blob: 5feeb4a03ed6df9815da5a90411fd07af513cd38 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
|
%{
# include <stdio.h>
# include <ctype.h>
int regs[26];
int base;
int yylex(void);
static void yyerror(const char *s);
%}
%start list
%token OP_ADD "ADD-operator"
%token OP_SUB "SUB-operator"
%token OP_MUL "MUL-operator"
%token OP_DIV "DIV-operator"
%token OP_MOD "MOD-operator"
%token OP_AND "AND-operator"
%token DIGIT LETTER
%left '|'
%left '&'
%left '+' '-'
%left '*' '/' '%'
%left UMINUS /* supplies precedence for unary minus */
%% /* beginning of rules section */
list : /* empty */
| list stat '\n'
| list error '\n'
{ yyerrok ; }
;
stat : expr
{ printf("%d\n",$1);}
| LETTER '=' expr
{ regs[$1] = $3; }
;
expr : '(' expr ')'
{ $$ = $2; }
| expr OP_ADD expr
{ $$ = $1 + $3; }
| expr OP_SUB expr
{ $$ = $1 - $3; }
| expr OP_MUL expr
{ $$ = $1 * $3; }
| expr OP_DIV expr
{ $$ = $1 / $3; }
| expr OP_MOD expr
{ $$ = $1 % $3; }
| expr OP_AND expr
{ $$ = $1 & $3; }
| expr '|' expr
{ $$ = $1 | $3; }
| OP_SUB expr %prec UMINUS
{ $$ = - $2; }
| LETTER
{ $$ = regs[$1]; }
| number
;
number: DIGIT
{ $$ = $1; base = ($1==0) ? 8 : 10; }
| number DIGIT
{ $$ = base * $1 + $2; }
;
%% /* start of programs */
int
main (void)
{
while(!feof(stdin)) {
yyparse();
}
return 0;
}
static void
yyerror(const char *s)
{
fprintf(stderr, "%s\n", s);
}
int
yylex(void) {
/* lexical analysis routine */
/* returns LETTER for a lower case letter, yylval = 0 through 25 */
/* return DIGIT for a digit, yylval = 0 through 9 */
/* all other characters are returned immediately */
int c;
while( (c=getchar()) == ' ' ) { /* skip blanks */ }
/* c is now nonblank */
if( islower( c )) {
yylval = c - 'a';
return ( LETTER );
}
if( isdigit( c )) {
yylval = c - '0';
return ( DIGIT );
}
return( c );
}
|
