Current File : //lib/python3/dist-packages/mypy/semanal_enum.py
"""Semantic analysis of call-based Enum definitions.
This is conceptually part of mypy.semanal (semantic analyzer pass 2).
"""
from typing import List, Tuple, Optional, Union, cast
from typing_extensions import Final
from mypy.nodes import (
Expression, Context, TypeInfo, AssignmentStmt, NameExpr, CallExpr, RefExpr, StrExpr,
UnicodeExpr, TupleExpr, ListExpr, DictExpr, Var, SymbolTableNode, MDEF, ARG_POS,
ARG_NAMED, EnumCallExpr, MemberExpr
)
from mypy.semanal_shared import SemanticAnalyzerInterface
from mypy.options import Options
from mypy.types import get_proper_type, LiteralType, ENUM_REMOVED_PROPS
# Note: 'enum.EnumMeta' is deliberately excluded from this list. Classes that directly use
# enum.EnumMeta do not necessarily automatically have the 'name' and 'value' attributes.
ENUM_BASES: Final = frozenset((
'enum.Enum', 'enum.IntEnum', 'enum.Flag', 'enum.IntFlag', 'enum.StrEnum',
))
ENUM_SPECIAL_PROPS: Final = frozenset((
'name', 'value', '_name_', '_value_', *ENUM_REMOVED_PROPS,
# Also attributes from `object`:
'__module__', '__annotations__', '__doc__', '__slots__', '__dict__',
))
class EnumCallAnalyzer:
def __init__(self, options: Options, api: SemanticAnalyzerInterface) -> None:
self.options = options
self.api = api
def process_enum_call(self, s: AssignmentStmt, is_func_scope: bool) -> bool:
"""Check if s defines an Enum; if yes, store the definition in symbol table.
Return True if this looks like an Enum definition (but maybe with errors),
otherwise return False.
"""
if len(s.lvalues) != 1 or not isinstance(s.lvalues[0], (NameExpr, MemberExpr)):
return False
lvalue = s.lvalues[0]
name = lvalue.name
enum_call = self.check_enum_call(s.rvalue, name, is_func_scope)
if enum_call is None:
return False
if isinstance(lvalue, MemberExpr):
self.fail("Enum type as attribute is not supported", lvalue)
return False
# Yes, it's a valid Enum definition. Add it to the symbol table.
self.api.add_symbol(name, enum_call, s)
return True
def check_enum_call(self,
node: Expression,
var_name: str,
is_func_scope: bool) -> Optional[TypeInfo]:
"""Check if a call defines an Enum.
Example:
A = enum.Enum('A', 'foo bar')
is equivalent to:
class A(enum.Enum):
foo = 1
bar = 2
"""
if not isinstance(node, CallExpr):
return None
call = node
callee = call.callee
if not isinstance(callee, RefExpr):
return None
fullname = callee.fullname
if fullname not in ENUM_BASES:
return None
items, values, ok = self.parse_enum_call_args(call, fullname.split('.')[-1])
if not ok:
# Error. Construct dummy return value.
info = self.build_enum_call_typeinfo(var_name, [], fullname, node.line)
else:
name = cast(Union[StrExpr, UnicodeExpr], call.args[0]).value
if name != var_name or is_func_scope:
# Give it a unique name derived from the line number.
name += '@' + str(call.line)
info = self.build_enum_call_typeinfo(name, items, fullname, call.line)
# Store generated TypeInfo under both names, see semanal_namedtuple for more details.
if name != var_name or is_func_scope:
self.api.add_symbol_skip_local(name, info)
call.analyzed = EnumCallExpr(info, items, values)
call.analyzed.set_line(call.line, call.column)
info.line = node.line
return info
def build_enum_call_typeinfo(self, name: str, items: List[str], fullname: str,
line: int) -> TypeInfo:
base = self.api.named_type_or_none(fullname)
assert base is not None
info = self.api.basic_new_typeinfo(name, base, line)
info.metaclass_type = info.calculate_metaclass_type()
info.is_enum = True
for item in items:
var = Var(item)
var.info = info
var.is_property = True
var._fullname = '{}.{}'.format(info.fullname, item)
info.names[item] = SymbolTableNode(MDEF, var)
return info
def parse_enum_call_args(self, call: CallExpr,
class_name: str) -> Tuple[List[str],
List[Optional[Expression]], bool]:
"""Parse arguments of an Enum call.
Return a tuple of fields, values, was there an error.
"""
args = call.args
if not all([arg_kind in [ARG_POS, ARG_NAMED] for arg_kind in call.arg_kinds]):
return self.fail_enum_call_arg("Unexpected arguments to %s()" % class_name, call)
if len(args) < 2:
return self.fail_enum_call_arg("Too few arguments for %s()" % class_name, call)
if len(args) > 6:
return self.fail_enum_call_arg("Too many arguments for %s()" % class_name, call)
valid_name = [None, 'value', 'names', 'module', 'qualname', 'type', 'start']
for arg_name in call.arg_names:
if arg_name not in valid_name:
self.fail_enum_call_arg('Unexpected keyword argument "{}"'.format(arg_name), call)
value, names = None, None
for arg_name, arg in zip(call.arg_names, args):
if arg_name == 'value':
value = arg
if arg_name == 'names':
names = arg
if value is None:
value = args[0]
if names is None:
names = args[1]
if not isinstance(value, (StrExpr, UnicodeExpr)):
return self.fail_enum_call_arg(
"%s() expects a string literal as the first argument" % class_name, call)
items = []
values: List[Optional[Expression]] = []
if isinstance(names, (StrExpr, UnicodeExpr)):
fields = names.value
for field in fields.replace(',', ' ').split():
items.append(field)
elif isinstance(names, (TupleExpr, ListExpr)):
seq_items = names.items
if all(isinstance(seq_item, (StrExpr, UnicodeExpr)) for seq_item in seq_items):
items = [cast(Union[StrExpr, UnicodeExpr], seq_item).value
for seq_item in seq_items]
elif all(isinstance(seq_item, (TupleExpr, ListExpr))
and len(seq_item.items) == 2
and isinstance(seq_item.items[0], (StrExpr, UnicodeExpr))
for seq_item in seq_items):
for seq_item in seq_items:
assert isinstance(seq_item, (TupleExpr, ListExpr))
name, value = seq_item.items
assert isinstance(name, (StrExpr, UnicodeExpr))
items.append(name.value)
values.append(value)
else:
return self.fail_enum_call_arg(
"%s() with tuple or list expects strings or (name, value) pairs" %
class_name,
call)
elif isinstance(names, DictExpr):
for key, value in names.items:
if not isinstance(key, (StrExpr, UnicodeExpr)):
return self.fail_enum_call_arg(
"%s() with dict literal requires string literals" % class_name, call)
items.append(key.value)
values.append(value)
elif isinstance(args[1], RefExpr) and isinstance(args[1].node, Var):
proper_type = get_proper_type(args[1].node.type)
if (proper_type is not None
and isinstance(proper_type, LiteralType)
and isinstance(proper_type.value, str)):
fields = proper_type.value
for field in fields.replace(',', ' ').split():
items.append(field)
elif args[1].node.is_final and isinstance(args[1].node.final_value, str):
fields = args[1].node.final_value
for field in fields.replace(',', ' ').split():
items.append(field)
else:
return self.fail_enum_call_arg(
"%s() expects a string, tuple, list or dict literal as the second argument" %
class_name,
call)
else:
# TODO: Allow dict(x=1, y=2) as a substitute for {'x': 1, 'y': 2}?
return self.fail_enum_call_arg(
"%s() expects a string, tuple, list or dict literal as the second argument" %
class_name,
call)
if len(items) == 0:
return self.fail_enum_call_arg("%s() needs at least one item" % class_name, call)
if not values:
values = [None] * len(items)
assert len(items) == len(values)
return items, values, True
def fail_enum_call_arg(self, message: str,
context: Context) -> Tuple[List[str],
List[Optional[Expression]], bool]:
self.fail(message, context)
return [], [], False
# Helpers
def fail(self, msg: str, ctx: Context) -> None:
self.api.fail(msg, ctx)
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