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use crate::{windows, Null, ValidateHandle};
use windows::{
core::HRESULT,
Win32::Foundation::{E_FAIL, E_HANDLE},
};
pub trait ResultExt<T> {
/// Returns `Ok(())`, or `Err`, based on [`windows::core::Error::from_win32()`].
fn from_win32() -> windows::core::Result<()>;
/// Returns `Err` with [`windows::core::Error::from_win32()`].
fn err_from_win32() -> windows::core::Result<T>;
/// Passes a `T` through to an `Ok` value, if the check is successful, or otherwise returns `Err` with [`windows::core::Error::from_win32()`].
///
/// Can be used transitionally in new cases, until this crate might offer a more suitable solution.
fn from_checked_or_win32<F>(t: T, check: F) -> windows::core::Result<T>
where
F: FnOnce(&T) -> bool;
/// Passes a `T` through to an `Ok` value, if the check is successful, or otherwise returns `Err` with [`HRESULT`](windows::core::HRESULT) [`E_FAIL`](windows::Win32::Foundation::E_FAIL).
///
/// To be used with functions that don't offer an error code via `GetLastError()`.
///
/// Can be used transitionally in new cases, until this crate might offer a more suitable solution.
fn from_checked_or_e_fail<F>(t: T, check: F) -> windows::core::Result<T>
where
F: FnOnce(&T) -> bool;
}
impl<T> ResultExt<T> for windows::core::Result<T> {
fn from_win32() -> windows::core::Result<()> {
let error = windows::core::Error::from_win32();
if error.code().is_ok() {
Ok(())
} else {
Err(error)
}
}
fn err_from_win32() -> windows::core::Result<T> {
Err(windows::core::Error::from_win32())
}
fn from_checked_or_win32<F>(t: T, check: F) -> windows::core::Result<T>
where
F: FnOnce(&T) -> bool,
{
if check(&t) {
Ok(t)
} else {
Err(windows::core::Error::from_win32())
}
}
fn from_checked_or_e_fail<F>(t: T, check: F) -> windows::core::Result<T>
where
F: FnOnce(&T) -> bool,
{
if check(&t) {
Ok(t)
} else {
Err(E_FAIL.into())
}
}
}
pub trait CheckNumberError
where
Self: num_traits::Zero + Sized,
{
/// Passes a non-zero `self` through to an `Ok` value, or, in case of it being zero, returns `Err` with [`windows::core::Error::from_win32()`], if it yields an error code, or `Ok(0)` otherwise.
///
/// To be used with functions that communicate valid values as well as errors by a return value of 0 and need an additional call to `GetLastError()` to check whether an error has occurred (e.g., `SetWindowLongPtrW()`). Note that, depending on whether the function calls `SetLastError()` under all circumstances, you may need to precede the call for which you call this function by `SetLastError(ERROR_SUCCESS)`.
fn nonzero_with_win32_or_err(self) -> windows::core::Result<Self>;
/// Passes a non-zero `self` through to an `Ok` value, or, in case of it being zero, returns `Err` with [`windows::core::Error::from_win32()`].
fn nonzero_or_win32_err(self) -> windows::core::Result<Self>;
/// Passes a non-zero `self` through to an `Ok` value, or, in case of it being zero, returns `Err` with [`HRESULT`](windows::core::HRESULT) [`E_FAIL`](windows::Win32::Foundation::E_FAIL).
///
/// To be used with functions that don't offer an error code via `GetLastError()`.
fn nonzero_or_e_fail(self) -> windows::core::Result<Self>;
}
impl<T> CheckNumberError for T
where
T: num_traits::Zero,
{
fn nonzero_with_win32_or_err(self) -> windows::core::Result<Self> {
if self.is_zero() {
let error = windows::core::Error::from_win32();
if error.code().is_ok() {
Ok(self)
} else {
Err(error)
}
} else {
Ok(self)
}
}
fn nonzero_or_win32_err(self) -> windows::core::Result<Self> {
if self.is_zero() {
Err(windows::core::Error::from_win32())
} else {
Ok(self)
}
}
fn nonzero_or_e_fail(self) -> windows::core::Result<Self> {
if self.is_zero() {
Err(E_FAIL.into())
} else {
Ok(self)
}
}
}
pub trait CheckNullError
where
Self: Null + Sized,
{
/// Passes a non-null `self` through to an `Ok` value, or, in case of it being null, returns `Err` with [`HRESULT`](windows::core::HRESULT) [`E_HANDLE`](windows::Win32::Foundation::E_HANDLE).
///
/// To be used with functions like `CreateBitmap()` that return a handle type or null, not offering an error code via `GetLastError()`.
fn nonnull_or_e_handle(self) -> windows::core::Result<Self>;
}
impl<T> CheckNullError for T
where
T: Null,
{
fn nonnull_or_e_handle(self) -> windows::core::Result<Self> {
if self.is_null() {
Err(E_HANDLE.into())
} else {
Ok(self)
}
}
}
pub trait CheckHandleError
where
Self: ValidateHandle + Sized,
{
/// Passes a `self`, if successfully validated with `is_invalid()`, through to an `Ok` value, or, in case of it being invalid, returns `Err` with [`HRESULT`](windows::core::HRESULT) [`E_HANDLE`](windows::Win32::Foundation::E_HANDLE).
///
/// To be used with functions that don't offer an error code via `GetLastError()`, and when there's a need to validate with `is_invalid()`.
fn valid_or_e_handle(self) -> windows::core::Result<Self>;
}
impl<T> CheckHandleError for T
where
T: ValidateHandle,
{
fn valid_or_e_handle(self) -> windows::core::Result<Self> {
if self.is_invalid() {
Err(E_HANDLE.into())
} else {
Ok(self)
}
}
}
pub trait HResultExt {
/// Like [`HRESULT::ok()`](windows::core::HRESULT), but with success `HRESULT`s forwarded instead of giving `()`. Useful when working with functions that can return multiple success return values, like [`AssocQueryStringW()`][1].
///
/// [1]: https://learn.microsoft.com/en-us/windows/win32/api/shlwapi/nf-shlwapi-assocquerystringw
fn ok_with_hresult(self) -> windows::core::Result<HRESULT>;
}
impl HResultExt for HRESULT {
fn ok_with_hresult(self) -> windows::core::Result<HRESULT> {
if self.is_ok() {
Ok(self)
} else {
Err(self.into())
}
}
}
#[cfg(all(test, feature = "windows_latest_compatible_all"))]
mod tests {
use crate::{
core::{CheckNumberError, HResultExt},
windows,
};
use windows::Win32::{
Foundation::{ERROR_INSUFFICIENT_BUFFER, E_FAIL, E_UNEXPECTED, S_FALSE, S_OK},
Globalization::{
GetLocaleInfoEx, LOCALE_ICURRDIGITS, LOCALE_NAME_INVARIANT, LOCALE_RETURN_NUMBER,
},
};
#[test]
fn nonzero_or_win32_err() {
let mut two_wide_chars = [u16::MAX, u16::MAX];
assert_eq!(
unsafe {
GetLocaleInfoEx(
LOCALE_NAME_INVARIANT,
LOCALE_ICURRDIGITS | LOCALE_RETURN_NUMBER,
Some(&mut two_wide_chars),
)
}
.nonzero_or_win32_err(),
Ok(2)
);
let value = unsafe { *two_wide_chars.as_ptr().cast::<u32>() };
assert!(value <= 2); // As per docs on `LOCALE_ICURRDIGITS`.
assert_eq!(
unsafe {
GetLocaleInfoEx(
LOCALE_NAME_INVARIANT,
LOCALE_ICURRDIGITS | LOCALE_RETURN_NUMBER,
Some(&mut [0]), // Invalid.
)
}
.nonzero_or_win32_err(),
Err(ERROR_INSUFFICIENT_BUFFER.into())
);
}
#[test]
fn hresult_ext_ok_with_hresult() {
assert_eq!(S_OK.ok_with_hresult(), Ok(S_OK));
assert_eq!(S_FALSE.ok_with_hresult(), Ok(S_FALSE));
assert_eq!(E_FAIL.ok_with_hresult(), Err(E_FAIL.into()));
assert_eq!(E_UNEXPECTED.ok_with_hresult(), Err(E_UNEXPECTED.into()));
}
}