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Add support for C++17 trailing return types

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This commit is contained in:
Dustin Spicuzza 2021-01-04 21:55:29 -05:00
parent 43431f3fe4
commit 8c9f8fd8ba
4 changed files with 174 additions and 2 deletions
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2
cxxheaderparser/lexer.py
View File

@ -149,6 +149,7 @@ class Lexer:
"DBL_RBRACKET",
"DBL_COLON",
"DBL_AMP",
"ARROW",
"SHIFT_LEFT",
] + list(keywords)
@ -217,6 +218,7 @@ class Lexer:
t_DBL_RBRACKET = r"\]\]"
t_DBL_COLON = r"::"
t_DBL_AMP = r"&&"
t_ARROW = r"->"
t_SHIFT_LEFT = r"<<"
# SHIFT_RIGHT introduces ambiguity

36
cxxheaderparser/parser.py
View File

@ -1515,6 +1515,31 @@ class CxxParser:
return params, vararg
_auto_return_typename = PQName([AutoSpecifier()])
def _parse_trailing_return_type(
self, fn: typing.Union[Function, FunctionType]
) -> None:
# entry is "->"
return_type = fn.return_type
if not (
isinstance(return_type, Type)
and not return_type.const
and not return_type.volatile
and return_type.typename == self._auto_return_typename
):
raise CxxParseError(
f"function with trailing return type must specify return type of 'auto', not {return_type}"
)
parsed_type, mods = self._parse_type(None)
mods.validate(var_ok=False, meth_ok=False, msg="parsing trailing return type")
dtype = self._parse_cv_ptr(parsed_type)
fn.has_trailing_return = True
fn.return_type = dtype
def _parse_fn_end(self, fn: Function) -> None:
"""
Consumes the various keywords after the parameters in a function
@ -1535,6 +1560,8 @@ class CxxParser:
if self.lex.token_if("{"):
self._discard_contents("{", "}")
fn.has_body = True
elif self.lex.token_if("ARROW"):
self._parse_trailing_return_type(fn)
def _parse_method_end(self, method: Method) -> None:
"""
@ -1577,6 +1604,9 @@ class CxxParser:
setattr(method, tok_value, True)
elif tok_value in ("&", "&&"):
method.ref_qualifier = tok_value
elif tok_value == "ARROW":
self._parse_trailing_return_type(method)
break
elif tok_value == "throw":
tok = self._next_token_must_be("(")
method.throw = self._create_value(self._consume_balanced_tokens(tok))
@ -1667,7 +1697,7 @@ class CxxParser:
self.visitor.on_class_method(state, method)
return method.has_body
return method.has_body or method.has_trailing_return
else:
fn = Function(
@ -1682,7 +1712,7 @@ class CxxParser:
self._parse_fn_end(fn)
self.visitor.on_function(state, fn)
return fn.has_body
return fn.has_body or fn.has_trailing_return
#
# Decorated type parsing
@ -1736,6 +1766,8 @@ class CxxParser:
fn_params, vararg = self._parse_parameters()
dtype = FunctionType(dtype, fn_params, vararg)
if self.lex.token_if("ARROW"):
self._parse_trailing_return_type(dtype)
else:
# Check to see if this is a grouping paren or something else

10
cxxheaderparser/types.py
View File

@ -230,6 +230,11 @@ class FunctionType:
#: Set to True if ends with ``...``
vararg: bool = False
#: True if function has a trailing return type (``auto foo() -> int``).
#: In this case, the 'auto' return type is removed and replaced with
#: whatever the trailing return type was
has_trailing_return: bool = False
@dataclass
class Type:
@ -469,6 +474,11 @@ class Function:
#: If true, the body of the function is present
has_body: bool = False
#: True if function has a trailing return type (``auto foo() -> int``).
#: In this case, the 'auto' return type is removed and replaced with
#: whatever the trailing return type was
has_trailing_return: bool = False
template: typing.Optional[TemplateDecl] = None
throw: typing.Optional[Value] = None

128
tests/test_fn.py
View File

@ -585,3 +585,131 @@ def test_fn_return_std_function():
assert data1 == expected
assert data2 == expected
def test_fn_return_std_function_trailing():
content = """
std::function<auto(int)->int> fn();
"""
data = parse_string(content, cleandoc=True)
assert data == ParsedData(
namespace=NamespaceScope(
functions=[
Function(
return_type=Type(
typename=PQName(
segments=[
NameSpecifier(name="std"),
NameSpecifier(
name="function",
specialization=TemplateSpecialization(
args=[
TemplateArgument(
arg=FunctionType(
return_type=Type(
typename=PQName(
segments=[
FundamentalSpecifier(
name="int"
)
]
)
),
parameters=[
Parameter(
type=Type(
typename=PQName(
segments=[
FundamentalSpecifier(
name="int"
)
]
)
)
)
],
has_trailing_return=True,
)
)
]
),
),
]
)
),
name=PQName(segments=[NameSpecifier(name="fn")]),
parameters=[],
)
]
)
)
def test_fn_trailing_return_simple():
content = """
auto fn() -> int;
"""
data = parse_string(content, cleandoc=True)
assert data == ParsedData(
namespace=NamespaceScope(
functions=[
Function(
return_type=Type(
typename=PQName(segments=[FundamentalSpecifier(name="int")])
),
name=PQName(segments=[NameSpecifier(name="fn")]),
parameters=[],
has_trailing_return=True,
)
]
)
)
def test_fn_trailing_return_std_function():
content = """
auto fn() -> std::function<int()>;
"""
data = parse_string(content, cleandoc=True)
assert data == ParsedData(
namespace=NamespaceScope(
functions=[
Function(
return_type=Type(
typename=PQName(
segments=[
NameSpecifier(name="std"),
NameSpecifier(
name="function",
specialization=TemplateSpecialization(
args=[
TemplateArgument(
arg=FunctionType(
return_type=Type(
typename=PQName(
segments=[
FundamentalSpecifier(
name="int"
)
]
)
),
parameters=[],
)
)
]
),
),
]
)
),
name=PQName(segments=[NameSpecifier(name="fn")]),
parameters=[],
has_trailing_return=True,
)
]
)
)