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.gremlin.transform;
  
  import java.util.*;
  
  public class ExprResult {
      // store the tag and the corresponding by_traversal as expression if it can be converted,
      // otherwise is Optional.empty
      // especially, tag is "" if no tag exists, i.e. values(..), valueMap(..)
      private Map<String, Optional<String>> tagExprMap;
  
      public ExprResult() {
          this.tagExprMap = new LinkedHashMap<>();
      }
  
      public Map<String, Optional<String>> getTagExprMap() {
          return Collections.unmodifiableMap(tagExprMap);
      }
  
      public ExprResult addTagExpr(String tag, Optional<String> exprOpt) {
          this.tagExprMap.put(tag, exprOpt);
          return this;
      }
  
      // return the first expression in tagExprMap
      public Optional<String> getSingleExpr() {
          return this.tagExprMap.values().iterator().next();
      }
  }
  