/*
**********************************************************************
* Copyright (C) 2001-2005 IBM and others. All rights reserved.
**********************************************************************
* Date Name Description
* 06/28/2001 synwee Creation.
**********************************************************************
*/
#ifndef USEARCH_H
#define USEARCH_H
#include "unicode/utypes.h"
#if !UCONFIG_NO_COLLATION
#include "unicode/ucol.h"
#include "unicode/ucoleitr.h"
#include "unicode/ubrk.h"
/**
* \file
* \brief C API: StringSearch
*
* C Apis for an engine that provides language-sensitive text searching based
* on the comparison rules defined in a <tt>UCollator</tt> data struct,
* see <tt>ucol.h</tt>. This ensures that language eccentricity can be
* handled, e.g. for the German collator, characters ß and SS will be matched
* if case is chosen to be ignored.
* See the <a href="http://dev.icu-project.org/cgi-bin/viewcvs.cgi/~checkout~/icuhtml/design/collation/ICU_collation_design.htm">
* "ICU Collation Design Document"</a> for more information.
* <p>
* The algorithm implemented is a modified form of the Boyer Moore's search.
* For more information see
* <a href="http://icu.sourceforge.net/docs/papers/efficient_text_searching_in_java.html">
* "Efficient Text Searching in Java"</a>, published in <i>Java Report</i>
* in February, 1999, for further information on the algorithm.
* <p>
* There are 2 match options for selection:<br>
* Let S' be the sub-string of a text string S between the offsets start and
* end <start, end>.
* <br>
* A pattern string P matches a text string S at the offsets <start, end>
* if
* <pre>
* option 1. Some canonical equivalent of P matches some canonical equivalent
* of S'
* option 2. P matches S' and if P starts or ends with a combining mark,
* there exists no non-ignorable combining mark before or after S'
* in S respectively.
* </pre>
* Option 2. will be the default.
* <p>
* This search has APIs similar to that of other text iteration mechanisms
* such as the break iterators in <tt>ubrk.h</tt>. Using these
* APIs, it is easy to scan through text looking for all occurances of
* a given pattern. This search iterator allows changing of direction by
* calling a <tt>reset</tt> followed by a <tt>next</tt> or <tt>previous</tt>.
* Though a direction change can occur without calling <tt>reset</tt> first,
* this operation comes with some speed penalty.
* Generally, match results in the forward direction will match the result
* matches in the backwards direction in the reverse order
* <p>
* <tt>usearch.h</tt> provides APIs to specify the starting position
* within the text string to be searched, e.g. <tt>usearch_setOffset</tt>,
* <tt>usearch_preceding</tt> and <tt>usearch_following</tt>. Since the
* starting position will be set as it is specified, please take note that
* there are some dangerous positions which the search may render incorrect
* results:
* <ul>
* <li> The midst of a substring that requires normalization.
* <li> If the following match is to be found, the position should not be the
* second character which requires to be swapped with the preceding
* character. Vice versa, if the preceding match is to be found,
* position to search from should not be the first character which
* requires to be swapped with the next character. E.g certain Thai and
* Lao characters require swapping.
* <li> If a following pattern match is to be found, any position within a
* contracting sequence except the first will fail. Vice versa if a
* preceding pattern match is to be found, a invalid starting point
* would be any character within a contracting sequence except the last.
* </ul>
* <p>
* A breakiterator can be used if only matches at logical breaks are desired.
* Using a breakiterator will only give you results that exactly matches the
* boundaries given by the breakiterator. For instance the pattern "e" will
* not be found in the string "\u00e9" if a character break iterator is used.
* <p>
* Options are provided to handle overlapping matches.
* E.g. In English, overlapping matches produces the result 0 and 2
* for the pattern "abab" in the text "ababab", where else mutually
* exclusive matches only produce the result of 0.
* <p>
* Though collator attributes will be taken into consideration while
* performing matches, there are no APIs here for setting and getting the
* attributes. These attributes can be set by getting the collator
* from <tt>usearch_getCollator</tt> and using the APIs in <tt>ucol.h</tt>.
* Lastly to update String Search to the new collator attributes,
* usearch_reset() has to be called.
* <p>
* Restriction: <br>
* Currently there are no composite characters that consists of a
* character with combining class > 0 before a character with combining
* class == 0. However, if such a character exists in the future, the
* search mechanism does not guarantee the results for option 1.
*
* <p>
* Example of use:<br>
* <pre><code>
* char *tgtstr = "The quick brown fox jumped over the lazy fox";
* char *patstr = "fox";
* UChar target[64];
* UChar pattern[16];
* UErrorCode status = U_ZERO_ERROR;
* u_uastrcpy(target, tgtstr);
* u_uastrcpy(pattern, patstr);
*
* UStringSearch *search = usearch_open(pattern, -1, target, -1, "en_US",
* &status);
* if (U_SUCCESS(status)) {
* for (int pos = usearch_first(search, &status);
* pos != USEARCH_DONE;
* pos = usearch_next(search, &status)) {
* printf("Found match at %d pos, length is %d\n", pos,
* usearch_getMatchLength(search));
* }
* }
* </code></pre>
* @stable ICU 2.4
*/
/**
* DONE is returned by previous() and next() after all valid matches have
* been returned, and by first() and last() if there are no matches at all.
* @stable ICU 2.4
*/
#define USEARCH_DONE -1
/**
* Data structure for searching
* @stable ICU 2.4
*/
struct UStringSearch;
/**
* Data structure for searching
* @stable ICU 2.4
*/
typedef struct UStringSearch UStringSearch;
/**
* @stable ICU 2.4
*/
typedef enum {
/** Option for overlapping matches */
USEARCH_OVERLAP,
/**
Option for canonical matches. option 1 in header documentation.
The default value will be USEARCH_OFF
*/
USEARCH_CANONICAL_MATCH,
USEARCH_ATTRIBUTE_COUNT
} USearchAttribute;
/**
* @stable ICU 2.4
*/
typedef enum {
/** default value for any USearchAttribute */
USEARCH_DEFAULT = -1,
/** value for USEARCH_OVERLAP and USEARCH_CANONICAL_MATCH */
USEARCH_OFF,
/** value for USEARCH_OVERLAP and USEARCH_CANONICAL_MATCH */
USEARCH_ON,
USEARCH_ATTRIBUTE_VALUE_COUNT
} USearchAttributeValue;
/* open and close ------------------------------------------------------ */
/**
* Creating a search iterator data struct using the argument locale language
* rule set. A collator will be created in the process, which will be owned by
* this search and will be deleted in <tt>usearch_close</tt>.
* @param pattern for matching
* @param patternlength length of the pattern, -1 for null-termination
* @param text text string
* @param textlength length of the text string, -1 for null-termination
* @param locale name of locale for the rules to be used
* @param breakiter A BreakIterator that will be used to restrict the points
* at which matches are detected. If a match is found, but
* the match's start or end index is not a boundary as
* determined by the <tt>BreakIterator</tt>, the match will
* be rejected and another will be searched for.
* If this parameter is <tt>NULL</tt>, no break detection is
* attempted.
* @param status for errors if it occurs. If pattern or text is NULL, or if
* patternlength or textlength is 0 then an
* U_ILLEGAL_ARGUMENT_ERROR is returned.
* @return search iterator data structure, or NULL if there is an error.
* @stable ICU 2.4
*/
U_STABLE UStringSearch * U_EXPORT2 usearch_open(const UChar *pattern,
int32_t patternlength,
const UChar *text,
int32_t textlength,
const char *locale,
UBreakIterator *breakiter,
UErrorCode *status);
/**
* Creating a search iterator data struct using the argument collator language
* rule set. Note, user retains the ownership of this collator, thus the
* responsibility of deletion lies with the user.
* NOTE: string search cannot be instantiated from a collator that has
* collate digits as numbers (CODAN) turned on.
* @param pattern for matching
* @param patternlength length of the pattern, -1 for null-termination
* @param text text string
* @param textlength length of the text string, -1 for null-termination
* @param collator used for the language rules
* @param breakiter A BreakIterator that will be used to restrict the points
* at which matches are detected. If a match is found, but
* the match's start or end index is not a boundary as
* determined by the <tt>BreakIterator</tt>, the match will
* be rejected and another will be searched for.
* If this parameter is <tt>NULL</tt>, no break detection is
* attempted.
* @param status for errors if it occurs. If collator, pattern or text is NULL,
* or if patternlength or textlength is 0 then an
* U_ILLEGAL_ARGUMENT_ERROR is returned.
* @return search iterator data structure, or NULL if there is an error.
* @stable ICU 2.4
*/
U_STABLE UStringSearch * U_EXPORT2 usearch_openFromCollator(
const UChar *pattern,
int32_t patternlength,
const UChar *text,
int32_t textlength,
const UCollator *collator,
UBreakIterator *breakiter,
UErrorCode *status);
/**
* Destroying and cleaning up the search iterator data struct.
* If a collator is created in <tt>usearch_open</tt>, it will be destroyed here.
* @param searchiter data struct to clean up
* @stable ICU 2.4
*/
U_STABLE void U_EXPORT2 usearch_close(UStringSearch *searchiter);
/* get and set methods -------------------------------------------------- */
/**
* Sets the current position in the text string which the next search will
* start from. Clears previous states.
* This method takes the argument index and sets the position in the text
* string accordingly without checking if the index is pointing to a
* valid starting point to begin searching.
* Search positions that may render incorrect results are highlighted in the
* header comments
* @param strsrch search iterator data struct
* @param position position to start next search from. If position is less
* than or greater than the text range for searching,
* an U_INDEX_OUTOFBOUNDS_ERROR will be returned
* @param status error status if any.
* @stable ICU 2.4
*/
U_STABLE void U_EXPORT2 usearch_setOffset(UStringSearch *strsrch,
int32_t position,
UErrorCode *status);
/**
* Return the current index in the string text being searched.
* If the iteration has gone past the end of the text (or past the beginning
* for a backwards search), <tt>USEARCH_DONE</tt> is returned.
* @param strsrch search iterator data struct
* @see #USEARCH_DONE
* @stable ICU 2.4
*/
U_STABLE int32_t U_EXPORT2 usearch_getOffset(const UStringSearch *strsrch);
/**
* Sets the text searching attributes located in the enum USearchAttribute
* with values from the enum USearchAttributeValue.
* <tt>USEARCH_DEFAULT</tt> can be used for all attributes for resetting.
* @param strsrch search iterator data struct
* @param attribute text attribute to be set
* @param value text attribute value
* @param status for errors if it occurs
* @see #usearch_getAttribute
* @stable ICU 2.4
*/
U_STABLE void U_EXPORT2 usearch_setAttribute(UStringSearch *strsrch,
USearchAttribute attribute,
USearchAttributeValue value,
UErrorCode *status);
/**
* Gets the text searching attributes.
* @param strsrch search iterator data struct
* @param attribute text attribute to be retrieve
* @return text attribute value
* @see #usearch_setAttribute
* @stable ICU 2.4
*/
U_STABLE USearchAttributeValue U_EXPORT2 usearch_getAttribute(
const UStringSearch *strsrch,
USearchAttribute attribute);
/**
* Returns the index to the match in the text string that was searched.
* This call returns a valid result only after a successful call to
* <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
* or <tt>usearch_last</tt>.
* Just after construction, or after a searching method returns
* <tt>USEARCH_DONE</tt>, this method will return <tt>USEARCH_DONE</tt>.
* <p>
* Use <tt>usearch_getMatchedLength</tt> to get the matched string length.
* @param strsrch search iterator data struct
* @return index to a substring within the text string that is being
* searched.
* @see #usearch_first
* @see #usearch_next
* @see #usearch_previous
* @see #usearch_last
* @see #USEARCH_DONE
* @stable ICU 2.4
*/
U_STABLE int32_t U_EXPORT2 usearch_getMatchedStart(
const UStringSearch *strsrch);
/**
* Returns the length of text in the string which matches the search pattern.
* This call returns a valid result only after a successful call to
* <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
* or <tt>usearch_last</tt>.
* Just after construction, or after a searching method returns
* <tt>USEARCH_DONE</tt>, this method will return 0.
* @param strsrch search iterator data struct
* @return The length of the match in the string text, or 0 if there is no
* match currently.
* @see #usearch_first
* @see #usearch_next
* @see #usearch_previous
* @see #usearch_last
* @see #USEARCH_DONE
* @stable ICU 2.4
*/
U_STABLE int32_t U_EXPORT2 usearch_getMatchedLength(
const UStringSearch *strsrch);
/**
* Returns the text that was matched by the most recent call to
* <tt>usearch_first</tt>, <tt>usearch_next</tt>, <tt>usearch_previous</tt>,
* or <tt>usearch_last</tt>.
* If the iterator is not pointing at a valid match (e.g. just after
* construction or after <tt>USEARCH_DONE</tt> has been returned, returns
* an empty string. If result is not large enough to store the matched text,
* result will be filled with the partial text and an U_BUFFER_OVERFLOW_ERROR
* will be returned in status. result will be null-terminated whenever
* possible. If the buffer fits the matched text exactly, a null-termination
* is not possible, then a U_STRING_NOT_TERMINATED_ERROR set in status.
* Pre-flighting can be either done with length = 0 or the API
* <tt>usearch_getMatchLength</tt>.
* @param strsrch search iterator data struct
* @param result UChar buffer to store the matched string
* @param resultCapacity length of the result buffer
* @param status error returned if result is not large enough
* @return exact length of the matched text, not counting the null-termination
* @see #usearch_first
* @see #usearch_next
* @see #usearch_previous
* @see #usearch_last
* @see #USEARCH_DONE
* @stable ICU 2.4
*/
U_STABLE int32_t U_EXPORT2 usearch_getMatchedText(const UStringSearch *strsrch,
UChar *result,
int32_t resultCapacity,
UErrorCode *status);
#if !UCONFIG_NO_BREAK_ITERATION
/**
* Set the BreakIterator that will be used to restrict the points at which
* matches are detected.
* @param strsrch search iterator data struct
* @param breakiter A BreakIterator that will be used to restrict the points
* at which matches are detected. If a match is found, but
* the match's start or end index is not a boundary as
* determined by the <tt>BreakIterator</tt>, the match will
* be rejected and another will be searched for.
* If this parameter is <tt>NULL</tt>, no break detection is
* attempted.
* @param status for errors if it occurs
* @see #usearch_getBreakIterator
* @stable ICU 2.4
*/
U_STABLE void U_EXPORT2 usearch_setBreakIterator(UStringSearch *strsrch,
UBreakIterator *breakiter,
UErrorCode *status);
/**
* Returns the BreakIterator that is used to restrict the points at which
* matches are detected. This will be the same object that was passed to the
* constructor or to <tt>usearch_setBreakIterator</tt>. Note that
* <tt>NULL</tt>
* is a legal value; it means that break detection should not be attempted.
* @param strsrch search iterator data struct
* @return break iterator used
* @see #usearch_setBreakIterator
* @stable ICU 2.4
*/
U_STABLE const UBreakIterator * U_EXPORT2 usearch_getBreakIterator(
const UStringSearch *strsrch);
#endif
/**
* Set the string text to be searched. Text iteration will hence begin at the
* start of the text string. This method is useful if you want to re-use an
* iterator to search for the same pattern within a different body of text.
* @param strsrch search iterator data struct
* @param text new string to look for match
* @param textlength length of the new string, -1 for null-termination
* @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.
* @see #usearch_getText
* @stable ICU 2.4
*/
U_STABLE void U_EXPORT2 usearch_setText( UStringSearch *strsrch,
const UChar *text,
int32_t textlength,
UErrorCode *status);
/**
* Return the string text to be searched.
* @param strsrch search iterator data struct
* @param length returned string text length
* @return string text
* @see #usearch_setText
* @stable ICU 2.4
*/
U_STABLE const UChar * U_EXPORT2 usearch_getText(const UStringSearch *strsrch,
int32_t *length);
/**
* Gets the collator used for the language rules.
* <p>
* Deleting the returned <tt>UCollator</tt> before calling
* <tt>usearch_close</tt> would cause the string search to fail.
* <tt>usearch_close</tt> will delete the collator if this search owns it.
* @param strsrch search iterator data struct
* @return collator
* @stable ICU 2.4
*/
U_STABLE UCollator * U_EXPORT2 usearch_getCollator(
const UStringSearch *strsrch);
/**
* Sets the collator used for the language rules. User retains the ownership
* of this collator, thus the responsibility of deletion lies with the user.
* This method causes internal data such as Boyer-Moore shift tables to
* be recalculated, but the iterator's position is unchanged.
* @param strsrch search iterator data struct
* @param collator to be used
* @param status for errors if it occurs
* @stable ICU 2.4
*/
U_STABLE void U_EXPORT2 usearch_setCollator( UStringSearch *strsrch,
const UCollator *collator,
UErrorCode *status);
/**
* Sets the pattern used for matching.
* Internal data like the Boyer Moore table will be recalculated, but the
* 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.
* @stable ICU 2.4
*/
U_STABLE 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
* @stable ICU 2.4
*/
U_STABLE 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
* @stable ICU 2.4
*/
U_STABLE 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
* @stable ICU 2.4
*/
U_STABLE 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
* @stable ICU 2.4
*/
U_STABLE 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
* @stable ICU 2.4
*/
U_STABLE 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
* @stable ICU 2.4
*/
U_STABLE 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
* @stable ICU 2.4
*/
U_STABLE 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
* @stable ICU 2.4
*/
U_STABLE void U_EXPORT2 usearch_reset(UStringSearch *strsrch);
#endif /* #if !UCONFIG_NO_COLLATION */
#endif