MethodBodyCommentsCheck.java

/*
 * SPDX-FileCopyrightText: Copyright (c) 2011-2025 Yegor Bugayenko
 * SPDX-License-Identifier: MIT
 */
package com.qulice.checkstyle;

import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import java.util.Arrays;

/**
 * Checks method bodies for comments. All comments in method bodies are
 * prohibited.
 *
 * <p>We believe that in-code comments and empty lines are evil. If you
 * need to use
 * a comment inside a method - your code needs refactoring. Either move that
 * comment to a method javadoc block or add a logging mechanism with the same
 * text.
 *
 * @since 0.3
 * @todo #260 Add handling of multiple anonymous classes inside methods by
 *  looking at the recursive tree.
 */
public final class MethodBodyCommentsCheck extends AbstractCheck {

    @Override
    public int[] getDefaultTokens() {
        return new int[] {
            TokenTypes.CTOR_DEF,
            TokenTypes.METHOD_DEF,
        };
    }

    @Override
    public int[] getAcceptableTokens() {
        return this.getDefaultTokens();
    }

    @Override
    public int[] getRequiredTokens() {
        return this.getDefaultTokens();
    }

    @Override
    public void visitToken(final DetailAST ast) {
        final DetailAST start = ast.findFirstToken(TokenTypes.SLIST);
        final String[] lines = Arrays.copyOf(
            this.getLines(), this.getLines().length
        );
        if (start != null) {
            DetailAST ostart = start.findFirstToken(TokenTypes.VARIABLE_DEF);
            final int[] tokens = {
                TokenTypes.ASSIGN, TokenTypes.EXPR,
                TokenTypes.LITERAL_NEW, TokenTypes.OBJBLOCK,
            };
            for (final int token : tokens) {
                if (ostart != null) {
                    ostart = ostart.findFirstToken(token);
                }
            }
            if (ostart != null
                && ostart.getType() == tokens[tokens.length - 1]) {
                Arrays.fill(
                    lines, ostart.getLineNo(),
                    ostart.findFirstToken(TokenTypes.RCURLY).getLineNo(), ""
                );
            }
            this.checkMethod(
                lines,
                start.getLineNo(),
                start.findFirstToken(TokenTypes.RCURLY).getLineNo() - 1
            );
        }
    }

    /**
     * Checks method body for comments.
     * @param lines Array of lines, containing code to check.
     * @param start Start line of the method body.
     * @param end End line of the method body.
     */
    private void checkMethod(final String[] lines, final int start,
        final int end) {
        final boolean oneliner = start == end - 1;
        for (int pos = start; pos < end; ++pos) {
            final String line = lines[pos].trim();
            if (line.startsWith("//") || line.startsWith("/*")) {
                final String comment = line.substring(2).trim();
                if (!comment.startsWith("@checkstyle") && !oneliner) {
                    this.log(pos + 1, "Comments in method body are prohibited");
                }
            }
        }
    }
}