Add starlark load statement to grammar

To support starlark files using existing python tooling, we have to transform file load() calls into python import statements.
Adding a load() call to the recoggnized grammar allows us to easily transform the AST node, and support file autocomplete later.

parso/python/grammar26.txt

@@ -139,7 +139,7 @@ dictorsetmaker: test ':' test (',' test ':' test)* [',']
 classdef: 'class' NAME ['(' [testlist] ')'] ':' suite
 
 arglist: (argument ',')* (argument [',']
-                         |'*' test (',' argument)* [',' '**' test] 
+                         |'*' test (',' argument)* [',' '**' test]
                          |'**' test)
 argument: test [gen_for] | test '=' test  # Really [keyword '='] test
 
@@ -157,3 +157,6 @@ testlist1: test (',' test)*
 encoding_decl: NAME
 
 yield_expr: 'yield' [testlist]
+
+import_from_starlark: 'load' '(' STRING ',' starlark_imported_names ')'
+starlark_imported_names: STRING (',' STRING)*

parso/python/grammar27.txt

@@ -121,7 +121,7 @@ dictorsetmaker: ( (test ':' test (sync_comp_for | (',' test ':' test)* [','])) |
 classdef: 'class' NAME ['(' [testlist] ')'] ':' suite
 
 arglist: (argument ',')* (argument [',']
-                         |'*' test (',' argument)* [',' '**' test] 
+                         |'*' test (',' argument)* [',' '**' test]
                          |'**' test)
 # The reason that keywords are test nodes instead of NAME is that using NAME
 # results in an ambiguity. ast.c makes sure it's a NAME.
@@ -141,3 +141,6 @@ testlist1: test (',' test)*
 encoding_decl: NAME
 
 yield_expr: 'yield' [testlist]
+
+import_from_starlark: 'load' '(' STRING ',' starlark_imported_names ')'
+starlark_imported_names: STRING (',' STRING)*

parso/python/grammar33.txt

@@ -118,7 +118,7 @@ dictorsetmaker: ( (test ':' test (sync_comp_for | (',' test ':' test)* [','])) |
 classdef: 'class' NAME ['(' [arglist] ')'] ':' suite
 
 arglist: (argument ',')* (argument [',']
-                         |'*' test (',' argument)* [',' '**' test] 
+                         |'*' test (',' argument)* [',' '**' test]
                          |'**' test)
 # The reason that keywords are test nodes instead of NAME is that using NAME
 # results in an ambiguity. ast.c makes sure it's a NAME.
@@ -132,3 +132,6 @@ encoding_decl: NAME
 
 yield_expr: 'yield' [yield_arg]
 yield_arg: 'from' test | testlist
+
+import_from_starlark: 'load' '(' STRING ',' starlark_imported_names ')'
+starlark_imported_names: STRING (',' STRING)*

parso/python/grammar34.txt

@@ -118,7 +118,7 @@ dictorsetmaker: ( (test ':' test (sync_comp_for | (',' test ':' test)* [','])) |
 classdef: 'class' NAME ['(' [arglist] ')'] ':' suite
 
 arglist: (argument ',')* (argument [',']
-                         |'*' test (',' argument)* [',' '**' test] 
+                         |'*' test (',' argument)* [',' '**' test]
                          |'**' test)
 # The reason that keywords are test nodes instead of NAME is that using NAME
 # results in an ambiguity. ast.c makes sure it's a NAME.
@@ -132,3 +132,6 @@ encoding_decl: NAME
 
 yield_expr: 'yield' [yield_arg]
 yield_arg: 'from' test | testlist
+
+import_from_starlark: 'load' '(' STRING ',' starlark_imported_names ')'
+starlark_imported_names: STRING (',' STRING)*

parso/python/grammar35.txt

@@ -151,3 +151,6 @@ encoding_decl: NAME
 
 yield_expr: 'yield' [yield_arg]
 yield_arg: 'from' test | testlist
+
+import_from_starlark: 'load' '(' STRING ',' starlark_imported_names ')'
+starlark_imported_names: STRING (',' STRING)*

parso/python/grammar36.txt

@@ -156,3 +156,6 @@ fstring_content: FSTRING_STRING | fstring_expr
 fstring_conversion: '!' NAME
 fstring_expr: '{' testlist_comp [ fstring_conversion ] [ fstring_format_spec ] '}'
 fstring_format_spec: ':' fstring_content*
+
+import_from_starlark: 'load' '(' STRING ',' starlark_imported_names ')'
+starlark_imported_names: STRING (',' STRING)*

parso/python/grammar37.txt

@@ -52,7 +52,7 @@ continue_stmt: 'continue'
 return_stmt: 'return' [testlist]
 yield_stmt: yield_expr
 raise_stmt: 'raise' [test ['from' test]]
-import_stmt: import_name | import_from
+import_stmt: import_name | import_from | import_from_starlark
 import_name: 'import' dotted_as_names
 # note below: the ('.' | '...') is necessary because '...' is tokenized as ELLIPSIS
 import_from: ('from' (('.' | '...')* dotted_name | ('.' | '...')+)
@@ -154,3 +154,6 @@ fstring_content: FSTRING_STRING | fstring_expr
 fstring_conversion: '!' NAME
 fstring_expr: '{' testlist [ fstring_conversion ] [ fstring_format_spec ] '}'
 fstring_format_spec: ':' fstring_content*
+
+import_from_starlark: 'load' '(' STRING ',' starlark_imported_names ')'
+starlark_imported_names: STRING (',' STRING)*

parso/python/grammar38.txt

@@ -169,3 +169,6 @@ fstring_content: FSTRING_STRING | fstring_expr
 fstring_conversion: '!' NAME
 fstring_expr: '{' testlist ['='] [ fstring_conversion ] [ fstring_format_spec ] '}'
 fstring_format_spec: ':' fstring_content*
+
+import_from_starlark: 'load' '(' STRING ',' starlark_imported_names ')'
+starlark_imported_names: STRING (',' STRING)*

parso/python/grammar39.txt

@@ -169,3 +169,6 @@ fstring_content: FSTRING_STRING | fstring_expr
 fstring_conversion: '!' NAME
 fstring_expr: '{' testlist ['='] [ fstring_conversion ] [ fstring_format_spec ] '}'
 fstring_format_spec: ':' fstring_content*
+
+import_from_starlark: 'load' '(' STRING ',' starlark_imported_names ')'
+starlark_imported_names: STRING (',' STRING)*

parso/python/pep8.py

@@ -6,7 +6,7 @@
 from parso.python.tree import search_ancestor, Flow, Scope
 
 
-_IMPORT_TYPES = ('import_name', 'import_from')
+_IMPORT_TYPES = ('import_name', 'import_from', 'import_from_starlark')
 _SUITE_INTRODUCERS = ('classdef', 'funcdef', 'if_stmt', 'while_stmt',
                       'for_stmt', 'try_stmt', 'with_stmt')
 _NON_STAR_TYPES = ('term', 'import_from', 'power')

parso/python/tree.py

@@ -60,9 +60,9 @@
 _FUNC_CONTAINERS = set(['suite', 'simple_stmt', 'decorated']) | _FLOW_CONTAINERS
 _GET_DEFINITION_TYPES = set([
     'expr_stmt', 'sync_comp_for', 'with_stmt', 'for_stmt', 'import_name',
-    'import_from', 'param'
+    'import_from', 'import_from_starlark', 'param'
 ])
-_IMPORTS = set(['import_name', 'import_from'])
+_IMPORTS = set(['import_name', 'import_from', 'import_from_starlark'])
 
 
 class DocstringMixin(object):
@@ -352,7 +352,7 @@ def iter_imports(self):
         """
         Returns a generator of `import_name` and `import_from` nodes.
         """
-        return self._search_in_scope('import_name', 'import_from')
+        return self._search_in_scope('import_name', 'import_from', 'import_from_starlark')
 
     def _search_in_scope(self, *names):
         def scan(children):