Add eval_type_call which gets the result type of a function call at type check time. (#41)

For example, given:
```py
    def func[T](x: T) -> T: ...
```

we can evaluate the result type of when calling func on arguments of
known types.
```
    res = eval_type_call(func, int)
    assert res is int
```

Author: dnwpark

tests/test_qblike.py

@@ -2,7 +2,11 @@
 
 from typing import Literal, Unpack
 
-from typemap.type_eval import eval_call, eval_typing
+from typemap.type_eval import (
+    eval_call,
+    eval_call_with_types,
+    eval_typing,
+)
 from typemap.typing import (
     BaseTypedDict,
     NewProtocol,
@@ -124,3 +128,21 @@ class select[...]:
         class PropsOnly[tests.test_qblike.Tgt]:
             name: tests.test_qblike.Property[str]
     """)
+
+
+def test_qblike_4():
+    t = eval_call_with_types(
+        select,
+        A,
+        x=bool,
+        w=bool,
+        z=bool,
+    )
+    fmt = format_helper.format_class(t)
+
+    assert fmt == textwrap.dedent("""\
+        class select[...]:
+            x: tests.test_qblike.Property[int]
+            w: tests.test_qblike.Property[list[str]]
+            z: tests.test_qblike.Link[tests.test_qblike.PropsOnly[tests.test_qblike.Tgt]]
+        """)

tests/test_type_eval.py

@@ -17,10 +17,11 @@
 
 import pytest
 
-from typemap.type_eval import eval_typing
+from typemap.type_eval import eval_call_with_types, eval_typing
 from typemap.typing import (
     Attrs,
     FromUnion,
+    GenericCallable,
     GetArg,
     GetArgs,
     GetAttr,
@@ -1025,3 +1026,321 @@ def test_type_eval_annotated_03():
 def test_type_eval_annotated_04():
     res = eval_typing(GetAnnotations[GetAttr[AnnoTest, Literal["b"]]])
     assert res == Literal["blah"]
+
+
+def test_type_call_callable_01():
+    res = eval_call_with_types(Callable[[], int])
+    assert res is int
+
+
+def test_type_call_callable_02():
+    res = eval_call_with_types(Callable[[Param[Literal["x"], int]], int], int)
+    assert res is int
+
+
+def test_type_call_callable_03():
+    res = eval_call_with_types(
+        Callable[[Param[Literal["x"], int, Literal["keyword"]]], int], x=int
+    )
+    assert res is int
+
+
+def test_type_call_callable_04():
+    class C: ...
+
+    res = eval_call_with_types(Callable[[Param[Literal["self"], Self]], int], C)
+    assert res is int
+
+
+def test_type_call_callable_05():
+    class C: ...
+
+    res = eval_call_with_types(Callable[[Param[Literal["self"], Self]], C], C)
+    assert res is C
+
+
+def test_type_call_callable_06():
+    class C: ...
+
+    res = eval_call_with_types(
+        Callable[[Param[Literal["self"], Self], Param[Literal["x"], int]], int],
+        C,
+        int,
+    )
+    assert res is int
+
+
+def test_type_call_callable_07():
+    class C: ...
+
+    res = eval_call_with_types(
+        Callable[
+            [
+                Param[Literal["self"], Self],
+                Param[Literal["x"], int, Literal["keyword"]],
+            ],
+            int,
+        ],
+        C,
+        x=int,
+    )
+    assert res is int
+
+
+def test_type_call_callable_08():
+    T = TypeVar("T")
+    res = eval_call_with_types(Callable[[Param[Literal["x"], T]], str], int)
+    assert res is str
+
+
+def test_type_call_callable_09():
+    T = TypeVar("T")
+    res = eval_call_with_types(Callable[[Param[Literal["x"], T]], T], int)
+    assert res is int
+
+
+def test_type_call_callable_10():
+    T = TypeVar("T")
+
+    class C(Generic[T]): ...
+
+    res = eval_call_with_types(Callable[[Param[Literal["x"], C[T]]], T], C[int])
+    assert res is int
+
+
+def test_type_call_callable_11():
+    T = TypeVar("T")
+
+    class C(Generic[T]): ...
+
+    class D(C[int]): ...
+
+    class E(D): ...
+
+    res = eval_call_with_types(Callable[[Param[Literal["x"], C[T]]], T], D)
+    assert res is int
+    res = eval_call_with_types(Callable[[Param[Literal["x"], C[T]]], T], E)
+    assert res is int
+
+
+def test_type_call_local_function_01():
+    def func(x: int) -> int: ...
+
+    res = eval_call_with_types(func, int)
+    assert res is int
+
+
+def test_type_call_local_function_02():
+    def func(*, x: int) -> int: ...
+
+    res = eval_call_with_types(func, x=int)
+    assert res is int
+
+
+def test_type_call_local_function_03():
+    def func[T](x: T) -> T: ...
+
+    res = eval_call_with_types(func, int)
+    assert res is int
+
+
+def test_type_call_local_function_04():
+    class C: ...
+
+    def func(x: C) -> C: ...
+
+    res = eval_call_with_types(func, C)
+    assert res is C
+
+
+def test_type_call_local_function_05():
+    class C: ...
+
+    def func[T](x: T) -> T: ...
+
+    res = eval_call_with_types(func, C)
+    assert res is C
+
+
+def test_type_call_local_function_06():
+    T = TypeVar("T")
+
+    class C(Generic[T]): ...
+
+    def func[U](x: C[U]) -> C[U]: ...
+
+    res = eval_call_with_types(func, C[int])
+    assert res == C[int]
+
+
+def test_type_call_local_function_07():
+    T = TypeVar("T")
+
+    class C(Generic[T]): ...
+
+    class D(C[int]): ...
+
+    class E(D): ...
+
+    def func[U](x: C[U]) -> U: ...
+
+    res = eval_call_with_types(func, D)
+    assert res is int
+    res = eval_call_with_types(func, E)
+    assert res is int
+
+
+def test_type_call_local_function_08():
+    class C[T]: ...
+
+    class D(C[int]): ...
+
+    class E(C[str]): ...
+
+    class F(D, E): ...
+
+    def func[U](x: C[U]) -> U: ...
+
+    res = eval_call_with_types(func, F)
+    assert res is int
+
+
+def test_type_call_local_function_09():
+    class C[T, U]: ...
+
+    def func[V](x: C[int, V]) -> V: ...
+
+    res = eval_call_with_types(func, C[int, str])
+    assert res is str
+
+
+def test_type_call_bind_error_01():
+    T = TypeVar("T")
+
+    with pytest.raises(
+        ValueError, match="Type variable T is already bound to int, but got str"
+    ):
+        eval_call_with_types(
+            Callable[[Param[Literal["x"], T], Param[Literal["y"], T]], T],
+            int,
+            str,
+        )
+
+
+def test_type_call_bind_error_02():
+    def func[T](x: T, y: T) -> T: ...
+
+    with pytest.raises(
+        ValueError, match="Type variable T is already bound to int, but got str"
+    ):
+        eval_call_with_types(func, int, str)
+
+
+def test_type_call_bind_error_03():
+    T = TypeVar("T")
+
+    class C(Generic[T]): ...
+
+    with pytest.raises(
+        ValueError, match="Type variable T is already bound to int, but got str"
+    ):
+        eval_call_with_types(
+            Callable[[Param[Literal["x"], C[T]], Param[Literal["y"], C[T]]], T],
+            C[int],
+            C[str],
+        )
+
+
+def test_type_call_bind_error_04():
+    class C[T]: ...
+
+    def func[T](x: C[T], y: C[T]) -> T: ...
+
+    with pytest.raises(
+        ValueError, match="Type variable T is already bound to int, but got str"
+    ):
+        eval_call_with_types(func, C[int], C[str])
+
+
+def test_type_call_bind_error_05():
+    class C[T]: ...
+
+    class D[T]: ...
+
+    def func[T](x: C[T]) -> T: ...
+
+    with pytest.raises(ValueError, match="Argument type mismatch for x"):
+        eval_call_with_types(func, D[int])
+
+
+type GetCallableMember[T, N: str] = GetArg[
+    tuple[
+        *[
+            GetType[m]
+            for m in Iter[Members[T]]
+            if (
+                IsSub[GetType[m], Callable]
+                or IsSub[GetType[m], GenericCallable]
+            )
+            and IsSub[GetName[m], N]
+        ]
+    ],
+    tuple,
+    0,
+]
+
+
+def test_type_call_member_01():
+    class C:
+        def invoke(self, x: int) -> int: ...
+
+    res = eval_call_with_types(GetCallableMember[C, Literal["invoke"]], C, int)
+    assert res is int
+
+
+def test_type_call_member_02():
+    class C:
+        def invoke[T](self, x: T) -> T: ...
+
+    res = eval_call_with_types(GetCallableMember[C, Literal["invoke"]], C, int)
+    assert res is int
+
+
+def test_type_call_member_03():
+    class C[T]:
+        def invoke(self, x: str) -> str: ...
+
+    res = eval_call_with_types(
+        GetCallableMember[C[int], Literal["invoke"]], C[int], str
+    )
+    assert res is str
+
+
+def test_type_call_member_04():
+    class C[T]:
+        def invoke(self, x: T) -> T: ...
+
+    res = eval_call_with_types(
+        GetCallableMember[C[int], Literal["invoke"]], C[int], int
+    )
+    assert res is int
+
+
+def test_type_call_member_05():
+    class C[T]:
+        def invoke(self) -> C[T]: ...
+
+    res = eval_call_with_types(
+        GetCallableMember[C[int], Literal["invoke"]], C[int]
+    )
+    assert res == C[int]
+
+
+def test_type_call_member_06():
+    class C[T]:
+        def invoke[U](self, x: U) -> C[U]: ...
+
+    res = eval_call_with_types(
+        GetCallableMember[C[int], Literal["invoke"]], C[int], str
+    )
+    assert res == C[str]

typemap/type_eval/__init__.py

@@ -7,7 +7,7 @@
 from ._apply_generic import flatten_class
 
 # XXX: this needs to go second due to nasty circularity -- try to fix that!!
-from ._eval_call import eval_call
+from ._eval_call import eval_call, eval_call_with_types
 from ._subtype import issubtype
 from ._subsim import issubsimilar
 
@@ -19,6 +19,7 @@
     "eval_typing",
     "register_evaluator",
     "eval_call",
+    "eval_call_with_types",
     "flatten_class",
     "issubtype",
     "issubsimilar",