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 /*

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

 *   Copyright (C) 2001-2008 IBM and others. All rights reserved.

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

 *   Date        Name        Description

 *  03/22/2000   helena      Creation.

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

 */

 #ifndef STSEARCH_H

 #define STSEARCH_H

 #include "unicode/utypes.h"

 /**

  * \file 

  * \brief C++ API: Service for searching text based on RuleBasedCollator.

  */

 #if !UCONFIG_NO_COLLATION && !UCONFIG_NO_BREAK_ITERATION

 #include "unicode/tblcoll.h"

 #include "unicode/coleitr.h"

 #include "unicode/search.h"

 U_NAMESPACE_BEGIN

 /** 

  *

  * <tt>StringSearch</tt> is a <tt>SearchIterator</tt> that provides

  * language-sensitive text searching based on the comparison rules defined

  * in a {@link RuleBasedCollator} object.

  * StringSearch 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://source.icu-project.org/repos/icu/icuhtml/trunk/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-project.org/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>BreakIterator</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.

  * Match results in the forward direction will match the result matches in 

  * the backwards direction in the reverse order

  * <p>

  * <tt>SearchIterator</tt> provides APIs to specify the starting position 

  * within the text string to be searched, e.g. <tt>setOffset</tt>,

  * <tt>preceding</tt> and <tt>following</tt>. Since the 

  * starting position will be set as it is specified, please take note that 

  * there are some danger points 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>getCollator</tt> and using the APIs in <tt>coll.h</tt>.

  * Lastly to update StringSearch to the new collator attributes, 

  * 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,  

  * StringSearch does not guarantee the results for option 1.

  * <p>

  * Consult the <tt>SearchIterator</tt> documentation for information on

  * and examples of how to use instances of this class to implement text

  * searching.

  * <pre><code>

  * UnicodeString target("The quick brown fox jumps over the lazy dog.");

  * UnicodeString pattern("fox");

  *

  * UErrorCode      error = U_ZERO_ERROR;

  * StringSearch iter(pattern, target, Locale::getUS(), NULL, status);

  * for (int pos = iter.first(error);

  *      pos != USEARCH_DONE; 

  *      pos = iter.next(error))

  * {

  *     printf("Found match at %d pos, length is %d\n", pos, 

  *                                             iter.getMatchLength());

  * }

  * </code></pre>

  * <p>

  * Note, StringSearch is not to be subclassed.

  * </p>

  * @see SearchIterator

  * @see RuleBasedCollator

  * @since ICU 2.0

  */

 class U_I18N_API StringSearch : public SearchIterator

 {

 public:

     // public constructors and destructors --------------------------------

     /**

      * Creating a <tt>StringSearch</tt> instance using the argument locale 

      * language rule set. A collator will be created in the process, which 

      * will be owned by this instance and will be deleted during 

      * destruction

      * @param pattern The text for which this object will search.

      * @param text    The text in which to search for the pattern.

      * @param locale  A locale which defines the language-sensitive 

      *                comparison rules used to determine whether text in the 

      *                pattern and target matches. 

      * @param breakiter A <tt>BreakIterator</tt> object used to constrain 

      *                the matches that are found. Matches whose start and end 

      *                indices in the target text are not boundaries as 

      *                determined by the <tt>BreakIterator</tt> are 

      *                ignored. If this behavior is not desired, 

      *                <tt>NULL</tt> can be passed in instead.

      * @param status  for errors if any. If pattern or text is NULL, or if

      *               either the length of pattern or text is 0 then an 

      *               U_ILLEGAL_ARGUMENT_ERROR is returned.

      * @stable ICU 2.0

      */

     StringSearch(const UnicodeString &pattern, const UnicodeString &text,

                  const Locale        &locale,       

                        BreakIterator *breakiter,

                        UErrorCode    &status);

     /**

      * Creating a <tt>StringSearch</tt> instance using the argument collator 

      * language rule set. Note, user retains the ownership of this collator, 

      * it does not get destroyed during this instance's destruction.

      * @param pattern The text for which this object will search.

      * @param text    The text in which to search for the pattern.

      * @param coll    A <tt>RuleBasedCollator</tt> object which defines 

      *                the language-sensitive comparison rules used to 

      *                determine whether text in the pattern and target 

      *                matches. User is responsible for the clearing of this

      *                object.

      * @param breakiter A <tt>BreakIterator</tt> object used to constrain 

      *                the matches that are found. Matches whose start and end 

      *                indices in the target text are not boundaries as 

      *                determined by the <tt>BreakIterator</tt> are 

      *                ignored. If this behavior is not desired, 

      *                <tt>NULL</tt> can be passed in instead.

      * @param status for errors if any. If either the length of pattern or 

      *               text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned.

      * @stable ICU 2.0

      */

     StringSearch(const UnicodeString     &pattern, 

                  const UnicodeString     &text,

                        RuleBasedCollator *coll,       

                        BreakIterator     *breakiter,

                        UErrorCode        &status);

     /**

      * Creating a <tt>StringSearch</tt> instance using the argument locale 

      * language rule set. A collator will be created in the process, which 

      * will be owned by this instance and will be deleted during 

      * destruction

      * <p>

      * Note: No parsing of the text within the <tt>CharacterIterator</tt> 

      * will be done during searching for this version. The block of text 

      * in <tt>CharacterIterator</tt> will be used as it is.

      * @param pattern The text for which this object will search.

      * @param text    The text iterator in which to search for the pattern.

      * @param locale  A locale which defines the language-sensitive 

      *                comparison rules used to determine whether text in the 

      *                pattern and target matches. User is responsible for 

      *                the clearing of this object.

      * @param breakiter A <tt>BreakIterator</tt> object used to constrain 

      *                the matches that are found. Matches whose start and end 

      *                indices in the target text are not boundaries as 

      *                determined by the <tt>BreakIterator</tt> are 

      *                ignored. If this behavior is not desired, 

      *                <tt>NULL</tt> can be passed in instead.

      * @param status for errors if any. If either the length of pattern or 

      *               text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned.

      * @stable ICU 2.0

      */

     StringSearch(const UnicodeString &pattern, CharacterIterator &text,

                  const Locale        &locale, 

                        BreakIterator *breakiter,

                        UErrorCode    &status);

     /**

      * Creating a <tt>StringSearch</tt> instance using the argument collator 

      * language rule set. Note, user retains the ownership of this collator, 

      * it does not get destroyed during this instance's destruction.

      * <p>

      * Note: No parsing of the text within the <tt>CharacterIterator</tt> 

      * will be done during searching for this version. The block of text 

      * in <tt>CharacterIterator</tt> will be used as it is.

      * @param pattern The text for which this object will search.

      * @param text    The text in which to search for the pattern.

      * @param coll    A <tt>RuleBasedCollator</tt> object which defines 

      *                the language-sensitive comparison rules used to 

      *                determine whether text in the pattern and target 

      *                matches. User is responsible for the clearing of this

      *                object.

      * @param breakiter A <tt>BreakIterator</tt> object used to constrain 

      *                the matches that are found. Matches whose start and end 

      *                indices in the target text are not boundaries as 

      *                determined by the <tt>BreakIterator</tt> are 

      *                ignored. If this behavior is not desired, 

      *                <tt>NULL</tt> can be passed in instead.

      * @param status for errors if any. If either the length of pattern or 

      *               text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned.

      * @stable ICU 2.0

      */

     StringSearch(const UnicodeString     &pattern, CharacterIterator &text,

                        RuleBasedCollator *coll, 

                        BreakIterator     *breakiter,

                        UErrorCode        &status);

     /**

      * Copy constructor that creates a StringSearch instance with the same 

      * behavior, and iterating over the same text.

      * @param that StringSearch instance to be copied.

      * @stable ICU 2.0

      */

     StringSearch(const StringSearch &that);

     /**

     * Destructor. Cleans up the search iterator data struct.

     * If a collator is created in the constructor, it will be destroyed here.

     * @stable ICU 2.0

     */

     virtual ~StringSearch(void);

     /**

      * Clone this object.

      * Clones can be used concurrently in multiple threads.

      * If an error occurs, then NULL is returned.

      * The caller must delete the clone.

      *

      * @return a clone of this object

      *

      * @see getDynamicClassID

      * @stable ICU 2.8

      */

     StringSearch *clone() const;

     // operator overloading ---------------------------------------------

     /**

      * Assignment operator. Sets this iterator to have the same behavior,

      * and iterate over the same text, as the one passed in.

      * @param that instance to be copied.

      * @stable ICU 2.0

      */

     StringSearch & operator=(const StringSearch &that);

     /**

      * Equality operator. 

      * @param that instance to be compared.

      * @return TRUE if both instances have the same attributes, 

      *         breakiterators, collators and iterate over the same text 

      *         while looking for the same pattern.

      * @stable ICU 2.0

      */

     virtual UBool operator==(const SearchIterator &that) const;

     // public get and set methods ----------------------------------------

     /**

      * Sets the index to point to the given position, and clears any state 

      * that's affected.

      * <p>

      * 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. 

      * @param position within the text to be set. If position is less

      *          than or greater than the text range for searching, 

      *          an U_INDEX_OUTOFBOUNDS_ERROR will be returned

      * @param status for errors if it occurs

      * @stable ICU 2.0

      */

     virtual void setOffset(int32_t position, UErrorCode &status);

     /**

      * Return the current index in the text being searched.

      * If the iteration has gone past the end of the text

      * (or past the beginning for a backwards search), USEARCH_DONE

      * is returned.

      * @return current index in the text being searched.

      * @stable ICU 2.0

      */

     virtual int32_t getOffset(void) const;

     /**

      * Set the target 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 text text string to be searched

      * @param status for errors if any. If the text length is 0 then an 

      *        U_ILLEGAL_ARGUMENT_ERROR is returned.

      * @stable ICU 2.0

      */

     virtual void setText(const UnicodeString &text, UErrorCode &status);

     /**

      * Set the target 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.

      * Note: No parsing of the text within the <tt>CharacterIterator</tt> 

      * will be done during searching for this version. The block of text 

      * in <tt>CharacterIterator</tt> will be used as it is.

      * @param text text string to be searched

      * @param status for errors if any. If the text length is 0 then an 

      *        U_ILLEGAL_ARGUMENT_ERROR is returned.

      * @stable ICU 2.0

      */

     virtual void setText(CharacterIterator &text, UErrorCode &status);

     /**

      * Gets the collator used for the language rules.

      * <p>

      * Caller may modify but <b>must not</b> delete the <tt>RuleBasedCollator</tt>!

      * Modifications to this collator will affect the original collator passed in to 

      * the <tt>StringSearch></tt> constructor or to setCollator, if any.

      * @return collator used for string search

      * @stable ICU 2.0

      */

     RuleBasedCollator * getCollator() const;

     /**

      * 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 coll    collator 

      * @param status  for errors if any

      * @stable ICU 2.0

      */

     void setCollator(RuleBasedCollator *coll, 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 pattern search pattern to be found

      * @param status for errors if any. If the pattern length is 0 then an 

      *               U_ILLEGAL_ARGUMENT_ERROR is returned.

      * @stable ICU 2.0

      */

     void setPattern(const UnicodeString &pattern, UErrorCode &status);

     /**

      * Gets the search pattern.

      * @return pattern used for matching

      * @stable ICU 2.0

      */

     const UnicodeString & getPattern() const;

     // public methods ----------------------------------------------------

     /** 

      * 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.

      * @stable ICU 2.0

      */

     virtual void reset();

     /**

      * Returns a copy of StringSearch with the same behavior, and 

      * iterating over the same text, as this one. Note that all data will be

      * replicated, except for the user-specified collator and the

      * breakiterator.

      * @return cloned object

      * @stable ICU 2.0

      */

     virtual SearchIterator * safeClone(void) const;

     /**

      * ICU "poor man's RTTI", returns a UClassID for the actual class.

      *

      * @stable ICU 2.2

      */

     virtual UClassID getDynamicClassID() const;

     /**

      * ICU "poor man's RTTI", returns a UClassID for this class.

      *

      * @stable ICU 2.2

      */

     static UClassID U_EXPORT2 getStaticClassID();

 protected:

     // protected method -------------------------------------------------

     /**

      * Search forward for matching text, starting at a given location.

      * Clients should not call this method directly; instead they should 

      * call {@link SearchIterator#next }.

      * <p>

      * If a match is found, this method returns the index at which the match

      * starts and calls {@link SearchIterator#setMatchLength } with the number 

      * of characters in the target text that make up the match. If no match 

      * is found, the method returns <tt>USEARCH_DONE</tt>.

      * <p>

      * The <tt>StringSearch</tt> is adjusted so that its current index 

      * (as returned by {@link #getOffset }) is the match position if one was 

      * found.

      * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and

      * the <tt>StringSearch</tt> will be adjusted to the index USEARCH_DONE.

      * @param position The index in the target text at which the search 

      *                 starts

      * @param status for errors if any occurs

      * @return The index at which the matched text in the target starts, or 

      *         USEARCH_DONE if no match was found.

      * @stable ICU 2.0

      */

     virtual int32_t handleNext(int32_t position, UErrorCode &status);

     /**

      * Search backward for matching text, starting at a given location.

      * Clients should not call this method directly; instead they should call

      * <tt>SearchIterator.previous()</tt>, which this method overrides.

      * <p>

      * If a match is found, this method returns the index at which the match

      * starts and calls {@link SearchIterator#setMatchLength } with the number 

      * of characters in the target text that make up the match. If no match 

      * is found, the method returns <tt>USEARCH_DONE</tt>.

      * <p>

      * The <tt>StringSearch</tt> is adjusted so that its current index 

      * (as returned by {@link #getOffset }) is the match position if one was 

      * found.

      * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and

      * the <tt>StringSearch</tt> will be adjusted to the index USEARCH_DONE.

      * @param position The index in the target text at which the search 

      *                 starts.

      * @param status for errors if any occurs

      * @return The index at which the matched text in the target starts, or 

      *         USEARCH_DONE if no match was found.

      * @stable ICU 2.0

      */

     virtual int32_t handlePrev(int32_t position, UErrorCode &status);

 private :

     StringSearch(); // default constructor not implemented

     // private data members ----------------------------------------------

     /**

     * RuleBasedCollator, contains exactly the same UCollator * in m_strsrch_

     * @stable ICU 2.0

     */

     RuleBasedCollator  m_collator_;

     /**

     * Pattern text

     * @stable ICU 2.0

     */

     UnicodeString      m_pattern_;

     /**

     * String search struct data

     * @stable ICU 2.0

     */

     UStringSearch     *m_strsrch_;

 };

 U_NAMESPACE_END

 #endif /* #if !UCONFIG_NO_COLLATION */

 #endif