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comparison expr.py @ 3:5ac8eed85684

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consolidate token classes
author Ted Mielczarek <ted.mielczarek@gmail.com>
date Thu, 02 Jun 2011 07:47:33 -0400
parents 94a293b914af
children a42bb6dc2fa7
comparison
equal deleted inserted replaced
2:94a293b914af 3:5ac8eed85684
32 def nud(self, parser): 32 def nud(self, parser):
33 # identifiers take their value from the value mappings passed 33 # identifiers take their value from the value mappings passed
34 # to the parser 34 # to the parser
35 return parser.value(self.value) 35 return parser.value(self.value)
36 36
37 class int_token: 37 class literal_token:
38 def __init__(self, value): 38 def __init__(self, value):
39 self.value = int(value) 39 self.value = value
40 def nud(self, parser):
41 return self.value
42
43 class bool_token:
44 def __init__(self, value):
45 self.value = {'true':True, 'false':False}[value]
46 def nud(self, parser): 40 def nud(self, parser):
47 return self.value 41 return self.value
48 42
49 class eq_op_token: 43 class eq_op_token:
50 "==" 44 "=="
82 76
83 class rparen_token: 77 class rparen_token:
84 ")" 78 ")"
85 lbp = 0 79 lbp = 0
86 80
87 class string_token:
88 def __init__(self, value):
89 self.value = value
90 def nud(self, parser):
91 return self.value
92
93 class end_token: 81 class end_token:
94 # lowest left binding power, always ends parsing 82 # lowest left binding power, always ends parsing
95 lbp = 0 83 lbp = 0
96 84
97 class ParseError(Exception): 85 class ParseError(Exception):
109 def _tokenize(self): 97 def _tokenize(self):
110 """ 98 """
111 Lex the input text into tokens and yield them in sequence. 99 Lex the input text into tokens and yield them in sequence.
112 """ 100 """
113 # scanner callbacks 101 # scanner callbacks
114 def bool_(scanner, t): return bool_token(t) 102 def bool_(scanner, t): return literal_token({'true':True, 'false':False}[t])
115 def identifier(scanner, t): return ident_token(t) 103 def identifier(scanner, t): return ident_token(t)
116 def integer(scanner, t): return int_token(t) 104 def integer(scanner, t): return literal_token(int(t))
117 def eq(scanner, t): return eq_op_token() 105 def eq(scanner, t): return eq_op_token()
118 def neq(scanner, t): return neq_op_token() 106 def neq(scanner, t): return neq_op_token()
119 def or_(scanner, t): return or_op_token() 107 def or_(scanner, t): return or_op_token()
120 def and_(scanner, t): return and_op_token() 108 def and_(scanner, t): return and_op_token()
121 def lparen(scanner, t): return lparen_token() 109 def lparen(scanner, t): return lparen_token()
122 def rparen(scanner, t): return rparen_token() 110 def rparen(scanner, t): return rparen_token()
123 def string_(scanner, t): return string_token(t[1:-1]) 111 def string_(scanner, t): return literal_token(t[1:-1])
124 112
125 scanner = re.Scanner([ 113 scanner = re.Scanner([
126 (r"true|false", bool_), 114 (r"true|false", bool_),
127 (r"[a-zA-Z_]\w*", identifier), 115 (r"[a-zA-Z_]\w*", identifier),
128 (r"[0-9]+", integer), 116 (r"[0-9]+", integer),