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83 lines
2.5 KiB
Python
83 lines
2.5 KiB
Python
from __future__ import absolute_import, division, print_function, unicode_literals
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"""A function that can be specified at the command line, with an argument."""
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import importlib
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import re
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import tokenize
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from StringIO import StringIO
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MATCHER = re.compile(r'([\w.]+)(.*)')
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REMAPPINGS = {
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'false': False,
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'true': True,
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'null': None,
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'False': False,
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'True': True,
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'None': None,
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}
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def eval_arguments(args):
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args = args.strip()
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if not args or (args == '()'):
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return ()
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tokens = list(tokenize.generate_tokens(StringIO(args).readline))
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def remap():
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for type, name, _, _, _ in tokens:
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if type == tokenize.NAME and name not in REMAPPINGS:
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yield tokenize.STRING, '"%s"' % name
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else:
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yield type, name
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untok = tokenize.untokenize(remap())
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if untok[1:-1].strip():
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untok = untok[:-1] + ',)' # Force a tuple.
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try:
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return eval(untok, REMAPPINGS)
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except Exception as e:
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raise ValueError('Couldn\'t evaluate expression "%s" (became "%s"), '
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'error "%s"' % (args, untok, str(e)))
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class Function(object):
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def __init__(self, desc='', default_path=''):
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self.desc = desc.strip()
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if not self.desc:
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# Make an empty function that does nothing.
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self.args = ()
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self.function = lambda *args, **kwds: None
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return
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m = MATCHER.match(desc)
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if not m:
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raise ValueError('"%s" is not a function' % desc)
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self.function, self.args = (g.strip() for g in m.groups())
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self.args = eval_arguments(self.args)
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if '.' not in self.function:
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if default_path and not default_path.endswith('.'):
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default_path += '.'
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self.function = default_path + self.function
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p, m = self.function.rsplit('.', 1)
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mod = importlib.import_module(p)
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# Errors in modules are swallowed here.
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# except:
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# raise ValueError('Can\'t find Python module "%s"' % p)
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try:
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self.function = getattr(mod, m)
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except:
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raise ValueError('No function "%s" in module "%s"' % (m, p))
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def __str__(self):
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return self.desc
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def __call__(self, *args, **kwds):
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return self.function(*(args + self.args), **kwds)
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def __eq__(self, other):
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return self.function == other.function and self.args == other.args
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def __ne__(self, other):
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return not (self == other)
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