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SQL Parser and Optimizer

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to you under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in com.hazelcast.com.liance with
 * the License.  You may obtain a copy of the License at
 *
 * http://www.apache.com.hazelcast.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.hazelcast.org.apache.calcite.sql.type;

import com.hazelcast.org.apache.calcite.rel.type.RelDataType;
import com.hazelcast.org.apache.calcite.sql.SqlOperatorBinding;

import com.hazelcast.com.google.com.hazelcast.com.on.collect.ImmutableList;

/**
 * Strategy to infer the type of an operator call from the type of the operands
 * by using a series of {@link SqlReturnTypeInference} rules in a given order.
 * If a rule fails to find a return type (by returning NULL), next rule is tried
 * until there are no more rules in which case NULL will be returned.
 */
public class SqlReturnTypeInferenceChain implements SqlReturnTypeInference {
  //~ Instance fields --------------------------------------------------------

  private final ImmutableList rules;

  //~ Constructors -----------------------------------------------------------

  /**
   * Creates a SqlReturnTypeInferenceChain from an array of rules.
   *
   * Package-protected.
   * Use {@link com.hazelcast.org.apache.calcite.sql.type.ReturnTypes#chain}.
   */
  SqlReturnTypeInferenceChain(SqlReturnTypeInference... rules) {
    assert rules != null;
    assert rules.length > 1;
    for (SqlReturnTypeInference rule : rules) {
      assert rule != null;
    }
    this.rules = ImmutableList.copyOf(rules);
  }

  //~ Methods ----------------------------------------------------------------

  public RelDataType inferReturnType(SqlOperatorBinding opBinding) {
    for (SqlReturnTypeInference rule : rules) {
      RelDataType ret = rule.inferReturnType(opBinding);
      if (ret != null) {
        return ret;
      }
    }
    return null;
  }
}