org.sonar.javascript.checks.ExpressionComplexityCheck.java Source code

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Here is the source code for org.sonar.javascript.checks.ExpressionComplexityCheck.java

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/*
 * SonarQube JavaScript Plugin
 * Copyright (C) 2011-2016 SonarSource SA
 * mailto:contact 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.javascript.checks;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import java.util.ArrayList;
import java.util.List;
import org.sonar.api.server.rule.RulesDefinition;
import org.sonar.check.Priority;
import org.sonar.check.Rule;
import org.sonar.check.RuleProperty;
import org.sonar.plugins.javascript.api.tree.Tree;
import org.sonar.plugins.javascript.api.tree.Tree.Kind;
import org.sonar.plugins.javascript.api.tree.expression.BinaryExpressionTree;
import org.sonar.plugins.javascript.api.tree.expression.ConditionalExpressionTree;
import org.sonar.plugins.javascript.api.tree.lexical.SyntaxToken;
import org.sonar.plugins.javascript.api.visitors.PreciseIssue;
import org.sonar.plugins.javascript.api.visitors.SubscriptionVisitorCheck;
import org.sonar.squidbridge.annotations.ActivatedByDefault;
import org.sonar.squidbridge.annotations.SqaleLinearWithOffsetRemediation;
import org.sonar.squidbridge.annotations.SqaleSubCharacteristic;

@Rule(key = "S1067", name = "Expressions should not be too complex", priority = Priority.MAJOR, tags = {
        Tags.BRAIN_OVERLOAD })
@SqaleSubCharacteristic(RulesDefinition.SubCharacteristics.UNIT_TESTABILITY)
@SqaleLinearWithOffsetRemediation(coeff = "1min", offset = "5min", effortToFixDescription = "per complexity point above the threshold")
@ActivatedByDefault
public class ExpressionComplexityCheck extends SubscriptionVisitorCheck {

    private static final int DEFAULT = 3;
    private static final String MESSAGE = "Reduce the number of conditional operators (%s) used in the expression (maximum allowed %s).";

    @RuleProperty(description = "Maximum number of allowed conditional operators in an expression", defaultValue = ""
            + DEFAULT)
    public int max = DEFAULT;

    private List<ExpressionComplexity> statementLevel = Lists.newArrayList();
    private static final Kind[] SCOPES = { Kind.FUNCTION_EXPRESSION, Kind.GENERATOR_FUNCTION_EXPRESSION,
            Kind.OBJECT_LITERAL, Kind.CALL_EXPRESSION, Kind.JSX_JAVASCRIPT_EXPRESSION };

    private static final Kind[] CONDITIONAL_EXPRS = { Kind.CONDITIONAL_EXPRESSION, Kind.CONDITIONAL_AND,
            Kind.CONDITIONAL_OR };

    @Override
    public List<Kind> nodesToVisit() {
        return ImmutableList.<Kind>builder().add(CONDITIONAL_EXPRS).add(SCOPES).build();
    }

    public static class ExpressionComplexity {
        private int nestedLevel = 0;
        private List<SyntaxToken> operators = new ArrayList<>();

        public void addOperator(SyntaxToken operator) {
            operators.add(operator);
        }

        public void incrementNestedExprLevel() {
            nestedLevel++;
        }

        public void decrementNestedExprLevel() {
            nestedLevel--;
        }

        public boolean isOnFirstExprLevel() {
            return nestedLevel == 0;
        }

        public List<SyntaxToken> getComplexityOperators() {
            return operators;
        }

        public void resetExpressionComplexityOperators() {
            operators = new ArrayList<>();
        }
    }

    @Override
    public void visitFile(Tree scriptTree) {
        statementLevel.clear();
        statementLevel.add(new ExpressionComplexity());
    }

    @Override
    public void visitNode(Tree tree) {
        if (tree.is(CONDITIONAL_EXPRS)) {
            Iterables.getLast(statementLevel).incrementNestedExprLevel();
            Iterables.getLast(statementLevel).addOperator(getOperatorToken(tree));

        } else if (tree.is(SCOPES)) {
            statementLevel.add(new ExpressionComplexity());
        }
    }

    private static SyntaxToken getOperatorToken(Tree tree) {
        if (tree.is(Kind.CONDITIONAL_EXPRESSION)) {
            return ((ConditionalExpressionTree) tree).query();

        } else if (tree.is(Kind.CONDITIONAL_AND, Kind.CONDITIONAL_OR)) {
            return ((BinaryExpressionTree) tree).operator();
        }

        throw new IllegalStateException("Cannot get operator for " + tree);
    }

    @Override
    public void leaveNode(Tree tree) {
        if (tree.is(CONDITIONAL_EXPRS)) {
            ExpressionComplexity currentExpression = Iterables.getLast(statementLevel);
            currentExpression.decrementNestedExprLevel();

            if (currentExpression.isOnFirstExprLevel()) {
                List<SyntaxToken> complexityOperators = currentExpression.getComplexityOperators();

                if (complexityOperators.size() > max) {
                    addIssue(tree, complexityOperators);
                }
                currentExpression.resetExpressionComplexityOperators();
            }

        } else if (tree.is(SCOPES)) {
            statementLevel.remove(statementLevel.size() - 1);
        }
    }

    private void addIssue(Tree expression, List<SyntaxToken> complexityOperators) {
        int complexity = complexityOperators.size();
        String message = String.format(MESSAGE, complexity, max);

        PreciseIssue issue = addIssue(expression, message);
        for (SyntaxToken complexityOperator : complexityOperators) {
            issue.secondary(complexityOperator, "+1");
        }

        issue.cost((double) complexity - max);
    }

}