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// to you under the Apache License, Version 2.0 (the
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// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
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package org.apache.impala.planner;

import org.apache.impala.analysis.Analyzer;
import org.apache.impala.analysis.BinaryPredicate;
import org.apache.impala.analysis.CompoundPredicate;
import org.apache.impala.analysis.Expr;
import org.apache.impala.analysis.Predicate;
import org.apache.impala.common.AnalysisException;
import org.apache.impala.common.InternalException;
import org.apache.impala.service.FeSupport;
import com.google.common.base.Preconditions;

/**
 * Representation of a two-sided interval of values. Either one of the sides
 * is optional, and can be exclusive or inclusive. For a range representing a single
 * value, both bounds are set.
 */
public class ValueRange {

  private Expr lowerBound_;
  private boolean lowerBoundInclusive_;
  private Expr upperBound_;
  private boolean upperBoundInclusive_;

  Expr getLowerBound() { return lowerBound_; }
  void setLowerBound(Expr e) { lowerBound_ = e; }
  boolean getLowerBoundInclusive() { return lowerBoundInclusive_; }
  void setLowerBoundInclusive(boolean b) { lowerBoundInclusive_ = b; }
  Expr getUpperBound() { return upperBound_; }
  void setUpperBound(Expr e) { upperBound_ = e; }
  boolean getUpperBoundInclusive() { return upperBoundInclusive_; }
  void setUpperBoundInclusive(boolean b) { upperBoundInclusive_ = b; }

  static public ValueRange createEqRange(Expr valueExpr) {
    ValueRange result = new ValueRange();
    result.lowerBound_ = valueExpr;
    result.lowerBoundInclusive_ = true;
    result.upperBound_ = valueExpr;
    result.upperBoundInclusive_ = true;
    return result;
  }

  public boolean isEqRange() {
    return lowerBound_ == upperBound_ && lowerBoundInclusive_ && upperBoundInclusive_;
  }

  /**
   * Determines whether a given constant expr is within the range.
   * Does this by constructing predicate that represents the range,
   * with the valueExpr inserted appropriately, and then calls the
   * backend for evaluation.
   */
  public boolean isInRange(Analyzer analyzer, Expr valueExpr) throws
      InternalException {
    Preconditions.checkState(valueExpr.isConstant());
    Preconditions.checkState(lowerBound_ != null || upperBound_ != null);

    // construct predicate
    Predicate p = null;
    if (lowerBound_ != null && upperBound_ != null
        && lowerBoundInclusive_ && upperBoundInclusive_
        && lowerBound_ == upperBound_) {
      // construct "=" predicate
      p = new BinaryPredicate(BinaryPredicate.Operator.EQ, valueExpr, lowerBound_);
    } else {
      // construct range predicate
      if (lowerBound_ != null) {
        p = new BinaryPredicate(
            lowerBoundInclusive_
              ? BinaryPredicate.Operator.GE : BinaryPredicate.Operator.GT,
            valueExpr, lowerBound_);
      }
      if (upperBound_ != null) {
        Predicate p2 = new BinaryPredicate(
            upperBoundInclusive_
              ? BinaryPredicate.Operator.GE : BinaryPredicate.Operator.GT,
            upperBound_, valueExpr);
        if (p != null) {
          p = new CompoundPredicate(CompoundPredicate.Operator.AND, p, p2);
        } else {
          p = p2;
        }
      }
    }

    Preconditions.checkState(p.isConstant());
    // analyze to insert casts, etc.
    try {
      p.analyze(analyzer);
    } catch (AnalysisException e) {
      // this should never happen
      throw new InternalException(
          "couldn't analyze predicate " + p.toSql() + "\n" + e.toString());
    }

    // call backend
    return FeSupport.EvalPredicate(p, analyzer.getQueryCtx());
  }

}