bug #4774 Ensure filters/attributes aren't mistaken for operators (brandonkelly)

This PR was merged into the 3.x branch.

Discussion
----------

Ensure filters/attributes aren't mistaken for operators

Updates the regex in `Lexer::getOperatorRegex()` to account for filters/attributes that have a space between their `|`/`.` operator and the filter/attribute name, to ensure they aren’t mistaken for operators.

A test is included that checks the following template.

```twig
{{ 'foo'|and }}
{{ 'bar' | and }}
{{ foo.and }}
{{ bar . and }}
{{ foo and bar }}
```

(Only the `and` in the last tag should be considered an operator.)

Fixes #4767

Commits
-------

a9ac993938 Ensure filters/attributes aren't mistaken for operators

src/Lexer.php

@@ -544,7 +544,7 @@ class Lexer
 
             // an operator that begins with a character must not have a dot or pipe before
             if (ctype_alpha($expressionParser[0])) {
-                $r = '(?<![\.\|])'.$r;
+                $r = '(?<![\.\|]\s|.[\.\|])'.$r;
             }
 
             // an operator with a space can be any amount of whitespaces

tests/LexerTest.php

@@ -420,6 +420,43 @@ class LexerTest extends TestCase
         $this->addToAssertionCount(1);
     }
 
+    public function testFilterAndAttributeNamedAfterOperator()
+    {
+        // Ensure that filters/attributes aren't mistaken for operators when their names conflict
+        // (see https://github.com/twigphp/Twig/issues/4767)
+        $template = '{{ \'foo\'|and }}'
+            .'{{ \'bar\' | and }}'
+            .'{{ foo.and }}'
+            .'{{ bar . and }}'
+            .'{{ foo and bar }}';
+
+        $lexer = new Lexer(new Environment(new ArrayLoader()));
+        $stream = $lexer->tokenize(new Source($template, 'index'));
+        foreach (['foo', 'bar'] as $value) {
+            $stream->expect(Token::VAR_START_TYPE);
+            $stream->expect(Token::STRING_TYPE, $value);
+            $stream->expect(Token::OPERATOR_TYPE, '|');
+            $stream->expect(Token::NAME_TYPE, 'and');
+            $stream->expect(Token::VAR_END_TYPE);
+        }
+        foreach (['foo', 'bar'] as $value) {
+            $stream->expect(Token::VAR_START_TYPE);
+            $stream->expect(Token::NAME_TYPE, $value);
+            $stream->expect(Token::OPERATOR_TYPE, '.');
+            $stream->expect(Token::NAME_TYPE, 'and');
+            $stream->expect(Token::VAR_END_TYPE);
+        }
+        $stream->expect(Token::VAR_START_TYPE);
+        $stream->expect(Token::NAME_TYPE, 'foo');
+        $stream->expect(Token::OPERATOR_TYPE, 'and');
+        $stream->expect(Token::NAME_TYPE, 'bar');
+        $stream->expect(Token::VAR_END_TYPE);
+
+        // add a dummy assertion here to satisfy PHPUnit, the only thing we want to test is that the code above
+        // can be executed without throwing any exceptions
+        $this->addToAssertionCount(1);
+    }
+
     public function testUnterminatedVariable()
     {
         $template = '