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/*
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* Copyright 1997-2006 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Sun designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Sun in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*/
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package javax.swing.text;
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import java.text.CharacterIterator;
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/**
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* A segment of a character array representing a fragment
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* of text. It should be treated as immutable even though
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* the array is directly accessible. This gives fast access
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* to fragments of text without the overhead of copying
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* around characters. This is effectively an unprotected
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* String.
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* <p>
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* The Segment implements the java.text.CharacterIterator
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* interface to support use with the i18n support without
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* copying text into a string.
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*
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* @author Timothy Prinzing
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*/
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public class Segment implements Cloneable, CharacterIterator, CharSequence {
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/**
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* This is the array containing the text of
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* interest. This array should never be modified;
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* it is available only for efficiency.
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*/
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public char[] array;
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/**
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* This is the offset into the array that
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* the desired text begins.
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*/
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public int offset;
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/**
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* This is the number of array elements that
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* make up the text of interest.
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*/
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public int count;
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private boolean partialReturn;
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/**
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* Creates a new segment.
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*/
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public Segment() {
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this(null, 0, 0);
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}
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/**
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* Creates a new segment referring to an existing array.
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*
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* @param array the array to refer to
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* @param offset the offset into the array
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* @param count the number of characters
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*/
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public Segment(char[] array, int offset, int count) {
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this.array = array;
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this.offset = offset;
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this.count = count;
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partialReturn = false;
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}
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/**
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* Flag to indicate that partial returns are valid. If the flag is true,
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* an implementation of the interface method Document.getText(position,length,Segment)
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* should return as much text as possible without making a copy. The default
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* state of the flag is false which will cause Document.getText(position,length,Segment)
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* to provide the same return behavior it always had, which may or may not
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* make a copy of the text depending upon the request.
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*
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* @param p whether or not partial returns are valid.
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* @since 1.4
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*/
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public void setPartialReturn(boolean p) {
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partialReturn = p;
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}
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/**
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* Flag to indicate that partial returns are valid.
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*
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* @return whether or not partial returns are valid.
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* @since 1.4
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*/
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public boolean isPartialReturn() {
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return partialReturn;
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}
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/**
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* Converts a segment into a String.
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*
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* @return the string
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*/
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public String toString() {
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if (array != null) {
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return new String(array, offset, count);
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}
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return new String();
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}
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// --- CharacterIterator methods -------------------------------------
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/**
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* Sets the position to getBeginIndex() and returns the character at that
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* position.
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* @return the first character in the text, or DONE if the text is empty
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* @see #getBeginIndex
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* @since 1.3
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*/
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public char first() {
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pos = offset;
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if (count != 0) {
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return array[pos];
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}
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return DONE;
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}
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/**
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* Sets the position to getEndIndex()-1 (getEndIndex() if the text is empty)
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* and returns the character at that position.
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* @return the last character in the text, or DONE if the text is empty
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* @see #getEndIndex
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* @since 1.3
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*/
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public char last() {
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pos = offset + count;
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if (count != 0) {
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pos -= 1;
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return array[pos];
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}
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return DONE;
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}
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/**
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* Gets the character at the current position (as returned by getIndex()).
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* @return the character at the current position or DONE if the current
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* position is off the end of the text.
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* @see #getIndex
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* @since 1.3
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*/
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public char current() {
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if (count != 0 && pos < offset + count) {
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return array[pos];
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}
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return DONE;
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}
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/**
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* Increments the iterator's index by one and returns the character
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* at the new index. If the resulting index is greater or equal
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* to getEndIndex(), the current index is reset to getEndIndex() and
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* a value of DONE is returned.
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* @return the character at the new position or DONE if the new
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* position is off the end of the text range.
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* @since 1.3
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*/
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public char next() {
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pos += 1;
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int end = offset + count;
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if (pos >= end) {
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pos = end;
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return DONE;
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}
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return current();
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}
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/**
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* Decrements the iterator's index by one and returns the character
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* at the new index. If the current index is getBeginIndex(), the index
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* remains at getBeginIndex() and a value of DONE is returned.
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* @return the character at the new position or DONE if the current
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* position is equal to getBeginIndex().
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* @since 1.3
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*/
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public char previous() {
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if (pos == offset) {
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return DONE;
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}
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pos -= 1;
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return current();
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}
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/**
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* Sets the position to the specified position in the text and returns that
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* character.
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* @param position the position within the text. Valid values range from
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* getBeginIndex() to getEndIndex(). An IllegalArgumentException is thrown
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* if an invalid value is supplied.
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* @return the character at the specified position or DONE if the specified position is equal to getEndIndex()
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* @since 1.3
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*/
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public char setIndex(int position) {
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int end = offset + count;
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if ((position < offset) || (position > end)) {
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throw new IllegalArgumentException("bad position: " + position);
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}
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pos = position;
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if ((pos != end) && (count != 0)) {
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return array[pos];
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}
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return DONE;
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}
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/**
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* Returns the start index of the text.
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* @return the index at which the text begins.
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* @since 1.3
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*/
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public int getBeginIndex() {
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return offset;
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}
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/**
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* Returns the end index of the text. This index is the index of the first
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* character following the end of the text.
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* @return the index after the last character in the text
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* @since 1.3
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*/
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public int getEndIndex() {
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return offset + count;
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}
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/**
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* Returns the current index.
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* @return the current index.
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* @since 1.3
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*/
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public int getIndex() {
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return pos;
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}
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// --- CharSequence methods -------------------------------------
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/**
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* {@inheritDoc}
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* @since 1.6
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*/
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public char charAt(int index) {
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if (index < 0
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|| index >= count) {
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throw new StringIndexOutOfBoundsException(index);
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}
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return array[offset + index];
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}
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/**
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* {@inheritDoc}
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* @since 1.6
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*/
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public int length() {
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return count;
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}
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/**
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* {@inheritDoc}
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* @since 1.6
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*/
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public CharSequence subSequence(int start, int end) {
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if (start < 0) {
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throw new StringIndexOutOfBoundsException(start);
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}
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if (end > count) {
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throw new StringIndexOutOfBoundsException(end);
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}
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if (start > end) {
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throw new StringIndexOutOfBoundsException(end - start);
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}
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Segment segment = new Segment();
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segment.array = this.array;
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segment.offset = this.offset + start;
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segment.count = end - start;
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return segment;
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}
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/**
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* Creates a shallow copy.
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*
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* @return the copy
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*/
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public Object clone() {
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Object o;
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try {
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o = super.clone();
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} catch (CloneNotSupportedException cnse) {
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o = null;
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}
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return o;
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}
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private int pos;
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}
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