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 * <p> 029 * Restricts nested if-else blocks to a specified depth. 030 * </p> 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 * <p> 039 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 040 * </p> 041 * <p> 042 * Violation Message Keys: 043 * </p> 044 * <ul> 045 * <li> 046 * {@code nested.if.depth} 047 * </li> 048 * </ul> 049 * 050 * @since 3.2 051 */ 052@FileStatefulCheck 053public final class NestedIfDepthCheck extends AbstractCheck { 054 055 /** 056 * A key is pointing to the warning message text in "messages.properties" 057 * file. 058 */ 059 public static final String MSG_KEY = "nested.if.depth"; 060 061 /** Specify maximum allowed nesting depth. */ 062 private int max = 1; 063 /** Current nesting depth. */ 064 private int depth; 065 066 /** 067 * Setter to specify maximum allowed nesting depth. 068 * 069 * @param max maximum allowed nesting depth. 070 * @since 3.2 071 */ 072 public void setMax(int max) { 073 this.max = max; 074 } 075 076 @Override 077 public int[] getDefaultTokens() { 078 return getRequiredTokens(); 079 } 080 081 @Override 082 public int[] getAcceptableTokens() { 083 return getRequiredTokens(); 084 } 085 086 @Override 087 public int[] getRequiredTokens() { 088 return new int[] {TokenTypes.LITERAL_IF}; 089 } 090 091 @Override 092 public void visitToken(DetailAST literalIf) { 093 if (!isElseIf(literalIf)) { 094 if (depth > max) { 095 log(literalIf, MSG_KEY, depth, max); 096 } 097 ++depth; 098 } 099 } 100 101 @Override 102 public void leaveToken(DetailAST literalIf) { 103 if (!isElseIf(literalIf)) { 104 --depth; 105 } 106 } 107 108 /** 109 * Returns whether a token represents an ELSE as part of an ELSE / IF set. 110 * 111 * @param ast the token to check 112 * @return whether it is 113 */ 114 private static boolean isElseIf(DetailAST ast) { 115 final DetailAST parentAST = ast.getParent(); 116 117 return isElse(parentAST) || isElseWithCurlyBraces(parentAST); 118 } 119 120 /** 121 * Returns whether a token represents an ELSE. 122 * 123 * @param ast the token to check 124 * @return whether the token represents an ELSE 125 */ 126 private static boolean isElse(DetailAST ast) { 127 return ast.getType() == TokenTypes.LITERAL_ELSE; 128 } 129 130 /** 131 * Returns whether a token represents an SLIST as part of an ELSE 132 * statement. 133 * 134 * @param ast the token to check 135 * @return whether the toke does represent an SLIST as part of an ELSE 136 */ 137 private static boolean isElseWithCurlyBraces(DetailAST ast) { 138 return ast.getChildCount() == 2 && isElse(ast.getParent()); 139 } 140}