113 lines
2.0 KiB
Plaintext
113 lines
2.0 KiB
Plaintext
|
%{
|
||
|
|
# 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 );
|
||
|
|
}
|