001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2024 the original author or authors.
004//
005// This library is free software; you can redistribute it and/or
006// modify it under the terms of the GNU Lesser General Public
007// License as published by the Free Software Foundation; either
008// version 2.1 of the License, or (at your option) any later version.
009//
010// This library is distributed in the hope that it will be useful,
011// but WITHOUT ANY WARRANTY; without even the implied warranty of
012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
013// Lesser General Public License for more details.
014//
015// You should have received a copy of the GNU Lesser General Public
016// License along with this library; if not, write to the Free Software
017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
018///////////////////////////////////////////////////////////////////////////////////////////////
019
020package com.puppycrawl.tools.checkstyle.checks.sizes;
021
022import com.puppycrawl.tools.checkstyle.StatelessCheck;
023import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
024import com.puppycrawl.tools.checkstyle.api.DetailAST;
025import com.puppycrawl.tools.checkstyle.api.TokenTypes;
026
027/**
028 * <p>
029 * Checks lambda body length.
030 * </p>
031 * <p>
032 * Rationale: Similar to anonymous inner classes, if lambda body becomes very long
033 * it is hard to understand and to see the flow of the method
034 * where the lambda is defined. Therefore, long lambda body
035 * should usually be extracted to method.
036 * </p>
037 * <ul>
038 * <li>
039 * Property {@code max} - Specify the maximum number of lines allowed.
040 * Type is {@code int}.
041 * Default value is {@code 10}.
042 * </li>
043 * </ul>
044 * <p>
045 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
046 * </p>
047 * <p>
048 * Violation Message Keys:
049 * </p>
050 * <ul>
051 * <li>
052 * {@code maxLen.lambdaBody}
053 * </li>
054 * </ul>
055 *
056 * @since 8.37
057 */
058@StatelessCheck
059public class LambdaBodyLengthCheck extends AbstractCheck {
060
061    /**
062     * A key is pointing to the warning message text in "messages.properties"
063     * file.
064     */
065    public static final String MSG_KEY = "maxLen.lambdaBody";
066
067    /** Default maximum number of lines. */
068    private static final int DEFAULT_MAX = 10;
069
070    /** Specify the maximum number of lines allowed. */
071    private int max = DEFAULT_MAX;
072
073    /**
074     * Setter to specify the maximum number of lines allowed.
075     *
076     * @param length the maximum length of lambda body.
077     * @since 8.37
078     */
079    public void setMax(int length) {
080        max = length;
081    }
082
083    @Override
084    public int[] getDefaultTokens() {
085        return getRequiredTokens();
086    }
087
088    @Override
089    public int[] getAcceptableTokens() {
090        return getRequiredTokens();
091    }
092
093    @Override
094    public int[] getRequiredTokens() {
095        return new int[] {TokenTypes.LAMBDA};
096    }
097
098    @Override
099    public void visitToken(DetailAST ast) {
100        if (ast.getParent().getType() != TokenTypes.SWITCH_RULE) {
101            final int length = getLength(ast);
102            if (length > max) {
103                log(ast, MSG_KEY, length, max);
104            }
105        }
106    }
107
108    /**
109     * Get length of lambda body.
110     *
111     * @param ast lambda body node.
112     * @return length of lambda body.
113     */
114    private static int getLength(DetailAST ast) {
115        final DetailAST lambdaBody = ast.getLastChild();
116        final int length;
117        if (lambdaBody.getType() == TokenTypes.SLIST) {
118            length = lambdaBody.getLastChild().getLineNo() - lambdaBody.getLineNo();
119        }
120        else {
121            length = getLastNodeLineNumber(lambdaBody) - getFirstNodeLineNumber(lambdaBody);
122        }
123        return length + 1;
124    }
125
126    /**
127     * Get last child node in the tree line number.
128     *
129     * @param lambdaBody lambda body node.
130     * @return last child node in the tree line number.
131     */
132    private static int getLastNodeLineNumber(DetailAST lambdaBody) {
133        DetailAST node = lambdaBody;
134        int result;
135        do {
136            result = node.getLineNo();
137            node = node.getLastChild();
138        } while (node != null);
139        return result;
140    }
141
142    /**
143     * Get first child node in the tree line number.
144     *
145     * @param lambdaBody lambda body node.
146     * @return first child node in the tree line number.
147     */
148    private static int getFirstNodeLineNumber(DetailAST lambdaBody) {
149        DetailAST node = lambdaBody;
150        int result;
151        do {
152            result = node.getLineNo();
153            node = node.getFirstChild();
154        } while (node != null);
155        return result;
156    }
157
158}