1 /* $NetBSD: calc2.y,v 1.1.1.3 2011/09/10 21:22:06 christos Exp $ */ 2 3 %parse-param { int regs[26] } 4 %parse-param { int *base } 5 6 %lex-param { int *base } 7 8 %{ 9 # include <stdio.h> 10 # include <ctype.h> 11 12 %} 13 14 %start list 15 16 %token DIGIT LETTER 17 18 %left '|' 19 %left '&' 20 %left '+' '-' 21 %left '*' '/' '%' 22 %left UMINUS /* supplies precedence for unary minus */ 23 24 %% /* beginning of rules section */ 25 26 list : /* empty */ 27 | list stat '\n' 28 | list error '\n' 29 { yyerrok ; } 30 ; 31 32 stat : expr 33 { printf("%d\n",$1);} 34 | LETTER '=' expr 35 { regs[$1] = $3; } 36 ; 37 38 expr : '(' expr ')' 39 { $$ = $2; } 40 | expr '+' expr 41 { $$ = $1 + $3; } 42 | expr '-' expr 43 { $$ = $1 - $3; } 44 | expr '*' expr 45 { $$ = $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 %prec UMINUS 55 { $$ = - $2; } 56 | LETTER 57 { $$ = regs[$1]; } 58 | number 59 ; 60 61 number: DIGIT 62 { $$ = $1; (*base) = ($1==0) ? 8 : 10; } 63 | number DIGIT 64 { $$ = (*base) * $1 + $2; } 65 ; 66 67 %% /* start of programs */ 68 69 #ifdef YYBYACC 70 extern int YYLEX_DECL(); 71 static void YYERROR_DECL(); 72 #endif 73 74 int 75 main (void) 76 { 77 int regs[26]; 78 int base = 10; 79 80 while(!feof(stdin)) { 81 yyparse(regs, &base); 82 } 83 return 0; 84 } 85 86 static void 87 YYERROR_DECL() 88 { 89 fprintf(stderr, "%s\n", s); 90 } 91 92 int 93 yylex(int *base) 94 { 95 /* lexical analysis routine */ 96 /* returns LETTER for a lower case letter, yylval = 0 through 25 */ 97 /* return DIGIT for a digit, yylval = 0 through 9 */ 98 /* all other characters are returned immediately */ 99 100 int c; 101 102 while( (c=getchar()) == ' ' ) { /* skip blanks */ } 103 104 /* c is now nonblank */ 105 106 if( islower( c )) { 107 yylval = c - 'a'; 108 return ( LETTER ); 109 } 110 if( isdigit( c )) { 111 yylval = (c - '0') % (*base); 112 return ( DIGIT ); 113 } 114 return( c ); 115 } 116