[ExpressionLanguage] make a proposal in SyntaxError message

src/Symfony/Component/ExpressionLanguage/Parser.php

@@ -195,13 +195,13 @@ class Parser
                     default:
                         if ('(' === $this->stream->current->value) {
                             if (false === isset($this->functions[$token->value])) {
-                                throw new SyntaxError(sprintf('The function "%s" does not exist', $token->value), $token->cursor, $this->stream->getExpression());
+                                throw new SyntaxError(sprintf('The function "%s" does not exist', $token->value), $token->cursor, $this->stream->getExpression(), $token->value, array_keys($this->functions));
                             }
 
                             $node = new Node\FunctionNode($token->value, $this->parseArguments());
                         } else {
                             if (!in_array($token->value, $this->names, true)) {
-                                throw new SyntaxError(sprintf('Variable "%s" is not valid', $token->value), $token->cursor, $this->stream->getExpression());
+                                throw new SyntaxError(sprintf('Variable "%s" is not valid', $token->value), $token->cursor, $this->stream->getExpression(), $token->value, $this->names);
                             }
 
                             // is the name used in the compiled code different

src/Symfony/Component/ExpressionLanguage/SyntaxError.php

@@ -13,7 +13,7 @@ namespace Symfony\Component\ExpressionLanguage;
 
 class SyntaxError extends \LogicException
 {
-    public function __construct($message, $cursor = 0, $expression = '')
+    public function __construct($message, $cursor = 0, $expression = '', $subject = null, array $proposals = null)
     {
         $message = sprintf('%s around position %d', $message, $cursor);
         if ($expression) {
@@ -21,6 +21,21 @@ class SyntaxError extends \LogicException
         }
         $message .= '.';
 
+        if (null !== $subject && null !== $proposals) {
+            $minScore = INF;
+            foreach ($proposals as $proposal) {
+                $distance = levenshtein($subject, $proposal);
+                if ($distance < $minScore) {
+                    $guess = $proposal;
+                    $minScore = $distance;
+                }
+            }
+
+            if (isset($guess) && $minScore < 3) {
+                $message .= sprintf(' Did you mean "%s"?', $guess);
+            }
+        }
+
         parent::__construct($message);
     }
 }

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

@@ -195,4 +195,16 @@ class ParserTest extends TestCase
             ),
         );
     }
+
+    /**
+     * @expectedException \Symfony\Component\ExpressionLanguage\SyntaxError
+     * @expectedExceptionMessage Did you mean "baz"?
+     */
+    public function testNameProposal()
+    {
+        $lexer = new Lexer();
+        $parser = new Parser(array());
+
+        $parser->parse($lexer->tokenize('foo > bar'), array('foo', 'baz'));
+    }
 }