/*

 * Copyright 1999-2006 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package com.sun.tools.javac.util;

import java.lang.ref.WeakReference;

/**

 * Implementation of Name.Table that stores names in individual arrays

 * using weak references. It is recommended for use when a single shared

 * byte array is unsuitable.

 *

 *  <p><b>This is NOT part of any API supported by Sun Microsystems.  If

 *  you write code that depends on this, you do so at your own risk.

 *  This code and its internal interfaces are subject to change or

 *  deletion without notice.</b>

 */

public class UnsharedNameTable extends Name.Table {

    static public Name.Table create(Names names) {

        return new UnsharedNameTable(names);

    }

    static class HashEntry extends WeakReference<NameImpl> {

        HashEntry next;

        HashEntry(NameImpl referent) {

            super(referent);

        }

    }

    /** The hash table for names.

     */

    private HashEntry[] hashes = null;

    /** The mask to be used for hashing

     */

    private int hashMask;

    /** Index counter for names in this table.

     */

    public int index;

    /** Allocator

     *  @param names The main name table

     *  @param hashSize the (constant) size to be used for the hash table

     *                  needs to be a power of two.

     */

    public UnsharedNameTable(Names names, int hashSize) {

        super(names);

        hashMask = hashSize - 1;

        hashes = new HashEntry[hashSize];

    }

    public UnsharedNameTable(Names names) {

        this(names, 0x8000);

    }

    @Override

    public Name fromChars(char[] cs, int start, int len) {

        byte[] name = new byte[len * 3];

        int nbytes = Convert.chars2utf(cs, start, name, 0, len);

        return fromUtf(name, 0, nbytes);

    }

    @Override

    public Name fromUtf(byte[] cs, int start, int len) {

        int h = hashValue(cs, start, len) & hashMask;

        HashEntry element = hashes[h];

        NameImpl n = null;

        HashEntry previousNonNullTableEntry = null;

        HashEntry firstTableEntry = element;

        while (element != null) {

            if (element == null) {

                break;

            }

            n = element.get();

            if (n == null) {

                if (firstTableEntry == element) {

                    hashes[h] = firstTableEntry = element.next;

                }

                else {

                    assert previousNonNullTableEntry != null : "previousNonNullTableEntry cannot be null here.";

                    previousNonNullTableEntry.next = element.next;

                }

            }

            else {

                if (n.getByteLength() == len && equals(n.bytes, 0, cs, start, len)) {

                    return n;

                }

                previousNonNullTableEntry = element;

            }

            element = element.next;

        }

        byte[] bytes = new byte[len];

        System.arraycopy(cs, start, bytes, 0, len);

        n = new NameImpl(this, bytes, index++);

        System.arraycopy(cs, start, n.bytes, 0, len);

        HashEntry newEntry = new HashEntry(n);

        if (previousNonNullTableEntry == null) { // We are not the first name with that hashCode.

            hashes[h] = newEntry;

        }

        else {

            assert previousNonNullTableEntry.next == null : "previousNonNullTableEntry.next must be null.";

            previousNonNullTableEntry.next = newEntry;

        }

        return n;

    }

    @Override

    public void dispose() {

        hashes = null;

    }

    static class NameImpl extends Name {

        NameImpl(UnsharedNameTable table, byte[] bytes, int index) {

            super(table);

            this.bytes = bytes;

            this.index = index;

        }

        final byte[] bytes;

        final int index;

        @Override

        public int getIndex() {

            return index;

        }

        @Override

        public int getByteLength() {

            return bytes.length;

        }

        @Override

        public byte getByteAt(int i) {

            return bytes[i];

        }

        @Override

        public byte[] getByteArray() {

            return bytes;

        }

        @Override

        public int getByteOffset() {

            return 0;

        }

    }

}