mypy/plugins/common.py

from __future__ import annotations

from typing import NamedTuple

from mypy.argmap import map_actuals_to_formals
from mypy.fixup import TypeFixer
from mypy.nodes import (
    ARG_POS,
    MDEF,
    SYMBOL_FUNCBASE_TYPES,
    Argument,
    Block,
    CallExpr,
    ClassDef,
    Decorator,
    Expression,
    FuncDef,
    JsonDict,
    NameExpr,
    Node,
    OverloadedFuncDef,
    PassStmt,
    RefExpr,
    SymbolTableNode,
    TypeInfo,
    Var,
)
from mypy.plugin import CheckerPluginInterface, ClassDefContext, SemanticAnalyzerPluginInterface
from mypy.semanal_shared import (
    ALLOW_INCOMPATIBLE_OVERRIDE,
    parse_bool,
    require_bool_literal_argument,
    set_callable_name,
)
from mypy.typeops import try_getting_str_literals as try_getting_str_literals
from mypy.types import (
    AnyType,
    CallableType,
    Instance,
    LiteralType,
    NoneType,
    Overloaded,
    Type,
    TypeOfAny,
    TypeType,
    TypeVarType,
    deserialize_type,
    get_proper_type,
)
from mypy.types_utils import is_overlapping_none
from mypy.typevars import fill_typevars
from mypy.util import get_unique_redefinition_name


def _get_decorator_bool_argument(ctx: ClassDefContext, name: str, default: bool) -> bool:
    """Return the bool argument for the decorator.

    This handles both @decorator(...) and @decorator.
    """
    if isinstance(ctx.reason, CallExpr):
        return _get_bool_argument(ctx, ctx.reason, name, default)
    else:
        return default


def _get_bool_argument(ctx: ClassDefContext, expr: CallExpr, name: str, default: bool) -> bool:
    """Return the boolean value for an argument to a call or the
    default if it's not found.
    """
    attr_value = _get_argument(expr, name)
    if attr_value:
        return require_bool_literal_argument(ctx.api, attr_value, name, default)
    return default


def _get_argument(call: CallExpr, name: str) -> Expression | None:
    """Return the expression for the specific argument."""
    # To do this we use the CallableType of the callee to find the FormalArgument,
    # then walk the actual CallExpr looking for the appropriate argument.
    #
    # Note: I'm not hard-coding the index so that in the future we can support other
    # attrib and class makers.
    callee_type = _get_callee_type(call)
    if not callee_type:
        return None

    argument = callee_type.argument_by_name(name)
    if not argument:
        return None
    assert argument.name

    for i, (attr_name, attr_value) in enumerate(zip(call.arg_names, call.args)):
        if argument.pos is not None and not attr_name and i == argument.pos:
            return attr_value
        if attr_name == argument.name:
            return attr_value

    return None


def find_shallow_matching_overload_item(overload: Overloaded, call: CallExpr) -> CallableType:
    """Perform limited lookup of a matching overload item.

    Full overload resolution is only supported during type checking, but plugins
    sometimes need to resolve overloads. This can be used in some such use cases.

    Resolve overloads based on these things only:

    * Match using argument kinds and names
    * If formal argument has type None, only accept the "None" expression in the callee
    * If formal argument has type Literal[True] or Literal[False], only accept the
      relevant bool literal

    Return the first matching overload item, or the last one if nothing matches.
    """
    for item in overload.items[:-1]:
        ok = True
        mapped = map_actuals_to_formals(
            call.arg_kinds,
            call.arg_names,
            item.arg_kinds,
            item.arg_names,
            lambda i: AnyType(TypeOfAny.special_form),
        )

        # Look for extra actuals
        matched_actuals = set()
        for actuals in mapped:
            matched_actuals.update(actuals)
        if any(i not in matched_actuals for i in range(len(call.args))):
            ok = False

        for arg_type, kind, actuals in zip(item.arg_types, item.arg_kinds, mapped):
            if kind.is_required() and not actuals:
                # Missing required argument
                ok = False
                break
            elif actuals:
                args = [call.args[i] for i in actuals]
                arg_type = get_proper_type(arg_type)
                arg_none = any(isinstance(arg, NameExpr) and arg.name == "None" for arg in args)
                if isinstance(arg_type, NoneType):
                    if not arg_none:
                        ok = False
                        break
                elif (
                    arg_none
                    and not is_overlapping_none(arg_type)
                    and not (
                        isinstance(arg_type, Instance)
                        and arg_type.type.fullname == "builtins.object"
                    )
                    and not isinstance(arg_type, AnyType)
                ):
                    ok = False
                    break
                elif isinstance(arg_type, LiteralType) and isinstance(arg_type.value, bool):
                    if not any(parse_bool(arg) == arg_type.value for arg in args):
                        ok = False
                        break
        if ok:
            return item
    return overload.items[-1]


def _get_callee_type(call: CallExpr) -> CallableType | None:
    """Return the type of the callee, regardless of its syntactic form."""

    callee_node: Node | None = call.callee

    if isinstance(callee_node, RefExpr):
        callee_node = callee_node.node

    # Some decorators may be using typing.dataclass_transform, which is itself a decorator, so we
    # need to unwrap them to get at the true callee
    if isinstance(callee_node, Decorator):
        callee_node = callee_node.func

    if isinstance(callee_node, (Var, SYMBOL_FUNCBASE_TYPES)) and callee_node.type:
        callee_node_type = get_proper_type(callee_node.type)
        if isinstance(callee_node_type, Overloaded):
            return find_shallow_matching_overload_item(callee_node_type, call)
        elif isinstance(callee_node_type, CallableType):
            return callee_node_type

    return None


def add_method(
    ctx: ClassDefContext,
    name: str,
    args: list[Argument],
    return_type: Type,
    self_type: Type | None = None,
    tvar_def: TypeVarType | None = None,
    is_classmethod: bool = False,
    is_staticmethod: bool = False,
) -> None:
    """
    Adds a new method to a class.
    Deprecated, use add_method_to_class() instead.
    """
    add_method_to_class(
        ctx.api,
        ctx.cls,
        name=name,
        args=args,
        return_type=return_type,
        self_type=self_type,
        tvar_def=tvar_def,
        is_classmethod=is_classmethod,
        is_staticmethod=is_staticmethod,
    )


class MethodSpec(NamedTuple):
    """Represents a method signature to be added, except for `name`."""

    args: list[Argument]
    return_type: Type
    self_type: Type | None = None
    tvar_defs: list[TypeVarType] | None = None


def add_method_to_class(
    api: SemanticAnalyzerPluginInterface | CheckerPluginInterface,
    cls: ClassDef,
    name: str,
    # MethodSpec items kept for backward compatibility:
    args: list[Argument],
    return_type: Type,
    self_type: Type | None = None,
    tvar_def: list[TypeVarType] | TypeVarType | None = None,
    is_classmethod: bool = False,
    is_staticmethod: bool = False,
) -> FuncDef | Decorator:
    """Adds a new method to a class definition."""
    _prepare_class_namespace(cls, name)

    if tvar_def is not None and not isinstance(tvar_def, list):
        tvar_def = [tvar_def]

    func, sym = _add_method_by_spec(
        api,
        cls.info,
        name,
        MethodSpec(args=args, return_type=return_type, self_type=self_type, tvar_defs=tvar_def),
        is_classmethod=is_classmethod,
        is_staticmethod=is_staticmethod,
    )
    cls.info.names[name] = sym
    cls.info.defn.defs.body.append(func)
    return func


def add_overloaded_method_to_class(
    api: SemanticAnalyzerPluginInterface | CheckerPluginInterface,
    cls: ClassDef,
    name: str,
    items: list[MethodSpec],
    is_classmethod: bool = False,
    is_staticmethod: bool = False,
) -> OverloadedFuncDef:
    """Adds a new overloaded method to a class definition."""
    assert len(items) >= 2, "Overloads must contain at least two cases"

    # Save old definition, if it exists.
    _prepare_class_namespace(cls, name)

    # Create function bodies for each passed method spec.
    funcs: list[Decorator | FuncDef] = []
    for item in items:
        func, _sym = _add_method_by_spec(
            api,
            cls.info,
            name=name,
            spec=item,
            is_classmethod=is_classmethod,
            is_staticmethod=is_staticmethod,
        )
        if isinstance(func, FuncDef):
            var = Var(func.name, func.type)
            var.set_line(func.line)
            func.is_decorated = True

            deco = Decorator(func, [], var)
        else:
            deco = func
        deco.is_overload = True
        funcs.append(deco)

    # Create the final OverloadedFuncDef node:
    overload_def = OverloadedFuncDef(funcs)
    overload_def.info = cls.info
    overload_def.is_class = is_classmethod
    overload_def.is_static = is_staticmethod
    sym = SymbolTableNode(MDEF, overload_def)
    sym.plugin_generated = True

    cls.info.names[name] = sym
    cls.info.defn.defs.body.append(overload_def)
    return overload_def


def _prepare_class_namespace(cls: ClassDef, name: str) -> None:
    info = cls.info
    assert info

    # First remove any previously generated methods with the same name
    # to avoid clashes and problems in the semantic analyzer.
    if name in info.names:
        sym = info.names[name]
        if sym.plugin_generated and isinstance(sym.node, FuncDef):
            cls.defs.body.remove(sym.node)

    # NOTE: we would like the plugin generated node to dominate, but we still
    # need to keep any existing definitions so they get semantically analyzed.
    if name in info.names:
        # Get a nice unique name instead.
        r_name = get_unique_redefinition_name(name, info.names)
        info.names[r_name] = info.names[name]


def _add_method_by_spec(
    api: SemanticAnalyzerPluginInterface | CheckerPluginInterface,
    info: TypeInfo,
    name: str,
    spec: MethodSpec,
    *,
    is_classmethod: bool,
    is_staticmethod: bool,
) -> tuple[FuncDef | Decorator, SymbolTableNode]:
    args, return_type, self_type, tvar_defs = spec

    assert not (
        is_classmethod is True and is_staticmethod is True
    ), "Can't add a new method that's both staticmethod and classmethod."

    if isinstance(api, SemanticAnalyzerPluginInterface):
        function_type = api.named_type("builtins.function")
    else:
        function_type = api.named_generic_type("builtins.function", [])

    if is_classmethod:
        self_type = self_type or TypeType(fill_typevars(info))
        first = [Argument(Var("_cls"), self_type, None, ARG_POS, True)]
    elif is_staticmethod:
        first = []
    else:
        self_type = self_type or fill_typevars(info)
        first = [Argument(Var("self"), self_type, None, ARG_POS)]
    args = first + args

    arg_types, arg_names, arg_kinds = [], [], []
    for arg in args:
        assert arg.type_annotation, "All arguments must be fully typed."
        arg_types.append(arg.type_annotation)
        arg_names.append(arg.variable.name)
        arg_kinds.append(arg.kind)

    signature = CallableType(arg_types, arg_kinds, arg_names, return_type, function_type)
    if tvar_defs:
        signature.variables = tvar_defs

    func = FuncDef(name, args, Block([PassStmt()]))
    func.info = info
    func.type = set_callable_name(signature, func)
    func.is_class = is_classmethod
    func.is_static = is_staticmethod
    func._fullname = info.fullname + "." + name
    func.line = info.line

    # Add decorator for is_staticmethod. It's unnecessary for is_classmethod.
    if is_staticmethod:
        func.is_decorated = True
        v = Var(name, func.type)
        v.info = info
        v._fullname = func._fullname
        v.is_staticmethod = True
        dec = Decorator(func, [], v)
        dec.line = info.line
        sym = SymbolTableNode(MDEF, dec)
        sym.plugin_generated = True
        return dec, sym

    sym = SymbolTableNode(MDEF, func)
    sym.plugin_generated = True
    return func, sym


def add_attribute_to_class(
    api: SemanticAnalyzerPluginInterface,
    cls: ClassDef,
    name: str,
    typ: Type,
    final: bool = False,
    no_serialize: bool = False,
    override_allow_incompatible: bool = False,
    fullname: str | None = None,
    is_classvar: bool = False,
    overwrite_existing: bool = False,
) -> Var:
    """
    Adds a new attribute to a class definition.
    This currently only generates the symbol table entry and no corresponding AssignmentStatement
    """
    info = cls.info

    # NOTE: we would like the plugin generated node to dominate, but we still
    # need to keep any existing definitions so they get semantically analyzed.
    if name in info.names and not overwrite_existing:
        # Get a nice unique name instead.
        r_name = get_unique_redefinition_name(name, info.names)
        info.names[r_name] = info.names[name]

    node = Var(name, typ)
    node.info = info
    node.is_final = final
    node.is_classvar = is_classvar
    if name in ALLOW_INCOMPATIBLE_OVERRIDE:
        node.allow_incompatible_override = True
    else:
        node.allow_incompatible_override = override_allow_incompatible

    if fullname:
        node._fullname = fullname
    else:
        node._fullname = info.fullname + "." + name

    info.names[name] = SymbolTableNode(
        MDEF, node, plugin_generated=True, no_serialize=no_serialize
    )
    return node


def deserialize_and_fixup_type(data: str | JsonDict, api: SemanticAnalyzerPluginInterface) -> Type:
    typ = deserialize_type(data)
    typ.accept(TypeFixer(api.modules, allow_missing=False))
    return typ