content: /*
   * 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 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 org.apache.calcite.linq4j.tree;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  import java.util.Objects;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Represents an expression that has a conditional operator.
   *
   * <p>With an odd number of expressions
   * {c0, e0, c1, e1, ..., c<sub>n-1</sub>, e<sub>n-1</sub>, e<sub>n</sub>}
   * represents "if (c0) e0 else if (c1) e1 ... else e<sub>n</sub>";
   * with an even number of expressions
   * {c0, e0, c1, e1, ..., c<sub>n-1</sub>, e<sub>n-1</sub>}
   * represents
   * "if (c0) e0 else if (c1) e1 ... else if (c<sub>n-1</sub>) e<sub>n-1</sub>".
   */
  public class ConditionalStatement extends Statement {
    public final List<Node> expressionList;
  
    public ConditionalStatement(List<Node> expressionList) {
      super(ExpressionType.Conditional, Void.TYPE);
      this.expressionList = requireNonNull(expressionList, "expressionList");
    }
  
    @Override public Statement accept(Shuttle shuttle) {
      shuttle = shuttle.preVisit(this);
      List<Node> list = Expressions.acceptNodes(expressionList, shuttle);
      return shuttle.visit(this, list);
    }
  
    @Override public <R> R accept(Visitor<R> visitor) {
      return visitor.visit(this);
    }
  
    @Override void accept0(ExpressionWriter writer) {
      for (int i = 0; i < expressionList.size() - 1; i += 2) {
        if (i > 0) {
          writer.backUp();
          writer.append(" else ");
        }
        writer.append("if (")
            .append(expressionList.get(i))
            .append(") ")
            .append(Blocks.toBlock(expressionList.get(i + 1)));
      }
      if (expressionList.size() % 2 == 1) {
        writer.backUp();
        writer.append(" else ")
            .append(Blocks.toBlock(last(expressionList)));
      }
    }
  
    private static <E> E last(List<E> collection) {
      return collection.get(collection.size() - 1);
    }
  
    @Override public boolean equals(@Nullable Object o) {
      if (this == o) {
        return true;
      }
      if (o == null || getClass() != o.getClass()) {
        return false;
      }
      if (!super.equals(o)) {
        return false;
      }
  
      ConditionalStatement that = (ConditionalStatement) o;
      return expressionList.equals(that.expressionList);
    }
  
    @Override public int hashCode() {
      return Objects.hash(nodeType, type, expressionList);
    }
  }
  