content: /*
   * Copyright 2020 Alibaba Group Holding Limited.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License 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.alibaba.graphscope.common.ir.tools;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.concurrent.atomic.AtomicInteger;
  
  public class AliasIdGenerator {
      private final AtomicInteger idGenerator;
      private Map<String, Integer> aliasNameToIdMap;
  
      public AliasIdGenerator() {
          this.idGenerator = new AtomicInteger();
          this.aliasNameToIdMap = new HashMap<>();
      }
  
      public int generate(@Nullable String aliasName) {
          if (AliasInference.isDefaultAlias(aliasName)) {
              return AliasInference.DEFAULT_ID;
          }
          Integer aliasId = aliasNameToIdMap.get(aliasName);
          if (aliasId == null) {
              aliasId = idGenerator.getAndIncrement();
              aliasNameToIdMap.put(aliasName, aliasId);
          }
          return aliasId;
      }
  }
  