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