org.sonar.java.se.AlwaysTrueOrFalseExpressionCollector.java Source code

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Here is the source code for org.sonar.java.se.AlwaysTrueOrFalseExpressionCollector.java

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/*
 * SonarQube Java
 * Copyright (C) 2012-2017 SonarSource SA
 * mailto:info AT sonarsource DOT com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package org.sonar.java.se;

import com.google.common.base.Preconditions;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.common.collect.Multimap;
import com.google.common.collect.Sets;

import org.sonar.java.se.constraint.BooleanConstraint;
import org.sonar.java.se.constraint.Constraint;
import org.sonar.java.se.constraint.ObjectConstraint;
import org.sonar.plugins.java.api.JavaFileScannerContext;
import org.sonar.plugins.java.api.tree.BinaryExpressionTree;
import org.sonar.plugins.java.api.tree.IfStatementTree;
import org.sonar.plugins.java.api.tree.Tree;

import javax.annotation.Nullable;

import java.util.Collection;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

public class AlwaysTrueOrFalseExpressionCollector {

    private final Multimap<Tree, ExplodedGraph.Node> falseEvaluations = HashMultimap.create();
    private final Multimap<Tree, ExplodedGraph.Node> trueEvaluations = HashMultimap.create();

    void evaluatedToFalse(Tree condition, ExplodedGraph.Node node) {
        falseEvaluations.put(condition, node);
    }

    void evaluatedToTrue(Tree condition, ExplodedGraph.Node node) {
        trueEvaluations.put(condition, node);
    }

    public Set<Tree> alwaysTrue() {
        return Sets.difference(trueEvaluations.keySet(), falseEvaluations.keySet());
    }

    public Set<Tree> alwaysFalse() {
        return Sets.difference(falseEvaluations.keySet(), trueEvaluations.keySet());
    }

    public Set<List<JavaFileScannerContext.Location>> flowForExpression(Tree expression) {
        Collection<ExplodedGraph.Node> nodes = getNodes(expression);
        return collectFlow(nodes);
    }

    private Collection<ExplodedGraph.Node> getNodes(Tree expression) {
        Collection<ExplodedGraph.Node> falseNodes = falseEvaluations.get(expression);
        return falseNodes.isEmpty() ? trueEvaluations.get(expression) : falseNodes;
    }

    private static Set<List<JavaFileScannerContext.Location>> collectFlow(Collection<ExplodedGraph.Node> nodes) {
        return nodes.stream().map(AlwaysTrueOrFalseExpressionCollector::flowFromNode).flatMap(Set::stream)
                .filter(f -> !f.isEmpty()).collect(Collectors.toSet());
    }

    private static Set<List<JavaFileScannerContext.Location>> flowFromNode(ExplodedGraph.Node node) {
        List<Class<? extends Constraint>> domains = Lists.newArrayList(ObjectConstraint.class,
                BooleanConstraint.class);
        return FlowComputation.flow(node.parent(), node.programState.peekValue(), domains,
                node.programState.peekValueSymbol().symbol);
    }

    public static List<JavaFileScannerContext.Location> addIssueLocation(List<JavaFileScannerContext.Location> flow,
            Tree issueTree, boolean conditionIsAlwaysTrue) {
        return ImmutableList.<JavaFileScannerContext.Location>builder()
                .add(new JavaFileScannerContext.Location("Expression is always " + conditionIsAlwaysTrue + ".",
                        issueTree))
                .addAll(flow).build();
    }

    public static boolean hasUnreachableCode(Tree booleanExpr, boolean isTrue) {
        Tree parent = biggestTreeWithSameEvaluation(booleanExpr, isTrue);
        if (parent.is(Tree.Kind.IF_STATEMENT)) {
            IfStatementTree ifStatementTree = (IfStatementTree) parent;
            return !isTrue || ifStatementTree.elseStatement() != null;
        }
        // Tree.Kind.DO_STATEMENT not considered, because it is always executed at least once
        if (parent.is(Tree.Kind.WHILE_STATEMENT) && !isTrue) {
            return true;
        }
        return parent.is(Tree.Kind.CONDITIONAL_EXPRESSION);
    }

    private static Tree biggestTreeWithSameEvaluation(Tree booleanExpr, boolean isTrue) {
        Tree child = booleanExpr;
        Tree parent = booleanExpr.parent();
        while (isBiggerTreeWithSameTruthiness(parent, child, isTrue)) {
            child = parent;
            parent = parent.parent();
        }
        Preconditions.checkState(parent != null, "Error getting parent tree with same evaluation, parent is null");
        return parent;
    }

    private static boolean isBiggerTreeWithSameTruthiness(@Nullable Tree parent, Tree child, boolean isTrue) {
        if (parent == null) {
            return false;
        }
        if (parent.is(Tree.Kind.PARENTHESIZED_EXPRESSION)) {
            return true;
        }
        Tree.Kind operator = isTrue ? Tree.Kind.CONDITIONAL_OR : Tree.Kind.CONDITIONAL_AND;
        return parent.is(operator) && ((BinaryExpressionTree) parent).leftOperand() == child;
    }
}