54 lines
1.6 KiB
Rust
54 lines
1.6 KiB
Rust
/// A trait for adding some helper routines to pointers.
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pub(crate) trait Pointer {
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/// Returns the distance, in units of `T`, between `self` and `origin`.
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///
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/// # Safety
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///
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/// Same as `ptr::offset_from` in addition to `self >= origin`.
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unsafe fn distance(self, origin: Self) -> usize;
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/// Casts this pointer to `usize`.
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///
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/// Callers should not convert the `usize` back to a pointer if at all
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/// possible. (And if you believe it's necessary, open an issue to discuss
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/// why. Otherwise, it has the potential to violate pointer provenance.)
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/// The purpose of this function is just to be able to do arithmetic, i.e.,
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/// computing offsets or alignments.
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fn as_usize(self) -> usize;
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}
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impl<T> Pointer for *const T {
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unsafe fn distance(self, origin: *const T) -> usize {
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// TODO: Replace with `ptr::sub_ptr` once stabilized.
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usize::try_from(self.offset_from(origin)).unwrap_unchecked()
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}
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fn as_usize(self) -> usize {
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self as usize
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}
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}
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impl<T> Pointer for *mut T {
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unsafe fn distance(self, origin: *mut T) -> usize {
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(self as *const T).distance(origin as *const T)
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}
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fn as_usize(self) -> usize {
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(self as *const T).as_usize()
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}
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}
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/// A trait for adding some helper routines to raw bytes.
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#[cfg(test)]
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pub(crate) trait Byte {
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/// Converts this byte to a `char` if it's ASCII. Otherwise panics.
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fn to_char(self) -> char;
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}
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#[cfg(test)]
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impl Byte for u8 {
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fn to_char(self) -> char {
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assert!(self.is_ascii());
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char::from(self)
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}
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}
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