001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2017 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;
023import java.util.ArrayDeque;
024import java.util.Deque;
025
026import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
027import com.puppycrawl.tools.checkstyle.api.DetailAST;
028import com.puppycrawl.tools.checkstyle.api.TokenTypes;
029
030/**
031 * Checks cyclomatic complexity against a specified limit. The complexity is
032 * measured by the number of "if", "while", "do", "for", "?:", "catch",
033 * "switch", "case", "&&" and "||" statements (plus one) in the body of
034 * the member. It is a measure of the minimum number of possible paths through
035 * the source and therefore the number of required tests. Generally 1-4 is
036 * considered good, 5-7 ok, 8-10 consider re-factoring, and 11+ re-factor now!
037 *
038 * <p>Check has following properties:
039 *
040 * <p><b>switchBlockAsSingleDecisionPoint</b> - controls whether to treat the whole switch
041 * block as a single decision point. Default value is <b>false</b>
042 *
043 *
044 * @author <a href="mailto:simon@redhillconsulting.com.au">Simon Harris</a>
045 * @author Oliver Burn
046 * @author <a href="mailto:andreyselkin@gmail.com">Andrei Selkin</a>
047 */
048public class CyclomaticComplexityCheck
049    extends AbstractCheck {
050
051    /**
052     * A key is pointing to the warning message text in "messages.properties"
053     * file.
054     */
055    public static final String MSG_KEY = "cyclomaticComplexity";
056
057    /** The initial current value. */
058    private static final BigInteger INITIAL_VALUE = BigInteger.ONE;
059
060    /** Default allowed complexity. */
061    private static final int DEFAULT_COMPLEXITY_VALUE = 10;
062
063    /** Stack of values - all but the current value. */
064    private final Deque<BigInteger> valueStack = new ArrayDeque<>();
065
066    /** Whether to treat the whole switch block as a single decision point.*/
067    private boolean switchBlockAsSingleDecisionPoint;
068
069    /** The current value. */
070    private BigInteger currentValue = INITIAL_VALUE;
071
072    /** Threshold to report error for. */
073    private int max = DEFAULT_COMPLEXITY_VALUE;
074
075    /**
076     * Sets whether to treat the whole switch block as a single decision point.
077     * @param switchBlockAsSingleDecisionPoint whether to treat the whole switch
078     *                                          block as a single decision point.
079     */
080    public void setSwitchBlockAsSingleDecisionPoint(boolean switchBlockAsSingleDecisionPoint) {
081        this.switchBlockAsSingleDecisionPoint = switchBlockAsSingleDecisionPoint;
082    }
083
084    /**
085     * Set the maximum threshold allowed.
086     *
087     * @param max the maximum threshold
088     */
089    public final void setMax(int max) {
090        this.max = max;
091    }
092
093    @Override
094    public int[] getDefaultTokens() {
095        return new int[] {
096            TokenTypes.CTOR_DEF,
097            TokenTypes.METHOD_DEF,
098            TokenTypes.INSTANCE_INIT,
099            TokenTypes.STATIC_INIT,
100            TokenTypes.LITERAL_WHILE,
101            TokenTypes.LITERAL_DO,
102            TokenTypes.LITERAL_FOR,
103            TokenTypes.LITERAL_IF,
104            TokenTypes.LITERAL_SWITCH,
105            TokenTypes.LITERAL_CASE,
106            TokenTypes.LITERAL_CATCH,
107            TokenTypes.QUESTION,
108            TokenTypes.LAND,
109            TokenTypes.LOR,
110        };
111    }
112
113    @Override
114    public int[] getAcceptableTokens() {
115        return new int[] {
116            TokenTypes.CTOR_DEF,
117            TokenTypes.METHOD_DEF,
118            TokenTypes.INSTANCE_INIT,
119            TokenTypes.STATIC_INIT,
120            TokenTypes.LITERAL_WHILE,
121            TokenTypes.LITERAL_DO,
122            TokenTypes.LITERAL_FOR,
123            TokenTypes.LITERAL_IF,
124            TokenTypes.LITERAL_SWITCH,
125            TokenTypes.LITERAL_CASE,
126            TokenTypes.LITERAL_CATCH,
127            TokenTypes.QUESTION,
128            TokenTypes.LAND,
129            TokenTypes.LOR,
130        };
131    }
132
133    @Override
134    public final int[] getRequiredTokens() {
135        return new int[] {
136            TokenTypes.CTOR_DEF,
137            TokenTypes.METHOD_DEF,
138            TokenTypes.INSTANCE_INIT,
139            TokenTypes.STATIC_INIT,
140        };
141    }
142
143    @Override
144    public void visitToken(DetailAST ast) {
145        switch (ast.getType()) {
146            case TokenTypes.CTOR_DEF:
147            case TokenTypes.METHOD_DEF:
148            case TokenTypes.INSTANCE_INIT:
149            case TokenTypes.STATIC_INIT:
150                visitMethodDef();
151                break;
152            default:
153                visitTokenHook(ast);
154        }
155    }
156
157    @Override
158    public void leaveToken(DetailAST ast) {
159        switch (ast.getType()) {
160            case TokenTypes.CTOR_DEF:
161            case TokenTypes.METHOD_DEF:
162            case TokenTypes.INSTANCE_INIT:
163            case TokenTypes.STATIC_INIT:
164                leaveMethodDef(ast);
165                break;
166            default:
167                break;
168        }
169    }
170
171    /**
172     * Hook called when visiting a token. Will not be called the method
173     * definition tokens.
174     *
175     * @param ast the token being visited
176     */
177    protected final void visitTokenHook(DetailAST ast) {
178        if (switchBlockAsSingleDecisionPoint) {
179            if (ast.getType() != TokenTypes.LITERAL_CASE) {
180                incrementCurrentValue(BigInteger.ONE);
181            }
182        }
183        else if (ast.getType() != TokenTypes.LITERAL_SWITCH) {
184            incrementCurrentValue(BigInteger.ONE);
185        }
186    }
187
188    /**
189     * Process the end of a method definition.
190     *
191     * @param ast the token representing the method definition
192     */
193    private void leaveMethodDef(DetailAST ast) {
194        final BigInteger bigIntegerMax = BigInteger.valueOf(max);
195        if (currentValue.compareTo(bigIntegerMax) > 0) {
196            log(ast, MSG_KEY, currentValue, bigIntegerMax);
197        }
198        popValue();
199    }
200
201    /**
202     * Increments the current value by a specified amount.
203     *
204     * @param amount the amount to increment by
205     */
206    protected final void incrementCurrentValue(BigInteger amount) {
207        currentValue = currentValue.add(amount);
208    }
209
210    /** Push the current value on the stack. */
211    protected final void pushValue() {
212        valueStack.push(currentValue);
213        currentValue = INITIAL_VALUE;
214    }
215
216    /**
217     * Pops a value off the stack and makes it the current value.
218     * @return pop a value off the stack and make it the current value
219     */
220    protected final BigInteger popValue() {
221        currentValue = valueStack.pop();
222        return currentValue;
223    }
224
225    /** Process the start of the method definition. */
226    private void visitMethodDef() {
227        pushValue();
228    }
229}