src/main/java/net/hydromatic/linq4j/expressions/BinaryExpression.java

/*
// Licensed to Julian Hyde under one or more contributor license
// agreements. See the NOTICE file distributed with this work for
// additional information regarding copyright ownership.
//
// Julian Hyde 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 net.hydromatic.linq4j.expressions;

import java.lang.reflect.Type;

/**
 * Represents an expression that has a binary operator.
 */
public class BinaryExpression extends Expression {
  public final Expression expression0;
  public final Expression expression1;
  private final Primitive primitive;

  BinaryExpression(ExpressionType nodeType, Type type, Expression expression0,
      Expression expression1) {
    super(nodeType, type);
    this.expression0 = expression0;
    this.expression1 = expression1;
    this.primitive = Primitive.of(expression0.getType());
  }

  @Override
  public boolean equals(Object obj) {
    if (obj == this) {
      return true;
    }
    if (obj instanceof BinaryExpression) {
      final BinaryExpression binary = (BinaryExpression) obj;
      return nodeType == binary.nodeType
             && type.equals(binary.type)
             && expression0.equals(binary.expression0)
             && expression1.equals(binary.expression1);
    }
    return false;
  }

  @Override
  public int hashCode() {
    return nodeType.hashCode()
           ^ expression0.hashCode()
           ^ expression1.hashCode();
  }

  @Override
  public Expression accept(Visitor visitor) {
    Expression expression0 = this.expression0.accept(visitor);
    Expression expression1 = this.expression1.accept(visitor);
    return visitor.visit(this, expression0, expression1);
  }

  public Object evaluate(Evaluator evaluator) {
    switch (nodeType) {
    case AndAlso:
      return (Boolean) expression0.evaluate(evaluator)
             && (Boolean) expression1.evaluate(evaluator);
    case Add:
      switch (primitive) {
      case INT:
        return (Integer) expression0.evaluate(evaluator) + (Integer) expression1
            .evaluate(evaluator);
      case DOUBLE:
        return (Double) expression0.evaluate(evaluator)
               + (Double) expression1.evaluate(evaluator);
      default:
        throw cannotEvaluate();
      }
    case Divide:
      switch (primitive) {
      case INT:
        return (Integer) expression0.evaluate(evaluator) / (Integer) expression1
            .evaluate(evaluator);
      case DOUBLE:
        return (Double) expression0.evaluate(evaluator)
               / (Double) expression1.evaluate(evaluator);
      default:
        throw cannotEvaluate();
      }
    case Equal:
      return expression0.evaluate(evaluator).equals(expression1.evaluate(
          evaluator));
    case GreaterThan:
      switch (primitive) {
      case INT:
        return (Integer) expression0.evaluate(evaluator) > (Integer) expression1
            .evaluate(evaluator);
      case DOUBLE:
        return (Double) expression0.evaluate(evaluator)
               > (Double) expression1.evaluate(evaluator);
      default:
        throw cannotEvaluate();
      }
    case GreaterThanOrEqual:
      switch (primitive) {
      case INT:
        return (Integer) expression0.evaluate(evaluator)
               >= (Integer) expression1.evaluate(evaluator);
      case DOUBLE:
        return (Double) expression0.evaluate(evaluator)
               >= (Double) expression1.evaluate(evaluator);
      default:
        throw cannotEvaluate();
      }
    case LessThan:
      switch (primitive) {
      case INT:
        return (Integer) expression0.evaluate(evaluator) < (Integer) expression1
            .evaluate(evaluator);
      case DOUBLE:
        return (Double) expression0.evaluate(evaluator)
               < (Double) expression1.evaluate(evaluator);
      default:
        throw cannotEvaluate();
      }
    case LessThanOrEqual:
      switch (primitive) {
      case INT:
        return (Integer) expression0.evaluate(evaluator)
               <= (Integer) expression1.evaluate(evaluator);
      case DOUBLE:
        return (Double) expression0.evaluate(evaluator)
               <= (Double) expression1.evaluate(evaluator);
      default:
        throw cannotEvaluate();
      }
    case Multiply:
      switch (primitive) {
      case INT:
        return (Integer) expression0.evaluate(evaluator) * (Integer) expression1
            .evaluate(evaluator);
      case DOUBLE:
        return (Double) expression0.evaluate(evaluator)
               * (Double) expression1.evaluate(evaluator);
      default:
        throw cannotEvaluate();
      }
    case NotEqual:
      return !expression0.evaluate(evaluator).equals(expression1.evaluate(
          evaluator));
    case OrElse:
      return (Boolean) expression0.evaluate(evaluator)
             || (Boolean) expression1.evaluate(evaluator);
    case Subtract:
      switch (primitive) {
      case INT:
        return (Integer) expression0.evaluate(evaluator) - (Integer) expression1
            .evaluate(evaluator);
      case DOUBLE:
        return (Double) expression0.evaluate(evaluator)
               - (Double) expression1.evaluate(evaluator);
      default:
        throw cannotEvaluate();
      }
    default:
      throw cannotEvaluate();
    }
  }

  void accept(ExpressionWriter writer, int lprec, int rprec) {
    if (writer.requireParentheses(this, lprec, rprec)) {
      return;
    }
    expression0.accept(writer, lprec, nodeType.lprec);
    writer.append(nodeType.op);
    expression1.accept(writer, nodeType.rprec, rprec);
  }

  private RuntimeException cannotEvaluate() {
    return new RuntimeException("cannot evaluate "
                                + this
                                + ", nodeType="
                                + nodeType
                                + ", primitive="
                                + primitive);
  }
}

// End BinaryExpression.java