64 lines
1.8 KiB
Python
64 lines
1.8 KiB
Python
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import tokenize
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import string
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def parse_signature(sig):
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'''Parse generalized ufunc signature.
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NOTE: ',' (COMMA) is a delimiter; not separator.
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This means trailing comma is legal.
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'''
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def stripws(s):
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return ''.join(c for c in s if c not in string.whitespace)
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def tokenizer(src):
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def readline():
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yield src
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gen = readline()
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return tokenize.generate_tokens(lambda: next(gen))
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def parse(src):
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tokgen = tokenizer(src)
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while True:
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tok = next(tokgen)
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if tok[1] == '(':
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symbols = []
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while True:
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tok = next(tokgen)
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if tok[1] == ')':
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break
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elif tok[0] == tokenize.NAME:
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symbols.append(tok[1])
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elif tok[1] == ',':
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continue
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else:
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raise ValueError('bad token in signature "%s"' % tok[1])
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yield tuple(symbols)
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tok = next(tokgen)
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if tok[1] == ',':
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continue
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elif tokenize.ISEOF(tok[0]):
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break
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elif tokenize.ISEOF(tok[0]):
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break
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else:
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raise ValueError('bad token in signature "%s"' % tok[1])
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ins, _, outs = stripws(sig).partition('->')
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inputs = list(parse(ins))
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outputs = list(parse(outs))
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# check that all output symbols are defined in the inputs
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isym = set()
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osym = set()
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for grp in inputs:
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isym |= set(grp)
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for grp in outputs:
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osym |= set(grp)
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diff = osym.difference(isym)
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if diff:
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raise NameError('undefined output symbols: %s' % ','.join(sorted(diff)))
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return inputs, outputs
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