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"""
"""
import re
import builtins
class UnitRegistry:
class __Registry:
__shared_state = {}
def __init__(self):
self.__dict__ = self.__shared_state
self.__context = {}
def __getitem__(self, string):
# easy hack to prevent arbitrary evaluation of code
all_builtins = dir(builtins)
# because we have kilobytes, other bytes we have to remove bytes
all_builtins.remove("bytes")
# have to deal with octet as well
all_builtins.remove("oct")
# have to remove min which is short for minute
all_builtins.remove("min")
for builtin in all_builtins:
if builtin in string:
raise RuntimeError(f"String parsing error for `{string}`. Enter a string accepted by quantities")
try:
return eval(string, self.__context)
except NameError:
# could return self['UnitQuantity'](string)
raise LookupError(
'Unable to parse units: "%s"'%string
)
def __setitem__(self, string, val):
assert isinstance(string, str)
try:
assert string not in self.__context
except AssertionError:
if val == self.__context[string]:
return
raise KeyError(
'%s has already been registered for %s'
% (string, self.__context[string])
)
self.__context[string] = val
__regex = re.compile(r'([A-Za-z])\.([A-Za-z])')
__registry = __Registry()
def __getattr__(self, attr):
return getattr(self.__registry, attr)
def __setitem__(self, label, value):
self.__registry.__setitem__(label, value)
def __getitem__(self, label):
"""Parses a string description of a unit e.g., 'g/cc'"""
label = self.__regex.sub(
r"\g<1>*\g<2>", label.replace('^', '**').replace('ยท', '*'))
# make sure we can parse the label ....
if label == '': label = 'dimensionless'
if "%" in label: label = label.replace("%", "percent")
if label.lower() == "in": label = "inch"
return self.__registry[label]
unit_registry = UnitRegistry()
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