ICU 2.0
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*/
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U_CAPI UStringSearch * U_EXPORT2 usearch_openFromCollator(
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const UChar *pattern,
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int32_t patternlength,
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const UChar *text,
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int32_t textlength,
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const UCollator *collator,
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UBreakIterator *breakiter,
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UErrorCode *status);
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/**
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* Destroying and cleaning up the search iterator data struct.
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* If a collator is created in <tt>usearch_open</tt>, it will be destroyed here.
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* @param searchiter data struct to clean up
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* @draft ICU 2.0
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*/
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U_CAPI void U_EXPORT2 usearch_close(UStringSearch *strsrch);
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/* get and set methods -------------------------------------------------- */
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/**
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* Sets the current position in the text string which the next search will
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* start from. Clears previous states.
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* This method takes the argument index and sets the position in the text
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* string accordingly without checking if the index is pointing to a
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* valid starting point to begin searching.
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* Search positions that may render incorrect results are highlighted in the
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* header comments
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* @param strsrch search iterator data struct
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* @param position position to start next search from. If position is less
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* than or greater than the text range for searching,
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* an U_INDEX_OUTOFBOUNDS_ERROR will be returned
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* @param status error status if any.
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* @draft ICU 2.0
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*/
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U_CAPI void U_EXPORT2 usearch_setOffset(UStringSearch *strsrch,
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int32_t position,
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UErrorCode *status);
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/**
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* Return the current index in the string text being searched.
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* If the iteration has gone past the end of the text (or past the beginning
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* for a backwards search), <tt>USEARCH_DONE</tt> is returned.
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* @param strsrch search iterator data struct
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* @see #USEARCH_DONE
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* @draft ICU 2.0
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*/
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U_CAPI int32_t U_EXPORT2 usearch_getOffset(const UStringSearch *strsrch);
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/**
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* Sets the text searching attributes located in the enum USearchAttribute
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* with values from the enum USearchAttributeValue.
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* <tt>USEARCH_DEFAULT</tt> can be used for all attributes for resetting.
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* @param strsrch search iterator data struct
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* @param attribute text attribute to be set
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* @param value text attribute value
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* @param status for errors if it occurs
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* @see #usearch_getAttribute
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* @draft ICU 2.0
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*/
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U_CAPI void U_EXPORT2 usearch_setAttribute(UStringSearch *strsrch,
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USearchAttribute attribute,
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USearchAttributeValue value,
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UErrorCode *status);
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/**
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* Gets the text searching attributes.
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* @param strsrch search iterator data struct
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* @param attribute text attribute to be retrieve
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* @return text attribute value
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* @see #usearch_setAttribute
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* @draft ICU 2.0
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*/
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U_CAPI USearchAttributeValue U_EXPORT2 usearch_getAttribute(
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const UStringSearch *strsrch,
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USearchAttribute attribute);
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/**
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* Returns the index to the match in the text string that was searched.
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* This call returns a valid result only after a successful call to
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* <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
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* or <tt>usearch_last</tt>.
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* Just after construction, or after a searching method returns
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* <tt>USEARCH_DONE</tt>, this method will return <tt>USEARCH_DONE</tt>.
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* <p>
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* Use <tt>usearch_getMatchedLength</tt> to get the matched string length.
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* @param strsrch search iterator data struct
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* @return index to a substring within the text string that is being
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* searched.
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* @see #usearch_first
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* @see #usearch_next
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* @see #usearch_previous
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* @see #usearch_last
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* @see #USEARCH_DONE
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* @draft ICU 2.0
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*/
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U_CAPI int32_t U_EXPORT2 usearch_getMatchedStart(
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const UStringSearch *strsrch);
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/**
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* Returns the length of text in the string which matches the search pattern.
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* This call returns a valid result only after a successful call to
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* <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
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* or <tt>usearch_last</tt>.
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* Just after construction, or after a searching method returns
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* <tt>USEARCH_DONE</tt>, this method will return 0.
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* @param strsrch search iterator data struct
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* @return The length of the match in the string text, or 0 if there is no
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* match currently.
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* @see #usearch_first
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* @see #usearch_next
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* @see #usearch_previous
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* @see #usearch_last
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* @see #USEARCH_DONE
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* @draft ICU 2.0
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*/
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U_CAPI int32_t U_EXPORT2 usearch_getMatchedLength(
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const UStringSearch *strsrch);
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/**
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* Returns the text that was matched by the most recent call to
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* <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
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* or <tt>usearch_last</tt>.
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* If the iterator is not pointing at a valid match (e.g. just after
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* construction or after <tt>USEARCH_DONE</tt> has been returned, returns
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* an empty string. If result is not large enough to store the matched text,
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* result will be filled with the partial text and an U_BUFFER_OVERFLOW_ERROR
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* will be returned in status. result will be null-terminated whenever
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* possible. If the buffer fits the matched text exactly, a null-termination
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* is not possible, then a U_STRING_NOT_TERMINATED_ERROR set in status.
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* Pre-flighting can be either done with length = 0 or the API
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* <tt>usearch_getMatchLength</tt>.
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* @param strsrch search iterator data struct
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* @param result UChar buffer to store the matched string
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* @param resultCapacity length of the result buffer
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* @param status error returned if result is not large enough
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* @return exact length of the matched text, not counting the null-termination
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* @see #usearch_first
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* @see #usearch_next
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* @see #usearch_previous
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* @see #usearch_last
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* @see #USEARCH_DONE
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* @draft ICU 2.0
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*/
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U_CAPI int32_t U_EXPORT2 usearch_getMatchedText(const UStringSearch *strsrch,
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UChar *result,
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int32_t resultCapacity,
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UErrorCode *status);
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/**
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* Set the BreakIterator that will be used to restrict the points at which
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* matches are detected.
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* @param strsrch search iterator data struct
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* @param breakiter A BreakIterator that will be used to restrict the points
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* at which matches are detected. If a match is found, but
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* the match's start or end index is not a boundary as
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* determined by the <tt>BreakIterator</tt>, the match will
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* be rejected and another will be searched for.
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* If this parameter is <tt>NULL</tt>, no break detection is
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* attempted.
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* @param status for errors if it occurs
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* @see #usearch_getBreakIterator
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* @draft ICU 2.0
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*/
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U_CAPI void U_EXPORT2 usearch_setBreakIterator(UStringSearch *strsrch,
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UBreakIterator *breakiter,
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UErrorCode *status);
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/**
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* Returns the BreakIterator that is used to restrict the points at which
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* matches are detected. This will be the same object that was passed to the
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* constructor or to <tt>usearch_setBreakIterator</tt>. Note that
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* <tt>NULL</tt>
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* is a legal value; it means that break detection should not be attempted.
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* @param strsrch search iterator data struct
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* @return break iterator used
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* @see #usearch_setBreakIterator
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* @draft ICU 2.0
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*/
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U_CAPI const UBreakIterator * U_EXPORT2 usearch_getBreakIterator(
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const UStringSearch *strsrch);
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/**
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* Set the string text to be searched. Text iteration will hence begin at the
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* start of the text string. This method is useful if you want to re-use an
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* iterator to search for the same pattern within a different body of text.
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* @param strsrch search iterator data struct
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* @param text new string to look for match
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* @param textlength length of the new string, -1 for null-termination
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* @param status for errors if it occurs. If text is NULL, or textlength is 0
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* then an U_ILLEGAL_ARGUMENT_ERROR is returned with no change
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* done to strsrch.
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* @see #usearch_getText
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* @draft ICU 2.0
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*/
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U_CAPI void U_EXPORT2 usearch_setText( UStringSearch *strsrch,
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const UChar *text,
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int32_t textlength,
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UErrorCode *status);
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/**
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* Return the string text to be searched.
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* @param strsrch search iterator data struct
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* @param length returned string text length
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* @return string text
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* @see #usearch_setText
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* @draft ICU 2.0
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*/
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U_CAPI const UChar * U_EXPORT2 usearch_getText(const UStringSearch *strsrch,
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int32_t *length);
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/**
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* Gets the collator used for the language rules.
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* <p>
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* Deleting the returned <tt>UCollator</tt> before calling
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* <tt>usearch_close</tt> would cause the string search to fail.
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* <tt>usearch_close</tt> will delete the collator if this search owns it.
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* @param strsrch search iterator data struct
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* @return collator
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* @draft ICU 2.0
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*/
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U_CAPI UCollator * U_EXPORT2 usearch_getCollator(
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const UStringSearch *strsrch);
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/**
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* Sets the collator used for the language rules. User retains the ownership
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* of this collator, thus the responsibility of deletion lies with the user.
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* This method causes internal data such as Boyer-Moore shift tables to
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* be recalculated, but the iterator's position is unchanged.
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* @param strsrch search iterator data struct
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* @param collator to be used
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* @param status for errors if it occurs
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* @draft ICU 2.0
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*/
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U_CAPI void U_EXPORT2 usearch_setCollator( UStringSearch *strsrch,
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const UCollator *collator,
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UErrorCode *status);
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/**
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* Sets the pattern used for matching.
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* Internal data like the Boyer Moore table will be recalculated, but the
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* iterator's position is unchanged.
|
||
* @param strsrch search iterator data struct
|
||
* @param pattern string
|
||
* @param patternlength pattern length, -1 for null-terminated string
|
||
* @param status for errors if it occurs. If text is NULL, or textlength is 0
|
||
* then an U_ILLEGAL_ARGUMENT_ERROR is returned with no change
|
||
* done to strsrch.
|
||
* @draft ICU 2.0
|
||
*/
|
||
U_CAPI void U_EXPORT2 usearch_setPattern( UStringSearch *strsrch,
|
||
const UChar *pattern,
|
||
int32_t patternlength,
|
||
UErrorCode *status);
|
||
|
||
/**
|
||
* Gets the search pattern
|
||
* @param strsrch search iterator data struct
|
||
* @param length return length of the pattern, -1 indicates that the pattern
|
||
* is null-terminated
|
||
* @return pattern string
|
||
* @draft ICU 2.0
|
||
*/
|
||
U_CAPI const UChar * U_EXPORT2 usearch_getPattern(
|
||
const UStringSearch *strsrch,
|
||
int32_t *length);
|
||
|
||
/* methods ------------------------------------------------------------- */
|
||
|
||
/**
|
||
* Returns the first index at which the string text matches the search
|
||
* pattern.
|
||
* The iterator is adjusted so that its current index (as returned by
|
||
* <tt>usearch_getOffset</tt>) is the match position if one was found.
|
||
* If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
|
||
* the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>.
|
||
* @param strsrch search iterator data struct
|
||
* @param status for errors if it occurs
|
||
* @return The character index of the first match, or
|
||
* <tt>USEARCH_DONE</tt> if there are no matches.
|
||
* @see #usearch_getOffset
|
||
* @see #USEARCH_DONE
|
||
* @draft ICU 2.0
|
||
*/
|
||
U_CAPI int32_t U_EXPORT2 usearch_first(UStringSearch *strsrch,
|
||
UErrorCode *status);
|
||
|
||
/**
|
||
* Returns the first index greater than <tt>position</tt> at which the string
|
||
* text
|
||
* matches the search pattern. The iterator is adjusted so that its current
|
||
* index (as returned by <tt>usearch_getOffset</tt>) is the match position if
|
||
* one was found.
|
||
* If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
|
||
* the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
|
||
* <p>
|
||
* Search positions that may render incorrect results are highlighted in the
|
||
* header comments. If position is less than or greater than the text range
|
||
* for searching, an U_INDEX_OUTOFBOUNDS_ERROR will be returned
|
||
* @param strsrch search iterator data struct
|
||
* @param position to start the search at
|
||
* @param status for errors if it occurs
|
||
* @return The character index of the first match following <tt>pos</tt>,
|
||
* or <tt>USEARCH_DONE</tt> if there are no matches.
|
||
* @see #usearch_getOffset
|
||
* @see #USEARCH_DONE
|
||
* @draft ICU 2.0
|
||
*/
|
||
U_CAPI int32_t U_EXPORT2 usearch_following(UStringSearch *strsrch,
|
||
int32_t position,
|
||
UErrorCode *status);
|
||
|
||
/**
|
||
* Returns the last index in the target text at which it matches the search
|
||
* pattern. The iterator is adjusted so that its current
|
||
* index (as returned by <tt>usearch_getOffset</tt>) is the match position if
|
||
* one was found.
|
||
* If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
|
||
* the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>.
|
||
* @param strsrch search iterator data struct
|
||
* @param status for errors if it occurs
|
||
* @return The index of the first match, or <tt>USEARCH_DONE</tt> if there
|
||
* are no matches.
|
||
* @see #usearch_getOffset
|
||
* @see #USEARCH_DONE
|
||
* @draft ICU 2.0
|
||
*/
|
||
U_CAPI int32_t U_EXPORT2 usearch_last(UStringSearch *strsrch,
|
||
UErrorCode *status);
|
||
|
||
/**
|
||
* Returns the first index less than <tt>position</tt> at which the string text
|
||
* matches the search pattern. The iterator is adjusted so that its current
|
||
* index (as returned by <tt>usearch_getOffset</tt>) is the match position if
|
||
* one was found.
|
||
* If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
|
||
* the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
|
||
* <p>
|
||
* Search positions that may render incorrect results are highlighted in the
|
||
* header comments. If position is less than or greater than the text range
|
||
* for searching, an U_INDEX_OUTOFBOUNDS_ERROR will be returned
|
||
* @param strsrch search iterator data struct
|
||
* @param position index position the search is to begin at
|
||
* @param status for errors if it occurs
|
||
* @return The character index of the first match preceding <tt>pos</tt>,
|
||
* or <tt>USEARCH_DONE</tt> if there are no matches.
|
||
* @see #usearch_getOffset
|
||
* @see #USEARCH_DONE
|
||
* @draft ICU 2.0
|
||
*/
|
||
U_CAPI int32_t U_EXPORT2 usearch_preceding(UStringSearch *strsrch,
|
||
int32_t position,
|
||
UErrorCode *status);
|
||
|
||
/**
|
||
* Returns the index of the next point at which the string text matches the
|
||
* search pattern, starting from the current position.
|
||
* The iterator is adjusted so that its current
|
||
* index (as returned by <tt>usearch_getOffset</tt>) is the match position if
|
||
* one was found.
|
||
* If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
|
||
* the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
|
||
* @param strsrch search iterator data struct
|
||
* @param status for errors if it occurs
|
||
* @return The index of the next match after the current position, or
|
||
* <tt>USEARCH_DONE</tt> if there are no more matches.
|
||
* @see #usearch_first
|
||
* @see #usearch_getOffset
|
||
* @see #USEARCH_DONE
|
||
* @draft ICU 2.0
|
||
*/
|
||
U_CAPI int32_t U_EXPORT2 usearch_next(UStringSearch *strsrch,
|
||
UErrorCode *status);
|
||
|
||
/**
|
||
* Returns the index of the previous point at which the string text matches
|
||
* the search pattern, starting at the current position.
|
||
* The iterator is adjusted so that its current
|
||
* index (as returned by <tt>usearch_getOffset</tt>) is the match position if
|
||
* one was found.
|
||
* If a match is not found, <tt>USEARCH_DONE</tt> will be returned and
|
||
* the iterator will be adjusted to the index <tt>USEARCH_DONE</tt>
|
||
* @param strsrch search iterator data struct
|
||
* @param status for errors if it occurs
|
||
* @return The index of the previous match before the current position,
|
||
* or <tt>USEARCH_DONE</tt> if there are no more matches.
|
||
* @see #usearch_last
|
||
* @see #usearch_getOffset
|
||
* @see #USEARCH_DONE
|
||
* @draft ICU 2.0
|
||
*/
|
||
U_CAPI int32_t U_EXPORT2 usearch_previous(UStringSearch *strsrch,
|
||
UErrorCode *status);
|
||
|
||
/**
|
||
* Reset the iteration.
|
||
* Search will begin at the start of the text string if a forward iteration
|
||
* is initiated before a backwards iteration. Otherwise if a backwards
|
||
* iteration is initiated before a forwards iteration, the search will begin
|
||
* at the end of the text string.
|
||
* @param strsrch search iterator data struct
|
||
* @see #usearch_first
|
||
* @draft ICU 2.0
|
||
*/
|
||
U_CAPI void U_EXPORT2 usearch_reset(UStringSearch *strsrch);
|
||
|
||
#endif
|
||
|
||
|