/
hstring.rs
427 lines (359 loc) · 11.1 KB
/
hstring.rs
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use super::*;
/// A WinRT string ([HSTRING](https://docs.microsoft.com/en-us/windows/win32/winrt/hstring))
/// is reference-counted and immutable.
#[repr(transparent)]
pub struct HSTRING(*mut Header);
impl HSTRING {
/// Create an empty `HSTRING`.
///
/// This function does not allocate memory.
pub const fn new() -> Self {
Self(core::ptr::null_mut())
}
/// Returns `true` if the string is empty.
pub fn is_empty(&self) -> bool {
// An empty HSTRING is represented by a null pointer.
self.0.is_null()
}
/// Returns the length of the string.
pub fn len(&self) -> usize {
if self.is_empty() {
return 0;
}
unsafe { (*self.0).len as usize }
}
/// Get the string as 16-bit wide characters (wchars).
pub fn as_wide(&self) -> &[u16] {
unsafe { core::slice::from_raw_parts(self.as_ptr(), self.len()) }
}
/// Returns a raw pointer to the `HSTRING` buffer.
pub fn as_ptr(&self) -> *const u16 {
if self.is_empty() {
const EMPTY: [u16; 1] = [0];
EMPTY.as_ptr()
} else {
let header = self.0;
unsafe { (*header).data }
}
}
/// Create a `HSTRING` from a slice of 16 bit characters (wchars).
pub fn from_wide(value: &[u16]) -> Self {
unsafe { Self::from_wide_iter(value.iter().copied(), value.len() as u32) }
}
/// Get the contents of this `HSTRING` as a String lossily.
pub fn to_string_lossy(&self) -> alloc::string::String {
alloc::string::String::from_utf16_lossy(self.as_wide())
}
/// Get the contents of this `HSTRING` as a OsString.
#[cfg(windows)]
pub fn to_os_string(&self) -> std::ffi::OsString {
std::os::windows::ffi::OsStringExt::from_wide(self.as_wide())
}
/// # Safety
/// len must not be less than the number of items in the iterator.
unsafe fn from_wide_iter<I: Iterator<Item = u16>>(iter: I, len: u32) -> Self {
if len == 0 {
return Self::new();
}
let mut ptr = Header::alloc(len);
// Place each utf-16 character into the buffer and
// increase len as we go along.
for (index, wide) in iter.enumerate() {
debug_assert!((index as u32) < len);
core::ptr::write((*ptr).data.add(index), wide);
(*ptr).len = index as u32 + 1;
}
// Write a 0 byte to the end of the buffer.
core::ptr::write((*ptr).data.offset((*ptr).len as isize), 0);
Self(ptr)
}
}
unsafe impl Abi for HSTRING {
type Abi = core::mem::ManuallyDrop<Self>;
}
unsafe impl RuntimeType for HSTRING {
const SIGNATURE: ConstBuffer = ConstBuffer::from_slice(b"string");
type DefaultType = Self;
fn from_default(from: &Self::DefaultType) -> Result<Self> {
Ok(from.clone())
}
}
impl Default for HSTRING {
fn default() -> Self {
Self::new()
}
}
impl Clone for HSTRING {
fn clone(&self) -> Self {
if self.is_empty() {
return Self::new();
}
unsafe { Self((*self.0).duplicate()) }
}
}
impl Drop for HSTRING {
fn drop(&mut self) {
if self.is_empty() {
return;
}
unsafe {
let header = std::mem::replace(&mut self.0, core::ptr::null_mut());
// REFERENCE_FLAG indicates a string backed by static or stack memory that is
// thus not reference-counted and does not need to be freed.
if (*header).flags & REFERENCE_FLAG == 0 && (*header).count.release() == 0 {
heap_free(header as *mut core::ffi::c_void);
}
}
}
}
unsafe impl Send for HSTRING {}
unsafe impl Sync for HSTRING {}
impl core::fmt::Display for HSTRING {
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
write!(f, "{}", Decode(|| core::char::decode_utf16(self.as_wide().iter().cloned())))
}
}
impl core::fmt::Debug for HSTRING {
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
write!(f, "{}", self)
}
}
impl core::convert::From<&str> for HSTRING {
fn from(value: &str) -> Self {
unsafe { Self::from_wide_iter(value.encode_utf16(), value.len() as u32) }
}
}
impl core::convert::From<alloc::string::String> for HSTRING {
fn from(value: alloc::string::String) -> Self {
value.as_str().into()
}
}
impl core::convert::From<&alloc::string::String> for HSTRING {
fn from(value: &alloc::string::String) -> Self {
value.as_str().into()
}
}
#[cfg(windows)]
impl core::convert::From<&std::ffi::OsStr> for HSTRING {
fn from(value: &std::ffi::OsStr) -> Self {
unsafe { Self::from_wide_iter(std::os::windows::ffi::OsStrExt::encode_wide(value), value.len() as u32) }
}
}
#[cfg(windows)]
impl core::convert::From<std::ffi::OsString> for HSTRING {
fn from(value: std::ffi::OsString) -> Self {
value.as_os_str().into()
}
}
#[cfg(windows)]
impl core::convert::From<&std::ffi::OsString> for HSTRING {
fn from(value: &std::ffi::OsString) -> Self {
value.as_os_str().into()
}
}
impl PartialEq for HSTRING {
fn eq(&self, other: &Self) -> bool {
*self.as_wide() == *other.as_wide()
}
}
impl PartialEq<alloc::string::String> for HSTRING {
fn eq(&self, other: &alloc::string::String) -> bool {
*self == **other
}
}
impl PartialEq<alloc::string::String> for &HSTRING {
fn eq(&self, other: &alloc::string::String) -> bool {
**self == **other
}
}
impl PartialEq<&alloc::string::String> for HSTRING {
fn eq(&self, other: &&alloc::string::String) -> bool {
*self == ***other
}
}
impl PartialEq<str> for HSTRING {
fn eq(&self, other: &str) -> bool {
self.as_wide().iter().copied().eq(other.encode_utf16())
}
}
impl PartialEq<str> for &HSTRING {
fn eq(&self, other: &str) -> bool {
**self == *other
}
}
impl PartialEq<&str> for HSTRING {
fn eq(&self, other: &&str) -> bool {
*self == **other
}
}
impl PartialEq<HSTRING> for str {
fn eq(&self, other: &HSTRING) -> bool {
*other == *self
}
}
impl PartialEq<HSTRING> for &str {
fn eq(&self, other: &HSTRING) -> bool {
*other == **self
}
}
impl PartialEq<&HSTRING> for str {
fn eq(&self, other: &&HSTRING) -> bool {
**other == *self
}
}
impl PartialEq<HSTRING> for alloc::string::String {
fn eq(&self, other: &HSTRING) -> bool {
*other == **self
}
}
impl PartialEq<HSTRING> for &alloc::string::String {
fn eq(&self, other: &HSTRING) -> bool {
*other == ***self
}
}
impl PartialEq<&HSTRING> for alloc::string::String {
fn eq(&self, other: &&HSTRING) -> bool {
**other == **self
}
}
#[cfg(windows)]
impl PartialEq<std::ffi::OsString> for HSTRING {
fn eq(&self, other: &std::ffi::OsString) -> bool {
*self == **other
}
}
#[cfg(windows)]
impl PartialEq<std::ffi::OsString> for &HSTRING {
fn eq(&self, other: &std::ffi::OsString) -> bool {
**self == **other
}
}
#[cfg(windows)]
impl PartialEq<&std::ffi::OsString> for HSTRING {
fn eq(&self, other: &&std::ffi::OsString) -> bool {
*self == ***other
}
}
#[cfg(windows)]
impl PartialEq<std::ffi::OsStr> for HSTRING {
fn eq(&self, other: &std::ffi::OsStr) -> bool {
self.as_wide().iter().copied().eq(std::os::windows::ffi::OsStrExt::encode_wide(other))
}
}
#[cfg(windows)]
impl PartialEq<std::ffi::OsStr> for &HSTRING {
fn eq(&self, other: &std::ffi::OsStr) -> bool {
**self == *other
}
}
#[cfg(windows)]
impl PartialEq<&std::ffi::OsStr> for HSTRING {
fn eq(&self, other: &&std::ffi::OsStr) -> bool {
*self == **other
}
}
#[cfg(windows)]
impl PartialEq<HSTRING> for std::ffi::OsStr {
fn eq(&self, other: &HSTRING) -> bool {
*other == *self
}
}
#[cfg(windows)]
impl PartialEq<HSTRING> for &std::ffi::OsStr {
fn eq(&self, other: &HSTRING) -> bool {
*other == **self
}
}
#[cfg(windows)]
impl PartialEq<&HSTRING> for std::ffi::OsStr {
fn eq(&self, other: &&HSTRING) -> bool {
**other == *self
}
}
#[cfg(windows)]
impl PartialEq<HSTRING> for std::ffi::OsString {
fn eq(&self, other: &HSTRING) -> bool {
*other == **self
}
}
#[cfg(windows)]
impl PartialEq<HSTRING> for &std::ffi::OsString {
fn eq(&self, other: &HSTRING) -> bool {
*other == ***self
}
}
#[cfg(windows)]
impl PartialEq<&HSTRING> for std::ffi::OsString {
fn eq(&self, other: &&HSTRING) -> bool {
**other == **self
}
}
impl<'a> core::convert::TryFrom<&'a HSTRING> for alloc::string::String {
type Error = alloc::string::FromUtf16Error;
fn try_from(hstring: &HSTRING) -> core::result::Result<Self, Self::Error> {
alloc::string::String::from_utf16(hstring.as_wide())
}
}
impl core::convert::TryFrom<HSTRING> for alloc::string::String {
type Error = alloc::string::FromUtf16Error;
fn try_from(hstring: HSTRING) -> core::result::Result<Self, Self::Error> {
alloc::string::String::try_from(&hstring)
}
}
#[cfg(windows)]
impl<'a> core::convert::From<&'a HSTRING> for std::ffi::OsString {
fn from(hstring: &HSTRING) -> Self {
hstring.to_os_string()
}
}
#[cfg(windows)]
impl core::convert::From<HSTRING> for std::ffi::OsString {
fn from(hstring: HSTRING) -> Self {
Self::from(&hstring)
}
}
const REFERENCE_FLAG: u32 = 1;
#[repr(C)]
struct Header {
flags: u32,
len: u32,
_0: u32,
_1: u32,
data: *mut u16,
count: RefCount,
buffer_start: u16,
}
impl Header {
fn alloc(len: u32) -> *mut Header {
debug_assert!(len != 0);
// Allocate enough space for header and two bytes per character.
// The space for the terminating null character is already accounted for inside of `Header`.
let alloc_size = core::mem::size_of::<Header>() + 2 * len as usize;
// TODO: allow this failure to propagate
let header = heap_alloc(alloc_size).expect("Could not successfully allocate for HSTRING") as *mut Header;
// SAFETY: uses `std::ptr::write` (since `header` is unintialized). `Header` is safe to be all zeros.
unsafe {
header.write(std::mem::MaybeUninit::<Header>::zeroed().assume_init());
(*header).len = len;
(*header).count = RefCount::new(1);
(*header).data = &mut (*header).buffer_start;
}
header
}
fn duplicate(&self) -> *mut Header {
if self.flags & REFERENCE_FLAG == 0 {
// If this is not a "fast pass" string then simply increment the reference count.
self.count.add_ref();
self as *const Header as *mut Header
} else {
// Otherwise, allocate a new string and copy the value into the new string.
let copy = Header::alloc(self.len);
// SAFETY: since we are duplicating the string it is safe to copy all data from self to the initialized `copy`.
// We copy `len + 1` characters since `len` does not account for the terminating null character.
unsafe {
core::ptr::copy_nonoverlapping(self.data, (*copy).data, self.len as usize + 1);
}
copy
}
}
}