core/org.gnit.lucenekmp.jdkport/CharacterIterator

CharacterIterator

interface CharacterIterator : Cloneable<Any?>

This interface defines a protocol for bidirectional iteration over text. The iterator iterates over a bounded sequence of characters. Characters are indexed with values beginning with the value returned by getBeginIndex() and continuing through the value returned by getEndIndex()-1.

Iterators maintain a current character index, whose valid range is from getBeginIndex() to getEndIndex(); the value getEndIndex() is included to allow handling of zero-length text ranges and for historical reasons. The current index can be retrieved by calling getIndex() and set directly by calling setIndex(), first(), and last().

The methods previous() and next() are used for iteration. They return DONE if they would move outside the range from getBeginIndex() to getEndIndex() -1, signaling that the iterator has reached the end of the sequence. DONE is also returned by other methods to indicate that the current index is outside this range.

Examples:

Traverse the text from start to finish {@snippet lang=java :

public void traverseForward(CharacterIterator iter) {

for (char c = iter.first(); c != CharacterIterator.DONE; c = iter.next()) {

```
    processChar(c);
```
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```
}
```
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}
}

Traverse the text backwards, from end to start {@snippet lang=java :

public void traverseBackward(CharacterIterator iter) {

for (char c = iter.last(); c != CharacterIterator.DONE; c = iter.previous()) {

```
    processChar(c);
```
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```
}
```
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}
}

Traverse both forward and backward from a given position in the text. Calls to notBoundary() in this example represents some additional stopping criteria. {@snippet lang=java :

public void traverseOut(CharacterIterator iter, int pos) {
```
for (char c = iter.setIndex(pos);
```
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         c != CharacterIterator.DONE && notBoundary(c);

```
         c = iter.next()) {
```
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```
}
```
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```
int end = iter.getIndex();
```
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```
for (char c = iter.setIndex(pos);
```
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        c != CharacterIterator.DONE && notBoundary(c);

```
        c = iter.previous()) {
```
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```
}
```
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```
int start = iter.getIndex();
```
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```
processSection(start, end);
```
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}
}

Since

1.1

Inheritors

StringCharacterIterator

Types

Companion

object Companion

Properties

beginIndex

abstract val beginIndex: Int

Returns the start index of the text.

endIndex

abstract val endIndex: Int

Returns the end index of the text. This index is the index of the first character following the end of the text.

index

abstract val index: Int

Returns the current index.

Functions

clone

abstract override fun clone(): Any

Create a copy of this iterator

current

abstract fun current(): Char

Gets the character at the current position (as returned by getIndex()).

first

abstract fun first(): Char

Sets the position to getBeginIndex() and returns the character at that position.

last

abstract fun last(): Char

Sets the position to getEndIndex()-1 (getEndIndex() if the text is empty) and returns the character at that position.

abstract fun next(): Char

Increments the iterator's index by one and returns the character at the new index. If the resulting index is greater or equal to getEndIndex(), the current index is reset to getEndIndex() and a value of DONE is returned.

abstract fun previous(): Char

Decrements the iterator's index by one and returns the character at the new index. If the current index is getBeginIndex(), the index remains at getBeginIndex() and a value of DONE is returned.

setIndex

abstract fun setIndex(position: Int): Char

Sets the position to the specified position in the text and returns that character.