content: /*
   * Copyright (c) 1999, 2021, 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 openjdk.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 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, Context context) {
          return new UnsharedNameTable(names, context);
  
      }
  
      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, Context context, int hashSize) {
          super(names, context);
          hashMask = hashSize - 1;
          hashes = new HashEntry[hashSize];
      }
  
      public UnsharedNameTable(Names names, Context context) {
          this(names, context, 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) {
              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;
          }
  
      }
  
  }
  