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.rex;
  
  import org.apache.calcite.rel.type.RelDataType;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.Objects;
  
  /**
   * 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>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>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.
   */
  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 ----------------------------------------------------------------
  
    @Override public RelDataType getType() {
      return type;
    }
  
    public int getOffset() {
      return offset;
    }
  
    @Override public <R> R accept(RexVisitor<R> visitor) {
      return visitor.visitRangeRef(this);
    }
  
    @Override public <R, P> R accept(RexBiVisitor<R, P> visitor, P arg) {
      return visitor.visitRangeRef(this, arg);
    }
  
    @Override public boolean equals(@Nullable Object obj) {
      return this == obj
          || obj instanceof RexRangeRef
          && type.equals(((RexRangeRef) obj).type)
          && offset == ((RexRangeRef) obj).offset;
    }
  
    @Override public int hashCode() {
      return Objects.hash(type, offset);
    }
  
    @Override public String toString() {
      return "offset(" + offset + ")";
    }
  }
  