| /* |
| * 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.rex; |
| |
| import org.apache.calcite.rel.type.RelDataType; |
| |
| /** |
| * Reference to a range of columns. |
| * |
| * <p>This construct is used only during the process of translating a |
| * {@link org.apache.calcite.sql.SqlNode SQL} tree to a |
| * {@link org.apache.calcite.rel.RelNode rel}/{@link RexNode rex} |
| * tree. <em>Regular {@link RexNode rex} trees do not contain this |
| * construct.</em></p> |
| * |
| * <p>While translating a join of EMP(EMPNO, ENAME, DEPTNO) to DEPT(DEPTNO2, |
| * DNAME) we create <code>RexRangeRef(DeptType,3)</code> to represent the pair |
| * of columns (DEPTNO2, DNAME) which came from DEPT. The type has 2 columns, and |
| * therefore the range represents columns {3, 4} of the input.</p> |
| * |
| * <p>Suppose we later create a reference to the DNAME field of this |
| * RexRangeRef; it will return a <code>{@link RexInputRef}(5,Integer)</code>, |
| * and the {@link org.apache.calcite.rex.RexRangeRef} will disappear.</p> |
| */ |
| public class RexRangeRef extends RexNode { |
| //~ Instance fields -------------------------------------------------------- |
| |
| private final RelDataType type; |
| private final int offset; |
| |
| //~ Constructors ----------------------------------------------------------- |
| |
| /** |
| * Creates a range reference. |
| * |
| * @param rangeType Type of the record returned |
| * @param offset Offset of the first column within the input record |
| */ |
| RexRangeRef( |
| RelDataType rangeType, |
| int offset) { |
| this.type = rangeType; |
| this.offset = offset; |
| } |
| |
| //~ Methods ---------------------------------------------------------------- |
| |
| public RelDataType getType() { |
| return type; |
| } |
| |
| public int getOffset() { |
| return offset; |
| } |
| |
| public <R> R accept(RexVisitor<R> visitor) { |
| return visitor.visitRangeRef(this); |
| } |
| |
| public <R, P> R accept(RexBiVisitor<R, P> visitor, P arg) { |
| return visitor.visitRangeRef(this, arg); |
| } |
| } |
| |
| // End RexRangeRef.java |