Only support implicit tuples in variable expressionsGH-1194-formal-grammar

They cause super inconsistent parsing behaviour if they show up
pretty much anywhere else because there is no difference between an
implicit tuple and a set of comma-separated parameters.

2 files changed, 26 insertions, 13 deletions

diff --git a/grammar.ebnf b/grammar.ebnf
index 3fef91a..97ede84 100644
--- a/grammar.ebnf
+++ b/grammar.ebnf
@@ -174,7 +174,7 @@ block_parameter_value_only
 

 variable_expression

     =

-    variable_open type:`variable` name:conditional_expression variable_close

+    variable_open type:`variable` name:variable_expression_name variable_close

     ;

 

 variable_open

@@ -199,6 +199,12 @@ variable_close_symbol
     "}}"

     ;

 

+variable_expression_name

+    =

+    | TUPLE_LITERAL

+    | conditional_expression

+    ;

+

 variable_identifier

     =

     | variable_identifier_parentheses

@@ -523,7 +529,7 @@ LITERAL
     | BOOLEAN_LITERAL

     | DICTIONARY_LITERAL

     | LIST_LITERAL

-    | TUPLE_LITERAL

+    | EXPLICIT_TUPLE_LITERAL

     ;

 

 DICTIONARY_LITERAL

@@ -551,28 +557,32 @@ LIST_LITERAL
 

 TUPLE_LITERAL

     =

-    literal_type:`tuple`

-    (

-        | value:EXPLICIT_TUPLE_LITERAL

-        | value:IMPLICIT_TUPLE_LITERAL

-        | EMPTY_TUPLE_LITERAL

-    )

+    | EXPLICIT_TUPLE_LITERAL

+    | IMPLICIT_TUPLE_LITERAL

+    | EMPTY_TUPLE_LITERAL

     ;

 

 EXPLICIT_TUPLE_LITERAL

     =

-    | ( "(" {SP}* @+:LITERAL {SP}* { "," {SP}* @+:LITERAL {SP}* }+ ")" )

-    | ( "(" {SP}* @+:LITERAL {SP}* "," {SP}* ")" )

+    literal_type:`tuple`

+    "(" value:TUPLE_LITERAL_CONTENTS ")"

     ;

 

 IMPLICIT_TUPLE_LITERAL

     =

-    | ( @+:LITERAL {SP}* { "," {SP}* @+:LITERAL {SP}* }+ )

-    | ( @+:LITERAL {SP}* "," {SP}* )

+    literal_type:`tuple`

+    value:TUPLE_LITERAL_CONTENTS

+    ;

+

+TUPLE_LITERAL_CONTENTS

+    =

+    | ( @+:variable_identifier {SP}* { "," {SP}* @+:variable_identifier {SP}* }+ )

+    | ( @+:variable_identifier {SP}* "," {SP}* )

     ;

 

 EMPTY_TUPLE_LITERAL

     =

+    literal_type:`tuple`

     "(" {SP}* ")"

     ;

 

diff --git a/src/jinja2/new_parser.py b/src/jinja2/new_parser.py
index 844f9ae..76051f5 100644
--- a/src/jinja2/new_parser.py
+++ b/src/jinja2/new_parser.py
@@ -564,6 +564,9 @@ def parse_conditional_expression(ast):
     if 'variable' in ast:

         return parse_variable(ast)

 

+    if 'literal_type' in ast:

+        return parse_literal(ast)

+

     if 'concatenate' in ast:

         return parse_concatenate_expression(ast)

 

@@ -806,7 +809,7 @@ def parse_literal(ast):
             ast['value'] = []

 

         items = [

-            parse_literal(item) for item in ast['value']

+            parse_variable(item) for item in ast['value']

         ]

 

         return nodes.Tuple(