\$C /* Generate Main Module */ COMPILER Expr /* This is a simple expression calculator */ /*----------------- Scanner Specifications ----------------------*/ CHARACTERS letter = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz". digit = "0123456789". tab = CHR(9). eol = CHR(10). TOKENS ident = letter {letter|digit}. number = digit { digit }. IGNORE eol+tab COMMENTS FROM "--" TO eol /*--------------------Parser Specification -------------------*/ PRODUCTIONS Expr = StatSeq . StatSeq = SYNC { Stat ";" SYNC} . Stat = (. int value; .) Expression<&value> (. printf("%d\n", value); .) . Expression = (. int result1, result2; .) Term<&result1> { "+" Term<&result2> (. result1 += result2; .) | "-" Term<&result2> (. result1 -= result2; .) } (. *result = result1; .) . Term = (. int result1, result2; .) Factor<&result1> { '*' Factor<&result2> (. result1 *= result2; .) | '/' Factor<&result2> (. result1 /= result2; .) } (. *result = result1; .) . Factor = (. int sign = 1; .) [ "-" (. sign =- 1; .) ] ( Number | "(" Expression ")" ) (. *result *= sign; .) . Number = (. char buff[20]; .) number (. S_GetString(S_Pos, S_Len, buff, sizeof(buff) - 1); *result = atoi(buff); .) . /* Ident = ident (. S_GetString(S_Pos, S_Len, name, 20); .) . */ END Expr.