/*
 * Copyright (c) 2000, 2010, 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 sun.awt.motif;

import java.nio.CharBuffer;
import java.nio.charset.CoderResult;

    /**
     * Surrogate parsing support.  Charset implementations may use instances of
     * this class to handle the details of parsing UTF-16 surrogate pairs.
     */
    class SurrogateParser {

        public SurrogateParser() { }

        private int character;          // UCS-4
        private CoderResult error = CoderResult.UNDERFLOW;
        private boolean isPair;

        /**
         * Returns the UCS-4 character previously parsed.
         */
        public int character() {
            assert (error == null);
            return character;
        }

        /**
         * Tells whether or not the previously-parsed UCS-4 character was
         * originally represented by a surrogate pair.
         */
        public boolean isPair() {
            assert (error == null);
            return isPair;
        }

        /**
         * Returns the number of UTF-16 characters consumed by the previous
         * parse.
         */
        public int increment() {
            assert (error == null);
            return isPair ? 2 : 1;
        }

        /**
         * If the previous parse operation detected an error, return the object
         * describing that error.
         */
        public CoderResult error() {
            assert (error != null);
            return error;
        }

        /**
         * Returns an unmappable-input result object, with the appropriate
         * input length, for the previously-parsed character.
         */
        public CoderResult unmappableResult() {
            assert (error == null);
            return CoderResult.unmappableForLength(isPair ? 2 : 1);
        }

        /**
         * Parses a UCS-4 character from the given source buffer, handling
         * surrogates.
         *
         * @param  c    The first character
         * @param  in   The source buffer, from which one more character
         *              will be consumed if c is a high surrogate
         *
         * @returns  Either a parsed UCS-4 character, in which case the isPair()
         *           and increment() methods will return meaningful values, or
         *           -1, in which case error() will return a descriptive result
         *           object
         */
        public int parse(char c, CharBuffer in) {
            if (Character.isHighSurrogate(c)) {
                if (!in.hasRemaining()) {
                    error = CoderResult.UNDERFLOW;
                    return -1;
                }
                char d = in.get();
                if (Character.isLowSurrogate(d)) {
                    character = Character.toCodePoint(c, d);
                    isPair = true;
                    error = null;
                    return character;
                }
                error = CoderResult.malformedForLength(1);
                return -1;
            }
            if (Character.isLowSurrogate(c)) {
                error = CoderResult.malformedForLength(1);
                return -1;
            }
            character = c;
            isPair = false;
            error = null;
            return character;
        }

        /**
         * Parses a UCS-4 character from the given source buffer, handling
         * surrogates.
         *
         * @param  c    The first character
         * @param  ia   The input array, from which one more character
         *              will be consumed if c is a high surrogate
         * @param  ip   The input index
         * @param  il   The input limit
         *
         * @returns  Either a parsed UCS-4 character, in which case the isPair()
         *           and increment() methods will return meaningful values, or
         *           -1, in which case error() will return a descriptive result
         *           object
         */
        public int parse(char c, char[] ia, int ip, int il) {
            assert (ia[ip] == c);
            if (Character.isHighSurrogate(c)) {
                if (il - ip < 2) {
                    error = CoderResult.UNDERFLOW;
                    return -1;
                }
                char d = ia[ip + 1];
                if (Character.isLowSurrogate(d)) {
                    character = Character.toCodePoint(c, d);
                    isPair = true;
                    error = null;
                    return character;
                }
                error = CoderResult.malformedForLength(1);
                return -1;
            }
            if (Character.isLowSurrogate(c)) {
                error = CoderResult.malformedForLength(1);
                return -1;
            }
            character = c;
            isPair = false;
            error = null;
            return character;
        }

    }