Function AR_JOIN

src/arithmetic/string_funcs/string_funcs.c:216–291

given a list of strings and an optional delimiter return a concatenation of all the strings using the given delimiter string.join(list, delimiter = '') -> string

// return a concatenation of all the strings using the given delimiter
// string.join(list, delimiter = '') -> string
SIValue AR_JOIN(SIValue *argv, int argc, void *private_data) {
	SIValue list = argv[0];
	if(SI_TYPE(list) == T_NULL) {
		return SI_NullVal();
	}

	char *delimiter = "";
	if(argc == 2) {
		delimiter = argv[1].stringval;
	}

	int str_len = 0;                           // output string length
	uint32_t n = SIArray_Length(list);         // number of strings to join
	size_t delimeter_len = strlen(delimiter);  // length of the delimiter

	//--------------------------------------------------------------------------
	// compute required string length
	//--------------------------------------------------------------------------

	// delimeter length is added between each string
	if(n >= 2) {
		if(safe_mul(delimeter_len, n - 1, &str_len)) {
			ErrorCtx_SetError("String overflow");
			return SI_NullVal();
		}
	}

	// acount for each string length
	for(uint i = 0; i < n; i++) {
		SIValue str = SIArray_Get(list, i);
		if(SI_TYPE(str) != T_STRING) {
			// all elements in the list should be string.
			Error_SITypeMismatch(str, T_STRING);
			return SI_NullVal();
		}

		if(safe_add(str_len, strlen(str.stringval), &str_len)) {
			ErrorCtx_SetError("String overflow");
			return SI_NullVal();
		}
	}

	// acoun for null terminator
	if(safe_add(str_len, 1, &str_len)) {
		ErrorCtx_SetError("String overflow");
		return SI_NullVal();
	}

	//--------------------------------------------------------------------------
	// join strings
	//--------------------------------------------------------------------------

	int l = 0;                       // current string length
	int cur_len = 0;                 // offset into output string
	char *res = rm_malloc(str_len);  // output string

	for(uint i = 0; i < n - 1; i++) {
		SIValue str = SIArray_Get(list, i);