org.sosy_lab.cpachecker.util.expressions.And.java Source code

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Here is the source code for org.sosy_lab.cpachecker.util.expressions.And.java

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/*
 *  CPAchecker is a tool for configurable software verification.
 *  This file is part of CPAchecker.
 *
 *  Copyright (C) 2007-2015  Dirk Beyer
 *  All rights reserved.
 *
 *  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.
 *
 *
 *  CPAchecker web page:
 *    http://cpachecker.sosy-lab.org
 */
package org.sosy_lab.cpachecker.util.expressions;

import java.util.Collections;
import java.util.Iterator;

import com.google.common.base.Function;
import com.google.common.base.Predicates;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;

public class And<LeafType> extends AbstractExpressionTree<LeafType> implements Iterable<ExpressionTree<LeafType>> {

    private final ImmutableSet<ExpressionTree<LeafType>> operands;

    private final int hashCode;

    private And(ImmutableSet<ExpressionTree<LeafType>> pOperands) {
        assert Iterables.size(pOperands) >= 2;
        assert !Iterables.contains(pOperands, ExpressionTrees.getFalse());
        assert !Iterables.contains(pOperands, ExpressionTrees.getTrue());
        assert !FluentIterable.from(pOperands).anyMatch(Predicates.instanceOf(And.class));
        operands = pOperands;
        hashCode = operands.hashCode();
    }

    @Override
    public Iterator<ExpressionTree<LeafType>> iterator() {
        return operands.iterator();
    }

    @Override
    public <T, E extends Throwable> T accept(ExpressionTreeVisitor<LeafType, T, E> pVisitor) throws E {
        return pVisitor.visit(this);
    }

    @Override
    public int hashCode() {
        return hashCode;
    }

    @Override
    public boolean equals(Object pObj) {
        if (this == pObj) {
            return true;
        }
        if (pObj instanceof And) {
            And<?> other = (And<?>) pObj;
            return hashCode == other.hashCode && operands.equals(other.operands);
        }
        return false;
    }

    public static <LeafType> ExpressionTree<LeafType> of(ExpressionTree<LeafType> pOp1,
            ExpressionTree<LeafType> pOp2) {
        return of(ImmutableList.of(pOp1, pOp2));
    }

    public static <LeafType> ExpressionTree<LeafType> of(Iterable<ExpressionTree<LeafType>> pOperands) {
        // If one of the operands is false, return false
        if (Iterables.contains(pOperands, ExpressionTrees.getFalse())) {
            return ExpressionTrees.getFalse();
        }
        // Filter out trivial operands and flatten the hierarchy
        ImmutableSet<ExpressionTree<LeafType>> operands = FluentIterable.from(pOperands)
                .filter(Predicates.not(Predicates.equalTo(ExpressionTrees.<LeafType>getTrue())))
                .transformAndConcat(new Function<ExpressionTree<LeafType>, Iterable<ExpressionTree<LeafType>>>() {

                    @Override
                    public Iterable<ExpressionTree<LeafType>> apply(ExpressionTree<LeafType> pOperand) {
                        if (pOperand instanceof And) {
                            return (And<LeafType>) pOperand;
                        }
                        return Collections.singleton(pOperand);
                    }
                }).toSet();
        // If there are no operands, return the neutral element
        if (operands.isEmpty()) {
            return ExpressionTrees.getTrue();
        }
        // If there is only one operand, return it
        if (operands.size() == 1) {
            return operands.iterator().next();
        }
        return new And<>(operands);
    }

}