diff env/lib/python3.9/site-packages/pip/_vendor/resolvelib/structs.py @ 0:4f3585e2f14b draft default tip

"planemo upload commit 60cee0fc7c0cda8592644e1aad72851dec82c959"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/env/lib/python3.9/site-packages/pip/_vendor/resolvelib/structs.py	Mon Mar 22 18:12:50 2021 +0000
@@ -0,0 +1,149 @@
+from .compat import collections_abc
+
+
+class DirectedGraph(object):
+    """A graph structure with directed edges."""
+
+    def __init__(self):
+        self._vertices = set()
+        self._forwards = {}  # <key> -> Set[<key>]
+        self._backwards = {}  # <key> -> Set[<key>]
+
+    def __iter__(self):
+        return iter(self._vertices)
+
+    def __len__(self):
+        return len(self._vertices)
+
+    def __contains__(self, key):
+        return key in self._vertices
+
+    def copy(self):
+        """Return a shallow copy of this graph."""
+        other = DirectedGraph()
+        other._vertices = set(self._vertices)
+        other._forwards = {k: set(v) for k, v in self._forwards.items()}
+        other._backwards = {k: set(v) for k, v in self._backwards.items()}
+        return other
+
+    def add(self, key):
+        """Add a new vertex to the graph."""
+        if key in self._vertices:
+            raise ValueError("vertex exists")
+        self._vertices.add(key)
+        self._forwards[key] = set()
+        self._backwards[key] = set()
+
+    def remove(self, key):
+        """Remove a vertex from the graph, disconnecting all edges from/to it."""
+        self._vertices.remove(key)
+        for f in self._forwards.pop(key):
+            self._backwards[f].remove(key)
+        for t in self._backwards.pop(key):
+            self._forwards[t].remove(key)
+
+    def connected(self, f, t):
+        return f in self._backwards[t] and t in self._forwards[f]
+
+    def connect(self, f, t):
+        """Connect two existing vertices.
+
+        Nothing happens if the vertices are already connected.
+        """
+        if t not in self._vertices:
+            raise KeyError(t)
+        self._forwards[f].add(t)
+        self._backwards[t].add(f)
+
+    def iter_edges(self):
+        for f, children in self._forwards.items():
+            for t in children:
+                yield f, t
+
+    def iter_children(self, key):
+        return iter(self._forwards[key])
+
+    def iter_parents(self, key):
+        return iter(self._backwards[key])
+
+
+class _FactoryIterableView(object):
+    """Wrap an iterator factory returned by `find_matches()`.
+
+    Calling `iter()` on this class would invoke the underlying iterator
+    factory, making it a "collection with ordering" that can be iterated
+    through multiple times, but lacks random access methods presented in
+    built-in Python sequence types.
+    """
+
+    def __init__(self, factory):
+        self._factory = factory
+
+    def __repr__(self):
+        return "{}({})".format(type(self).__name__, list(self._factory()))
+
+    def __bool__(self):
+        try:
+            next(self._factory())
+        except StopIteration:
+            return False
+        return True
+
+    __nonzero__ = __bool__  # XXX: Python 2.
+
+    def __iter__(self):
+        return self._factory()
+
+    def for_preference(self):
+        """Provide an candidate iterable for `get_preference()`"""
+        return self._factory()
+
+    def excluding(self, candidates):
+        """Create a new instance excluding specified candidates."""
+
+        def factory():
+            return (c for c in self._factory() if c not in candidates)
+
+        return type(self)(factory)
+
+
+class _SequenceIterableView(object):
+    """Wrap an iterable returned by find_matches().
+
+    This is essentially just a proxy to the underlying sequence that provides
+    the same interface as `_FactoryIterableView`.
+    """
+
+    def __init__(self, sequence):
+        self._sequence = sequence
+
+    def __repr__(self):
+        return "{}({})".format(type(self).__name__, self._sequence)
+
+    def __bool__(self):
+        return bool(self._sequence)
+
+    __nonzero__ = __bool__  # XXX: Python 2.
+
+    def __iter__(self):
+        return iter(self._sequence)
+
+    def __len__(self):
+        return len(self._sequence)
+
+    def for_preference(self):
+        """Provide an candidate iterable for `get_preference()`"""
+        return self._sequence
+
+    def excluding(self, candidates):
+        """Create a new instance excluding specified candidates."""
+        return type(self)([c for c in self._sequence if c not in candidates])
+
+
+def build_iter_view(matches):
+    """Build an iterable view from the value returned by `find_matches()`."""
+    if callable(matches):
+        return _FactoryIterableView(matches)
+    if not isinstance(matches, collections_abc.Sequence):
+        matches = list(matches)
+    return _SequenceIterableView(matches)