+ * The algorithm implemented is a modified form of the Boyer Moore's search. + * For more information see + * + * "Efficient Text Searching in Java", published in Java Report + * in February, 1999, for further information on the algorithm. + *
+ * There are 2 match options for selection:
+ * This search has APIs similar to that of other text iteration mechanisms
+ * such as the break iterators in BreakIterator. 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 reset followed by a next or previous.
+ * Though a direction change can occur without calling reset 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
+ *
+ * SearchIterator provides APIs to specify the starting position
+ * within the text string to be searched, e.g. setOffset,
+ * preceding and following. 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:
+ *
+ * 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.
+ *
+ * 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.
+ *
+ * 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 getCollator and using the APIs in coll.h.
+ * Lastly to update StringSearch to the new collator attributes,
+ * reset() has to be called.
+ *
+ * Restriction:
+ * Consult the SearchIterator documentation for information on
+ * and examples of how to use instances of this class to implement text
+ * searching.
+ *
+ * Note, StringSearch is not to be subclassed.
+ *
+ * Note: No parsing of the text within the CharacterIterator
+ * will be done during searching for this version. The block of text
+ * in CharacterIterator 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 BreakIterator 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 BreakIterator are
+ * ignored. If this behavior is not desired,
+ * NULL 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 StringSearch 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.
+ *
+ * Note: No parsing of the text within the CharacterIterator
+ * will be done during searching for this version. The block of text
+ * in CharacterIterator 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 RuleBasedCollator 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 BreakIterator 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 BreakIterator are
+ * ignored. If this behavior is not desired,
+ * NULL 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.
+ *
+ * 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 CharacterIterator
+ * will be done during searching for this version. The block of text
+ * in CharacterIterator 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.
+ *
+ * Caller may modify but must not delete the RuleBasedCollator!
+ * Modifications to this collator will affect the original collator passed in to
+ * the StringSearch> 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 }.
+ *
+ * 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 USEARCH_DONE.
+ *
+ * The StringSearch 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, USEARCH_DONE will be returned and
+ * the StringSearch 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
+ * SearchIterator.previous(), which this method overrides.
+ *
+ * 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 USEARCH_DONE.
+ *
+ * The StringSearch 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, USEARCH_DONE will be returned and
+ * the StringSearch 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
+
+ * Let S' be the sub-string of a text string S between the offsets start and
+ * end
+ * A pattern string P matches a text string S at the offsets
+ * 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.
+ *
+ * Option 2. will be the default.
+ *
+ *
+ *
+ * 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.
+ *
+ *
+ * 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());
+ * }
+ *