/* $NetBSD: calc2.y,v 1.1.1.4 2013/04/06 14:45:29 christos Exp $ */ %parse-param { int regs[26] } %parse-param { int *base } %lex-param { int *base } %{ # include # include #ifdef YYBISON #define YYLEX_PARAM base #define YYLEX_DECL() yylex(int *YYLEX_PARAM) #define YYERROR_DECL() yyerror(int regs[26], int *base, const char *s) int YYLEX_DECL(); static void YYERROR_DECL(); #endif %} %start list %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 ')' { $$ = $2; } | expr '+' expr { $$ = $1 + $3; } | expr '-' expr { $$ = $1 - $3; } | expr '*' expr { $$ = $1 * $3; } | expr '/' expr { $$ = $1 / $3; } | expr '%' expr { $$ = $1 % $3; } | expr '&' expr { $$ = $1 & $3; } | expr '|' expr { $$ = $1 | $3; } | '-' expr %prec UMINUS { $$ = - $2; } | LETTER { $$ = regs[$1]; } | number ; number: DIGIT { $$ = $1; (*base) = ($1==0) ? 8 : 10; } | number DIGIT { $$ = (*base) * $1 + $2; } ; %% /* start of programs */ #ifdef YYBYACC extern int YYLEX_DECL(); #endif int main (void) { int regs[26]; int base = 10; while(!feof(stdin)) { yyparse(regs, &base); } return 0; } static void YYERROR_DECL() { fprintf(stderr, "%s\n", s); } int YYLEX_DECL() { /* 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') % (*base); return ( DIGIT ); } return( c ); }