module builtin import strings const cp_utf8 = 65001 // to_wide returns a pointer to an UTF-16 version of the string receiver. // In V, strings are encoded using UTF-8 internally, but on windows most APIs, // that accept strings, need them to be in UTF-16 encoding. // The returned pointer of .to_wide(), has a type of &u16, and is suitable // for passing to Windows APIs that expect LPWSTR or wchar_t* parameters. // See also MultiByteToWideChar ( https://learn.microsoft.com/en-us/windows/win32/api/stringapiset/nf-stringapiset-multibytetowidechar ) pub fn (_str string) to_wide() &u16 { $if windows { unsafe { num_chars := (C.MultiByteToWideChar(cp_utf8, 0, &char(_str.str), _str.len, 0, 0)) mut wstr := &u16(malloc_noscan((num_chars + 1) * 2)) // sizeof(wchar_t) if wstr != 0 { C.MultiByteToWideChar(cp_utf8, 0, &char(_str.str), _str.len, wstr, num_chars) C.memset(&u8(wstr) + num_chars * 2, 0, 2) } return wstr } } $else { srunes := _str.runes() unsafe { mut result := &u16(vcalloc_noscan((srunes.len + 1) * 2)) for i, r in srunes { result[i] = u16(r) } return result } } } // string_from_wide creates a V string, encoded in UTF-8, given a windows // style string encoded in UTF-16. [manualfree; unsafe] pub fn string_from_wide(_wstr &u16) string { $if windows { unsafe { wstr_len := C.wcslen(_wstr) return string_from_wide2(_wstr, wstr_len) } } $else { mut i := 0 for unsafe { _wstr[i] } != 0 { i++ } return unsafe { string_from_wide2(_wstr, i) } } } // string_from_wide2 creates a V string, encoded in UTF-8, given a windows // style string, encoded in UTF-16. It is more efficient, compared to // string_from_wide, but it requires you to know the input string length, // and to pass it as the second argument. [manualfree; unsafe] pub fn string_from_wide2(_wstr &u16, len int) string { $if windows { unsafe { num_chars := C.WideCharToMultiByte(cp_utf8, 0, _wstr, len, 0, 0, 0, 0) mut str_to := malloc_noscan(num_chars + 1) if str_to != 0 { C.WideCharToMultiByte(cp_utf8, 0, _wstr, len, &char(str_to), num_chars, 0, 0) C.memset(str_to + num_chars, 0, 1) } return tos2(str_to) } } $else { mut sb := strings.new_builder(len) defer { unsafe { sb.free() } } for i := 0; i < len; i++ { u := unsafe { rune(_wstr[i]) } sb.write_rune(u) } res := sb.str() return res } }