1234949Sbapt%{ 2234949Sbapt# include <stdio.h> 3234949Sbapt# include <ctype.h> 4234949Sbapt 5234949Sbaptint regs[26]; 6234949Sbaptint base; 7234949Sbapt 8234949Sbaptint yylex(void); 9234949Sbaptstatic void yyerror(const char *s); 10234949Sbapt 11234949Sbapt%} 12234949Sbapt 13234949Sbapt%start list 14234949Sbapt 15234949Sbapt%token OP_ADD "ADD-operator" 16234949Sbapt%token OP_SUB "SUB-operator" 17234949Sbapt%token OP_MUL "MUL-operator" 18234949Sbapt%token OP_DIV "DIV-operator" 19234949Sbapt%token OP_MOD "MOD-operator" 20234949Sbapt%token OP_AND "AND-operator" 21234949Sbapt 22234949Sbapt%token DIGIT LETTER 23234949Sbapt 24234949Sbapt%left '|' 25234949Sbapt%left '&' 26234949Sbapt%left '+' '-' 27234949Sbapt%left '*' '/' '%' 28234949Sbapt%left UMINUS /* supplies precedence for unary minus */ 29234949Sbapt 30234949Sbapt%% /* beginning of rules section */ 31234949Sbapt 32234949Sbaptlist : /* empty */ 33234949Sbapt | list stat '\n' 34234949Sbapt | list error '\n' 35234949Sbapt { yyerrok ; } 36234949Sbapt ; 37234949Sbapt 38234949Sbaptstat : expr 39234949Sbapt { printf("%d\n",$1);} 40234949Sbapt | LETTER '=' expr 41234949Sbapt { regs[$1] = $3; } 42234949Sbapt ; 43234949Sbapt 44234949Sbaptexpr : '(' expr ')' 45234949Sbapt { $$ = $2; } 46234949Sbapt | expr "ADD-operator" expr 47234949Sbapt { $$ = $1 + $3; } 48234949Sbapt | expr "SUB-operator" expr 49234949Sbapt { $$ = $1 - $3; } 50234949Sbapt | expr "MUL-operator" expr 51234949Sbapt { $$ = $1 * $3; } 52234949Sbapt | expr "DIV-operator" expr 53234949Sbapt { $$ = $1 / $3; } 54234949Sbapt | expr "MOD-operator" expr 55234949Sbapt { $$ = $1 % $3; } 56234949Sbapt | expr "AND-operator" expr 57234949Sbapt { $$ = $1 & $3; } 58234949Sbapt | expr '|' expr 59234949Sbapt { $$ = $1 | $3; } 60234949Sbapt | "SUB-operator" expr %prec UMINUS 61234949Sbapt { $$ = - $2; } 62234949Sbapt | LETTER 63234949Sbapt { $$ = regs[$1]; } 64234949Sbapt | number 65234949Sbapt ; 66234949Sbapt 67234949Sbaptnumber: DIGIT 68234949Sbapt { $$ = $1; base = ($1==0) ? 8 : 10; } 69234949Sbapt | number DIGIT 70234949Sbapt { $$ = base * $1 + $2; } 71234949Sbapt ; 72234949Sbapt 73234949Sbapt%% /* start of programs */ 74234949Sbapt 75234949Sbaptint 76234949Sbaptmain (void) 77234949Sbapt{ 78234949Sbapt while(!feof(stdin)) { 79234949Sbapt yyparse(); 80234949Sbapt } 81234949Sbapt return 0; 82234949Sbapt} 83234949Sbapt 84234949Sbaptstatic void 85234949Sbaptyyerror(const char *s) 86234949Sbapt{ 87234949Sbapt fprintf(stderr, "%s\n", s); 88234949Sbapt} 89234949Sbapt 90234949Sbaptint 91234949Sbaptyylex(void) { 92234949Sbapt /* lexical analysis routine */ 93234949Sbapt /* returns LETTER for a lower case letter, yylval = 0 through 25 */ 94234949Sbapt /* return DIGIT for a digit, yylval = 0 through 9 */ 95234949Sbapt /* all other characters are returned immediately */ 96234949Sbapt 97234949Sbapt int c; 98234949Sbapt 99234949Sbapt while( (c=getchar()) == ' ' ) { /* skip blanks */ } 100234949Sbapt 101234949Sbapt /* c is now nonblank */ 102234949Sbapt 103234949Sbapt if( islower( c )) { 104234949Sbapt yylval = c - 'a'; 105234949Sbapt return ( LETTER ); 106234949Sbapt } 107234949Sbapt if( isdigit( c )) { 108234949Sbapt yylval = c - '0'; 109234949Sbapt return ( DIGIT ); 110234949Sbapt } 111234949Sbapt return( c ); 112234949Sbapt} 113