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parsing.c
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parsing.c
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#include <stdio.h>
#include <stdlib.h>
#include "mpc.h"
char* LANG = "goose"; //dont forget to change the value
// in mpca_lang as well
#ifdef _WIN32
#include <string.h>
static char buffer[2048];
char* readline(char* prompt){
fputs(prompt,stdout);
fgets(buffer, 2048, stdin);
char* cpy = malloc(strlen(buffer)+ 1);
strcpy(cpy, buffer);
cpy[strlen(cpy)-1] = '\0';
return cpy;
}
void add_history(*char unused){}
#else
#include <editline/readline.h>
#endif
typedef struct{
int type;
long num;
int err;
}lval;
enum { LVAL_NUM, LVAL_ERR};
enum { LERR_DIV_ZERO, LERR_BAD_OP, LERR_BAD_NUM};
lval lval_num(long x){
lval v;
v.type = LVAL_NUM;
v.num = x;
return v;
}
lval lval_err(int x){
lval v;
v.type = LVAL_ERR;
v.err = x;
return v;
}
void lval_print(lval v){
switch (v.type){
case LVAL_NUM:
printf("%li", v.num);
break;
case LVAL_ERR:
if (v.err == LERR_DIV_ZERO){
printf("Error: Division By Zero !");
}
if (v.err == LERR_BAD_OP){
printf("Error: Invalid Operator!");
}
if (v.err == LERR_BAD_NUM){
printf("Error: Invalid Number!");
}
break;
}
}
void lval_println(lval v) {
lval_print(v);
putchar('\n');
}
lval eval_op(lval x, char *op, lval y) {
if (x.type == LVAL_ERR){
return x;
}
if (y.type == LVAL_ERR){
return y;
}
if(strcmp(op, "+") == 0) {
return lval_num(x.num + y.num);
}
if(strcmp(op, "-") == 0) {
return lval_num(x.num - y.num);
}
if(strcmp(op, "*") == 0) {
return lval_num(x.num * y.num);
}
if(strcmp(op, "/") == 0) {
return y.num == 0
? lval_err(LERR_DIV_ZERO)
: lval_num(x.num / y.num);
}
return lval_err(LERR_BAD_OP);
}
lval eval(mpc_ast_t* t){
if(strstr(t->tag, "number")){
errno = 0;
long x = strtol(t->contents, NULL, 10);
return errno != ERANGE ? lval_num(x) : lval_err(LERR_BAD_NUM);
}
char* op = t->children[1]->contents;
lval x = eval(t->children[2]);
int i = 3;
while(strstr(t->children[i]->tag,"expr")){
x = eval_op(x, op, eval(t->children[i]));
i++;
}
return x;
}
int main() {
mpc_parser_t* Number = mpc_new("number");
mpc_parser_t* Decimal = mpc_new("decimal");
mpc_parser_t* Operator = mpc_new("operator");
mpc_parser_t* Expr = mpc_new("expr");
mpc_parser_t* Lang = mpc_new(LANG);
mpca_lang(MPCA_LANG_DEFAULT,
" \
number : /-?[0-9]+/; \
decimal : <number>+ '.' <number>+; \
operator : '+' | '-' | '*' | '/'; \
expr : <number> | <decimal> | '(' <operator> <expr>+ ')'; \
goose : /^/ '('? <operator> <expr>+ ')'? /$/ ; \
",
Number, Decimal, Operator, Expr, Lang);
printf("%s Version 0.0.0.1", LANG);
puts("MIT License");
puts("Press CTR+C to Exit\n");
while (1) {
char tag[sizeof(LANG)];
strcpy(tag, LANG);
strcat(tag,"> ");
char *input = readline(tag);
add_history(input);
mpc_result_t r;
if(mpc_parse("<stdin",input,Lang, &r)){
lval result = eval(r.output);
lval_println(result);
mpc_ast_delete(r.output);
}else{
mpc_err_print(r.error);
mpc_err_print(r.error);
}
free(input);
}
mpc_cleanup(4, Number, Operator, Expr, Lang);
return 0;
}