Check in the pristine copy of ICU 4.6...

icu46/source/i18n/unicode/stsearch.h

+/*
+**********************************************************************
+*   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 &szlig; 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
+