You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
166 lines
4.7 KiB
Python
166 lines
4.7 KiB
Python
import itertools
|
|
|
|
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 IteratorMapping(collections_abc.Mapping):
|
|
def __init__(self, mapping, accessor, appends=None):
|
|
self._mapping = mapping
|
|
self._accessor = accessor
|
|
self._appends = appends or {}
|
|
|
|
def __repr__(self):
|
|
return "IteratorMapping({!r}, {!r}, {!r})".format(
|
|
self._mapping,
|
|
self._accessor,
|
|
self._appends,
|
|
)
|
|
|
|
def __bool__(self):
|
|
return bool(self._mapping or self._appends)
|
|
|
|
__nonzero__ = __bool__ # XXX: Python 2.
|
|
|
|
def __contains__(self, key):
|
|
return key in self._mapping or key in self._appends
|
|
|
|
def __getitem__(self, k):
|
|
try:
|
|
v = self._mapping[k]
|
|
except KeyError:
|
|
return iter(self._appends[k])
|
|
return itertools.chain(self._accessor(v), self._appends.get(k, ()))
|
|
|
|
def __iter__(self):
|
|
more = (k for k in self._appends if k not in self._mapping)
|
|
return itertools.chain(self._mapping, more)
|
|
|
|
def __len__(self):
|
|
more = sum(1 for k in self._appends if k not in self._mapping)
|
|
return len(self._mapping) + more
|
|
|
|
|
|
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()
|
|
|
|
|
|
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 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)
|