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