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Diffstat (limited to 'library/std/src/sys/windows/ext/ffi.rs')
| -rw-r--r-- | library/std/src/sys/windows/ext/ffi.rs | 134 |
1 files changed, 0 insertions, 134 deletions
diff --git a/library/std/src/sys/windows/ext/ffi.rs b/library/std/src/sys/windows/ext/ffi.rs deleted file mode 100644 index c89b9ff1efa..00000000000 --- a/library/std/src/sys/windows/ext/ffi.rs +++ /dev/null @@ -1,134 +0,0 @@ -//! Windows-specific extensions to the primitives in the `std::ffi` module. -//! -//! # Overview -//! -//! For historical reasons, the Windows API uses a form of potentially -//! ill-formed UTF-16 encoding for strings. Specifically, the 16-bit -//! code units in Windows strings may contain [isolated surrogate code -//! points which are not paired together][ill-formed-utf-16]. The -//! Unicode standard requires that surrogate code points (those in the -//! range U+D800 to U+DFFF) always be *paired*, because in the UTF-16 -//! encoding a *surrogate code unit pair* is used to encode a single -//! character. For compatibility with code that does not enforce -//! these pairings, Windows does not enforce them, either. -//! -//! While it is not always possible to convert such a string losslessly into -//! a valid UTF-16 string (or even UTF-8), it is often desirable to be -//! able to round-trip such a string from and to Windows APIs -//! losslessly. For example, some Rust code may be "bridging" some -//! Windows APIs together, just passing `WCHAR` strings among those -//! APIs without ever really looking into the strings. -//! -//! If Rust code *does* need to look into those strings, it can -//! convert them to valid UTF-8, possibly lossily, by substituting -//! invalid sequences with [`U+FFFD REPLACEMENT CHARACTER`][U+FFFD], as is -//! conventionally done in other Rust APIs that deal with string -//! encodings. -//! -//! # `OsStringExt` and `OsStrExt` -//! -//! [`OsString`] is the Rust wrapper for owned strings in the -//! preferred representation of the operating system. On Windows, -//! this struct gets augmented with an implementation of the -//! [`OsStringExt`] trait, which has a [`OsStringExt::from_wide`] method. This -//! lets you create an [`OsString`] from a `&[u16]` slice; presumably -//! you get such a slice out of a `WCHAR` Windows API. -//! -//! Similarly, [`OsStr`] is the Rust wrapper for borrowed strings from -//! preferred representation of the operating system. On Windows, the -//! [`OsStrExt`] trait provides the [`OsStrExt::encode_wide`] method, which -//! outputs an [`EncodeWide`] iterator. You can [`collect`] this -//! iterator, for example, to obtain a `Vec<u16>`; you can later get a -//! pointer to this vector's contents and feed it to Windows APIs. -//! -//! These traits, along with [`OsString`] and [`OsStr`], work in -//! conjunction so that it is possible to **round-trip** strings from -//! Windows and back, with no loss of data, even if the strings are -//! ill-formed UTF-16. -//! -//! [ill-formed-utf-16]: https://simonsapin.github.io/wtf-8/#ill-formed-utf-16 -//! [`collect`]: crate::iter::Iterator::collect -//! [U+FFFD]: crate::char::REPLACEMENT_CHARACTER - -#![stable(feature = "rust1", since = "1.0.0")] - -use crate::ffi::{OsStr, OsString}; -use crate::sealed::Sealed; -use crate::sys::os_str::Buf; -use crate::sys_common::wtf8::Wtf8Buf; -use crate::sys_common::{AsInner, FromInner}; - -#[stable(feature = "rust1", since = "1.0.0")] -pub use crate::sys_common::wtf8::EncodeWide; - -/// Windows-specific extensions to [`OsString`]. -/// -/// This trait is sealed: it cannot be implemented outside the standard library. -/// This is so that future additional methods are not breaking changes. -#[stable(feature = "rust1", since = "1.0.0")] -pub trait OsStringExt: Sealed { - /// Creates an `OsString` from a potentially ill-formed UTF-16 slice of - /// 16-bit code units. - /// - /// This is lossless: calling [`OsStrExt::encode_wide`] on the resulting string - /// will always return the original code units. - /// - /// # Examples - /// - /// ``` - /// use std::ffi::OsString; - /// use std::os::windows::prelude::*; - /// - /// // UTF-16 encoding for "Unicode". - /// let source = [0x0055, 0x006E, 0x0069, 0x0063, 0x006F, 0x0064, 0x0065]; - /// - /// let string = OsString::from_wide(&source[..]); - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - fn from_wide(wide: &[u16]) -> Self; -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl OsStringExt for OsString { - fn from_wide(wide: &[u16]) -> OsString { - FromInner::from_inner(Buf { inner: Wtf8Buf::from_wide(wide) }) - } -} - -/// Windows-specific extensions to [`OsStr`]. -/// -/// This trait is sealed: it cannot be implemented outside the standard library. -/// This is so that future additional methods are not breaking changes. -#[stable(feature = "rust1", since = "1.0.0")] -pub trait OsStrExt: Sealed { - /// Re-encodes an `OsStr` as a wide character sequence, i.e., potentially - /// ill-formed UTF-16. - /// - /// This is lossless: calling [`OsStringExt::from_wide`] and then - /// `encode_wide` on the result will yield the original code units. - /// Note that the encoding does not add a final null terminator. - /// - /// # Examples - /// - /// ``` - /// use std::ffi::OsString; - /// use std::os::windows::prelude::*; - /// - /// // UTF-16 encoding for "Unicode". - /// let source = [0x0055, 0x006E, 0x0069, 0x0063, 0x006F, 0x0064, 0x0065]; - /// - /// let string = OsString::from_wide(&source[..]); - /// - /// let result: Vec<u16> = string.encode_wide().collect(); - /// assert_eq!(&source[..], &result[..]); - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - fn encode_wide(&self) -> EncodeWide<'_>; -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl OsStrExt for OsStr { - fn encode_wide(&self) -> EncodeWide<'_> { - self.as_inner().inner.encode_wide() - } -} |