com.ibm.icu.text
public abstract class SearchIterator extends Object
SearchIterator is an abstract base class that defines a protocol for text searching. Subclasses provide concrete implementations of various search algorithms. A concrete subclass, StringSearch, is provided that implements language-sensitive pattern matching based on the comparison rules defined in a RuleBasedCollator object. Instances of SearchIterator maintain a current position and scan over the target text, returning the indices where a match is found and the length of each match. Generally, the sequence of forward matches will be equivalent to the sequence of backward matches.One case where this statement may not hold is when non-overlapping mode is set on and there are continuous repetitive patterns in the text. Consider the case searching for pattern "aba" in the text "ababababa", setting overlapping mode off will produce forward matches at offsets 0, 4. However when a backwards search is done, the results will be at offsets 6 and 2.
If matches searched for have boundary restrictions. BreakIterators can be used to define the valid boundaries of such a match. Once a BreakIterator is set, potential matches will be tested against the BreakIterator to determine if the boundaries are valid and that all characters in the potential match are equivalent to the pattern searched for. For example, looking for the pattern "fox" in the text "foxy fox" will produce match results at offset 0 and 5 with length 3 if no BreakIterators were set. However if a WordBreakIterator is set, the only match that would be found will be at the offset 5. Since, the SearchIterator guarantees that if a BreakIterator is set, all its matches will match the given pattern exactly, a potential match that passes the BreakIterator might still not produce a valid match. For instance the pattern "e" will not be found in the string "\u00e9" (latin small letter e with acute) if a CharacterBreakIterator is used. Even though "e" is a part of the character "\u00e9" and the potential match at offset 0 length 1 passes the CharacterBreakIterator test, "\u00e9" is not equivalent to "e", hence the SearchIterator rejects the potential match. By default, the SearchIterator does not impose any boundary restriction on the matches, it will return all results that match the pattern. Illustrating with the above example, "e" will be found in the string "\u00e9" if no BreakIterator is specified.
SearchIterator also provides a means to handle overlapping matches via the API setOverlapping(boolean). For example, if overlapping mode is set, searching for the pattern "abab" in the text "ababab" will match at positions 0 and 2, whereas if overlapping is not set, SearchIterator will only match at position 0. By default, overlapping mode is not set.
The APIs in SearchIterator are similar to that of other text iteration classes such as BreakIterator. Using this class, it is easy to scan through text looking for all occurances of a match.
Example of use:
String target = "The quick brown fox jumped over the lazy fox"; String pattern = "fox"; SearchIterator iter = new StringSearch(pattern, target); for (int pos = iter.first(); pos != SearchIterator.DONE; pos = iter.next()) { // println matches at offset 16 and 41 with length 3 System.out.println("Found match at " + pos + ", length is " + iter.getMatchLength()); } target = "ababababa"; pattern = "aba"; iter.setTarget(new StringCharacterIterator(pattern)); iter.setOverlapping(false); System.out.println("Overlapping mode set to false"); System.out.println("Forward matches of pattern " + pattern + " in text " + text + ": "); for (int pos = iter.first(); pos != SearchIterator.DONE; pos = iter.next()) { // println matches at offset 0 and 4 with length 3 System.out.println("offset " + pos + ", length " + iter.getMatchLength()); } System.out.println("Backward matches of pattern " + pattern + " in text " + text + ": "); for (int pos = iter.last(); pos != SearchIterator.DONE; pos = iter.previous()) { // println matches at offset 6 and 2 with length 3 System.out.println("offset " + pos + ", length " + iter.getMatchLength()); } System.out.println("Overlapping mode set to true"); System.out.println("Index set to 2"); iter.setIndex(2); iter.setOverlapping(true); System.out.println("Forward matches of pattern " + pattern + " in text " + text + ": "); for (int pos = iter.first(); pos != SearchIterator.DONE; pos = iter.next()) { // println matches at offset 2, 4 and 6 with length 3 System.out.println("offset " + pos + ", length " + iter.getMatchLength()); } System.out.println("Index set to 2"); iter.setIndex(2); System.out.println("Backward matches of pattern " + pattern + " in text " + text + ": "); for (int pos = iter.last(); pos != SearchIterator.DONE; pos = iter.previous()) { // println matches at offset 0 with length 3 System.out.println("offset " + pos + ", length " + iter.getMatchLength()); }
See Also: BreakIterator
UNKNOWN: ICU 2.0
Field Summary | |
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protected BreakIterator | breakIterator
The BreakIterator to define the boundaries of a logical match.
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static int | DONE
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. |
protected int | matchLength
Length of the most current match in target text.
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protected CharacterIterator | targetText
Target text for searching. |
Constructor Summary | |
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protected | SearchIterator(CharacterIterator target, BreakIterator breaker)
Protected constructor for use by subclasses.
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Method Summary | |
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int | first()
Return the index of the first forward match in the target text.
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int | following(int position)
Return the index of the first forward match in target text that
is at or after argument position.
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BreakIterator | getBreakIterator()
Returns the BreakIterator that is used to restrict the indexes at which
matches are detected. |
abstract int | getIndex()
Return the index in the target text at which the iterator is currently
positioned.
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String | getMatchedText()
Returns the text that was matched by the most recent call to
SearchIterator, SearchIterator, SearchIterator, or SearchIterator.
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int | getMatchLength() Returns the length of the most recent match in the target text. |
int | getMatchStart() Returns the index of the most recent match in the target text. |
CharacterIterator | getTarget()
Return the target text that is being searched. |
protected abstract int | handleNext(int start) Abstract method that subclasses override to provide the mechanism for finding the next forwards match in the target text. |
protected abstract int | handlePrevious(int startAt) Abstract method which subclasses override to provide the mechanism for finding the next backwards match in the target text. |
boolean | isOverlapping()
Return true if the overlapping property has been set.
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int | last()
Return the index of the first backward match in target text.
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int | next()
Search forwards in the target text for the next valid match,
starting the search from the current iterator position. |
int | preceding(int position)
Return the index of the first backwards match in target
text that ends at or before argument position.
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int | previous()
Search backwards in the target text for the next valid match,
starting the search from the current iterator position. |
void | reset() Resets the search iteration. |
void | setBreakIterator(BreakIterator breakiter)
Set the BreakIterator that is used to restrict the points at which
matches are detected.
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void | setIndex(int position) Sets the position in the target text at which the next search will start. |
protected void | setMatchLength(int length)
Sets the length of the most recent match in the target text.
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void | setOverlapping(boolean allowOverlap) Determines whether overlapping matches are returned. |
void | setTarget(CharacterIterator text)
Set the target text to be searched. |
See Also: setBreakIterator SearchIterator BreakIterator
UNKNOWN: ICU 2.0
See Also: SearchIterator SearchIterator
UNKNOWN: ICU 2.0
See Also: SearchIterator SearchIterator
UNKNOWN: ICU 2.0
See Also: setTarget SearchIterator
UNKNOWN: ICU 2.0
Parameters: target The target text to be searched. breaker A BreakIterator that is used to determine the boundaries of a logical match. This argument can be null.
Throws: IllegalArgumentException thrown when argument target is null, or of length 0
See Also: BreakIterator
UNKNOWN: ICU 2.0
Returns: The index of the first forward match, or DONE
if there are no matches.
See Also: SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator DONE
UNKNOWN: ICU 2.0
Returns: The index of the first forward match, or DONE
if there are no matches.
See Also: SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator DONE
UNKNOWN: ICU 2.0
setBreakIterator
.
If the BreakIterator has not been set, null will be returned.
See setBreakIterator for more information.Returns: the BreakIterator set to restrict logic matches
See Also: SearchIterator BreakIterator
UNKNOWN: ICU 2.0
Returns: index in the target text at which the iterator is currently positioned.
See Also: SearchIterator SearchIterator SearchIterator SearchIterator DONE
UNKNOWN: ICU 2.8
Returns: the substring in the target text of the most recent match
See Also: SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator DONE
UNKNOWN: ICU 2.0
Returns the length of the most recent match in the target text. This call returns a valid result only after a successful call to SearchIterator, SearchIterator, SearchIterator, or SearchIterator. Just after construction, or after a searching method returns DONE, this method will return 0. See getMatchStart() for more details.
Returns: The length of the most recent match in the target text, or 0 if there is no match.
See Also: SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator DONE
UNKNOWN: ICU 2.0
Returns the index of the most recent match in the target text. This call returns a valid result only after a successful call to SearchIterator, SearchIterator, SearchIterator, or SearchIterator. Just after construction, or after a searching method returns DONE, this method will return DONE.
Use getMatchLength to get the length of the matched text. getMatchedText will return the subtext in the searched target text from index getMatchStart() with length getMatchLength().
Returns: index to a substring within the text string that is being searched.
See Also: SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator DONE
UNKNOWN: ICU 2.8
Returns: target text being searched.
See Also: SearchIterator
UNKNOWN: ICU 2.0
Abstract method that subclasses override to provide the mechanism for finding the next forwards match in the target text. This allows different subclasses to provide different search algorithms.
If a match is found, this function must call setMatchLength(int) to set the length of the result match. The iterator is adjusted so that its current index, as returned by SearchIterator, is the starting position of the match if one was found. If a match is not found, DONE will be returned.
Parameters: start index in the target text at which the forwards search should begin.
Returns: the starting index of the next forwards match if found, DONE otherwise
See Also: SearchIterator SearchIterator DONE
UNKNOWN: ICU 2.0
Abstract method which subclasses override to provide the mechanism for finding the next backwards match in the target text. This allows different subclasses to provide different search algorithms.
If a match is found, this function must call setMatchLength(int) to set the length of the result match. The iterator is adjusted so that its current index, as returned by SearchIterator, is the starting position of the match if one was found. If a match is not found, DONE will be returned.
Parameters: startAt index in the target text at which the backwards search should begin.
Returns: the starting index of the next backwards match if found, DONE otherwise
See Also: SearchIterator SearchIterator DONE
UNKNOWN: ICU 2.0
Returns: true if the overlapping property has been set, false otherwise
See Also: SearchIterator
UNKNOWN: ICU 2.8
Returns: The starting index of the first backward match, or
DONE
if there are no matches.
See Also: SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator DONE
UNKNOWN: ICU 2.0
Returns: The starting index of the next forward match after the current iterator position, or DONE if there are no more matches.
See Also: SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator DONE
UNKNOWN: ICU 2.0
Returns: The starting index of the first backwards match, or
DONE
if there are no matches.
See Also: SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator DONE
UNKNOWN: ICU 2.0
Returns: The starting index of the next backwards match after the current iterator position, or DONE if there are no more matches.
See Also: SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator SearchIterator DONE
UNKNOWN: ICU 2.0
Resets the search iteration. All properties will be reset to their default values.
If a forward iteration is initiated, the next search will begin at the start of the target text. Otherwise, if a backwards iteration is initiated, the next search will begin at the end of the target text.
UNKNOWN: ICU 2.8
Parameters: breakiter A BreakIterator that will be used to restrict the points at which matches are detected.
See Also: SearchIterator BreakIterator
UNKNOWN: ICU 2.0
Sets the position in the target text at which the next search will start. This method clears any previous match.
Parameters: position position from which to start the next search
Throws: IndexOutOfBoundsException thrown if argument position is out of the target text range.
See Also: SearchIterator
UNKNOWN: ICU 2.8
Parameters: length new length to set
See Also: SearchIterator SearchIterator
UNKNOWN: ICU 2.0
Determines whether overlapping matches are returned. See the class documentation for more information about overlapping matches.
The default setting of this property is false
Parameters: allowOverlap flag indicator if overlapping matches are allowed
See Also: SearchIterator
UNKNOWN: ICU 2.8
Parameters: text new text iterator to look for match,
Throws: IllegalArgumentException thrown when text is null or has 0 length
See Also: SearchIterator
UNKNOWN: ICU 2.4