Raise IncompleteExpressionError where appropriate

There were a few cases where ParseError was being
raised instead of a more specific IncompleteExpressionError including:

* Missing closing function parens
* Missing closing rbracket for multiselect lists

Author: jamesls

jmespath/exceptions.py

@@ -22,8 +22,8 @@ def __str__(self):
         # self.lex_position +1 to account for the starting double quote char.
         underline = ' ' * (self.lex_position + 1) + '^'
         return (
-            '%s: Parse error at column %s near '
-            'token "%s" (%s) for expression:\n"%s"\n%s' % (
+            '%s: Parse error at column %s, '
+            'token "%s" (%s), for expression:\n"%s"\n%s' % (
                 self.msg, self.lex_position, self.token_value, self.token_type,
                 self.expression, underline))
 

jmespath/parser.py

@@ -427,6 +427,9 @@ def _assert_not_token(self, *token_types):
                 "Token %s not allowed to be: %s" % (actual_type, token_types))
 
     def _error_nud_token(self, token):
+        if token['type'] == 'eof':
+            raise exceptions.IncompleteExpressionError(
+                token['start'], token['value'], token['type'])
         raise exceptions.ParseError(token['start'], token['value'],
                                     token['type'], 'Invalid token.')
 

tests/test_parser.py

@@ -121,8 +121,8 @@ def test_bad_parse(self):
 
     def test_bad_parse_error_message(self):
         error_message = (
-            'Unexpected token: ]: Parse error at column 3 '
-            'near token "]" (RBRACKET) for expression:\n'
+            'Unexpected token: ]: Parse error at column 3, '
+            'token "]" (RBRACKET), for expression:\n'
             '"foo]baz"\n'
             '    ^')
         self.assert_error_message('foo]baz', error_message)
@@ -134,6 +134,13 @@ def test_bad_parse_error_message_with_multiselect(self):
             '                       ^')
         self.assert_error_message('foo.{bar: baz,bar: bar', error_message)
 
+    def test_incomplete_expression_with_missing_paren(self):
+        error_message = (
+            'Invalid jmespath expression: Incomplete expression:\n'
+            '"length(@,"\n'
+            '          ^')
+        self.assert_error_message('length(@,', error_message)
+
     def test_bad_lexer_values(self):
         error_message = (
             'Bad jmespath expression: '