SortInfo.java

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// Copyright 2012 Cloudera Inc.
//
// Licensed 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.cloudera.impala.analysis;

import java.util.List;

import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;

public class SortInfo {
  private List<Expr> orderingExprs_;
  private final List<Boolean> isAscOrder_;
  // True if "NULLS FIRST", false if "NULLS LAST", null if not specified.
  private final List<Boolean> nullsFirstParams_;
  // The single tuple that is materialized, sorted and output by a sort operator
  // (i.e. SortNode or TopNNode)
  private TupleDescriptor sortTupleDesc_;
  // Input expressions materialized into sortTupleDesc_. One expr per slot in
  // sortTupleDesc_.
  private List<Expr> sortTupleSlotExprs_;

  public SortInfo(List<Expr> orderingExprs, List<Boolean> isAscOrder,
      List<Boolean> nullsFirstParams) {
    Preconditions.checkArgument(orderingExprs.size() == isAscOrder.size());
    Preconditions.checkArgument(orderingExprs.size() == nullsFirstParams.size());
    orderingExprs_ = orderingExprs;
    isAscOrder_ = isAscOrder;
    nullsFirstParams_ = nullsFirstParams;
  }

  public void setMaterializedTupleInfo(
      TupleDescriptor tupleDesc, List<Expr> tupleSlotExprs) {
    sortTupleDesc_ = tupleDesc;
    sortTupleSlotExprs_ = tupleSlotExprs;
    for (int i = 0; i < sortTupleDesc_.getSlots().size(); ++i) {
      SlotDescriptor slotDesc = sortTupleDesc_.getSlots().get(i);
      slotDesc.setSourceExpr(sortTupleSlotExprs_.get(i));
    }
  }
  public List<Expr> getOrderingExprs() { return orderingExprs_; }
  public List<Boolean> getIsAscOrder() { return isAscOrder_; }
  public List<Boolean> getNullsFirstParams() { return nullsFirstParams_; }
  public List<Expr> getSortTupleSlotExprs() { return sortTupleSlotExprs_; }
  public TupleDescriptor getSortTupleDescriptor() { return sortTupleDesc_; }

  public List<Boolean> getNullsFirst() {
    List<Boolean> nullsFirst = Lists.newArrayList();
    for (int i = 0; i < orderingExprs_.size(); ++i) {
      nullsFirst.add(OrderByElement.nullsFirst(nullsFirstParams_.get(i),
          isAscOrder_.get(i)));
    }
    return nullsFirst;
  }

  public void materializeRequiredSlots(Analyzer analyzer, ExprSubstitutionMap smap) {
    Preconditions.checkNotNull(sortTupleDesc_);
    Preconditions.checkNotNull(sortTupleSlotExprs_);
    Preconditions.checkState(sortTupleDesc_.isMaterialized());
    analyzer.materializeSlots(orderingExprs_);
    List<SlotDescriptor> sortTupleSlotDescs = sortTupleDesc_.getSlots();
    List<Expr> materializedExprs = Lists.newArrayList();
    for (int i = 0; i < sortTupleSlotDescs.size(); ++i) {
      if (sortTupleSlotDescs.get(i).isMaterialized()) {
        materializedExprs.add(sortTupleSlotExprs_.get(i));
      }
    }
    List<Expr> substMaterializedExprs =
        Expr.substituteList(materializedExprs, smap, analyzer, false);
    analyzer.materializeSlots(substMaterializedExprs);
  }

  public void substituteOrderingExprs(ExprSubstitutionMap smap, Analyzer analyzer) {
    orderingExprs_ = Expr.substituteList(orderingExprs_, smap, analyzer, false);
  }

  public void checkConsistency() {
    for (Expr orderingExpr: orderingExprs_) {
      Preconditions.checkState(orderingExpr.isBound(sortTupleDesc_.getId()));
    }
  }
}