/*
 * Copyright (c) 1999, 2013, 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
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 */

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.
 
This is NOT part of any supported API.
 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.
/**
 * 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 supported API.
 *  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.
/** The hash table for names.
     */
    private HashEntry[] hashes = null;

    
The mask to be used for hashing
/** The mask to be used for hashing
     */
    private int hashMask;

    
Index counter for names in this table.
/** 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.
/** 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.checkNonNull(previousNonNullTableEntry, "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++);

        HashEntry newEntry = new HashEntry(n);

        if (previousNonNullTableEntry == null) { // We are not the first name with that hashCode.
            hashes[h] = newEntry;
        }
        else {
            Assert.checkNull(previousNonNullTableEntry.next, "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;
        }

    }

}