TableAliasGenerator.java

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// Copyright 2014 Cloudera Inc.
//
// 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.cloudera.impala.common;

import com.cloudera.impala.analysis.Analyzer;

import com.google.common.base.Preconditions;

public class TableAliasGenerator extends AliasGenerator {
  private static final String DEFAULT_TBL_ALIAS_PREFIX = "$a$";

  public TableAliasGenerator(Analyzer analyzer, String prefix) {
    Preconditions.checkNotNull(analyzer);
    aliasPrefix_ = prefix != null ? prefix : DEFAULT_TBL_ALIAS_PREFIX;
    Analyzer currentAnalyzer = analyzer;
    do {
      usedAliases_.addAll(currentAnalyzer.getAliases());
      usedAliases_.addAll(currentAnalyzer.getLocalViews().keySet());
      currentAnalyzer = currentAnalyzer.getParentAnalyzer();
    } while (currentAnalyzer != null);
  }
}