/* ********************************************************************** * 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