基本語法:
1 %token "%token" "%letter" "%start" ;
2 %token ":" ";" "->" "|" ;
3
4 %letter string : "{string}" ;
5 %letter symbol : "{symbol}" ;
6
7 %start program ;
8
9 string_list -> string_list string
10 | string
11 ;
12
13 symbol_list -> symbol_list symbol
14 | symbol
15 ;
16
17 program -> item_list
18 ;
19
20 item_list -> item_list item
21 | item
22 ;
23
24 item -> token_def ";"
25 | letter_def ";"
26 | start_def ";"
27 | rule_def ";"
28 | ";"
29 ;
30
31 token_def -> "%token" string_list
32 ;
33
34 letter_def -> "%letter" symbol ":" string_list
35 ;
36
37 start_def -> "%start" symbol
38 ;
39
40 rule_def -> symbol "->" rhs_list
41 ;
42
43 rhs_list -> rhs_list "|" rhs
44 | rhs
45 ;
46
47 rhs -> term_list
48 ;
49
50 term_list -> term_list string
51 | term_list symbol
52 | string
53 | symbol
54 ;
生成的分析表:
由于狀態(tài)數(shù)量和非終結(jié)符數(shù)量過多,所以給出文件
《分析表》 下面是四則混合運算的文法文件:
1 %token "+" "-" ;
2 %token "*" "/" ;
3 %token "(" ")" ;
4
5 %letter AddOp : "+" "-" ;
6 %letter MulOp : "*" "/" ;
7 %letter ID : "{digit}" ;
8 %letter LQ : "(" ;
9 %letter RQ : ")" ;
10
11 %start Program ;
12
13 Program -> Exp
14 ;
15
16 Exp -> Exp AddOp Term
17 | Term
18 ;
19
20 Term -> Term MulOp Factor
21 | Factor
22 ;
23
24 Factor -> LQ Exp RQ
25 | ID
26 ;
posted on 2010-08-03 20:21
lwch 閱讀(317)
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