001//////////////////////////////////////////////////////////////////////////////// 002// checkstyle: Checks Java source code for adherence to a set of rules. 003// Copyright (C) 2001-2014 Oliver Burn 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//////////////////////////////////////////////////////////////////////////////// 019package com.puppycrawl.tools.checkstyle.checks.coding; 020 021import com.puppycrawl.tools.checkstyle.api.Check; 022import com.puppycrawl.tools.checkstyle.api.DetailAST; 023import com.puppycrawl.tools.checkstyle.api.TokenTypes; 024import com.puppycrawl.tools.checkstyle.checks.CheckUtils; 025 026/** 027 * <p> 028 * Checks that each variable declaration is in its own statement 029 * and on its own line. 030 * </p> 031 * <p> 032 * Rationale: <a 033 * href="http://java.sun.com/docs/codeconv/html/CodeConventions.doc5.html#2991"> 034 * the SUN Code conventions chapter 6.1</a> recommends that 035 * declarations should be one per line. 036 * </p> 037 * <p> 038 * An example of how to configure the check is: 039 * </p> 040 * <pre> 041 * <module name="MultipleVariableDeclarations"/> 042 * </pre> 043 * @author o_sukhodolsky 044 */ 045public class MultipleVariableDeclarationsCheck extends Check 046{ 047 /** Creates new instance of the check. */ 048 public MultipleVariableDeclarationsCheck() 049 { 050 } 051 052 @Override 053 public int[] getDefaultTokens() 054 { 055 return new int[] {TokenTypes.VARIABLE_DEF}; 056 } 057 058 @Override 059 public void visitToken(DetailAST ast) 060 { 061 DetailAST nextNode = ast.getNextSibling(); 062 final boolean isCommaSeparated = 063 ((nextNode != null) && (nextNode.getType() == TokenTypes.COMMA)); 064 065 if (nextNode == null) { 066 // no next statement - no check 067 return; 068 } 069 070 if ((nextNode.getType() == TokenTypes.COMMA) 071 || (nextNode.getType() == TokenTypes.SEMI)) 072 { 073 nextNode = nextNode.getNextSibling(); 074 } 075 076 if ((nextNode != null) 077 && (nextNode.getType() == TokenTypes.VARIABLE_DEF)) 078 { 079 final DetailAST firstNode = CheckUtils.getFirstNode(ast); 080 if (isCommaSeparated) { 081 // Check if the multiple variable declarations are in a 082 // for loop initializer. If they are, then no warning 083 // should be displayed. Declaring multiple variables in 084 // a for loop initializer is a good way to minimize 085 // variable scope. Refer Feature Request Id - 2895985 086 // for more details 087 if (ast.getParent().getType() != TokenTypes.FOR_INIT) { 088 log(firstNode, "multiple.variable.declarations.comma"); 089 } 090 return; 091 } 092 093 final DetailAST lastNode = getLastNode(ast); 094 final DetailAST firstNextNode = CheckUtils.getFirstNode(nextNode); 095 096 if (firstNextNode.getLineNo() == lastNode.getLineNo()) { 097 log(firstNode, "multiple.variable.declarations"); 098 } 099 } 100 101 } 102 103 /** 104 * Finds sub-node for given node maximum (line, column) pair. 105 * @param node the root of tree for search. 106 * @return sub-node with maximum (line, column) pair. 107 */ 108 private static DetailAST getLastNode(final DetailAST node) 109 { 110 DetailAST currentNode = node; 111 DetailAST child = node.getFirstChild(); 112 while (child != null) { 113 final DetailAST newNode = getLastNode(child); 114 if ((newNode.getLineNo() > currentNode.getLineNo()) 115 || ((newNode.getLineNo() == currentNode.getLineNo()) 116 && (newNode.getColumnNo() > currentNode.getColumnNo()))) 117 { 118 currentNode = newNode; 119 } 120 child = child.getNextSibling(); 121 } 122 123 return currentNode; 124 } 125}