/* $NetBSD: quote_calc4.y,v 1.1.1.3 2016/01/09 21:59:45 christos Exp $ */ %{ # include # include 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 ')' { $$ = $2; } | expr "ADD-operator" expr { $$ = $1 + $3; } | expr "SUB-operator" expr { $$ = $1 - $3; } | expr "MUL-operator" expr { $$ = $1 * $3; } | expr "DIV-operator" expr { $$ = $1 / $3; } | expr "MOD-operator" expr { $$ = $1 % $3; } | expr "AND-operator" expr { $$ = $1 & $3; } | expr '|' expr { $$ = $1 | $3; } | "SUB-operator" 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 ); }