/*

 * 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

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 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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 * 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.

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/*

 * (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;

import java.lang.Character;

import java.util.Vector;

import sun.text.CollatorUtilities;

import sun.text.normalizer.NormalizerBase;

/**

 * The <code>CollationElementIterator</code> class is used as an iterator

 * to walk through each character of an international string. Use the iterator

 * to return the ordering priority of the positioned character. The ordering

 * priority of a character, which we refer to as a key, defines how a character

 * is collated in the given collation object.

 *

 * <p>

 * For example, consider the following in Spanish:

 * <blockquote>

 * <pre>

 * "ca" -> the first key is key('c') and second key is key('a').

 * "cha" -> the first key is key('ch') and second key is key('a').

 * </pre>

 * </blockquote>

 * And in German,

 * <blockquote>

 * <pre>

 * "\u00e4b"-> the first key is key('a'), the second key is key('e'), and

 * the third key is key('b').

 * </pre>

 * </blockquote>

 * The key of a character is an integer composed of primary order(short),

 * secondary order(byte), and tertiary order(byte). Java strictly defines

 * the size and signedness of its primitive data types. Therefore, the static

 * functions <code>primaryOrder</code>, <code>secondaryOrder</code>, and

 * <code>tertiaryOrder</code> return <code>int</code>, <code>short</code>,

 * and <code>short</code> respectively to ensure the correctness of the key

 * value.

 *

 * <p>

 * Example of the iterator usage,

 * <blockquote>

 * <pre>

 *

 *  String testString = "This is a test";

 *  RuleBasedCollator ruleBasedCollator = (RuleBasedCollator)Collator.getInstance();

 *  CollationElementIterator collationElementIterator = ruleBasedCollator.getCollationElementIterator(testString);

 *  int primaryOrder = CollationElementIterator.primaryOrder(collationElementIterator.next());

 * </pre>

 * </blockquote>

 *

 * <p>

 * <code>CollationElementIterator.next</code> returns the collation order

 * of the next character. A collation order consists of primary order,

 * secondary order and tertiary order. The data type of the collation

 * order is <strong>int</strong>. The first 16 bits of a collation order

 * is its primary order; the next 8 bits is the secondary order and the

 * last 8 bits is the tertiary order.

 *

 * @see                Collator

 * @see                RuleBasedCollator

 * @author             Helena Shih, Laura Werner, Richard Gillam

 */

public final class CollationElementIterator

{

    /**

     * Null order which indicates the end of string is reached by the

     * cursor.

     */

    public final static int NULLORDER = 0xffffffff;

    /**

     * CollationElementIterator constructor.  This takes the source string and

     * the collation object.  The cursor will walk thru the source string based

     * on the predefined collation rules.  If the source string is empty,

     * NULLORDER will be returned on the calls to next().

     * @param sourceText the source string.

     * @param order the collation object.

     */

    CollationElementIterator(String sourceText, RuleBasedCollator owner) {

        this.owner = owner;

        ordering = owner.getTables();

        if ( sourceText.length() != 0 ) {

            NormalizerBase.Mode mode =

                CollatorUtilities.toNormalizerMode(owner.getDecomposition());

            text = new NormalizerBase(sourceText, mode);

        }

    }

    /**

     * CollationElementIterator constructor.  This takes the source string and

     * the collation object.  The cursor will walk thru the source string based

     * on the predefined collation rules.  If the source string is empty,

     * NULLORDER will be returned on the calls to next().

     * @param sourceText the source string.

     * @param order the collation object.

     */

    CollationElementIterator(CharacterIterator sourceText, RuleBasedCollator owner) {

        this.owner = owner;

        ordering = owner.getTables();

        NormalizerBase.Mode mode =

            CollatorUtilities.toNormalizerMode(owner.getDecomposition());

        text = new NormalizerBase(sourceText, mode);

    }

    /**

     * Resets the cursor to the beginning of the string.  The next call

     * to next() will return the first collation element in the string.

     */

    public void reset()

    {

        if (text != null) {

            text.reset();

            NormalizerBase.Mode mode =

                CollatorUtilities.toNormalizerMode(owner.getDecomposition());

            text.setMode(mode);

        }

        buffer = null;

        expIndex = 0;

        swapOrder = 0;

    }

    /**

     * Get the next collation element in the string.  <p>This iterator iterates

     * over a sequence of collation elements that were built from the string.

     * Because there isn't necessarily a one-to-one mapping from characters to

     * collation elements, this doesn't mean the same thing as "return the

     * collation element [or ordering priority] of the next character in the

     * string".</p>

     * <p>This function returns the collation element that the iterator is currently

     * pointing to and then updates the internal pointer to point to the next element.

     * previous() updates the pointer first and then returns the element.  This

     * means that when you change direction while iterating (i.e., call next() and

     * then call previous(), or call previous() and then call next()), you'll get

     * back the same element twice.</p>

     */

    public int next()

    {

        if (text == null) {

            return NULLORDER;

        }

        NormalizerBase.Mode textMode = text.getMode();

        // convert the owner's mode to something the Normalizer understands

        NormalizerBase.Mode ownerMode =

            CollatorUtilities.toNormalizerMode(owner.getDecomposition());

        if (textMode != ownerMode) {

            text.setMode(ownerMode);

        }

        // if buffer contains any decomposed char values

        // return their strength orders before continuing in

        // the Normalizer's CharacterIterator.

        if (buffer != null) {

            if (expIndex < buffer.length) {

                return strengthOrder(buffer[expIndex++]);

            } else {

                buffer = null;

                expIndex = 0;

            }

        } else if (swapOrder != 0) {

            if (Character.isSupplementaryCodePoint(swapOrder)) {

                char[] chars = Character.toChars(swapOrder);

                swapOrder = chars[1];

                return chars[0] << 16;

            }

            int order = swapOrder << 16;

            swapOrder = 0;

            return order;

        }

        int ch  = text.next();

        // are we at the end of Normalizer's text?

        if (ch == NormalizerBase.DONE) {

            return NULLORDER;

        }

        int value = ordering.getUnicodeOrder(ch);

        if (value == RuleBasedCollator.UNMAPPED) {

            swapOrder = ch;

            return UNMAPPEDCHARVALUE;

        }

        else if (value >= RuleBasedCollator.CONTRACTCHARINDEX) {

            value = nextContractChar(ch);

        }

        if (value >= RuleBasedCollator.EXPANDCHARINDEX) {

            buffer = ordering.getExpandValueList(value);

            expIndex = 0;

            value = buffer[expIndex++];

        }

        if (ordering.isSEAsianSwapping()) {

            int consonant;

            if (isThaiPreVowel(ch)) {

                consonant = text.next();

                if (isThaiBaseConsonant(consonant)) {

                    buffer = makeReorderedBuffer(consonant, value, buffer, true);

                    value = buffer[0];

                    expIndex = 1;

                } else if (consonant != NormalizerBase.DONE) {

                    text.previous();

                }

            }

            if (isLaoPreVowel(ch)) {

                consonant = text.next();

                if (isLaoBaseConsonant(consonant)) {

                    buffer = makeReorderedBuffer(consonant, value, buffer, true);

                    value = buffer[0];

                    expIndex = 1;

                } else if (consonant != NormalizerBase.DONE) {

                    text.previous();

                }

            }

        }

        return strengthOrder(value);

    }

    /**

     * Get the previous collation element in the string.  <p>This iterator iterates

     * over a sequence of collation elements that were built from the string.

     * Because there isn't necessarily a one-to-one mapping from characters to

     * collation elements, this doesn't mean the same thing as "return the

     * collation element [or ordering priority] of the previous character in the

     * string".</p>

     * <p>This function updates the iterator's internal pointer to point to the

     * collation element preceding the one it's currently pointing to and then

     * returns that element, while next() returns the current element and then

     * updates the pointer.  This means that when you change direction while

     * iterating (i.e., call next() and then call previous(), or call previous()

     * and then call next()), you'll get back the same element twice.</p>

     * @since 1.2

     */

    public int previous()

    {

        if (text == null) {

            return NULLORDER;

        }

        NormalizerBase.Mode textMode = text.getMode();

        // convert the owner's mode to something the Normalizer understands

        NormalizerBase.Mode ownerMode =

            CollatorUtilities.toNormalizerMode(owner.getDecomposition());

        if (textMode != ownerMode) {

            text.setMode(ownerMode);

        }

        if (buffer != null) {

            if (expIndex > 0) {

                return strengthOrder(buffer[--expIndex]);

            } else {

                buffer = null;

                expIndex = 0;

            }

        } else if (swapOrder != 0) {

            if (Character.isSupplementaryCodePoint(swapOrder)) {

                char[] chars = Character.toChars(swapOrder);

                swapOrder = chars[1];

                return chars[0] << 16;

            }

            int order = swapOrder << 16;

            swapOrder = 0;

            return order;

        }

        int ch = text.previous();

        if (ch == NormalizerBase.DONE) {

            return NULLORDER;

        }

        int value = ordering.getUnicodeOrder(ch);

        if (value == RuleBasedCollator.UNMAPPED) {

            swapOrder = UNMAPPEDCHARVALUE;

            return ch;

        } else if (value >= RuleBasedCollator.CONTRACTCHARINDEX) {

            value = prevContractChar(ch);

        }

        if (value >= RuleBasedCollator.EXPANDCHARINDEX) {

            buffer = ordering.getExpandValueList(value);

            expIndex = buffer.length;

            value = buffer[--expIndex];

        }

        if (ordering.isSEAsianSwapping()) {

            int vowel;

            if (isThaiBaseConsonant(ch)) {

                vowel = text.previous();

                if (isThaiPreVowel(vowel)) {

                    buffer = makeReorderedBuffer(vowel, value, buffer, false);

                    expIndex = buffer.length - 1;

                    value = buffer[expIndex];

                } else {

                    text.next();

                }

            }

            if (isLaoBaseConsonant(ch)) {

                vowel = text.previous();

                if (isLaoPreVowel(vowel)) {

                    buffer = makeReorderedBuffer(vowel, value, buffer, false);

                    expIndex = buffer.length - 1;

                    value = buffer[expIndex];

                } else {

                    text.next();

                }

            }

        }

        return strengthOrder(value);

    }

    /**

     * Return the primary component of a collation element.

     * @param order the collation element

     * @return the element's primary component

     */

    public final static int primaryOrder(int order)

    {

        order &= RBCollationTables.PRIMARYORDERMASK;

        return (order >>> RBCollationTables.PRIMARYORDERSHIFT);

    }

    /**

     * Return the secondary component of a collation element.

     * @param order the collation element

     * @return the element's secondary component

     */

    public final static short secondaryOrder(int order)

    {

        order = order & RBCollationTables.SECONDARYORDERMASK;

        return ((short)(order >> RBCollationTables.SECONDARYORDERSHIFT));

    }

    /**

     * Return the tertiary component of a collation element.

     * @param order the collation element

     * @return the element's tertiary component

     */

    public final static short tertiaryOrder(int order)

    {

        return ((short)(order &= RBCollationTables.TERTIARYORDERMASK));

    }

    /**

     *  Get the comparison order in the desired strength.  Ignore the other

     *  differences.

     *  @param order The order value

     */

    final int strengthOrder(int order)

    {

        int s = owner.getStrength();

        if (s == Collator.PRIMARY)

        {

            order &= RBCollationTables.PRIMARYDIFFERENCEONLY;

        } else if (s == Collator.SECONDARY)

        {

            order &= RBCollationTables.SECONDARYDIFFERENCEONLY;

        }

        return order;

    }

    /**

     * Sets the iterator to point to the collation element corresponding to

     * the specified character (the parameter is a CHARACTER offset in the

     * original string, not an offset into its corresponding sequence of

     * collation elements).  The value returned by the next call to next()

     * will be the collation element corresponding to the specified position

     * in the text.  If that position is in the middle of a contracting

     * character sequence, the result of the next call to next() is the

     * collation element for that sequence.  This means that getOffset()

     * is not guaranteed to return the same value as was passed to a preceding

     * call to setOffset().

     *

     * @param newOffset The new character offset into the original text.

     * @since 1.2

     */

    public void setOffset(int newOffset)

    {

        if (text != null) {

            if (newOffset < text.getBeginIndex()

                || newOffset >= text.getEndIndex()) {

                    text.setIndexOnly(newOffset);

            } else {

                int c = text.setIndex(newOffset);

                // if the desired character isn't used in a contracting character

                // sequence, bypass all the backing-up logic-- we're sitting on

                // the right character already

                if (ordering.usedInContractSeq(c)) {

                    // walk backwards through the string until we see a character

                    // that DOESN'T participate in a contracting character sequence

                    while (ordering.usedInContractSeq(c)) {

                        c = text.previous();

                    }

                    // now walk forward using this object's next() method until

                    // we pass the starting point and set our current position

                    // to the beginning of the last "character" before or at

                    // our starting position

                    int last = text.getIndex();

                    while (text.getIndex() <= newOffset) {

                        last = text.getIndex();

                        next();

                    }

                    text.setIndexOnly(last);

                    // we don't need this, since last is the last index

                    // that is the starting of the contraction which encompass

                    // newOffset

                    // text.previous();

                }

            }

        }

        buffer = null;

        expIndex = 0;

        swapOrder = 0;

    }

    /**

     * Returns the character offset in the original text corresponding to the next

     * collation element.  (That is, getOffset() returns the position in the text

     * corresponding to the collation element that will be returned by the next

     * call to next().)  This value will always be the index of the FIRST character

     * corresponding to the collation element (a contracting character sequence is

     * when two or more characters all correspond to the same collation element).

     * This means if you do setOffset(x) followed immediately by getOffset(), getOffset()

     * won't necessarily return x.

     *

     * @return The character offset in the original text corresponding to the collation

     * element that will be returned by the next call to next().

     * @since 1.2

     */

    public int getOffset()

    {

        return (text != null) ? text.getIndex() : 0;

    }

    /**

     * Return the maximum length of any expansion sequences that end

     * with the specified comparison order.

     * @param order a collation order returned by previous or next.

     * @return the maximum length of any expansion sequences ending

     *         with the specified order.

     * @since 1.2

     */

    public int getMaxExpansion(int order)

    {

        return ordering.getMaxExpansion(order);

    }

    /**

     * Set a new string over which to iterate.

     *

     * @param source  the new source text

     * @since 1.2

     */

    public void setText(String source)

    {

        buffer = null;

        swapOrder = 0;

        expIndex = 0;

        NormalizerBase.Mode mode =

            CollatorUtilities.toNormalizerMode(owner.getDecomposition());

        if (text == null) {

            text = new NormalizerBase(source, mode);

        } else {

            text.setMode(mode);

            text.setText(source);

        }

    }

    /**

     * Set a new string over which to iterate.

     *

     * @param source  the new source text.

     * @since 1.2

     */

    public void setText(CharacterIterator source)

    {

        buffer = null;

        swapOrder = 0;

        expIndex = 0;

        NormalizerBase.Mode mode =

            CollatorUtilities.toNormalizerMode(owner.getDecomposition());

        if (text == null) {

            text = new NormalizerBase(source, mode);

        } else {

            text.setMode(mode);

            text.setText(source);

        }

    }

    //============================================================

    // privates

    //============================================================

    /**

     * Determine if a character is a Thai vowel (which sorts after