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 * <div> 029 * Checks lambda body length. 030 * </div> 031 * 032 * <p> 033 * Rationale: Similar to anonymous inner classes, if lambda body becomes very long 034 * it is hard to understand and to see the flow of the method 035 * where the lambda is defined. Therefore, long lambda body 036 * should usually be extracted to method. 037 * </p> 038 * <ul> 039 * <li> 040 * Property {@code max} - Specify the maximum number of lines allowed. 041 * Type is {@code int}. 042 * Default value is {@code 10}. 043 * </li> 044 * </ul> 045 * 046 * <p> 047 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 048 * </p> 049 * 050 * <p> 051 * Violation Message Keys: 052 * </p> 053 * <ul> 054 * <li> 055 * {@code maxLen.lambdaBody} 056 * </li> 057 * </ul> 058 * 059 * @since 8.37 060 */ 061@StatelessCheck 062public class LambdaBodyLengthCheck extends AbstractCheck { 063 064 /** 065 * A key is pointing to the warning message text in "messages.properties" 066 * file. 067 */ 068 public static final String MSG_KEY = "maxLen.lambdaBody"; 069 070 /** Default maximum number of lines. */ 071 private static final int DEFAULT_MAX = 10; 072 073 /** Specify the maximum number of lines allowed. */ 074 private int max = DEFAULT_MAX; 075 076 /** 077 * Setter to specify the maximum number of lines allowed. 078 * 079 * @param length the maximum length of lambda body. 080 * @since 8.37 081 */ 082 public void setMax(int length) { 083 max = length; 084 } 085 086 @Override 087 public int[] getDefaultTokens() { 088 return getRequiredTokens(); 089 } 090 091 @Override 092 public int[] getAcceptableTokens() { 093 return getRequiredTokens(); 094 } 095 096 @Override 097 public int[] getRequiredTokens() { 098 return new int[] {TokenTypes.LAMBDA}; 099 } 100 101 @Override 102 public void visitToken(DetailAST ast) { 103 if (ast.getParent().getType() != TokenTypes.SWITCH_RULE) { 104 final int length = getLength(ast); 105 if (length > max) { 106 log(ast, MSG_KEY, length, max); 107 } 108 } 109 } 110 111 /** 112 * Get length of lambda body. 113 * 114 * @param ast lambda body node. 115 * @return length of lambda body. 116 */ 117 private static int getLength(DetailAST ast) { 118 final DetailAST lambdaBody = ast.getLastChild(); 119 final int length; 120 if (lambdaBody.getType() == TokenTypes.SLIST) { 121 length = lambdaBody.getLastChild().getLineNo() - lambdaBody.getLineNo(); 122 } 123 else { 124 length = getLastNodeLineNumber(lambdaBody) - getFirstNodeLineNumber(lambdaBody); 125 } 126 return length + 1; 127 } 128 129 /** 130 * Get last child node in the tree line number. 131 * 132 * @param lambdaBody lambda body node. 133 * @return last child node in the tree line number. 134 */ 135 private static int getLastNodeLineNumber(DetailAST lambdaBody) { 136 DetailAST node = lambdaBody; 137 int result; 138 do { 139 result = node.getLineNo(); 140 node = node.getLastChild(); 141 } while (node != null); 142 return result; 143 } 144 145 /** 146 * Get first child node in the tree line number. 147 * 148 * @param lambdaBody lambda body node. 149 * @return first child node in the tree line number. 150 */ 151 private static int getFirstNodeLineNumber(DetailAST lambdaBody) { 152 DetailAST node = lambdaBody; 153 int result; 154 do { 155 result = node.getLineNo(); 156 node = node.getFirstChild(); 157 } while (node != null); 158 return result; 159 } 160 161}