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.naming;
021
022import java.util.Arrays;
023import java.util.Optional;
024
025import com.puppycrawl.tools.checkstyle.api.DetailAST;
026import com.puppycrawl.tools.checkstyle.api.TokenTypes;
027import com.puppycrawl.tools.checkstyle.utils.CheckUtil;
028import com.puppycrawl.tools.checkstyle.utils.ScopeUtil;
029
030/**
031 * <p>
032 * Checks that method parameter names conform to a specified pattern.
033 * By using {@code accessModifiers} property it is possible
034 * to specify different formats for methods at different visibility levels.
035 * </p>
036 * <p>
037 * To validate {@code catch} parameters please use
038 * <a href="https://checkstyle.org/config_naming.html#CatchParameterName">CatchParameterName</a>.
039 * </p>
040 * <p>
041 * To validate lambda parameters please use
042 * <a href="https://checkstyle.org/config_naming.html#LambdaParameterName">LambdaParameterName</a>.
043 * </p>
044 * <ul>
045 * <li>
046 * Property {@code format} - Specifies valid identifiers.
047 * Type is {@code java.util.regex.Pattern}.
048 * Default value is {@code "^[a-z][a-zA-Z0-9]*$"}.
049 * </li>
050 * <li>
051 * Property {@code ignoreOverridden} - Allows to skip methods with Override annotation from
052 * validation. For example, the following method's parameter will be skipped from validation,
053 * if ignoreOverridden is true:
054 * <pre>
055 * &#64;Override
056 * public boolean equals(Object o) {
057 *   return super.equals(o);
058 * }
059 * </pre>
060 * Type is {@code boolean}.
061 * Default value is {@code false}.
062 * </li>
063 * <li>
064 * Property {@code accessModifiers} - Access modifiers of methods where parameters are
065 * checked.
066 * Type is {@code com.puppycrawl.tools.checkstyle.checks.naming.AccessModifierOption[]}.
067 * Default value is {@code public, protected, package, private}.
068 * </li>
069 * </ul>
070 * <p>
071 * An example of how to configure the check:
072 * </p>
073 * <pre>
074 * &lt;module name=&quot;ParameterName&quot;/&gt;
075 * </pre>
076 * <p>Code Example:</p>
077 * <pre>
078 * class MyClass {
079 *   void method1(int v1) {} // OK
080 *   void method2(int V2) {} // violation, name 'V2' must match pattern '^[a-z][a-zA-Z0-9]*$'
081 * }
082 * </pre>
083 * <p>
084 * An example of how to configure the check for names that begin with
085 * a lower case letter, followed by letters, digits, and underscores:
086 * </p>
087 * <pre>
088 * &lt;module name=&quot;ParameterName&quot;&gt;
089 *   &lt;property name=&quot;format&quot; value=&quot;^[a-z][_a-zA-Z0-9]+$&quot;/&gt;
090 * &lt;/module&gt;
091 * </pre>
092 * <p>Code Example:</p>
093 * <pre>
094 * class MyClass {
095 *   void method1(int v1) {} // OK
096 *   void method2(int v_2) {} // OK
097 *   void method3(int V3) {} // violation, name 'V3' must match pattern '^[a-z][_a-zA-Z0-9]+$'
098 * }
099 * </pre>
100 * <p>
101 * An example of how to configure the check to skip methods with Override annotation from
102 * validation:
103 * </p>
104 * <pre>
105 * &lt;module name=&quot;ParameterName&quot;&gt;
106 *   &lt;property name=&quot;ignoreOverridden&quot; value=&quot;true&quot;/&gt;
107 * &lt;/module&gt;
108 * </pre>
109 * <p>Code Example:</p>
110 * <pre>
111 * class MyClass {
112 *   void method1(int v1) {} // OK
113 *   void method2(int V2) {} // violation, name 'V2' must match pattern '^[a-z][a-zA-Z0-9]*$'
114 *   &#064;Override
115 *   public boolean equals(Object V3) { // OK
116 *       return true;
117 *   }
118 * }
119 * </pre>
120 * <p>
121 * An example of how to configure the check for names that begin with a lower case letter, followed
122 * by letters and digits is:
123 * </p>
124 * <pre>
125 * &lt;module name=&quot;ParameterName&quot;&gt;
126 *   &lt;property name=&quot;format&quot; value=&quot;^[a-z][a-zA-Z0-9]+$&quot;/&gt;
127 * &lt;/module&gt;
128 * </pre>
129 * <p>Code Example:</p>
130 * <pre>
131 * class MyClass {
132 *   void method1(int v1) {} // OK
133 *   void method2(int v_2) {} // violation, name 'v_2' must match pattern '^[a-z][a-zA-Z0-9]+$'
134 *   void method3(int V3) {} // violation, name 'V3' must match pattern '^[a-z][a-zA-Z0-9]+$'
135 * }
136 * </pre>
137 * <p>
138 * The following configuration checks that the parameters always start with two lowercase
139 * characters and, in addition, that public method parameters cannot be one character long:
140 * </p>
141 * <pre>
142 * &lt;module name=&quot;ParameterName&quot;&gt;
143 *   &lt;property name=&quot;format&quot; value=&quot;^[a-z]([a-z0-9][a-zA-Z0-9]*)?$&quot;/&gt;
144 *   &lt;property name=&quot;accessModifiers&quot;
145 *     value=&quot;protected, package, private&quot;/&gt;
146 *   &lt;message key=&quot;name.invalidPattern&quot;
147 *     value=&quot;Parameter name ''{0}'' must match pattern ''{1}''&quot;/&gt;
148 * &lt;/module&gt;
149 * &lt;module name=&quot;ParameterName&quot;&gt;
150 *   &lt;property name=&quot;format&quot; value=&quot;^[a-z][a-z0-9][a-zA-Z0-9]*$&quot;/&gt;
151 *   &lt;property name=&quot;accessModifiers&quot; value=&quot;public&quot;/&gt;
152 *   &lt;message key=&quot;name.invalidPattern&quot;
153 *     value=&quot;Parameter name ''{0}'' must match pattern ''{1}''&quot;/&gt;
154 * &lt;/module&gt;
155 * </pre>
156 * <p>Code Example:</p>
157 * <pre>
158 * class MyClass {
159 *   void method1(int v1) {} // OK
160 *   protected method2(int V2) {} // violation, Parameter name 'V2'
161 *                                // must match pattern '^[a-z]([a-z0-9][a-zA-Z0-9]*)?$'
162 *   private method3(int a) {} // OK
163 *   public method4(int b) {} // violation, Parameter name 'b'
164 *                            // must match pattern '^[a-z][a-z0-9][a-zA-Z0-9]*$'
165 * }
166 * </pre>
167 * <p>
168 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
169 * </p>
170 * <p>
171 * Violation Message Keys:
172 * </p>
173 * <ul>
174 * <li>
175 * {@code name.invalidPattern}
176 * </li>
177 * </ul>
178 *
179 * @since 3.0
180 */
181public class ParameterNameCheck extends AbstractNameCheck {
182
183    /**
184     * Allows to skip methods with Override annotation from validation. For example, the following
185     * method's parameter will be skipped from validation, if ignoreOverridden is true:
186     * <pre>
187     * &#64;Override
188     * public boolean equals(Object o) {
189     *   return super.equals(o);
190     * }
191     * </pre>
192     */
193    private boolean ignoreOverridden;
194
195    /** Access modifiers of methods where parameters are checked. */
196    private AccessModifierOption[] accessModifiers = {
197        AccessModifierOption.PUBLIC,
198        AccessModifierOption.PROTECTED,
199        AccessModifierOption.PACKAGE,
200        AccessModifierOption.PRIVATE,
201    };
202
203    /**
204     * Creates a new {@code ParameterNameCheck} instance.
205     */
206    public ParameterNameCheck() {
207        super("^[a-z][a-zA-Z0-9]*$");
208    }
209
210    /**
211     * Setter to allows to skip methods with Override annotation from validation. For example, the
212     * following method's parameter will be skipped from validation, if ignoreOverridden is true:
213     * <pre>
214     * &#64;Override
215     * public boolean equals(Object o) {
216     *   return super.equals(o);
217     * }
218     * </pre>
219     *
220     * @param ignoreOverridden Flag for skipping methods with Override annotation.
221     */
222    public void setIgnoreOverridden(boolean ignoreOverridden) {
223        this.ignoreOverridden = ignoreOverridden;
224    }
225
226    /**
227     * Setter to access modifiers of methods where parameters are checked.
228     *
229     * @param accessModifiers access modifiers of methods which should be checked.
230     */
231    public void setAccessModifiers(AccessModifierOption... accessModifiers) {
232        this.accessModifiers =
233            Arrays.copyOf(accessModifiers, accessModifiers.length);
234    }
235
236    @Override
237    public int[] getDefaultTokens() {
238        return getRequiredTokens();
239    }
240
241    @Override
242    public int[] getAcceptableTokens() {
243        return getRequiredTokens();
244    }
245
246    @Override
247    public int[] getRequiredTokens() {
248        return new int[] {TokenTypes.PARAMETER_DEF};
249    }
250
251    @Override
252    protected boolean mustCheckName(DetailAST ast) {
253        boolean checkName = true;
254        if (ignoreOverridden && isOverriddenMethod(ast)
255                || ast.getParent().getType() == TokenTypes.LITERAL_CATCH
256                || ast.getParent().getParent().getType() == TokenTypes.LAMBDA
257                || CheckUtil.isReceiverParameter(ast)
258                || !matchAccessModifiers(getAccessModifier(ast))) {
259            checkName = false;
260        }
261        return checkName;
262    }
263
264    /**
265     * Returns the access modifier of the method/constructor at the specified AST. If
266     * the method is in an interface or annotation block, the access modifier is assumed
267     * to be public.
268     *
269     * @param ast the token of the method/constructor.
270     * @return the access modifier of the method/constructor.
271     */
272    private static AccessModifierOption getAccessModifier(final DetailAST ast) {
273        final AccessModifierOption accessModifier;
274
275        if (ScopeUtil.isInInterfaceOrAnnotationBlock(ast)) {
276            accessModifier = AccessModifierOption.PUBLIC;
277        }
278        else {
279            final DetailAST params = ast.getParent();
280            final DetailAST meth = params.getParent();
281            final DetailAST modsToken = meth.findFirstToken(TokenTypes.MODIFIERS);
282            accessModifier = CheckUtil.getAccessModifierFromModifiersToken(modsToken);
283        }
284
285        return accessModifier;
286    }
287
288    /**
289     * Checks whether a method has the correct access modifier to be checked.
290     *
291     * @param accessModifier the access modifier of the method.
292     * @return whether the method matches the expected access modifier.
293     */
294    private boolean matchAccessModifiers(final AccessModifierOption accessModifier) {
295        return Arrays.stream(accessModifiers)
296                .anyMatch(modifier -> modifier == accessModifier);
297    }
298
299    /**
300     * Checks whether a method is annotated with Override annotation.
301     *
302     * @param ast method parameter definition token.
303     * @return true if a method is annotated with Override annotation.
304     */
305    private static boolean isOverriddenMethod(DetailAST ast) {
306        boolean overridden = false;
307
308        final DetailAST parent = ast.getParent().getParent();
309        final Optional<DetailAST> annotation =
310            Optional.ofNullable(parent.getFirstChild().getFirstChild());
311
312        if (annotation.isPresent()) {
313            final Optional<DetailAST> overrideToken =
314                Optional.ofNullable(annotation.get().findFirstToken(TokenTypes.IDENT));
315            if (overrideToken.isPresent() && "Override".equals(overrideToken.get().getText())) {
316                overridden = true;
317            }
318        }
319        return overridden;
320    }
321
322}