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/*
 * 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 com.hazelcast.org.apache.calcite.rex;

import com.hazelcast.org.apache.calcite.rel.RelNode;
import com.hazelcast.org.apache.calcite.rel.type.RelDataTypeField;
import com.hazelcast.org.apache.calcite.util.mapping.Mappings;

import com.hazelcast.com.google.common.collect.ImmutableList;

import com.hazelcast.org.checkerframework.checker.nullness.qual.Nullable;

import java.util.List;

/**
 * Shuttle which applies a permutation to its input fields.
 *
 * @see RexPermutationShuttle
 * @see RexUtil#apply(com.hazelcast.org.apache.calcite.util.mapping.Mappings.TargetMapping, RexNode)
 */
public class RexPermuteInputsShuttle extends RexShuttle {
  //~ Instance fields --------------------------------------------------------

  private final Mappings.TargetMapping mapping;
  private final ImmutableList fields;

  //~ Constructors -----------------------------------------------------------

  /**
   * Creates a RexPermuteInputsShuttle.
   *
   * 

The mapping provides at most one target for every source. If a source * has no targets and is referenced in the expression, * {@link com.hazelcast.org.apache.calcite.util.mapping.Mappings.TargetMapping#getTarget(int)} * will give an error. Otherwise the mapping gives a unique target. * * @param mapping Mapping * @param inputs Input relational expressions */ public RexPermuteInputsShuttle( Mappings.TargetMapping mapping, RelNode... inputs) { this(mapping, fields(inputs)); } private RexPermuteInputsShuttle( Mappings.TargetMapping mapping, ImmutableList fields) { this.mapping = mapping; this.fields = fields; } /** Creates a shuttle with an empty field list. It cannot handle GET calls but * otherwise works OK. */ public static RexPermuteInputsShuttle of(Mappings.TargetMapping mapping) { return new RexPermuteInputsShuttle(mapping, ImmutableList.of()); } //~ Methods ---------------------------------------------------------------- private static ImmutableList fields(RelNode[] inputs) { final ImmutableList.Builder fields = ImmutableList.builder(); for (RelNode input : inputs) { fields.addAll(input.getRowType().getFieldList()); } return fields.build(); } @Override public RexNode visitInputRef(RexInputRef local) { final int index = local.getIndex(); int target = mapping.getTarget(index); return new RexInputRef( target, local.getType()); } @Override public RexNode visitCall(RexCall call) { if (call.getOperator() == RexBuilder.GET_OPERATOR) { final String name = (String) ((RexLiteral) call.getOperands().get(1)).getValue2(); final int i = lookup(fields, name); if (i >= 0) { return RexInputRef.of(i, fields); } } return super.visitCall(call); } private static int lookup(List fields, @Nullable String name) { for (int i = 0; i < fields.size(); i++) { final RelDataTypeField field = fields.get(i); if (field.getName().equals(name)) { return i; } } return -1; } }





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