| 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768 |
- from .utils import _toposort, groupby
- class AmbiguityWarning(Warning):
- pass
- def supercedes(a, b):
- """ A is consistent and strictly more specific than B """
- return len(a) == len(b) and all(map(issubclass, a, b))
- def consistent(a, b):
- """ It is possible for an argument list to satisfy both A and B """
- return (len(a) == len(b) and
- all(issubclass(aa, bb) or issubclass(bb, aa)
- for aa, bb in zip(a, b)))
- def ambiguous(a, b):
- """ A is consistent with B but neither is strictly more specific """
- return consistent(a, b) and not (supercedes(a, b) or supercedes(b, a))
- def ambiguities(signatures):
- """ All signature pairs such that A is ambiguous with B """
- signatures = list(map(tuple, signatures))
- return {(a, b) for a in signatures for b in signatures
- if hash(a) < hash(b)
- and ambiguous(a, b)
- and not any(supercedes(c, a) and supercedes(c, b)
- for c in signatures)}
- def super_signature(signatures):
- """ A signature that would break ambiguities """
- n = len(signatures[0])
- assert all(len(s) == n for s in signatures)
- return [max([type.mro(sig[i]) for sig in signatures], key=len)[0]
- for i in range(n)]
- def edge(a, b, tie_breaker=hash):
- """ A should be checked before B
- Tie broken by tie_breaker, defaults to ``hash``
- """
- if supercedes(a, b):
- if supercedes(b, a):
- return tie_breaker(a) > tie_breaker(b)
- else:
- return True
- return False
- def ordering(signatures):
- """ A sane ordering of signatures to check, first to last
- Topoological sort of edges as given by ``edge`` and ``supercedes``
- """
- signatures = list(map(tuple, signatures))
- edges = [(a, b) for a in signatures for b in signatures if edge(a, b)]
- edges = groupby(lambda x: x[0], edges)
- for s in signatures:
- if s not in edges:
- edges[s] = []
- edges = {k: [b for a, b in v] for k, v in edges.items()}
- return _toposort(edges)
|
