81 lines
2.4 KiB
Python
81 lines
2.4 KiB
Python
from functools import wraps
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from pyrsistent._pmap import PMap, pmap
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from pyrsistent._pset import PSet, pset
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from pyrsistent._pvector import PVector, pvector
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def freeze(o):
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"""
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Recursively convert simple Python containers into pyrsistent versions
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of those containers.
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- list is converted to pvector, recursively
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- dict is converted to pmap, recursively on values (but not keys)
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- set is converted to pset, but not recursively
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- tuple is converted to tuple, recursively.
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Sets and dict keys are not recursively frozen because they do not contain
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mutable data by convention. The main exception to this rule is that
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dict keys and set elements are often instances of mutable objects that
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support hash-by-id, which this function can't convert anyway.
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>>> freeze(set([1, 2]))
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pset([1, 2])
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>>> freeze([1, {'a': 3}])
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pvector([1, pmap({'a': 3})])
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>>> freeze((1, []))
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(1, pvector([]))
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"""
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typ = type(o)
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if typ is dict:
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return pmap(dict((k, freeze(v)) for k, v in o.items()))
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if typ is list:
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return pvector(map(freeze, o))
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if typ is tuple:
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return tuple(map(freeze, o))
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if typ is set:
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return pset(o)
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return o
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def thaw(o):
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"""
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Recursively convert pyrsistent containers into simple Python containers.
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- pvector is converted to list, recursively
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- pmap is converted to dict, recursively on values (but not keys)
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- pset is converted to set, but not recursively
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- tuple is converted to tuple, recursively.
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>>> from pyrsistent import s, m, v
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>>> thaw(s(1, 2))
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{1, 2}
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>>> thaw(v(1, m(a=3)))
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[1, {'a': 3}]
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>>> thaw((1, v()))
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(1, [])
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"""
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if isinstance(o, PVector):
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return list(map(thaw, o))
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if isinstance(o, PMap):
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return dict((k, thaw(v)) for k, v in o.iteritems())
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if isinstance(o, PSet):
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return set(o)
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if type(o) is tuple:
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return tuple(map(thaw, o))
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return o
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def mutant(fn):
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"""
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Convenience decorator to isolate mutation to within the decorated function (with respect
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to the input arguments).
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All arguments to the decorated function will be frozen so that they are guaranteed not to change.
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The return value is also frozen.
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"""
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@wraps(fn)
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def inner_f(*args, **kwargs):
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return freeze(fn(*[freeze(e) for e in args], **dict(freeze(item) for item in kwargs.items())))
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return inner_f
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