init

.venv/lib/python3.8/site-packages/mypy/plugins/functools.py

@@ -0,0 +1,106 @@
+"""Plugin for supporting the functools standard library module."""
+from typing import Dict, NamedTuple, Optional
+from typing_extensions import Final
+
+import mypy.plugin
+from mypy.nodes import ARG_POS, ARG_STAR2, Argument, FuncItem, Var
+from mypy.plugins.common import add_method_to_class
+from mypy.types import AnyType, CallableType, get_proper_type, Type, TypeOfAny, UnboundType
+
+
+functools_total_ordering_makers: Final = {
+    'functools.total_ordering',
+}
+
+_ORDERING_METHODS: Final = {
+    '__lt__',
+    '__le__',
+    '__gt__',
+    '__ge__',
+}
+
+
+_MethodInfo = NamedTuple('_MethodInfo', [('is_static', bool), ('type', CallableType)])
+
+
+def functools_total_ordering_maker_callback(ctx: mypy.plugin.ClassDefContext,
+                                            auto_attribs_default: bool = False) -> None:
+    """Add dunder methods to classes decorated with functools.total_ordering."""
+    if ctx.api.options.python_version < (3,):
+        # This plugin is not supported in Python 2 mode (it's a no-op).
+        return
+
+    comparison_methods = _analyze_class(ctx)
+    if not comparison_methods:
+        ctx.api.fail(
+            'No ordering operation defined when using "functools.total_ordering": < > <= >=',
+            ctx.reason)
+        return
+
+    # prefer __lt__ to __le__ to __gt__ to __ge__
+    root = max(comparison_methods, key=lambda k: (comparison_methods[k] is None, k))
+    root_method = comparison_methods[root]
+    if not root_method:
+        # None of the defined comparison methods can be analysed
+        return
+
+    other_type = _find_other_type(root_method)
+    bool_type = ctx.api.named_type('builtins.bool')
+    ret_type: Type = bool_type
+    if root_method.type.ret_type != ctx.api.named_type('builtins.bool'):
+        proper_ret_type = get_proper_type(root_method.type.ret_type)
+        if not (isinstance(proper_ret_type, UnboundType)
+                and proper_ret_type.name.split('.')[-1] == 'bool'):
+            ret_type = AnyType(TypeOfAny.implementation_artifact)
+    for additional_op in _ORDERING_METHODS:
+        # Either the method is not implemented
+        # or has an unknown signature that we can now extrapolate.
+        if not comparison_methods.get(additional_op):
+            args = [Argument(Var('other', other_type), other_type, None, ARG_POS)]
+            add_method_to_class(ctx.api, ctx.cls, additional_op, args, ret_type)
+
+
+def _find_other_type(method: _MethodInfo) -> Type:
+    """Find the type of the ``other`` argument in a comparison method."""
+    first_arg_pos = 0 if method.is_static else 1
+    cur_pos_arg = 0
+    other_arg = None
+    for arg_kind, arg_type in zip(method.type.arg_kinds, method.type.arg_types):
+        if arg_kind.is_positional():
+            if cur_pos_arg == first_arg_pos:
+                other_arg = arg_type
+                break
+
+            cur_pos_arg += 1
+        elif arg_kind != ARG_STAR2:
+            other_arg = arg_type
+            break
+
+    if other_arg is None:
+        return AnyType(TypeOfAny.implementation_artifact)
+
+    return other_arg
+
+
+def _analyze_class(ctx: mypy.plugin.ClassDefContext) -> Dict[str, Optional[_MethodInfo]]:
+    """Analyze the class body, its parents, and return the comparison methods found."""
+    # Traverse the MRO and collect ordering methods.
+    comparison_methods: Dict[str, Optional[_MethodInfo]] = {}
+    # Skip object because total_ordering does not use methods from object
+    for cls in ctx.cls.info.mro[:-1]:
+        for name in _ORDERING_METHODS:
+            if name in cls.names and name not in comparison_methods:
+                node = cls.names[name].node
+                if isinstance(node, FuncItem) and isinstance(node.type, CallableType):
+                    comparison_methods[name] = _MethodInfo(node.is_static, node.type)
+                    continue
+
+                if isinstance(node, Var):
+                    proper_type = get_proper_type(node.type)
+                    if isinstance(proper_type, CallableType):
+                        comparison_methods[name] = _MethodInfo(node.is_staticmethod, proper_type)
+                        continue
+
+                comparison_methods[name] = None
+
+    return comparison_methods