Support keyword-only arguments

src/sciline/__init__.py

@@ -10,14 +10,15 @@
     __version__ = "0.0.0"
 
 from . import scheduler
+from ._provider import UnboundTypeVar
 from .domain import Scope, ScopeTwoParams
 from .handler import (
     HandleAsBuildTimeException,
     HandleAsComputeTimeException,
     UnsatisfiedRequirement,
 )
 from .param_table import ParamTable
-from .pipeline import AmbiguousProvider, Pipeline, UnboundTypeVar
+from .pipeline import AmbiguousProvider, Pipeline
 from .series import Series
 
 __all__ = [

src/sciline/_provider.py

@@ -0,0 +1,254 @@
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
+"""Handling of providers and their arguments."""
+from __future__ import annotations
+
+import inspect
+from dataclasses import dataclass
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Callable,
+    Generator,
+    Literal,
+    Optional,
+    TypeVar,
+    Union,
+    get_args,
+    get_origin,
+    get_type_hints,
+)
+
+if TYPE_CHECKING:
+    from .typing import Key
+
+
+ToProvider = Callable[..., Any]
+"""Callable that can be converted to a provider."""
+
+ProviderKind = Literal[
+    'function', 'parameter', 'series', 'table_cell', 'sentinel', 'unsatisfied'
+]
+"""Identifies the kind of a provider, most are used internally."""
+
+
+class UnboundTypeVar(Exception):
+    """
+    Raised when a parameter of a generic provider is not bound to a concrete type.
+    """
+
+
+class Provider:
+    """A provider.
+
+    This class wraps a function that returns the provided values.
+    That function can be a user-provided callable, in which case
+    ``kind = 'function'``, or an internally constructed function
+    for providing parameters or other special values.
+    """
+
+    def __init__(
+        self,
+        *,
+        func: ToProvider,
+        arg_spec: ArgSpec,
+        kind: ProviderKind,
+        location: Optional[ProviderLocation] = None,
+    ) -> None:
+        self._func = func
+        self._arg_spec = arg_spec
+        self._kind = kind
+        self._location = (
+            location if location is not None else ProviderLocation.from_function(func)
+        )
+
+    @classmethod
+    def from_function(cls, func: ToProvider) -> Provider:
+        """Construct from a function or other callable."""
+        return cls(func=func, arg_spec=ArgSpec.from_function(func), kind='function')
+
+    @classmethod
+    def parameter(cls, param: Any) -> Provider:
+        """Construct a provider that always returns the given value."""
+        return cls(
+            func=lambda: param,
+            arg_spec=ArgSpec.null(),
+            kind='parameter',
+            location=ProviderLocation(
+                name=f'param({type(param).__name__})', module=_module_name(param)
+            ),
+        )
+
+    @classmethod
+    def table_cell(cls, param: Any) -> Provider:
+        """Construct a provider that returns the label for a table row."""
+        return cls(
+            func=lambda: param,
+            arg_spec=ArgSpec.null(),
+            kind='table_cell',
+            location=ProviderLocation(
+                name=f'table_cell({type(param).__name__})', module=_module_name(param)
+            ),
+        )
+
+    @classmethod
+    def provide_none(cls) -> Provider:
+        """Provider that takes no arguments and returns None."""
+        return cls(
+            func=lambda: None,
+            arg_spec=ArgSpec.null(),
+            kind='function',
+            location=ProviderLocation(name='provide_none', module='sciline'),
+        )
+
+    @property
+    def func(self) -> ToProvider:
+        """Return the function that implements the provider."""
+        return self._func
+
+    @property
+    def arg_spec(self) -> ArgSpec:
+        """Return the argument specification for the provider."""
+        return self._arg_spec
+
+    @property
+    def kind(self) -> ProviderKind:
+        """Return the kind of the provider."""
+        return self._kind
+
+    @property
+    def location(self) -> ProviderLocation:
+        """Return the location of the provider in source code."""
+        return self._location
+
+    def deduce_key(self) -> Any:
+        """Attempt to determine the key (return type) of the provider."""
+        if (key := get_type_hints(self._func).get('return')) is None:
+            raise ValueError(
+                f'Provider {self} lacks type-hint for return value or returns NOne.'
+            )
+        return key
+
+    def bind_type_vars(self, bound: dict[TypeVar, Key]) -> Provider:
+        """Replace TypeVars with their corresponding keys."""
+        return Provider(
+            func=self._func,
+            arg_spec=self._arg_spec.bind_type_vars(bound),
+            kind=self._kind,
+        )
+
+    def map_arg_keys(self, transform: Callable[[Key], Key]) -> Provider:
+        """Return a new provider with transformed argument keys."""
+        return Provider(
+            func=self._func,
+            arg_spec=self._arg_spec.map_keys(transform),
+            kind=self._kind,
+        )
+
+    def __str__(self) -> str:
+        return f"Provider('{self.location.name}')"
+
+    def __repr__(self) -> str:
+        return (
+            f"Provider('{self.location.module}.{self.location.name}', "
+            f"func={self._func})"
+        )
+
+    def call(self, values: dict[Key, Any]) -> Any:
+        """Call the provider with arguments extracted from ``values``."""
+        return self._func(
+            *(values[arg] for arg in self._arg_spec.args),
+            **{key: values[arg] for key, arg in self._arg_spec.kwargs},
+        )
+
+
+class ArgSpec:
+    """Argument specification for a provider."""
+
+    def __init__(self, *, args: dict[str, Key], kwargs: dict[str, Key]) -> None:
+        """Build from components, use dedicated creation functions instead."""
+        self._args = args
+        self._kwargs = kwargs
+
+    @classmethod
+    def from_function(cls, provider: ToProvider) -> ArgSpec:
+        """Parse the argument spec of a provider."""
+        hints = get_type_hints(provider)
+        signature = inspect.getfullargspec(provider)
+        args = {name: hints[name] for name in signature.args}
+        kwargs = {name: hints[name] for name in signature.kwonlyargs}
+        return cls(args=args, kwargs=kwargs)
+
+    @classmethod
+    def from_args(cls, *args: Key) -> ArgSpec:
+        """Create ArgSpec from positional arguments."""
+        return cls(args={f'unknown_{i}': arg for i, arg in enumerate(args)}, kwargs={})
+
+    @classmethod
+    def null(cls) -> ArgSpec:
+        """Create ArgSpec for a nullary function (no args)."""
+        return cls(args={}, kwargs={})
+
+    @property
+    def args(self) -> Generator[Key, None, None]:
+        yield from self._args.values()
+
+    @property
+    def kwargs(self) -> Generator[tuple[str, Key], None, None]:
+        yield from self._kwargs.items()
+
+    def keys(self) -> Generator[Key, None, None]:
+        """Flat iterator over all argument types."""
+        yield from self._args.values()
+        yield from self._kwargs.values()
+
+    def bind_type_vars(self, bound: dict[TypeVar, Key]) -> ArgSpec:
+        """Bind concrete types to TypeVars."""
+        return self.map_keys(lambda arg: _bind_free_typevars(arg, bound=bound))
+
+    def map_keys(self, transform: Callable[[Key], Key]) -> ArgSpec:
+        """Return a new ArgSpec with the keys mapped by ``callback``."""
+        return ArgSpec(
+            args={name: transform(arg) for name, arg in self._args.items()},
+            kwargs={name: transform(arg) for name, arg in self._kwargs.items()},
+        )
+
+
+@dataclass
+class ProviderLocation:
+    name: str
+    module: str
+
+    @classmethod
+    def from_function(cls, func: ToProvider) -> ProviderLocation:
+        return cls(name=func.__name__, module=_module_name(func))
+
+    @property
+    def qualname(self) -> str:
+        """Fully qualified name of the provider.
+
+        Note that this always includes the module name unlike
+        ``provider.func.__qualname__`` which depends on how the provider was imported.
+        """
+        if self.module:
+            return f'{self.module}.{self.name}'
+        return self.name
+
+
+def _bind_free_typevars(tp: Union[TypeVar, Key], bound: dict[TypeVar, Key]) -> Key:
+    if isinstance(tp, TypeVar):
+        if (result := bound.get(tp)) is None:
+            raise UnboundTypeVar(f'Unbound type variable {tp}')
+        return result
+    elif (origin := get_origin(tp)) is not None:
+        result = origin[tuple(_bind_free_typevars(arg, bound) for arg in get_args(tp))]
+        if result is None:
+            raise ValueError(f'Binding type variables in {tp} resulted in `None`')
+        return result
+    else:
+        return tp
+
+
+def _module_name(x: Any) -> str:
+    # getmodule might return None
+    return getattr(inspect.getmodule(x), '__name__', '')

src/sciline/display.py

@@ -1,9 +1,11 @@
-import inspect
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
 from html import escape
 from typing import Iterable, List, Tuple, TypeVar, Union
 
-from .typing import Item, Key, Provider
-from .utils import groupby, keyname, kind_of_provider
+from ._provider import Provider
+from .typing import Item, Key
+from .utils import groupby, keyname
 
 
 def _details(summary: str, body: str) -> str:
@@ -30,18 +32,16 @@ def _provider_source(
     p: Tuple[Key, Tuple[Union[Key, TypeVar], ...], List[Provider]]
 ) -> str:
     key, _, (v, *rest) = p
-    kind = kind_of_provider(v)
-    if kind == 'table':
+    if v.kind == 'table_cell':
         # This is always the case, but mypy complains
         if isinstance(key, Item):
             return escape(
                 f'ParamTable({keyname(key.label[0].tp)}, length={len((v, *rest))})'
             )
-    if kind == 'function':
-        module = getattr(inspect.getmodule(v), '__name__', '')
+    if v.kind == 'function':
         return _details(
-            escape(v.__name__),
-            escape(f'{module}.{v.__name__}'),
+            escape(v.location.name),
+            escape(f'{v.location.module}.{v.location.name}'),
         )
     return ''
 
@@ -50,9 +50,8 @@ def _provider_value(
     p: Tuple[Key, Tuple[Union[Key, TypeVar], ...], List[Provider]]
 ) -> str:
     _, _, (v, *_) = p
-    kind = kind_of_provider(v)
-    if kind == 'parameter':
-        html = escape(str(v())).strip()
+    if v.kind == 'parameter':
+        html = escape(str(v.call({}))).strip()
         return _details(f'{html[:30]}...', html) if len(html) > 30 else html
     return ''
 

src/sciline/handler.py

@@ -2,9 +2,10 @@
 # Copyright (c) 2023 Scipp contributors (https://github.com/scipp)
 from __future__ import annotations
 
-from typing import Callable, NoReturn, Protocol, Type, TypeVar, Union
+from typing import NoReturn, Protocol, TypeVar
 
-from .typing import Item
+from ._provider import ArgSpec, Provider
+from .typing import Key
 
 T = TypeVar('T')
 
@@ -16,9 +17,7 @@ class UnsatisfiedRequirement(Exception):
 class ErrorHandler(Protocol):
     """Error handling protocol for pipelines."""
 
-    def handle_unsatisfied_requirement(
-        self, tp: Union[Type[T], Item[T]]
-    ) -> Callable[[], T]:
+    def handle_unsatisfied_requirement(self, tp: Key) -> Provider:
         ...
 
 
@@ -30,7 +29,7 @@ class HandleAsBuildTimeException(ErrorHandler):
     ensuring that errors are caught early, before starting costly computation.
     """
 
-    def handle_unsatisfied_requirement(self, tp: Union[Type[T], Item[T]]) -> NoReturn:
+    def handle_unsatisfied_requirement(self, tp: Key) -> NoReturn:
         """Raise an exception when a type cannot be provided."""
         raise UnsatisfiedRequirement('No provider found for type', tp)
 
@@ -43,12 +42,12 @@ class HandleAsComputeTimeException(ErrorHandler):
     visualization. This is helpful when visualizing a graph that is not yet complete.
     """
 
-    def handle_unsatisfied_requirement(
-        self, tp: Union[Type[T], Item[T]]
-    ) -> Callable[[], T]:
+    def handle_unsatisfied_requirement(self, tp: Key) -> Provider:
         """Return a function that raises an exception when called."""
 
         def unsatisfied_sentinel() -> NoReturn:
             raise UnsatisfiedRequirement('No provider found for type', tp)
 
-        return unsatisfied_sentinel
+        return Provider(
+            func=unsatisfied_sentinel, arg_spec=ArgSpec.null(), kind='unsatisfied'
+        )