/*
 * 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.phoenix.parse;

import java.sql.SQLException;
import java.util.Collections;
import java.util.List;

/**
 * Abstract node representing an expression node that has children
 * @since 0.1
 */
public abstract class CompoundParseNode extends ParseNode {

  private final List<ParseNode> children;
  private final boolean isStateless;

  CompoundParseNode(List<ParseNode> children) {
    this.children = Collections.unmodifiableList(children);
    boolean isStateless = true;
    for (ParseNode child : children) {
      isStateless &= child.isStateless();
      if (!isStateless) {
        break;
      }
    }
    this.isStateless = isStateless;
  }

  @Override
  public boolean isStateless() {
    return isStateless;
  }

  @Override
  public final List<ParseNode> getChildren() {
    return children;
  }

  final <T> List<T> acceptChildren(ParseNodeVisitor<T> visitor) throws SQLException {
    List<T> l = visitor.newElementList(children.size());
    for (int i = 0; i < children.size(); i++) {
      T e = children.get(i).accept(visitor);
      visitor.addElement(l, e);
    }
    return l;
  }

  @Override
  public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((children == null) ? 0 : children.hashCode());
    result = prime * result + (isStateless ? 1231 : 1237);
    return result;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj) return true;
    if (obj == null) return false;
    if (getClass() != obj.getClass()) return false;
    CompoundParseNode other = (CompoundParseNode) obj;
    if (children == null) {
      if (other.children != null) return false;
    } else if (!children.equals(other.children)) return false;
    if (isStateless != other.isStateless) return false;
    return true;
  }
}
