/*

**********************************************************************

*   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