sorta kinda working on strings for cmenu. being lazy

cmenu/utf.c

@@ -0,0 +1,65 @@
+#include <stddef.h>
+
+#include "utf.h"
+#include "str.h"
+
+typedef struct Utf8Parser {
+	String str;
+} Utf8Parser;
+
+bool Utf8ParserNextCodePoint(Utf8Parser *this, CodePoint *out_codepoint) {
+	uitn8_t const flag_1_bytes = 0;
+	uint8_t const mask_1_bytes = 1 << 7;
+
+	uint8_t const flag_continuation = mask_1_bytes;
+	uint8_t const mask_continuation = (1 << 7) | (1 << 6);
+
+	uint8_t const flag_2_bytes = mask_continuation;
+	uint8_t const mask_2_bytes = (1 << 7) | (1 << 6) | (1 << 5);
+
+	uint8_t const flag_3_bytes = mask_2_bytes;
+	uint8_t const mask_3_bytes = (1 << 7) | (1 << 6) | (1 << 5) | (1 << 4);
+
+	uint8_t const flag_4_bytes = mask_3_bytes;
+	uint8_t const mask_4_bytes = (1 << 7) | (1 << 6) | (1 << 5) | (1 << 4) | (1 << 3);
+
+	if (this->str.size == 0) {
+		*out_codepoint = 0;
+		return false;
+	}
+
+	if ((this->str.buffer[0] & mask_1_bytes) == flag_1_bytes) {
+		*out_codepoint = (CodePoint) str[0];
+		bool ok = StringSub(this->str, 1, -1, &this->str);
+		assert(ok && "has to be ok since the size is not 0");
+		return ok;
+	} else
+}
+
+// max must be less than or equal to the capacity of target.
+bool CodePointsFromUtf8String(
+	uint8_t const *str,
+	CodePoint *target,
+	int max
+) {
+
+	for (size_t i = 0; str[i] != '\0' && max > 0;) {
+		if ((str[i] & mask_1_bytes) == flag_1_bytes) {
+			*target = (CodePoint) str[i];
+
+			target += 1;
+			max -= 1;
+			i += 1;
+		} else
+		if ((str[i] & mask_2_bytes) == flag_2_bytes) {
+		} else
+		if ((str[i] & mask_3_bytes) == flag_3_bytes) {
+		} else
+		if ((str[i] & mask_4_bytes) == flag_4_bytes) {
+		} else {
+			false;
+		}
+	}
+
+	return true;
+}