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comparison python/pyburg.py @ 318:e84047f29c78

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Add burg and yacc initial attempts
author Windel Bouwman
date Tue, 31 Dec 2013 12:38:15 +0100
parents
children 8d07a4254f04
comparison
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317:e30a77ae359b 318:e84047f29c78
1 #!/usr/bin/python
2
3 """ Bottom up rewrite generator in python """
4 import sys
5 import re
6 import argparse
7 from ppci import Token
8 import burg_parser
9
10
11 class BurgLexer:
12 def feed(self, txt):
13 tok_spec = [
14 ('ID', r'[A-Za-z][A-Za-z\d_]*'),
15 ('STRING', r"'[^']*'"),
16 ('BRACEDCODE', r"\{[^\}]*\}"),
17 ('OTHER', r'[:;\|]'),
18 ('SKIP', r'[ ]')
19 ]
20 tok_re = '|'.join('(?P<%s>%s)' % pair for pair in tok_spec)
21 gettok = re.compile(tok_re).match
22
23 lines = txt.split('\n')
24 def tokenize_line(line):
25 """ Generator that splits up a line into tokens """
26 mo = gettok(line)
27 pos = 0
28 while mo:
29 typ = mo.lastgroup
30 val = mo.group(typ)
31 if typ == 'ID':
32 yield Token(typ, val)
33 elif typ == 'STRING':
34 typ = 'ID'
35 yield Token(typ, val[1:-1])
36 elif typ == 'OTHER':
37 typ = val
38 yield Token(typ, val)
39 elif typ == 'BRACEDCODE':
40 yield Token(typ, val)
41 elif typ == 'SKIP':
42 pass
43 else:
44 raise NotImplementedError(str(typ))
45 pos = mo.end()
46 mo = gettok(line, pos)
47 if len(line) != pos:
48 raise ParseError('Lex fault at {}'.format(line))
49
50 def tokenize():
51 section = 0
52 for line in lines:
53 line = line.strip()
54 if not line:
55 continue # Skip empty lines
56 if line == '%%':
57 section += 1
58 yield Token('%%', '%%')
59 continue
60 if section == 0:
61 if line.startswith('%tokens'):
62 yield Token('%tokens', '%tokens')
63 yield from tokenize_line(line[7:])
64 else:
65 yield Token('HEADER', line)
66 elif section == 1:
67 yield from tokenize_line(line)
68 yield Token('eof', 'eof')
69 self.tokens = tokenize()
70 self.token = self.tokens.__next__()
71
72 def next_token(self):
73 t = self.token
74 if t.typ != 'eof':
75 self.token = self.tokens.__next__()
76 return t
77
78
79 class BurgParser(burg_parser.Parser):
80 """ Derive from automatically generated parser """
81 def add_rule(self, *args):
82 print(args)
83
84
85 def main():
86 # Parse arguments:
87 parser = argparse.ArgumentParser(description='pyburg bottom up rewrite system generator compiler compiler')
88 parser.add_argument('source', type=argparse.FileType('r'), \
89 help='the parser specification')
90 parser.add_argument('-o', '--output', type=argparse.FileType('w'), \
91 default=sys.stdout)
92 args = parser.parse_args()
93 src = args.source.read()
94 args.source.close()
95
96 l = BurgLexer()
97 p = BurgParser()
98 l.feed(src)
99 p.parse(l)
100
101 if __name__ == '__main__':
102 main()