/*
* @(#)Segment.java 1.25 06/04/07
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package javax.swing.text;
import java.text.CharacterIterator;
/**
* A segment of a character array representing a fragment
* of text. It should be treated as immutable even though
* the array is directly accessible. This gives fast access
* to fragments of text without the overhead of copying
* around characters. This is effectively an unprotected
* String.
* <p>
* The Segment implements the java.text.CharacterIterator
* interface to support use with the i18n support without
* copying text into a string.
*
* @author Timothy Prinzing
* @version 1.25 04/07/06
*/
public class Segment implements Cloneable, CharacterIterator, CharSequence {
/**
* This is the array containing the text of
* interest. This array should never be modified;
* it is available only for efficiency.
*/
public char[] array;
/**
* This is the offset into the array that
* the desired text begins.
*/
public int offset;
/**
* This is the number of array elements that
* make up the text of interest.
*/
public int count;
private boolean partialReturn;
/**
* Creates a new segment.
*/
public Segment() {
this(null, 0, 0);
}
/**
* Creates a new segment referring to an existing array.
*
* @param array the array to refer to
* @param offset the offset into the array
* @param count the number of characters
*/
public Segment(char[] array, int offset, int count) {
this.array = array;
this.offset = offset;
this.count = count;
partialReturn = false;
}
/**
* Flag to indicate that partial returns are valid. If the flag is true,
* an implementation of the interface method Document.getText(position,length,Segment)
* should return as much text as possible without making a copy. The default
* state of the flag is false which will cause Document.getText(position,length,Segment)
* to provide the same return behavior it always had, which may or may not
* make a copy of the text depending upon the request.
*
* @param p whether or not partial returns are valid.
* @since 1.4
*/
public void setPartialReturn(boolean p) {
partialReturn = p;
}
/**
* Flag to indicate that partial returns are valid.
*
* @return whether or not partial returns are valid.
* @since 1.4
*/
public boolean isPartialReturn() {
return partialReturn;
}
/**
* Converts a segment into a String.
*
* @return the string
*/
public String toString() {
if (array != null) {
return new String(array, offset, count);
}
return new String();
}
// --- CharacterIterator methods -------------------------------------
/**
* Sets the position to getBeginIndex() and returns the character at that
* position.
* @return the first character in the text, or DONE if the text is empty
* @see #getBeginIndex
* @since 1.3
*/
public char first() {
pos = offset;
if (count != 0) {
return array[pos];
}
return DONE;
}
/**
* Sets the position to getEndIndex()-1 (getEndIndex() if the text is empty)
* and returns the character at that position.
* @return the last character in the text, or DONE if the text is empty
* @see #getEndIndex
* @since 1.3
*/
public char last() {
pos = offset + count;
if (count != 0) {
pos -= 1;
return array[pos];
}
return DONE;
}
/**
* Gets the character at the current position (as returned by getIndex()).
* @return the character at the current position or DONE if the current
* position is off the end of the text.
* @see #getIndex
* @since 1.3
*/
public char current() {
if (count != 0 && pos < offset + count) {
return array[pos];
}
return DONE;
}
/**
* 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.
* @return the character at the new position or DONE if the new
* position is off the end of the text range.
* @since 1.3
*/
public char next() {
pos += 1;
int end = offset + count;
if (pos >= end) {
pos = end;
return DONE;
}
return current();
}
/**
* 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.
* @return the character at the new position or DONE if the current
* position is equal to getBeginIndex().
* @since 1.3
*/
public char previous() {
if (pos == offset) {
return DONE;
}
pos -= 1;
return current();
}
/**
* Sets the position to the specified position in the text and returns that
* character.
* @param position the position within the text. Valid values range from
* getBeginIndex() to getEndIndex(). An IllegalArgumentException is thrown
* if an invalid value is supplied.
* @return the character at the specified position or DONE if the specified position is equal to getEndIndex()
* @since 1.3
*/
public char setIndex(int position) {
int end = offset + count;
if ((position < offset) || (position > end)) {
throw new IllegalArgumentException("bad position: " + position);
}
pos = position;
if ((pos != end) && (count != 0)) {
return array[pos];
}
return DONE;
}
/**
* Returns the start index of the text.
* @return the index at which the text begins.
* @since 1.3
*/
public int getBeginIndex() {
return offset;
}
/**
* Returns the end index of the text. This index is the index of the first
* character following the end of the text.
* @return the index after the last character in the text
* @since 1.3
*/
public int getEndIndex() {
return offset + count;
}
/**
* Returns the current index.
* @return the current index.
* @since 1.3
*/
public int getIndex() {
return pos;
}
// --- CharSequence methods -------------------------------------
/**
* {@inheritDoc}
* @since 1.6
*/
public char charAt(int index) {
if (index < 0
|| index >= count) {
throw new StringIndexOutOfBoundsException(index);
}
return array[offset + index];
}
/**
* {@inheritDoc}
* @since 1.6
*/
public int length() {
return count;
}
/**
* {@inheritDoc}
* @since 1.6
*/
public CharSequence subSequence(int start, int end) {
if (start < 0) {
throw new StringIndexOutOfBoundsException(start);
}
if (end > count) {
throw new StringIndexOutOfBoundsException(end);
}
if (start > end) {
throw new StringIndexOutOfBoundsException(end - start);
}
Segment segment = new Segment();
segment.array = this.array;
segment.offset = this.offset + start;
segment.count = end - start;
return segment;
}
/**
* Creates a shallow copy.
*
* @return the copy
*/
public Object clone() {
Object o;
try {
o = super.clone();
} catch (CloneNotSupportedException cnse) {
o = null;
}
return o;
}
private int pos;
}
|
