org.sonar.java.checks.CommentedOutCodeLineCheck.java Source code

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Here is the source code for org.sonar.java.checks.CommentedOutCodeLineCheck.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.checks;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;

import org.apache.commons.lang.StringUtils;
import org.sonar.check.Rule;
import org.sonar.java.RspecKey;
import org.sonar.plugins.java.api.IssuableSubscriptionVisitor;
import org.sonar.plugins.java.api.JavaFileScannerContext;
import org.sonar.plugins.java.api.tree.SyntaxTrivia;
import org.sonar.plugins.java.api.tree.Tree;
import org.sonar.squidbridge.recognizer.CodeRecognizer;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

@Rule(key = "CommentedOutCodeLine")
@RspecKey("S125")
public class CommentedOutCodeLineCheck extends IssuableSubscriptionVisitor {

    private static final double THRESHOLD = 0.9;
    private static final String START_JSNI = "/*-{";
    private static final String END_JSNI = "}-*/";

    private final CodeRecognizer codeRecognizer;

    private List<SyntaxTrivia> comments;

    public CommentedOutCodeLineCheck() {
        codeRecognizer = new CodeRecognizer(THRESHOLD, new JavaFootprint());
    }

    @Override
    public List<Tree.Kind> nodesToVisit() {
        return ImmutableList.of(Tree.Kind.TRIVIA);
    }

    @Override
    public void scanFile(JavaFileScannerContext context) {
        comments = Lists.newArrayList();
        super.scanFile(context);
        leaveFile();
    }

    @Override
    public void visitTrivia(SyntaxTrivia syntaxTrivia) {
        if (!isHeader(syntaxTrivia) && !isJavadoc(syntaxTrivia.comment()) && !isJSNI(syntaxTrivia.comment())) {
            comments.add(syntaxTrivia);
        }
    }

    /**
     * We assume that comment on a first line - is a header with license.
     * However possible to imagine corner case: file may contain commented-out code starting from first line.
     * But we assume that probability of this is really low.
     */
    private static boolean isHeader(SyntaxTrivia syntaxTrivia) {
        return syntaxTrivia.startLine() == 1;
    }

    /**
     * Detects commented-out code in remaining candidates.
     */
    private void leaveFile() {
        List<Integer> commentedOutCodeLines = Lists.newArrayList();
        for (SyntaxTrivia syntaxTrivia : comments) {
            commentedOutCodeLines.addAll(handleCommentsForTrivia(syntaxTrivia));
        }

        // Greedy algorithm to split lines on blocks and to report only one violation per block
        Collections.sort(commentedOutCodeLines);
        int prev = Integer.MIN_VALUE;
        for (Integer commentedOutCodeLine : commentedOutCodeLines) {
            if (prev + 1 < commentedOutCodeLine) {
                addIssue(commentedOutCodeLine, "This block of commented-out lines of code should be removed.");
            }
            prev = commentedOutCodeLine;
        }

        comments = null;
    }

    private List<Integer> handleCommentsForTrivia(SyntaxTrivia syntaxTrivia) {
        List<Integer> commentedOutCodeLines = new ArrayList<>();
        String[] lines = syntaxTrivia.comment().split("\r\n?|\n");
        for (int i = 0; i < lines.length; i++) {
            if (codeRecognizer.isLineOfCode(lines[i])) {
                // Mark all remaining lines from this comment as a commented out lines of code
                for (int j = i; j < lines.length; j++) {
                    commentedOutCodeLines.add(syntaxTrivia.startLine() + j);
                }
                break;
            }
        }
        return commentedOutCodeLines;
    }

    /**
     * From documentation for Javadoc-tool:
     * Documentation comments should be recognized only when placed
     * immediately before class, interface, constructor, method, or field declarations.
     */
    private static boolean isJavadoc(String comment) {
        return StringUtils.startsWith(comment, "/**");
    }

    /**
     * From GWT documentation:
     * JSNI methods are declared native and contain JavaScript code in a specially formatted comment block
     * between the end of the parameter list and the trailing semicolon.
     * A JSNI comment block begins with the exact token {@link #START_JSNI} and ends with the exact token {@link #END_JSNI}.
     */
    private static boolean isJSNI(String comment) {
        return StringUtils.startsWith(comment, START_JSNI) && StringUtils.endsWith(comment, END_JSNI);
    }

}