Mercurial > jdk8-mips64-public > langtools / file revision

 /*

  * Copyright (c) 1999, 2012, 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 com.sun.tools.javac.util;

 import java.lang.ref.SoftReference;

 /**

  * Implementation of Name.Table that stores all names in a single shared

  * byte array, expanding it as needed. This avoids the overhead incurred

  * by using an array of bytes for each name.

  *

  *  <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 SharedNameTable extends Name.Table {

     // maintain a freelist of recently used name tables for reuse.

     private static List<SoftReference<SharedNameTable>> freelist = List.nil();

     static public synchronized SharedNameTable create(Names names) {

         while (freelist.nonEmpty()) {

             SharedNameTable t = freelist.head.get();

             freelist = freelist.tail;

             if (t != null) {

                 return t;

             }

         }

         return new SharedNameTable(names);

     }

     static private synchronized void dispose(SharedNameTable t) {

         freelist = freelist.prepend(new SoftReference<SharedNameTable>(t));

     }

     /** The hash table for names.

      */

     private NameImpl[] hashes;

     /** The shared byte array holding all encountered names.

      */

     public byte[] bytes;

     /** The mask to be used for hashing

      */

     private int hashMask;

     /** The number of filled bytes in `names'.

      */

     private int nc = 0;

     /** 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.

      *  @param nameSize the initial size of the name table.

      */

     public SharedNameTable(Names names, int hashSize, int nameSize) {

         super(names);

         hashMask = hashSize - 1;

         hashes = new NameImpl[hashSize];

         bytes = new byte[nameSize];

     }

     public SharedNameTable(Names names) {

         this(names, 0x8000, 0x20000);

     }

     @Override

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

         int nc = this.nc;

         byte[] bytes = this.bytes = ArrayUtils.ensureCapacity(this.bytes, nc + len * 3);

         int nbytes = Convert.chars2utf(cs, start, bytes, nc, len) - nc;

         int h = hashValue(bytes, nc, nbytes) & hashMask;

         NameImpl n = hashes[h];

         while (n != null &&

                 (n.getByteLength() != nbytes ||

                 !equals(bytes, n.index, bytes, nc, nbytes))) {

             n = n.next;

         }

         if (n == null) {

             n = new NameImpl(this);

             n.index = nc;

             n.length = nbytes;

             n.next = hashes[h];

             hashes[h] = n;

             this.nc = nc + nbytes;

             if (nbytes == 0) {

                 this.nc++;

             }

         }

         return n;

     }

     @Override

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

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

         NameImpl n = hashes[h];

         byte[] names = this.bytes;

         while (n != null &&

                 (n.getByteLength() != len || !equals(names, n.index, cs, start, len))) {

             n = n.next;

         }

         if (n == null) {

             int nc = this.nc;

             names = this.bytes = ArrayUtils.ensureCapacity(names, nc + len);

             System.arraycopy(cs, start, names, nc, len);

             n = new NameImpl(this);

             n.index = nc;

             n.length = len;

             n.next = hashes[h];

             hashes[h] = n;

             this.nc = nc + len;

             if (len == 0) {

                 this.nc++;

             }

         }

         return n;

     }

     @Override

     public void dispose() {

         dispose(this);

     }

     static class NameImpl extends Name {

         /** The next name occupying the same hash bucket.

          */

         NameImpl next;

         /** The index where the bytes of this name are stored in the global name

          *  buffer `byte'.

          */

         int index;

         /** The number of bytes in this name.

          */

         int length;

         NameImpl(SharedNameTable table) {

             super(table);

         }

         @Override

         public int getIndex() {

             return index;

         }

         @Override

         public int getByteLength() {

             return length;

         }

         @Override

         public byte getByteAt(int i) {

             return getByteArray()[index + i];

         }

         @Override

         public byte[] getByteArray() {

             return ((SharedNameTable) table).bytes;

         }

         @Override

         public int getByteOffset() {

             return index;

         }

         /** Return the hash value of this name.

          */

         public int hashCode() {

             return index;

         }

         /** Is this name equal to other?

          */

         public boolean equals(Object other) {

             if (other instanceof Name)

                 return

                     table == ((Name)other).table && index == ((Name) other).getIndex();

             else return false;

         }

     }

 }