content: /*
   * Copyright 2007-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License").
   * You may not use this file except in compliance with the License.
   * A copy of the License is located at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * or in the "license" file accompanying this file. This file is distributed
   * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
   * express or implied. See the License for the specific language governing
   * permissions and limitations under the License.
   */
  
  package com.amazon.ion.impl;
  
  import static com.amazon.ion.impl._Private_Utils.symtabExtends;
  
  import com.amazon.ion.SymbolTable;
  
  /**
   * Cache to reduce unnecessary calls to
   * {@link _Private_Utils#symtabExtends(SymbolTable, SymbolTable)}. This is
   * only used if the writer is stream copy optimized.
   */
  public final class _Private_SymtabExtendsCache
  {
      private SymbolTable myWriterSymtab;
      private SymbolTable myReaderSymtab;
      private int myWriterSymtabMaxId;
      private int myReaderSymtabMaxId;
      private boolean myResult;
  
      public boolean symtabsCompat(SymbolTable writerSymtab,
                                   SymbolTable readerSymtab)
      {
          // If the refs. of both writer's and reader's symtab match and are
          // not modified, skip expensive symtab extends check and return
          // cached result.
  
          assert writerSymtab != null && readerSymtab != null:
              "writer's and reader's current symtab cannot be null";
  
          if (myWriterSymtab          == writerSymtab &&
              myReaderSymtab          == readerSymtab &&
              myWriterSymtabMaxId     == writerSymtab.getMaxId() &&
              myReaderSymtabMaxId     == readerSymtab.getMaxId())
          {
              // Not modified, return cached result
              return myResult;
          }
  
          myResult = symtabExtends(writerSymtab, readerSymtab);
  
          // Track refs.
          myWriterSymtab = writerSymtab;
          myReaderSymtab = readerSymtab;
  
          // Track modification
          myWriterSymtabMaxId = writerSymtab.getMaxId();
          myReaderSymtabMaxId = readerSymtab.getMaxId();
  
          return myResult;
      }
  }