deps: Split dependencies.base

Split the Factory and dependency classes out
of the base.py script to improve maintainability.

1 files changed, 125 insertions, 0 deletions

diff --git a/mesonbuild/dependencies/factory.py b/mesonbuild/dependencies/factory.py
new file mode 100644
index 0000000..760dba2
--- /dev/null
+++ b/mesonbuild/dependencies/factory.py
@@ -0,0 +1,125 @@
+# Copyright 2013-2021 The Meson development team
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from .base import Dependency, ExternalDependency
+from .base import DependencyException, DependencyMethods
+from .base import process_method_kw
+from .cmake import CMakeDependency
+from .framework import ExtraFrameworkDependency
+from .pkgconfig import PkgConfigDependency
+from ..mesonlib import MachineChoice
+import functools
+import typing as T
+
+if T.TYPE_CHECKING:
+    from ..environment import Environment
+    from .base import DependencyType
+    from .configtool import ConfigToolDependency
+    FactoryType = T.TypeVar('FactoryType', bound=T.Callable[..., T.List[T.Callable[[], 'Dependency']]])
+
+class DependencyFactory:
+
+    """Factory to get dependencies from multiple sources.
+
+    This class provides an initializer that takes a set of names and classes
+    for various kinds of dependencies. When the initialized object is called
+    it returns a list of callables return Dependency objects to try in order.
+
+    :name: The name of the dependency. This will be passed as the name
+        parameter of the each dependency unless it is overridden on a per
+        type basis.
+    :methods: An ordered list of DependencyMethods. This is the order
+        dependencies will be returned in unless they are removed by the
+        _process_method function
+    :*_name: This will overwrite the name passed to the coresponding class.
+        For example, if the name is 'zlib', but cmake calls the dependency
+        'Z', then using `cmake_name='Z'` will pass the name as 'Z' to cmake.
+    :*_class: A *type* or callable that creates a class, and has the
+        signature of an ExternalDependency
+    :system_class: If you pass DependencyMethods.SYSTEM in methods, you must
+        set this argument.
+    """
+
+    def __init__(self, name: str, methods: T.List[DependencyMethods], *,
+                 extra_kwargs: T.Optional[T.Dict[str, T.Any]] = None,
+                 pkgconfig_name: T.Optional[str] = None,
+                 pkgconfig_class: 'T.Type[PkgConfigDependency]' = PkgConfigDependency,
+                 cmake_name: T.Optional[str] = None,
+                 cmake_class: 'T.Type[CMakeDependency]' = CMakeDependency,
+                 configtool_class: 'T.Optional[T.Type[ConfigToolDependency]]' = None,
+                 framework_name: T.Optional[str] = None,
+                 framework_class: 'T.Type[ExtraFrameworkDependency]' = ExtraFrameworkDependency,
+                 system_class: 'T.Type[ExternalDependency]' = ExternalDependency):
+
+        if DependencyMethods.CONFIG_TOOL in methods and not configtool_class:
+            raise DependencyException('A configtool must have a custom class')
+
+        self.extra_kwargs = extra_kwargs or {}
+        self.methods = methods
+        self.classes = {
+            # Just attach the correct name right now, either the generic name
+            # or the method specific name.
+            DependencyMethods.EXTRAFRAMEWORK: functools.partial(framework_class, framework_name or name),
+            DependencyMethods.PKGCONFIG: functools.partial(pkgconfig_class, pkgconfig_name or name),
+            DependencyMethods.CMAKE: functools.partial(cmake_class, cmake_name or name),
+            DependencyMethods.SYSTEM: functools.partial(system_class, name),
+            DependencyMethods.CONFIG_TOOL: None,
+        }
+        if configtool_class is not None:
+            self.classes[DependencyMethods.CONFIG_TOOL] = functools.partial(configtool_class, name)
+
+    @staticmethod
+    def _process_method(method: DependencyMethods, env: 'Environment', for_machine: MachineChoice) -> bool:
+        """Report whether a method is valid or not.
+
+        If the method is valid, return true, otherwise return false. This is
+        used in a list comprehension to filter methods that are not possible.
+
+        By default this only remove EXTRAFRAMEWORK dependencies for non-mac platforms.
+        """
+        # Extra frameworks are only valid for macOS and other apple products
+        if (method is DependencyMethods.EXTRAFRAMEWORK and
+                not env.machines[for_machine].is_darwin()):
+            return False
+        return True
+
+    def __call__(self, env: 'Environment', for_machine: MachineChoice,
+                 kwargs: T.Dict[str, T.Any]) -> T.List['DependencyType']:
+        """Return a list of Dependencies with the arguments already attached."""
+        methods = process_method_kw(self.methods, kwargs)
+        nwargs = self.extra_kwargs.copy()
+        nwargs.update(kwargs)
+
+        return [functools.partial(self.classes[m], env, nwargs) for m in methods
+                if self._process_method(m, env, for_machine)]
+
+
+def factory_methods(methods: T.Set[DependencyMethods]) -> T.Callable[['FactoryType'], 'FactoryType']:
+    """Decorator for handling methods for dependency factory functions.
+
+    This helps to make factory functions self documenting
+    >>> @factory_methods([DependencyMethods.PKGCONFIG, DependencyMethods.CMAKE])
+    >>> def factory(env: Environment, for_machine: MachineChoice, kwargs: T.Dict[str, T.Any], methods: T.List[DependencyMethods]) -> T.List[T.Callable[[], 'Dependency']]:
+    >>>     pass
+    """
+
+    def inner(func: 'FactoryType') -> 'FactoryType':
+
+        @functools.wraps(func)
+        def wrapped(env: 'Environment', for_machine: MachineChoice, kwargs: T.Dict[str, T.Any]) -> T.List[T.Callable[[], 'Dependency']]:
+            return func(env, for_machine, kwargs, process_method_kw(methods, kwargs))
+
+        return T.cast('FactoryType', wrapped)
+
+    return inner