Add Branch defintion

Signed-off-by: Michael Carlstrom <[email protected]>

rosidl_parser/rosidl_parser/definition.py

@@ -17,6 +17,7 @@
 from typing import Final
 from typing import Iterable
 from typing import List
+from typing import Literal
 from typing import Optional
 from typing import Set
 from typing import Tuple
@@ -95,7 +96,7 @@
 )
 
 if TYPE_CHECKING:
-    from typing import Literal, TypeAlias
+    from typing_extensions import TypeAlias
     SignedNonexplicitIntegerTypeValues = Literal['short', 'long', 'long long']
     UnsignedNonexplicitIntegerTypeValues = Literal['unsigned short', 'unsigned long',
                                                    'unsigned long long']

rosidl_parser/rosidl_parser/parser.py

@@ -27,7 +27,6 @@
 
 from lark import Lark
 from lark.lexer import Token
-from lark.tree import Branch
 from lark.tree import ParseTree
 from lark.tree import pydot__tree_to_png
 from lark.tree import Tree
@@ -65,8 +64,20 @@
 from rosidl_parser.definition import ValueType
 
 if TYPE_CHECKING:
+    from typing_extensions import TypeAlias
+    from typing import TypeVar
+
+    # Definition taken from lark.tree to here since rhel's lark version does not have Branch.
+    _Leaf_T = TypeVar('_Leaf_T')
+    Branch: 'TypeAlias' = Union[_Leaf_T, 'Tree[_Leaf_T]']
+
     from rosidl_parser.definition import BasicTypeValues
 
+try:
+    from lark.tree import Branch
+except ImportError:
+    pass
+
 
 AbstractTypeAlias = Union[AbstractNestableType, BasicType, BoundedSequence, UnboundedSequence]
 
@@ -326,8 +337,8 @@ def get_child_identifier_value(tree: ParseTree) -> Any:
     return None
 
 
-def _find_tokens(token_type: Optional[Literal['IDENTIFIER']]) -> Callable[[Branch[Token]], bool]:
-    def find(t: Branch[Token]) -> bool:
+def _find_tokens(token_type: Optional[Literal['IDENTIFIER']]) -> Callable[['Branch[Token]'], bool]:
+    def find(t: 'Branch[Token]') -> bool:
         if isinstance(t, Token):
             if token_type is None or t.type == token_type:
                 return True
@@ -461,7 +472,7 @@ def get_abstract_type_from_type_spec(type_spec: ParseTree) -> AbstractTypeAlias:
     return get_abstract_type(child)
 
 
-def get_abstract_type(tree: Branch[Token]) -> AbstractTypeAlias:
+def get_abstract_type(tree: 'Branch[Token]') -> AbstractTypeAlias:
     assert isinstance(tree, Tree)
     if 'simple_type_spec' == tree.data:
         assert len(tree.children) == 1
@@ -590,7 +601,7 @@ def get_annotations(tree: ParseTree) -> List[Annotation]:
     return annotations
 
 
-def get_const_expr_value(const_expr: Branch[Token]) -> Union[str, int, float, bool]:
+def get_const_expr_value(const_expr: 'Branch[Token]') -> Union[str, int, float, bool]:
     assert isinstance(const_expr, Tree)
     # TODO support arbitrary expressions
     expr = list(const_expr.find_data('primary_expr'))
@@ -694,7 +705,8 @@ def get_string_literals_value(string_literals: ParseTree, *, allow_unicode: bool
     return value
 
 
-def get_string_literal_value(string_literal: Branch[Token], *, allow_unicode: bool = False) -> str:
+def get_string_literal_value(string_literal: 'Branch[Token]', *,
+                             allow_unicode: bool = False) -> str:
     assert isinstance(string_literal, Tree)
     if len(string_literal.children) == 0:
         return ''