Source code

001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2020 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 java.util.ArrayDeque;
023import java.util.Deque;
024import java.util.HashSet;
025import java.util.Set;
026
027import com.puppycrawl.tools.checkstyle.FileStatefulCheck;
028import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
029import com.puppycrawl.tools.checkstyle.api.DetailAST;
030import com.puppycrawl.tools.checkstyle.api.Scope;
031import com.puppycrawl.tools.checkstyle.api.TokenTypes;
032import com.puppycrawl.tools.checkstyle.utils.ScopeUtil;
033
034/**
035 * <p>
036 * Checks that the parts of a class or interface declaration appear in the order
037 * suggested by the
038 * <a href="https://checkstyle.org/styleguides/sun-code-conventions-19990420/CodeConventions.doc2.html#a1852">
039 * Code Conventions for the Java Programming Language</a>.
040 * </p>
041 * <p>
042 * According to
043 * <a href="https://checkstyle.org/styleguides/sun-code-conventions-19990420/CodeConventions.doc2.html#a1852">
044 * Code Conventions for the Java Programming Language</a>, the parts of a class
045 * or interface declaration should appear in the following order:
046 * </p>
047 * <ol>
048 * <li>
049 * Class (static) variables. First the public class variables, then
050 * protected, then package level (no access modifier), and then private.
051 * </li>
052 * <li> Instance variables. First the public class variables, then
053 * protected, then package level (no access modifier), and then private.
054 * </li>
055 * <li> Constructors </li>
056 * <li> Methods </li>
057 * </ol>
058 * <p>
059 * Purpose of <b>ignore*</b> option is to ignore related violations,
060 * however it still impacts on other class members.
061 * </p>
062 * <p>ATTENTION: the check skips class fields which have
063 * <a href="https://docs.oracle.com/javase/specs/jls/se11/html/jls-8.html#jls-8.3.3">
064 * forward references </a> from validation due to the fact that we have Checkstyle's limitations
065 * to clearly detect user intention of fields location and grouping. For example:
066 * </p>
067 * <pre>
068 * public class A {
069 *   private double x = 1.0;
070 *   private double y = 2.0;
071 *   public double slope = x / y; // will be skipped from validation due to forward reference
072 * }
073 * </pre>
074 * <ul>
075 * <li>
076 * Property {@code ignoreConstructors} - control whether to ignore constructors.
077 * Default value is {@code false}.
078 * </li>
079 * <li>
080 * Property {@code ignoreModifiers} - control whether to ignore modifiers (fields, ...).
081 * Default value is {@code false}.
082 * </li>
083 * </ul>
084 * <p>
085 * To configure the check:
086 * </p>
087 * <pre>
088 * &lt;module name=&quot;DeclarationOrder&quot;/&gt;
089 * </pre>
090 * <p>
091 * With default options:
092 * </p>
093 * <pre>
094 * class K {
095 *   int a;
096 *   void m(){}
097 *   K(){}  &lt;-- &quot;Constructor definition in wrong order&quot;
098 *   int b; &lt;-- &quot;Instance variable definition in wrong order&quot;
099 * }
100 * </pre>
101 * <p>
102 * With <b>ignoreConstructors</b> option:
103 * </p>
104 * <pre>
105 * class K {
106 *   int a;
107 *   void m(){}
108 *   K(){}
109 *   int b; &lt;-- &quot;Instance variable definition in wrong order&quot;
110 * }
111 * </pre>
112 * <p>
113 * With <b>ignoreConstructors</b> option and without a method definition in a source class:
114 * </p>
115 * <pre>
116 * class K {
117 *   int a;
118 *   K(){}
119 *   int b; &lt;-- &quot;Instance variable definition in wrong order&quot;
120 * }
121 * </pre>
122 *
123 * @since 3.2
124 */
125@FileStatefulCheck
126public class DeclarationOrderCheck extends AbstractCheck {
127
128    /**
129     * A key is pointing to the warning message text in "messages.properties"
130     * file.
131     */
132    public static final String MSG_CONSTRUCTOR = "declaration.order.constructor";
133
134    /**
135     * A key is pointing to the warning message text in "messages.properties"
136     * file.
137     */
138    public static final String MSG_STATIC = "declaration.order.static";
139
140    /**
141     * A key is pointing to the warning message text in "messages.properties"
142     * file.
143     */
144    public static final String MSG_INSTANCE = "declaration.order.instance";
145
146    /**
147     * A key is pointing to the warning message text in "messages.properties"
148     * file.
149     */
150    public static final String MSG_ACCESS = "declaration.order.access";
151
152    /** State for the VARIABLE_DEF. */
153    private static final int STATE_STATIC_VARIABLE_DEF = 1;
154
155    /** State for the VARIABLE_DEF. */
156    private static final int STATE_INSTANCE_VARIABLE_DEF = 2;
157
158    /** State for the CTOR_DEF. */
159    private static final int STATE_CTOR_DEF = 3;
160
161    /** State for the METHOD_DEF. */
162    private static final int STATE_METHOD_DEF = 4;
163
164    /**
165     * List of Declaration States. This is necessary due to
166     * inner classes that have their own state.
167     */
168    private Deque<ScopeState> scopeStates;
169
170    /** Set of all class field names.*/
171    private Set<String> classFieldNames;
172
173    /** Control whether to ignore constructors. */
174    private boolean ignoreConstructors;
175    /** Control whether to ignore modifiers (fields, ...). */
176    private boolean ignoreModifiers;
177
178    @Override
179    public int[] getDefaultTokens() {
180        return getRequiredTokens();
181    }
182
183    @Override
184    public int[] getAcceptableTokens() {
185        return getRequiredTokens();
186    }
187
188    @Override
189    public int[] getRequiredTokens() {
190        return new int[] {
191            TokenTypes.CTOR_DEF,
192            TokenTypes.METHOD_DEF,
193            TokenTypes.MODIFIERS,
194            TokenTypes.OBJBLOCK,
195            TokenTypes.VARIABLE_DEF,
196        };
197    }
198
199    @Override
200    public void beginTree(DetailAST rootAST) {
201        scopeStates = new ArrayDeque<>();
202        classFieldNames = new HashSet<>();
203    }
204
205    @Override
206    public void visitToken(DetailAST ast) {
207        final int parentType = ast.getParent().getType();
208
209        switch (ast.getType()) {
210            case TokenTypes.OBJBLOCK:
211                scopeStates.push(new ScopeState());
212                break;
213            case TokenTypes.MODIFIERS:
214                if (parentType == TokenTypes.VARIABLE_DEF
215                    && ast.getParent().getParent().getType() == TokenTypes.OBJBLOCK) {
216                    processModifiers(ast);
217                }
218                break;
219            case TokenTypes.CTOR_DEF:
220                if (parentType == TokenTypes.OBJBLOCK) {
221                    processConstructor(ast);
222                }
223                break;
224            case TokenTypes.METHOD_DEF:
225                if (parentType == TokenTypes.OBJBLOCK) {
226                    final ScopeState state = scopeStates.peek();
227                    // nothing can be bigger than method's state
228                    state.currentScopeState = STATE_METHOD_DEF;
229                }
230                break;
231            case TokenTypes.VARIABLE_DEF:
232                if (ScopeUtil.isClassFieldDef(ast)) {
233                    final DetailAST fieldDef = ast.findFirstToken(TokenTypes.IDENT);
234                    classFieldNames.add(fieldDef.getText());
235                }
236                break;
237            default:
238                break;
239        }
240    }
241
242    /**
243     * Processes constructor.
244     * @param ast constructor AST.
245     */
246    private void processConstructor(DetailAST ast) {
247        final ScopeState state = scopeStates.peek();
248        if (state.currentScopeState > STATE_CTOR_DEF) {
249            if (!ignoreConstructors) {
250                log(ast, MSG_CONSTRUCTOR);
251            }
252        }
253        else {
254            state.currentScopeState = STATE_CTOR_DEF;
255        }
256    }
257
258    /**
259     * Processes modifiers.
260     * @param ast ast of Modifiers.
261     */
262    private void processModifiers(DetailAST ast) {
263        final ScopeState state = scopeStates.peek();
264        final boolean isStateValid = processModifiersState(ast, state);
265        processModifiersSubState(ast, state, isStateValid);
266    }
267
268    /**
269     * Process if given modifiers are appropriate in given state
270     * ({@code STATE_STATIC_VARIABLE_DEF}, {@code STATE_INSTANCE_VARIABLE_DEF},
271     * ({@code STATE_CTOR_DEF}, {@code STATE_METHOD_DEF}), if it is
272     * it updates states where appropriate or logs violation.
273     * @param modifierAst modifiers to process
274     * @param state current state
275     * @return true if modifierAst is valid in given state, false otherwise
276     */
277    private boolean processModifiersState(DetailAST modifierAst, ScopeState state) {
278        boolean isStateValid = true;
279        if (modifierAst.findFirstToken(TokenTypes.LITERAL_STATIC) == null) {
280            if (state.currentScopeState > STATE_INSTANCE_VARIABLE_DEF) {
281                isStateValid = false;
282                log(modifierAst, MSG_INSTANCE);
283            }
284            else if (state.currentScopeState == STATE_STATIC_VARIABLE_DEF) {
285                state.declarationAccess = Scope.PUBLIC;
286                state.currentScopeState = STATE_INSTANCE_VARIABLE_DEF;
287            }
288        }
289        else {
290            if (state.currentScopeState > STATE_STATIC_VARIABLE_DEF) {
291                if (!ignoreModifiers
292                        || state.currentScopeState > STATE_INSTANCE_VARIABLE_DEF) {
293                    isStateValid = false;
294                    log(modifierAst, MSG_STATIC);
295                }
296            }
297            else {
298                state.currentScopeState = STATE_STATIC_VARIABLE_DEF;
299            }
300        }
301        return isStateValid;
302    }
303
304    /**
305     * Checks if given modifiers are valid in substate of given
306     * state({@code Scope}), if it is it updates substate or else it
307     * logs violation.
308     * @param modifiersAst modifiers to process
309     * @param state current state
310     * @param isStateValid is main state for given modifiers is valid
311     */
312    private void processModifiersSubState(DetailAST modifiersAst, ScopeState state,
313                                          boolean isStateValid) {
314        final Scope access = ScopeUtil.getScopeFromMods(modifiersAst);
315        if (state.declarationAccess.compareTo(access) > 0) {
316            if (isStateValid
317                    && !ignoreModifiers
318                    && !isForwardReference(modifiersAst.getParent())) {
319                log(modifiersAst, MSG_ACCESS);
320            }
321        }
322        else {
323            state.declarationAccess = access;
324        }
325    }
326
327    /**
328     * Checks whether an identifier references a field which has been already defined in class.
329     * @param fieldDef a field definition.
330     * @return true if an identifier references a field which has been already defined in class.
331     */
332    private boolean isForwardReference(DetailAST fieldDef) {
333        final DetailAST exprStartIdent = fieldDef.findFirstToken(TokenTypes.IDENT);
334        final Set<DetailAST> exprIdents = getAllTokensOfType(exprStartIdent, TokenTypes.IDENT);
335        boolean forwardReference = false;
336        for (DetailAST ident : exprIdents) {
337            if (classFieldNames.contains(ident.getText())) {
338                forwardReference = true;
339                break;
340            }
341        }
342        return forwardReference;
343    }
344
345    /**
346     * Collects all tokens of specific type starting with the current ast node.
347     * @param ast ast node.
348     * @param tokenType token type.
349     * @return a set of all tokens of specific type starting with the current ast node.
350     */
351    private static Set<DetailAST> getAllTokensOfType(DetailAST ast, int tokenType) {
352        DetailAST vertex = ast;
353        final Set<DetailAST> result = new HashSet<>();
354        final Deque<DetailAST> stack = new ArrayDeque<>();
355        while (vertex != null || !stack.isEmpty()) {
356            if (!stack.isEmpty()) {
357                vertex = stack.pop();
358            }
359            while (vertex != null) {
360                if (vertex.getType() == tokenType && !vertex.equals(ast)) {
361                    result.add(vertex);
362                }
363                if (vertex.getNextSibling() != null) {
364                    stack.push(vertex.getNextSibling());
365                }
366                vertex = vertex.getFirstChild();
367            }
368        }
369        return result;
370    }
371
372    @Override
373    public void leaveToken(DetailAST ast) {
374        if (ast.getType() == TokenTypes.OBJBLOCK) {
375            scopeStates.pop();
376        }
377    }
378
379    /**
380     * Setter to control whether to ignore constructors.
381     * @param ignoreConstructors whether to ignore constructors.
382     */
383    public void setIgnoreConstructors(boolean ignoreConstructors) {
384        this.ignoreConstructors = ignoreConstructors;
385    }
386
387    /**
388     * Setter to control whether to ignore modifiers (fields, ...).
389     * @param ignoreModifiers whether to ignore modifiers.
390     */
391    public void setIgnoreModifiers(boolean ignoreModifiers) {
392        this.ignoreModifiers = ignoreModifiers;
393    }
394
395    /**
396     * Private class to encapsulate the state.
397     */
398    private static class ScopeState {
399
400        /** The state the check is in. */
401        private int currentScopeState = STATE_STATIC_VARIABLE_DEF;
402
403        /** The sub-state the check is in. */
404        private Scope declarationAccess = Scope.PUBLIC;
405
406    }
407
408}