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.util.ArrayDeque;
023import java.util.Deque;
024
025import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
026import com.puppycrawl.tools.checkstyle.api.DetailAST;
027import com.puppycrawl.tools.checkstyle.api.TokenTypes;
028import com.puppycrawl.tools.checkstyle.utils.CheckUtils;
029
030/**
031 * Restricts nested boolean operators (&&, ||, &, | and ^) to
032 * a specified depth (default = 3).
033 * Note: &, | and ^ are not checked if they are part of constructor or
034 * method call because they can be applied to non boolean variables and
035 * Checkstyle does not know types of methods from different classes.
036 *
037 * @author <a href="mailto:simon@redhillconsulting.com.au">Simon Harris</a>
038 * @author o_sukhodolsky
039 */
040public final class BooleanExpressionComplexityCheck extends AbstractCheck {
041
042    /**
043     * A key is pointing to the warning message text in "messages.properties"
044     * file.
045     */
046    public static final String MSG_KEY = "booleanExpressionComplexity";
047
048    /** Default allowed complexity. */
049    private static final int DEFAULT_MAX = 3;
050
051    /** Stack of contexts. */
052    private final Deque<Context> contextStack = new ArrayDeque<>();
053    /** Maximum allowed complexity. */
054    private int max;
055    /** Current context. */
056    private Context context = new Context(false);
057
058    /** Creates new instance of the check. */
059    public BooleanExpressionComplexityCheck() {
060        max = DEFAULT_MAX;
061    }
062
063    @Override
064    public int[] getDefaultTokens() {
065        return new int[] {
066            TokenTypes.CTOR_DEF,
067            TokenTypes.METHOD_DEF,
068            TokenTypes.EXPR,
069            TokenTypes.LAND,
070            TokenTypes.BAND,
071            TokenTypes.LOR,
072            TokenTypes.BOR,
073            TokenTypes.BXOR,
074        };
075    }
076
077    @Override
078    public int[] getRequiredTokens() {
079        return new int[] {
080            TokenTypes.CTOR_DEF,
081            TokenTypes.METHOD_DEF,
082            TokenTypes.EXPR,
083        };
084    }
085
086    @Override
087    public int[] getAcceptableTokens() {
088        return new int[] {
089            TokenTypes.CTOR_DEF,
090            TokenTypes.METHOD_DEF,
091            TokenTypes.EXPR,
092            TokenTypes.LAND,
093            TokenTypes.BAND,
094            TokenTypes.LOR,
095            TokenTypes.BOR,
096            TokenTypes.BXOR,
097        };
098    }
099
100    /**
101     * Getter for maximum allowed complexity.
102     * @return value of maximum allowed complexity.
103     */
104    public int getMax() {
105        return max;
106    }
107
108    /**
109     * Setter for maximum allowed complexity.
110     * @param max new maximum allowed complexity.
111     */
112    public void setMax(int max) {
113        this.max = max;
114    }
115
116    @Override
117    public void visitToken(DetailAST ast) {
118        switch (ast.getType()) {
119            case TokenTypes.CTOR_DEF:
120            case TokenTypes.METHOD_DEF:
121                visitMethodDef(ast);
122                break;
123            case TokenTypes.EXPR:
124                visitExpr();
125                break;
126            case TokenTypes.BOR:
127                if (!isPipeOperator(ast) && !isPassedInParameter(ast)) {
128                    context.visitBooleanOperator();
129                }
130                break;
131            case TokenTypes.BAND:
132            case TokenTypes.BXOR:
133                if (!isPassedInParameter(ast)) {
134                    context.visitBooleanOperator();
135                }
136                break;
137            case TokenTypes.LAND:
138            case TokenTypes.LOR:
139                context.visitBooleanOperator();
140                break;
141            default:
142                throw new IllegalArgumentException("Unknown type: " + ast);
143        }
144    }
145
146    /**
147     * Checks if logical operator is part of constructor or method call.
148     * @param logicalOperator logical operator
149     * @return true if logical operator is part of constructor or method call
150     */
151    private static boolean isPassedInParameter(DetailAST logicalOperator) {
152        return logicalOperator.getParent().getType() == TokenTypes.EXPR
153            && logicalOperator.getParent().getParent().getType() == TokenTypes.ELIST;
154    }
155
156    /**
157     * Checks if {@link TokenTypes#BOR binary OR} is applied to exceptions
158     * in
159     * <a href="http://docs.oracle.com/javase/specs/jls/se8/html/jls-14.html#jls-14.20">
160     * multi-catch</a> (pipe-syntax).
161     * @param binaryOr {@link TokenTypes#BOR binary or}
162     * @return true if binary or is applied to exceptions in multi-catch.
163     */
164    private static boolean isPipeOperator(DetailAST binaryOr) {
165        return binaryOr.getParent().getType() == TokenTypes.TYPE;
166    }
167
168    @Override
169    public void leaveToken(DetailAST ast) {
170        switch (ast.getType()) {
171            case TokenTypes.CTOR_DEF:
172            case TokenTypes.METHOD_DEF:
173                leaveMethodDef();
174                break;
175            case TokenTypes.EXPR:
176                leaveExpr(ast);
177                break;
178            default:
179                // Do nothing
180        }
181    }
182
183    /**
184     * Creates new context for a given method.
185     * @param ast a method we start to check.
186     */
187    private void visitMethodDef(DetailAST ast) {
188        contextStack.push(context);
189        final boolean check = !CheckUtils.isEqualsMethod(ast);
190        context = new Context(check);
191    }
192
193    /** Removes old context. */
194    private void leaveMethodDef() {
195        context = contextStack.pop();
196    }
197
198    /** Creates and pushes new context. */
199    private void visitExpr() {
200        contextStack.push(context);
201        context = new Context(context.isChecking());
202    }
203
204    /**
205     * Restores previous context.
206     * @param ast expression we leave.
207     */
208    private void leaveExpr(DetailAST ast) {
209        context.checkCount(ast);
210        context = contextStack.pop();
211    }
212
213    /**
214     * Represents context (method/expression) in which we check complexity.
215     *
216     * @author <a href="mailto:simon@redhillconsulting.com.au">Simon Harris</a>
217     * @author o_sukhodolsky
218     */
219    private class Context {
220        /**
221         * Should we perform check in current context or not.
222         * Usually false if we are inside equals() method.
223         */
224        private final boolean checking;
225        /** Count of boolean operators. */
226        private int count;
227
228        /**
229         * Creates new instance.
230         * @param checking should we check in current context or not.
231         */
232        Context(boolean checking) {
233            this.checking = checking;
234            count = 0;
235        }
236
237        /**
238         * Getter for checking property.
239         * @return should we check in current context or not.
240         */
241        public boolean isChecking() {
242            return checking;
243        }
244
245        /** Increases operator counter. */
246        public void visitBooleanOperator() {
247            ++count;
248        }
249
250        /**
251         * Checks if we violates maximum allowed complexity.
252         * @param ast a node we check now.
253         */
254        public void checkCount(DetailAST ast) {
255            if (checking && count > getMax()) {
256                final DetailAST parentAST = ast.getParent();
257
258                log(parentAST.getLineNo(), parentAST.getColumnNo(),
259                    MSG_KEY, count, getMax());
260            }
261        }
262    }
263}