https://openjdk.java.net/ 
/*
 * Copyright (c) 1997, 2008, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
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.


The Segment implements the java.text.CharacterIterator
interface to support use with the i18n support without
copying text into a string.

Author: Timothy Prinzing
/**
 * 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
 */
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.

/**
     * 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.

/**
     * 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.

/**
     * This is the number of array elements that
     * make up the text of interest.
     */
    public int count;

    private boolean partialReturn;

    
Creates a new segment.

/**
     * Creates a new segment.
     */
    public Segment() {
        this(null, 0, 0);
    }

    
Creates a new segment referring to an existing array.

Params:
  • array – the array to refer to
  • offset – the offset into the array
  • count – the number of characters
/**
     * 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.

Params:
  • p – whether or not partial returns are valid.
Since:1.4
/**
     * 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.

Returns:whether or not partial returns are valid.
Since:1.4
/**
     * 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.

Returns:the string
/**
     * Converts a segment into a String.
     *
     * @return the string
     */
    public String toString() {
        if (array != null) {
            return new String(array, offset, count);
        }
        return "";
    }

    // --- CharacterIterator methods -------------------------------------

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

See Also:
Returns:the first character in the text, or DONE if the text is empty
Since:1.3
/**
     * 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.

See Also:
Returns:the last character in the text, or DONE if the text is empty
Since:1.3
/**
     * 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()).

See Also:
Returns:the character at the current position or DONE if the current
position is off the end of the text.
Since:1.3
/**
     * 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.

Returns:the character at the new position or DONE if the new
position is off the end of the text range.
Since:1.3
/**
     * 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.

Returns:the character at the new position or DONE if the current
position is equal to getBeginIndex().
Since:1.3
/**
     * 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.

Params:
  • position – the position within the text.  Valid values range from
getBeginIndex() to getEndIndex().  An IllegalArgumentException is thrown
if an invalid value is supplied.
Returns:the character at the specified position or DONE if the specified position is equal to getEndIndex()
Since:1.3
/**
     * 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.

Returns:the index at which the text begins.
Since:1.3
/**
     * 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.

Returns:the index after the last character in the text
Since:1.3
/**
     * 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.

Returns:the current index.
Since:1.3
/**
     * Returns the current index.
     * @return the current index.
     * @since 1.3
     */
    public int getIndex() {
        return pos;
    }

    // --- CharSequence methods -------------------------------------

    
{@inheritDoc}

Since:1.6
/**
     * {@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
/**
     * {@inheritDoc}
     * @since 1.6
     */
    public int length() {
        return count;
    }

    
{@inheritDoc}

Since:1.6
/**
     * {@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.

Returns:the copy
/**
     * 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;


}