Start refactor, restructure basic

src/basic/basic_unicode.h

@@ -0,0 +1,60 @@
+#pragma once
+
+struct UTF32Result {
+    uint32_t out_str;
+    int64_t  advance;
+    int64_t  error;
+};
+
+struct UTF8Result {
+    uint8_t out_str[4];
+    int64_t len;
+    int64_t error;
+};
+
+struct UTF16Result {
+    uint16_t out_str[2];
+    int64_t  len;
+    int64_t  error;
+};
+
+struct UTF8Iter {
+    char    *data;
+    int64_t  len;
+    int64_t  utf8_codepoint_byte_size;
+    int64_t  i;
+    uint32_t item;
+
+    UTF8Iter &operator++() {
+        void Advance(UTF8Iter * iter);
+        Advance(this);
+        return *this;
+    }
+    friend bool operator!=(const UTF8Iter &a, const UTF8Iter &b) { return a.item != b.item; }
+    UTF8Iter   &operator*() { return *this; }
+    UTF8Iter    begin() {
+        UTF8Iter IterateUTF8Ex(char *data, int64_t len);
+        return {IterateUTF8Ex(data, len)};
+    }
+    UTF8Iter end() { return {}; }
+};
+
+API UTF32Result UTF16ToUTF32(uint16_t *c, int64_t max_advance);
+API UTF8Result UTF32ToUTF8(uint32_t codepoint);
+API UTF32Result UTF8ToUTF32(uint8_t *c, int64_t max_advance);
+API UTF16Result UTF32ToUTF16(uint32_t codepoint);
+
+API int64_t CreateCharFromWidechar(char *buffer, int64_t buffer_size, char16_t *in, int64_t inlen);
+API int64_t CreateWidecharFromChar(char16_t *buffer, int64_t buffer_size, char *in, int64_t inlen);
+API char16_t *ToWidechar(Allocator allocator, String string);
+API String16 ToString16(Allocator allocator, String string);
+API String ToString(Allocator allocator, String16 string);
+API String ToString(Allocator allocator, char16_t *string, int64_t len);
+API String ToString(Allocator allocator, char16_t *wstring);
+
+API bool IsValid(UTF8Iter &iter);
+API void Advance(UTF8Iter *iter);
+API UTF8Iter IterateUTF8Ex(char *data, int64_t len);
+API UTF8Iter IterateUTF8(char *data);
+API UTF8Iter IterateUTF8(String string);
+API bool IsUTF8ContinuationByte(char c);