1 files changed, 145 insertions, 0 deletions
diff --git a/setuptools/_vendor/nspektr/__init__.py b/setuptools/_vendor/nspektr/__init__.py
new file mode 100644
index 0000000..938bbdb
--- /dev/null
+++ b/setuptools/_vendor/nspektr/__init__.py
@@ -0,0 +1,145 @@
+import itertools
+import functools
+import contextlib
+
+from setuptools.extern.packaging.requirements import Requirement
+from setuptools.extern.packaging.version import Version
+from setuptools.extern.more_itertools import always_iterable
+from setuptools.extern.jaraco.context import suppress
+from setuptools.extern.jaraco.functools import apply
+
+from ._compat import metadata, repair_extras
+
+
+def resolve(req: Requirement) -> metadata.Distribution:
+    """
+    Resolve the requirement to its distribution.
+
+    Ignore exception detail for Python 3.9 compatibility.
+
+    >>> resolve(Requirement('pytest<3'))  # doctest: +IGNORE_EXCEPTION_DETAIL
+    Traceback (most recent call last):
+    ...
+    importlib.metadata.PackageNotFoundError: No package metadata was found for pytest<3
+    """
+    dist = metadata.distribution(req.name)
+    if not req.specifier.contains(Version(dist.version), prereleases=True):
+        raise metadata.PackageNotFoundError(str(req))
+    dist.extras = req.extras  # type: ignore
+    return dist
+
+
+@apply(bool)
+@suppress(metadata.PackageNotFoundError)
+def is_satisfied(req: Requirement):
+    return resolve(req)
+
+
+unsatisfied = functools.partial(itertools.filterfalse, is_satisfied)
+
+
+class NullMarker:
+    @classmethod
+    def wrap(cls, req: Requirement):
+        return req.marker or cls()
+
+    def evaluate(self, *args, **kwargs):
+        return True
+
+
+def find_direct_dependencies(dist, extras=None):
+    """
+    Find direct, declared dependencies for dist.
+    """
+    simple = (
+        req
+        for req in map(Requirement, always_iterable(dist.requires))
+        if NullMarker.wrap(req).evaluate(dict(extra=None))
+    )
+    extra_deps = (
+        req
+        for req in map(Requirement, always_iterable(dist.requires))
+        for extra in always_iterable(getattr(dist, 'extras', extras))
+        if NullMarker.wrap(req).evaluate(dict(extra=extra))
+    )
+    return itertools.chain(simple, extra_deps)
+
+
+def traverse(items, visit):
+    """
+    Given an iterable of items, traverse the items.
+
+    For each item, visit is called to return any additional items
+    to include in the traversal.
+    """
+    while True:
+        try:
+            item = next(items)
+        except StopIteration:
+            return
+        yield item
+        items = itertools.chain(items, visit(item))
+
+
+def find_req_dependencies(req):
+    with contextlib.suppress(metadata.PackageNotFoundError):
+        dist = resolve(req)
+        yield from find_direct_dependencies(dist)
+
+
+def find_dependencies(dist, extras=None):
+    """
+    Find all reachable dependencies for dist.
+
+    dist is an importlib.metadata.Distribution (or similar).
+    TODO: create a suitable protocol for type hint.
+
+    >>> deps = find_dependencies(resolve(Requirement('nspektr')))
+    >>> all(isinstance(dep, Requirement) for dep in deps)
+    True
+    >>> not any('pytest' in str(dep) for dep in deps)
+    True
+    >>> test_deps = find_dependencies(resolve(Requirement('nspektr[testing]')))
+    >>> any('pytest' in str(dep) for dep in test_deps)
+    True
+    """
+
+    def visit(req, seen=set()):
+        if req in seen:
+            return ()
+        seen.add(req)
+        return find_req_dependencies(req)
+
+    return traverse(find_direct_dependencies(dist, extras), visit)
+
+
+class Unresolved(Exception):
+    def __iter__(self):
+        return iter(self.args[0])
+
+
+def missing(ep):
+    """
+    Generate the unresolved dependencies (if any) of ep.
+    """
+    return unsatisfied(find_dependencies(ep.dist, repair_extras(ep.extras)))
+
+
+def check(ep):
+    """
+    >>> ep, = metadata.entry_points(group='console_scripts', name='pip')
+    >>> check(ep)
+    >>> dist = metadata.distribution('nspektr')
+
+    Since 'docs' extras are not installed, requesting them should fail.
+
+    >>> ep = metadata.EntryPoint(
+    ...     group=None, name=None, value='nspektr [docs]')._for(dist)
+    >>> check(ep)
+    Traceback (most recent call last):
+    ...
+    nspektr.Unresolved: [...]
+    """
+    missed = list(missing(ep))
+    if missed:
+        raise Unresolved(missed)