/*

 * Copyright (c) 1996, 2002, 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.

 */

/*

 * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved

 * (C) Copyright IBM Corp. 1996 - 1998 - All Rights Reserved

 *

 * The original version of this source code and documentation

 * is copyrighted and owned by Taligent, Inc., a wholly-owned

 * subsidiary of IBM. These materials are provided under terms

 * of a License Agreement between Taligent and Sun. This technology

 * is protected by multiple US and International patents.

 *

 * This notice and attribution to Taligent may not be removed.

 * Taligent is a registered trademark of Taligent, Inc.

 *

 */

package java.text;

/**

 * <code>StringCharacterIterator</code> implements the

 * <code>CharacterIterator</code> protocol for a <code>String</code>.

 * The <code>StringCharacterIterator</code> class iterates over the

 * entire <code>String</code>.

 *

 * @see CharacterIterator

 */

public final class StringCharacterIterator implements CharacterIterator

{

    private String text;

    private int begin;

    private int end;

    // invariant: begin <= pos <= end

    private int pos;

    /**

     * Constructs an iterator with an initial index of 0.

     */

    public StringCharacterIterator(String text)

    {

        this(text, 0);

    }

    /**

     * Constructs an iterator with the specified initial index.

     *

     * @param  text   The String to be iterated over

     * @param  pos    Initial iterator position

     */

    public StringCharacterIterator(String text, int pos)

    {

    this(text, 0, text.length(), pos);

    }

    /**

     * Constructs an iterator over the given range of the given string, with the

     * index set at the specified position.

     *

     * @param  text   The String to be iterated over

     * @param  begin  Index of the first character

     * @param  end    Index of the character following the last character

     * @param  pos    Initial iterator position

     */

    public StringCharacterIterator(String text, int begin, int end, int pos) {

        if (text == null)

            throw new NullPointerException();

        this.text = text;

        if (begin < 0 || begin > end || end > text.length())

            throw new IllegalArgumentException("Invalid substring range");

        if (pos < begin || pos > end)

            throw new IllegalArgumentException("Invalid position");

        this.begin = begin;

        this.end = end;

        this.pos = pos;

    }

    /**

     * Reset this iterator to point to a new string.  This package-visible

     * method is used by other java.text classes that want to avoid allocating

     * new StringCharacterIterator objects every time their setText method

     * is called.

     *

     * @param  text   The String to be iterated over

     * @since 1.2

     */

    public void setText(String text) {

        if (text == null)

            throw new NullPointerException();

        this.text = text;

        this.begin = 0;

        this.end = text.length();

        this.pos = 0;

    }

    /**

     * Implements CharacterIterator.first() for String.

     * @see CharacterIterator#first

     */

    public char first()

    {

        pos = begin;

        return current();

    }

    /**

     * Implements CharacterIterator.last() for String.

     * @see CharacterIterator#last

     */

    public char last()

    {

        if (end != begin) {

            pos = end - 1;

        } else {

            pos = end;

        }

        return current();

     }

    /**

     * Implements CharacterIterator.setIndex() for String.

     * @see CharacterIterator#setIndex

     */

    public char setIndex(int p)

    {

    if (p < begin || p > end)

            throw new IllegalArgumentException("Invalid index");

        pos = p;

        return current();

    }

    /**

     * Implements CharacterIterator.current() for String.

     * @see CharacterIterator#current

     */

    public char current()

    {

        if (pos >= begin && pos < end) {

            return text.charAt(pos);

        }

        else {

            return DONE;

        }

    }

    /**

     * Implements CharacterIterator.next() for String.

     * @see CharacterIterator#next

     */

    public char next()

    {

        if (pos < end - 1) {

            pos++;

            return text.charAt(pos);

        }

        else {

            pos = end;

            return DONE;

        }

    }

    /**

     * Implements CharacterIterator.previous() for String.

     * @see CharacterIterator#previous

     */

    public char previous()

    {

        if (pos > begin) {

            pos--;

            return text.charAt(pos);

        }

        else {

            return DONE;

        }

    }

    /**

     * Implements CharacterIterator.getBeginIndex() for String.

     * @see CharacterIterator#getBeginIndex

     */

    public int getBeginIndex()

    {

        return begin;

    }

    /**

     * Implements CharacterIterator.getEndIndex() for String.

     * @see CharacterIterator#getEndIndex

     */

    public int getEndIndex()

    {

        return end;

    }

    /**

     * Implements CharacterIterator.getIndex() for String.

     * @see CharacterIterator#getIndex

     */

    public int getIndex()

    {

        return pos;

    }

    /**

     * Compares the equality of two StringCharacterIterator objects.

     * @param obj the StringCharacterIterator object to be compared with.

     * @return true if the given obj is the same as this

     * StringCharacterIterator object; false otherwise.

     */

    public boolean equals(Object obj)

    {

        if (this == obj)

            return true;

        if (!(obj instanceof StringCharacterIterator))

            return false;

        StringCharacterIterator that = (StringCharacterIterator) obj;

        if (hashCode() != that.hashCode())

            return false;

        if (!text.equals(that.text))

            return false;

        if (pos != that.pos || begin != that.begin || end != that.end)

            return false;

        return true;

    }

    /**

     * Computes a hashcode for this iterator.

     * @return A hash code

     */

    public int hashCode()

    {

        return text.hashCode() ^ pos ^ begin ^ end;

    }

    /**

     * Creates a copy of this iterator.

     * @return A copy of this

     */

    public Object clone()

    {

        try {

            StringCharacterIterator other

            = (StringCharacterIterator) super.clone();

            return other;

        }

        catch (CloneNotSupportedException e) {

            throw new InternalError();

        }

    }

}