com.puppycrawl.tools.checkstyle.meta.checks.coding.UnnecessaryParenthesesCheck.xml Maven / Gradle / Ivy

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<?xml version="1.0" encoding="UTF-8"?>
<checkstyle-metadata>
   <module>
      <check fully-qualified-name="com.puppycrawl.tools.checkstyle.checks.coding.UnnecessaryParenthesesCheck"
             name="UnnecessaryParentheses"
             parent="com.puppycrawl.tools.checkstyle.TreeWalker">
         <description>&lt;p&gt;
 Checks if unnecessary parentheses are used in a statement or expression.
 The check will flag the following with warnings:
 &lt;/p&gt;
 &lt;pre&gt;
 return (x);          // parens around identifier
 return (x + 1);      // parens around return value
 int x = (y / 2 + 1); // parens around assignment rhs
 for (int i = (0); i &amp;lt; 10; i++) {  // parens around literal
 t -= (z + 1);                     // parens around assignment rhs
 boolean a = (x &amp;gt; 7 &amp;amp;&amp;amp; y &amp;gt; 5)      // parens around expression
             || z &amp;lt; 9;
 boolean b = (~a) &amp;gt; -27            // parens around ~a
             &amp;amp;&amp;amp; (a-- &amp;lt; 30);        // parens around expression
 &lt;/pre&gt;
 &lt;p&gt;
 The check is not "type aware", that is to say, it can't tell if parentheses
 are unnecessary based on the types in an expression. The check is partially aware about
 operator precedence but unaware about operator associativity.
 It won't catch cases such as:
 &lt;/p&gt;
 &lt;pre&gt;
 int x = (a + b) + c; // 1st Case
 boolean p = true; // 2nd Case
 int q = 4;
 int r = 3;
 if (p == (q &amp;lt;= r)) {}&lt;/pre&gt;
 &lt;p&gt;
 In the first case, given that &lt;em&gt;a&lt;/em&gt;, &lt;em&gt;b&lt;/em&gt;, and &lt;em&gt;c&lt;/em&gt; are
 all {@code int} variables, the parentheses around {@code a + b}
 are not needed.
 In the second case, parentheses are required as &lt;em&gt;q&lt;/em&gt;, &lt;em&gt;r&lt;/em&gt; are
 of type {@code int} and &lt;em&gt;p&lt;/em&gt; is of type {@code boolean}
 and removing parentheses will give a compile-time error. Even if &lt;em&gt;q&lt;/em&gt;
 and &lt;em&gt;r&lt;/em&gt; were {@code boolean} still there will be no violation
 raised as check is not "type aware".
 &lt;/p&gt;
 &lt;p&gt;
 The partial support for operator precedence includes cases of the following type:
 &lt;/p&gt;
 &lt;pre&gt;
 boolean a = true, b = true;
 boolean c = false, d = false;
 if ((a &amp;amp;&amp;amp; b) || c) { // violation, unnecessary paren
 }
 if (a &amp;amp;&amp;amp; (b || c)) { // ok
 }
 if ((a == b) &amp;amp;&amp;amp; c) { // violation, unnecessary paren
 }
 String e = &amp;quot;e&amp;quot;;
 if ((e instanceof String) &amp;amp;&amp;amp; a || b) { // violation, unnecessary paren
 }
 int f = 0;
 int g = 0;
 if (!(f &amp;gt;= g) // ok
         &amp;amp;&amp;amp; (g &amp;gt; f)) { // violation, unnecessary paren
 }
 if ((++f) &amp;gt; g &amp;amp;&amp;amp; a) { // violation, unnecessary paren
 }
 &lt;/pre&gt;</description>
         <properties>
            <property default-value="EXPR,IDENT,NUM_DOUBLE,NUM_FLOAT,NUM_INT,NUM_LONG,STRING_LITERAL,LITERAL_NULL,LITERAL_FALSE,LITERAL_TRUE,ASSIGN,BAND_ASSIGN,BOR_ASSIGN,BSR_ASSIGN,BXOR_ASSIGN,DIV_ASSIGN,MINUS_ASSIGN,MOD_ASSIGN,PLUS_ASSIGN,SL_ASSIGN,SR_ASSIGN,STAR_ASSIGN,LAMBDA,TEXT_BLOCK_LITERAL_BEGIN,LAND,LOR,LITERAL_INSTANCEOF,GT,LT,GE,LE,EQUAL,NOT_EQUAL,UNARY_MINUS,UNARY_PLUS,INC,DEC,LNOT,BNOT,POST_INC,POST_DEC"
                      name="tokens"
                      type="java.lang.String[]"
                      validation-type="tokenSet">
               <description>tokens to check</description>
            </property>
         </properties>
         <message-keys>
            <message-key key="unnecessary.paren.assign"/>
            <message-key key="unnecessary.paren.expr"/>
            <message-key key="unnecessary.paren.ident"/>
            <message-key key="unnecessary.paren.lambda"/>
            <message-key key="unnecessary.paren.literal"/>
            <message-key key="unnecessary.paren.return"/>
            <message-key key="unnecessary.paren.string"/>
         </message-keys>
      </check>
   </module>
</checkstyle-metadata>