t018llstar.g revision 324c4644fee44b9898524c09511bd33c3f12e2df 
1grammar t018llstar;
2
3options {
4    language = JavaScript;
5}
6
7@members {
8this.olog = [];
9this.output = function(msg) {
10    this.olog.push(msg);
11};
12}
13
14program
15    :   declaration+
16    ;
17
18/** In this rule, the functionHeader left prefix on the last two
19 *  alternatives is not LL(k) for a fixed k.  However, it is
20 *  LL(*).  The LL(*) algorithm simply scans ahead until it sees
21 *  either the ';' or the '{' of the block and then it picks
22 *  the appropriate alternative.  Lookhead can be arbitrarily
23 *  long in theory, but is <=10 in most cases.  Works great.
24 *  Use ANTLRWorks to see the lookahead use (step by Location)
25 *  and look for blue tokens in the input window pane. :)
26 */
27declaration
28    :   variable
29    |   functionHeader ';'
30	{this.output($functionHeader.name+" is a declaration");}
31    |   functionHeader block
32	{this.output($functionHeader.name+" is a definition");}
33    ;
34
35variable
36    :   type declarator ';'
37    ;
38
39declarator
40    :   ID 
41    ;
42
43functionHeader returns [name]
44    :   type ID '(' ( formalParameter ( ',' formalParameter )* )? ')'
45	{$name = $ID.text}
46    ;
47
48formalParameter
49    :   type declarator        
50    ;
51
52type
53    :   'int'   
54    |   'char'  
55    |   'void'
56    |   ID        
57    ;
58
59block
60    :   '{'
61            variable*
62            stat*
63        '}'
64    ;
65
66stat: forStat
67    | expr ';'      
68    | block
69    | assignStat ';'
70    | ';'
71    ;
72
73forStat
74    :   'for' '(' assignStat ';' expr ';' assignStat ')' block        
75    ;
76
77assignStat
78    :   ID '=' expr        
79    ;
80
81expr:   condExpr
82    ;
83
84condExpr
85    :   aexpr ( ('==' | '<') aexpr )?
86    ;
87
88aexpr
89    :   atom ( '+' atom )*
90    ;
91
92atom
93    : ID      
94    | INT      
95    | '(' expr ')'
96    ; 
97
98ID  :   ('a'..'z'|'A'..'Z'|'_') ('a'..'z'|'A'..'Z'|'0'..'9'|'_')*
99    ;
100
101INT :	('0'..'9')+
102    ;
103
104WS  :   (   ' '
105        |   '\t'
106        |   '\r'
107        |   '\n'
108        )+
109        {$channel=HIDDEN}
110    ;    
111