61 lines
1.8 KiB
Python
61 lines
1.8 KiB
Python
import re
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dbg = False
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term_regex = r'''(?mx)
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\s*(?:
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(?P<brackl>\()|
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(?P<brackr>\))|
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(?P<num>\-?\d+\.\d+|\-?\d+)|
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(?P<sq>"[^"]*")|
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(?P<s>[^(^)\s]+)
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)'''
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def parse_sexp(sexp):
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stack = []
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out = []
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if dbg: print("%-6s %-14s %-44s %-s" % tuple("term value out stack".split()))
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for termtypes in re.finditer(term_regex, sexp):
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term, value = [(t,v) for t,v in termtypes.groupdict().items() if v][0]
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if dbg: print("%-7s %-14s %-44r %-r" % (term, value, out, stack))
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if term == 'brackl':
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stack.append(out)
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out = []
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elif term == 'brackr':
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assert stack, "Trouble with nesting of brackets"
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tmpout, out = out, stack.pop(-1)
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out.append(tmpout)
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elif term == 'num':
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v = float(value)
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if v.is_integer(): v = int(v)
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out.append(v)
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elif term == 'sq':
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out.append(value[1:-1])
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elif term == 's':
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out.append(value)
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else:
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raise NotImplementedError("Error: %r" % (term, value))
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assert not stack, "Trouble with nesting of brackets"
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return out[0]
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def print_sexp(exp):
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out = ''
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if type(exp) == type([]):
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out += '(' + ' '.join(print_sexp(x) for x in exp) + ')'
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elif type(exp) == type('') and re.search(r'[\s()]', exp):
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out += '"%s"' % repr(exp)[1:-1].replace('"', '\"')
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else:
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out += '%s' % exp
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return out
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if __name__ == '__main__':
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sexp = ''' ( ( data "quoted data" 123 4.5)
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(data (123 (4.5) "(more" "data)")))'''
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print('Input S-expression: %r' % (sexp, ))
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parsed = parse_sexp(sexp)
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print("\nParsed to Python:", parsed)
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print("\nThen back to: '%s'" % print_sexp(parsed))
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