| /** |
| * 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.tajo.algebra; |
| |
| import com.google.common.base.Objects; |
| import com.google.gson.annotations.Expose; |
| import com.google.gson.annotations.SerializedName; |
| import org.apache.tajo.util.TUtil; |
| |
| /** |
| * <code>NamedExpr</code> is an expression which can be aliased in a target list. |
| * |
| * <pre> |
| * SELECT col1 + col2 as a, sum(col2) as b, col3 as c, col4, ... FROM ... |
| * ^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^ ^^^^ |
| * expr1 expr2 expr3 expr4 |
| * </pre> |
| * |
| * We define each expression in expr1 - expr4 as a named expression. |
| * In database community, each of them is called target or an expression in a select list, |
| * Each expression can be explicitly aliased as an given name. |
| */ |
| public class NamedExpr extends UnaryOperator { |
| @Expose @SerializedName("AliasName") |
| private String alias; |
| |
| public NamedExpr(Expr expr) { |
| super(OpType.Target); |
| setChild(expr); |
| } |
| |
| public NamedExpr(Expr expr, String alias) { |
| this(expr); |
| setAlias(alias); |
| } |
| |
| public Expr getExpr() { |
| return getChild(); |
| } |
| |
| public boolean hasAlias() { |
| return this.alias != null; |
| } |
| |
| public String getAlias() { |
| return this.alias; |
| } |
| |
| public void setAlias(String alias) { |
| this.alias = alias; |
| } |
| |
| @Override |
| public int hashCode() { |
| return Objects.hashCode(alias, getChild()); |
| } |
| |
| @Override |
| public boolean equalsTo(Expr obj) { |
| if (obj instanceof NamedExpr) { |
| NamedExpr another = (NamedExpr) obj; |
| return TUtil.checkEquals(alias, another.alias); |
| } |
| |
| return false; |
| } |
| |
| public String toString() { |
| return getChild().toString() + (hasAlias() ? " AS " + alias : ""); |
| } |
| |
| @Override |
| public String toJson() { |
| return JsonHelper.toJson(this); |
| } |
| |
| @Override |
| public NamedExpr clone() throws CloneNotSupportedException { |
| NamedExpr namedExpr = (NamedExpr) super.clone(); |
| namedExpr.alias = alias; |
| return namedExpr; |
| } |
| } |