SearchIterator
abstract class SearchIterator
kotlin.Any | |
↳ | android.icu.text.SearchIterator |
SearchIterator is an abstract base class that provides methods to search for a pattern within a text string. Instances of SearchIterator maintain a current position and scan over the target text, returning the indices the pattern is matched and the length of each match.
SearchIterator defines a protocol for text searching. Subclasses provide concrete implementations of various search algorithms. For example, StringSearch implements language-sensitive pattern matching based on the comparison rules defined in a RuleBasedCollator object.
Other options for searching include using a BreakIterator to restrict the points at which matches are detected.
SearchIterator provides an API that is similar to that of other text iteration classes such as BreakIterator. Using this class, it is easy to scan through text looking for all occurrences of a given pattern. The following example uses a StringSearch object to find all instances of "fox" in the target string. Any other subclass of SearchIterator can be used in an identical manner.
<code> 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()) { System.out.println("Found match at " + pos + ", length is " + iter.getMatchLength()); } </code>
Summary
Nested classes | |
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Option to control how collation elements are compared. |
Constants | |
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static Int |
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 constructors | |
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SearchIterator(target: CharacterIterator!, breaker: BreakIterator!) Protected constructor for use by subclasses. |
Public methods | |
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Int |
first() Returns the first index at which the string text matches the search pattern. |
Int |
Returns the first index equal or greater than position at which the string text matches the search pattern. |
open BreakIterator! |
Returns the BreakIterator that is used to restrict the indexes at which matches are detected. |
open SearchIterator.ElementComparisonType! |
Returns the collation element comparison type. |
abstract Int |
getIndex() Return the current index in the text being searched. |
open Int |
Returns the length of text in the string which matches the search pattern. |
open Int |
Returns the index to the match in the text string that was searched. |
open String! |
Returns the text that was matched by the most recent call to |
open CharacterIterator! |
Return the string text to be searched. |
open Boolean |
Return true if the overlapping property has been set. |
Int |
last() Returns the last index in the target text at which it matches the search pattern. |
open Int |
next() Returns the index of the next point at which the text matches the search pattern, starting from the current position The iterator is adjusted so that its current index (as returned by |
Int |
Returns the first index less than position at which the string text matches the search pattern. |
open Int |
previous() Returns the index of the previous point at which the string text matches the search pattern, starting at the current position. |
open Unit |
reset() Resets the iteration. |
open Unit |
setBreakIterator(breakiter: BreakIterator!) Set the BreakIterator that will be used to restrict the points at which matches are detected. |
open Unit |
Sets the collation element comparison type. |
open Unit |
Sets the position in the target text at which the next search will start. |
open Unit |
setOverlapping(allowOverlap: Boolean) Determines whether overlapping matches are returned. |
open Unit |
setTarget(text: CharacterIterator!) Set the target text to be searched. |
Protected methods | |
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abstract Int |
handleNext(start: Int) Abstract method which subclasses override to provide the mechanism for finding the next match in the target text. |
abstract Int |
handlePrevious(startAt: Int) Abstract method which subclasses override to provide the mechanism for finding the previous match in the target text. |
open Unit |
setMatchLength(length: Int) Sets the length of the most recent match in the target text. |
Properties | |
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BreakIterator! |
The BreakIterator to define the boundaries of a logical match. |
Int |
Length of the most current match in target text. |
CharacterIterator! |
Target text for searching. |
Constants
DONE
static val DONE: Int
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.
Value: -1
Protected constructors
SearchIterator
protected SearchIterator(
target: CharacterIterator!,
breaker: BreakIterator!)
Protected constructor for use by subclasses. Initializes the iterator with the argument target text for searching and sets the BreakIterator. See class documentation for more details on the use of the target text and BreakIterator
.
Parameters | |
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target |
CharacterIterator!: The target text to be searched. |
breaker |
BreakIterator!: A BreakIterator that is used to determine the boundaries of a logical match. This argument can be null. |
Exceptions | |
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java.lang.IllegalArgumentException |
thrown when argument target is null, or of length 0 |
See Also
Public methods
first
fun first(): Int
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 getIndex()
) is the match position if one was found. If a match is not found, DONE
will be returned and the iterator will be adjusted to the index DONE
.
Return | |
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Int |
The character index of the first match, or DONE if there are no matches. |
See Also
following
fun following(position: Int): Int
Returns the first index equal or greater than position at which the string text matches the search pattern. The iterator is adjusted so that its current index (as returned by getIndex()
) is the match position if one was found. If a match is not found, DONE
will be returned and the iterator will be adjusted to the index DONE
.
Parameters | |
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position |
Int: where search if to start from. |
Return | |
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Int |
The character index of the first match following position, or DONE if there are no matches. |
Exceptions | |
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java.lang.IndexOutOfBoundsException |
If position is less than or greater than the text range for searching. |
See Also
getBreakIterator
open fun getBreakIterator(): BreakIterator!
Returns the BreakIterator that is used to restrict the indexes at which matches are detected. This will be the same object that was passed to the constructor or to setBreakIterator
. If the BreakIterator
has not been set, null will be returned. See setBreakIterator
for more information.
Return | |
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BreakIterator! |
the BreakIterator set to restrict logic matches |
getElementComparisonType
open fun getElementComparisonType(): SearchIterator.ElementComparisonType!
Returns the collation element comparison type.
getIndex
abstract fun getIndex(): Int
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), DONE
is returned.
Return | |
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Int |
current index in the text being searched. |
getMatchLength
open fun getMatchLength(): Int
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 first
, next
, previous
, or last
. Just after construction, or after a searching method returns DONE
, this method will return 0.
Return | |
---|---|
Int |
The length of the match in the target text, or 0 if there is no match currently. |
getMatchStart
open fun getMatchStart(): Int
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 first
, next
, previous
, or last
. Just after construction, or after a searching method returns DONE
, this method will return DONE
.
Use getMatchLength
to get the matched string length.
Return | |
---|---|
Int |
index of a substring within the text string that is being searched. |
getMatchedText
open fun getMatchedText(): String!
Returns the text that was matched by the most recent call to first
, next
, previous
, or last
. If the iterator is not pointing at a valid match (e.g. just after construction or after DONE
has been returned, returns an empty string.
Return | |
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String! |
the substring in the target test of the most recent match, or null if there is no match currently. |
getTarget
open fun getTarget(): CharacterIterator!
Return the string text to be searched.
Return | |
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CharacterIterator! |
text string to be searched. |
isOverlapping
open fun isOverlapping(): Boolean
Return true if the overlapping property has been set. See setOverlapping(boolean)
for more information.
Return | |
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Boolean |
true if the overlapping property has been set, false otherwise |
See Also
last
fun last(): Int
Returns the last index in the target text at which it matches the search pattern. The iterator is adjusted so that its current index (as returned by getIndex
) is the match position if one was found. If a match is not found, DONE
will be returned and the iterator will be adjusted to the index DONE
.
Return | |
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Int |
The index of the first match, or DONE if there are no matches. |
See Also
next
open fun next(): Int
Returns the index of the next point at which the text matches the search pattern, starting from the current position The iterator is adjusted so that its current index (as returned by getIndex
) is the match position if one was found. If a match is not found, DONE
will be returned and the iterator will be adjusted to a position after the end of the text string.
Return | |
---|---|
Int |
The index of the next match after the current position, or DONE if there are no more matches. |
See Also
preceding
fun preceding(position: Int): Int
Returns the first index less than position at which the string text matches the search pattern. The iterator is adjusted so that its current index (as returned by getIndex
) is the match position if one was found. If a match is not found, DONE
will be returned and the iterator will be adjusted to the index DONE
When the overlapping option (isOverlapping
) is off, the last index of the result match is always less than position. When the overlapping option is on, the result match may span across position.
Parameters | |
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position |
Int: where search is to start from. |
Return | |
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Int |
The character index of the first match preceding position, or DONE if there are no matches. |
Exceptions | |
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java.lang.IndexOutOfBoundsException |
If position is less than or greater than the text range for searching |
See Also
previous
open fun previous(): Int
Returns the index of the previous point at which the string text matches the search pattern, starting at the current position. The iterator is adjusted so that its current index (as returned by getIndex
) is the match position if one was found. If a match is not found, DONE
will be returned and the iterator will be adjusted to the index DONE
.
Return | |
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Int |
The index of the previous match before the current position, or DONE if there are no more matches. |
See Also
reset
open fun reset(): Unit
Resets 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.
setBreakIterator
open fun setBreakIterator(breakiter: BreakIterator!): Unit
Set the BreakIterator that will be used to restrict the points at which matches are detected.
Parameters | |
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breakiter |
BreakIterator!: 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 BreakIterator , the match will be rejected and another will be searched for. If this parameter is null, no break detection is attempted. |
See Also
setElementComparisonType
open fun setElementComparisonType(type: SearchIterator.ElementComparisonType!): Unit
Sets the collation element comparison type.
The default comparison type is ElementComparisonType#STANDARD_ELEMENT_COMPARISON
.
setIndex
open fun setIndex(position: Int): Unit
Sets the position in the target text at which the next search will start. This method clears any previous match.
Parameters | |
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position |
Int: position from which to start the next search |
Exceptions | |
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java.lang.IndexOutOfBoundsException |
thrown if argument position is out of the target text range. |
See Also
setOverlapping
open fun setOverlapping(allowOverlap: Boolean): Unit
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 | |
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allowOverlap |
Boolean: flag indicator if overlapping matches are allowed |
See Also
setTarget
open fun setTarget(text: CharacterIterator!): Unit
Set the target text to be searched. Text iteration will then begin at the start of the text string. This method is useful if you want to reuse an iterator to search within a different body of text.
Parameters | |
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text |
CharacterIterator!: new text iterator to look for match, |
Exceptions | |
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java.lang.IllegalArgumentException |
thrown when text is null or has 0 length |
See Also
Protected methods
handleNext
protected abstract fun handleNext(start: Int): Int
Abstract method which subclasses override to provide the mechanism for finding the next match in the target text. This allows different subclasses to provide different search algorithms.
If a match is found, the implementation should return the index at which the match starts and should call setMatchLength
with the number of characters in the target text that make up the match. If no match is found, the method should return DONE
.
Parameters | |
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start |
Int: The index in the target text at which the search should start. |
Return | |
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Int |
index at which the match starts, else if match is not found DONE is returned |
See Also
handlePrevious
protected abstract fun handlePrevious(startAt: Int): Int
Abstract method which subclasses override to provide the mechanism for finding the previous match in the target text. This allows different subclasses to provide different search algorithms.
If a match is found, the implementation should return the index at which the match starts and should call setMatchLength
with the number of characters in the target text that make up the match. If no match is found, the method should return DONE
.
Parameters | |
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startAt |
Int: The index in the target text at which the search should start. |
Return | |
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Int |
index at which the match starts, else if match is not found DONE is returned |
See Also
setMatchLength
protected open fun setMatchLength(length: Int): Unit
Sets the length of the most recent match in the target text. Subclasses' handleNext() and handlePrevious() methods should call this after they find a match in the target text.
Parameters | |
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length |
Int: new length to set |
See Also
Properties
breakIterator
protected var breakIterator: BreakIterator!
The BreakIterator to define the boundaries of a logical match. This value can be a null. See class documentation for more information.
matchLength
protected var matchLength: Int
Length of the most current match in target text. Value 0 is the default value.
See Also
targetText
protected var targetText: CharacterIterator!
Target text for searching.
See Also