1/* $NetBSD: calc_code_imports.y,v 1.1.1.1 2021/02/20 20:30:07 christos Exp $ */ 2 3%code imports { /* CODE-IMPORTS */ } 4%code imports { /* CODE-IMPORTS2 */ } 5 6%{ 7# include <stdio.h> 8# include <ctype.h> 9 10int regs[26]; 11int base; 12 13extern int yylex(void); 14static void yyerror(const char *s); 15 16%} 17 18%start list 19 20%token DIGIT LETTER 21 22%left '|' 23%left '&' 24%left '+' '-' 25%left '*' '/' '%' 26%left UMINUS /* supplies precedence for unary minus */ 27 28%% /* beginning of rules section */ 29 30list : /* empty */ 31 | list stat '\n' 32 | list error '\n' 33 { yyerrok ; } 34 ; 35 36stat : expr 37 { printf("%d\n",$1);} 38 | LETTER '=' expr 39 { regs[$1] = $3; } 40 ; 41 42expr : '(' expr ')' 43 { $$ = $2; } 44 | expr '+' expr 45 { $$ = $1 + $3; } 46 | expr '-' expr 47 { $$ = $1 - $3; } 48 | expr '*' expr 49 { $$ = $1 * $3; } 50 | expr '/' expr 51 { $$ = $1 / $3; } 52 | expr '%' expr 53 { $$ = $1 % $3; } 54 | expr '&' expr 55 { $$ = $1 & $3; } 56 | expr '|' expr 57 { $$ = $1 | $3; } 58 | '-' expr %prec UMINUS 59 { $$ = - $2; } 60 | LETTER 61 { $$ = regs[$1]; } 62 | number 63 ; 64 65number: DIGIT 66 { $$ = $1; base = ($1==0) ? 8 : 10; } 67 | number DIGIT 68 { $$ = base * $1 + $2; } 69 ; 70 71%% /* start of programs */ 72 73int 74main (void) 75{ 76 while(!feof(stdin)) { 77 yyparse(); 78 } 79 return 0; 80} 81 82static void 83yyerror(const char *s) 84{ 85 fprintf(stderr, "%s\n", s); 86} 87 88int 89yylex(void) 90{ 91 /* lexical analysis routine */ 92 /* returns LETTER for a lower case letter, yylval = 0 through 25 */ 93 /* return DIGIT for a digit, yylval = 0 through 9 */ 94 /* all other characters are returned immediately */ 95 96 int c; 97 98 while( (c=getchar()) == ' ' ) { /* skip blanks */ } 99 100 /* c is now nonblank */ 101 102 if( islower( c )) { 103 yylval = c - 'a'; 104 return ( LETTER ); 105 } 106 if( isdigit( c )) { 107 yylval = c - '0'; 108 return ( DIGIT ); 109 } 110 return( c ); 111} 112