/*

* calculator

*/

%token NUMBER

%left '+' '-'

%left '*' '/'

%%

start: lines;

lines: /* empty */

| lines line { yylrec++ }

;

line : expr '\n' { mes $1 }

| '\n' { mes "(empty line ignored)" }

| error '\n'

;

expr : expr '+' expr { $$ = $1 + $3 }

| expr '-' expr { $$ = $1 - $3 }

| expr '*' expr { $$ = $1 * $3 }

| expr '/' expr { $$ = $1 / $3 }

| '(' expr ')' { $$ = $2 }

| NUMBER { $$ = $1 }

;

%%

#runtime "hsp3cl"

yyparse

end stat

*yylex

if start == 0 {

input expr,, 1

if peek( expr ) == 0 : return 0

expr_ptr = 0

start = 1

}

char = peek( expr, expr_ptr )

if char == 10 || char == 13 {

start = 0

return 10

}

if char == ' ' || char == '\t' {

expr_ptr ++

goto *yylex

}

if char >= '0' && char <= '9' {

yylval = char - '0'

expr_ptr ++

repeat

char = peek( expr, expr_ptr )

if char >= '0' && char <= '9' : else : break

yylval = yylval * 10 + char - '0'

expr_ptr ++

loop

return NUMBER

}

expr_ptr ++

return char

*yyerror

mes yyerrmsg

return