[ExpressionLanguage] fixed issues when parsing postfix expressions

Exception shall be thrown when parsing the following expressions:

foo."#", foo."bar", foo.**, foo.123

The original parser didn't throw exception for foo."#", foo.** and
foo.123

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

src/Symfony/Component/ExpressionLanguage/Parser.php

@@ -314,12 +314,20 @@ public function parsePostfixExpression($node)
                 if (
                     $token->type !== Token::NAME_TYPE
                     &&
-                    $token->type !== Token::NUMBER_TYPE
-                    &&
-                    // operators line "not" are valid method or property names
-                    ($token->type !== Token::OPERATOR_TYPE && preg_match('/[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*/A', $token->value))
+                    // Operators like "not" and "matches" are valid method or property names,
+                    //
+                    // In other words, besides NAME_TYPE, OPERATOR_TYPE could also be parsed as a property or method.
+                    // This is because operators are processed by the lexer prior to names. So "not" in "foo.not()" or "matches" in "foo.matches" will be recognized as an operator first.
+                    // But in fact, "not" and "matches" in such expressions shall be parsed as method or property names.
+                    //
+                    // And this ONLY works if the operator consists of valid characters for a property or method name.
+                    //
+                    // Other types, such as STRING_TYPE and NUMBER_TYPE, can't be parsed as property nor method names.
+                    //
+                    // As a result, if $token is NOT an operator OR $token->value is NOT a valid property or method name, an exception shall be thrown.
+                    ($token->type !== Token::OPERATOR_TYPE || !preg_match('/[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*/A', $token->value))
                 ) {
-                    throw new SyntaxError('Expected name or number', $token->cursor);
+                    throw new SyntaxError('Expected name', $token->cursor);
                 }
 
                 $arg = new Node\ConstantNode($token->value);

src/Symfony/Component/ExpressionLanguage/Tests/ParserTest.php

@@ -161,4 +161,37 @@ private function createGetAttrNode($node, $item, $type)
     {
         return new Node\GetAttrNode($node, new Node\ConstantNode($item), new Node\ArgumentsNode(), $type);
     }
+
+    /**
+     * @dataProvider getInvalidPostfixData
+     * @expectedException \Symfony\Component\ExpressionLanguage\SyntaxError
+     */
+    public function testParseWithInvalidPostfixData($expr, $names = array())
+    {
+        $lexer = new Lexer();
+        $parser = new Parser(array());
+        $parser->parse($lexer->tokenize($expr), $names);
+    }
+
+    public function getInvalidPostfixData()
+    {
+        return array(
+            array(
+                'foo."#"',
+                array('foo'),
+            ),
+            array(
+                'foo."bar"',
+                array('foo'),
+            ),
+            array(
+                'foo.**',
+                array('foo'),
+            ),
+            array(
+                'foo.123',
+                array('foo'),
+            ),
+        );
+    }
 }