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.coding; 021 022import com.puppycrawl.tools.checkstyle.FileStatefulCheck; 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 * Restricts nested if-else blocks to a specified depth. 030 * </div> 031 * <ul> 032 * <li> 033 * Property {@code max} - Specify maximum allowed nesting depth. 034 * Type is {@code int}. 035 * Default value is {@code 1}. 036 * </li> 037 * </ul> 038 * 039 * <p> 040 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 041 * </p> 042 * 043 * <p> 044 * Violation Message Keys: 045 * </p> 046 * <ul> 047 * <li> 048 * {@code nested.if.depth} 049 * </li> 050 * </ul> 051 * 052 * @since 3.2 053 */ 054@FileStatefulCheck 055public final class NestedIfDepthCheck extends AbstractCheck { 056 057 /** 058 * A key is pointing to the warning message text in "messages.properties" 059 * file. 060 */ 061 public static final String MSG_KEY = "nested.if.depth"; 062 063 /** Specify maximum allowed nesting depth. */ 064 private int max = 1; 065 /** Current nesting depth. */ 066 private int depth; 067 068 /** 069 * Setter to specify maximum allowed nesting depth. 070 * 071 * @param max maximum allowed nesting depth. 072 * @since 3.2 073 */ 074 public void setMax(int max) { 075 this.max = max; 076 } 077 078 @Override 079 public int[] getDefaultTokens() { 080 return getRequiredTokens(); 081 } 082 083 @Override 084 public int[] getAcceptableTokens() { 085 return getRequiredTokens(); 086 } 087 088 @Override 089 public int[] getRequiredTokens() { 090 return new int[] {TokenTypes.LITERAL_IF}; 091 } 092 093 @Override 094 public void visitToken(DetailAST literalIf) { 095 if (!isElseIf(literalIf)) { 096 if (depth > max) { 097 log(literalIf, MSG_KEY, depth, max); 098 } 099 ++depth; 100 } 101 } 102 103 @Override 104 public void leaveToken(DetailAST literalIf) { 105 if (!isElseIf(literalIf)) { 106 --depth; 107 } 108 } 109 110 /** 111 * Returns whether a token represents an ELSE as part of an ELSE / IF set. 112 * 113 * @param ast the token to check 114 * @return whether it is 115 */ 116 private static boolean isElseIf(DetailAST ast) { 117 final DetailAST parentAST = ast.getParent(); 118 119 return isElse(parentAST) || isElseWithCurlyBraces(parentAST); 120 } 121 122 /** 123 * Returns whether a token represents an ELSE. 124 * 125 * @param ast the token to check 126 * @return whether the token represents an ELSE 127 */ 128 private static boolean isElse(DetailAST ast) { 129 return ast.getType() == TokenTypes.LITERAL_ELSE; 130 } 131 132 /** 133 * Returns whether a token represents an SLIST as part of an ELSE 134 * statement. 135 * 136 * @param ast the token to check 137 * @return whether the toke does represent an SLIST as part of an ELSE 138 */ 139 private static boolean isElseWithCurlyBraces(DetailAST ast) { 140 return ast.getChildCount() == 2 && isElse(ast.getParent()); 141 } 142}