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comparison python/parserlib.py @ 212:62386bcee1ba

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Added parser combinator lib
author Windel Bouwman
date Sun, 30 Jun 2013 19:00:41 +0200
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211:99164160fb0b 212:62386bcee1ba
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4 class Token:
5 pass
6
7 # Base functions:
8 class Pbase:
9 def __init__(self):
10 self.pa = None
11 def parse(self, txt):
12 r = self.do(txt)
13 if r:
14 match, rest = r
15 # Apply action:
16 if self.ParseAction:
17 match = self.ParseAction(match)
18 return match, rest
19 else:
20 # TODO: fail in some way
21 pass
22 def getParseAction(self):
23 return self.pa
24 def setParseAction(self, pa):
25 self.pa = pa
26
27 ParseAction = property(getParseAction, setParseAction)
28
29 # basic elements:
30
31 class Literal(Pbase):
32 def __init__(self, s):
33 super().__init__()
34 self.pat = s
35 def do(self, txt):
36 if txt.startswith(self.pat):
37 return self.pat, txt[len(self.pat):]
38
39 class Or(Pbase):
40 def __init__(self, options):
41 super().__init__()
42 self.options = options
43 def do(self, txt):
44 for option in self.options:
45 r = option.parse(txt)
46 if r:
47 return r
48
49 class And:
50 def __init__(self, options):
51 self.options = options
52
53 class Sequence(Pbase):
54 def __init__(self, seq):
55 super().__init__()
56 self.seq = seq
57 def do(self, txt):
58 results = []
59 for thung in self.seq:
60 r = thung.parse(txt)
61 if r:
62 res, txt = r
63 results.append(res)
64 else:
65 return
66 return results, txt
67
68 class Optional(Pbase):
69 def __init__(self, thung):
70 super().__init__()
71 self.thung = thung
72 def do(self, txt):
73 r = self.thung.do(txt)
74 if r:
75 return r
76 return (0, txt)
77
78 # Contraptions of basic blocks:
79
80 def OneOrMore():
81 def __init__(self, thingy):
82 pass
83