001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2015 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.metrics;
021
022import java.math.BigInteger;
023
024import com.puppycrawl.tools.checkstyle.api.DetailAST;
025import com.puppycrawl.tools.checkstyle.api.TokenTypes;
026
027/**
028 * Checks the npath complexity against a specified limit (default = 200).
029 * The npath metric computes the number of possible execution paths
030 * through a function. Similar to the cyclomatic complexity but also
031 * takes into account the nesting of conditional statements and
032 * multi-part boolean expressions.
033 *
034 * @author <a href="mailto:simon@redhillconsulting.com.au">Simon Harris</a>
035 * @author o_sukhodolsky
036 */
037public final class NPathComplexityCheck extends AbstractComplexityCheck {
038
039    /**
040     * A key is pointing to the warning message text in "messages.properties"
041     * file.
042     */
043    public static final String MSG_KEY = "npathComplexity";
044
045    /** Default allowed complexity. */
046    private static final int DEFAULT_MAX = 200;
047
048    /** Creates new instance of the check. */
049    public NPathComplexityCheck() {
050        super(DEFAULT_MAX);
051    }
052
053    @Override
054    public int[] getDefaultTokens() {
055        return new int[] {
056            TokenTypes.CTOR_DEF,
057            TokenTypes.METHOD_DEF,
058            TokenTypes.STATIC_INIT,
059            TokenTypes.INSTANCE_INIT,
060            TokenTypes.LITERAL_WHILE,
061            TokenTypes.LITERAL_DO,
062            TokenTypes.LITERAL_FOR,
063            TokenTypes.LITERAL_IF,
064            TokenTypes.LITERAL_ELSE,
065            TokenTypes.LITERAL_SWITCH,
066            TokenTypes.LITERAL_CASE,
067            TokenTypes.LITERAL_TRY,
068            TokenTypes.LITERAL_CATCH,
069            TokenTypes.QUESTION,
070        };
071    }
072
073    @Override
074    public int[] getAcceptableTokens() {
075        return new int[] {
076            TokenTypes.CTOR_DEF,
077            TokenTypes.METHOD_DEF,
078            TokenTypes.STATIC_INIT,
079            TokenTypes.INSTANCE_INIT,
080            TokenTypes.LITERAL_WHILE,
081            TokenTypes.LITERAL_DO,
082            TokenTypes.LITERAL_FOR,
083            TokenTypes.LITERAL_IF,
084            TokenTypes.LITERAL_ELSE,
085            TokenTypes.LITERAL_SWITCH,
086            TokenTypes.LITERAL_CASE,
087            TokenTypes.LITERAL_TRY,
088            TokenTypes.LITERAL_CATCH,
089            TokenTypes.QUESTION,
090        };
091    }
092
093    @Override
094    public void visitToken(DetailAST ast) {
095        switch (ast.getType()) {
096            case TokenTypes.LITERAL_WHILE:
097            case TokenTypes.LITERAL_DO:
098            case TokenTypes.LITERAL_FOR:
099            case TokenTypes.LITERAL_IF:
100            case TokenTypes.QUESTION:
101            case TokenTypes.LITERAL_TRY:
102            case TokenTypes.LITERAL_SWITCH:
103                visitMultiplyingConditional();
104                break;
105            case TokenTypes.LITERAL_ELSE:
106            case TokenTypes.LITERAL_CATCH:
107            case TokenTypes.LITERAL_CASE:
108                visitAddingConditional();
109                break;
110            default:
111                super.visitToken(ast);
112        }
113    }
114
115    @Override
116    public void leaveToken(DetailAST ast) {
117        switch (ast.getType()) {
118            case TokenTypes.LITERAL_WHILE:
119            case TokenTypes.LITERAL_DO:
120            case TokenTypes.LITERAL_FOR:
121            case TokenTypes.LITERAL_IF:
122            case TokenTypes.QUESTION:
123            case TokenTypes.LITERAL_TRY:
124            case TokenTypes.LITERAL_SWITCH:
125                leaveMultiplyingConditional();
126                break;
127            case TokenTypes.LITERAL_ELSE:
128            case TokenTypes.LITERAL_CATCH:
129            case TokenTypes.LITERAL_CASE:
130                leaveAddingConditional();
131                break;
132            default:
133                super.leaveToken(ast);
134        }
135    }
136
137    @Override
138    protected String getMessageID() {
139        return MSG_KEY;
140    }
141
142    /** Visits else, catch or case. */
143    private void visitAddingConditional() {
144        pushValue();
145    }
146
147    /** Leaves else, catch or case. */
148    private void leaveAddingConditional() {
149        setCurrentValue(
150                getCurrentValue().subtract(BigInteger.ONE).add(popValue()));
151    }
152
153    /** Visits while, do, for, if, try, ? (in ?::) or switch. */
154    private void visitMultiplyingConditional() {
155        pushValue();
156    }
157
158    /** Leaves while, do, for, if, try, ? (in ?::) or switch. */
159    private void leaveMultiplyingConditional() {
160        setCurrentValue(
161                getCurrentValue().add(BigInteger.ONE).multiply(popValue()));
162    }
163}