83 lines
2.0 KiB
Rust
83 lines
2.0 KiB
Rust
use rustc_index::vec::{Idx, IndexVec};
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use std::mem;
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use std::ptr;
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pub trait IdFunctor {
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type Inner;
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fn map_id<F>(self, f: F) -> Self
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where
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F: FnMut(Self::Inner) -> Self::Inner;
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}
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impl<T> IdFunctor for Box<T> {
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type Inner = T;
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#[inline]
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fn map_id<F>(self, mut f: F) -> Self
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where
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F: FnMut(Self::Inner) -> Self::Inner,
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{
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let raw = Box::into_raw(self);
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unsafe {
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// SAFETY: The raw pointer points to a valid value of type `T`.
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let value = ptr::read(raw);
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// SAFETY: Converts `Box<T>` to `Box<MaybeUninit<T>>` which is the
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// inverse of `Box::assume_init()` and should be safe.
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let mut raw: Box<mem::MaybeUninit<T>> = Box::from_raw(raw.cast());
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// SAFETY: Write the mapped value back into the `Box`.
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raw.write(f(value));
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// SAFETY: We just initialized `raw`.
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raw.assume_init()
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}
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}
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}
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impl<T> IdFunctor for Vec<T> {
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type Inner = T;
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#[inline]
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fn map_id<F>(mut self, mut f: F) -> Self
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where
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F: FnMut(Self::Inner) -> Self::Inner,
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{
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// FIXME: We don't really care about panics here and leak
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// far more than we should, but that should be fine for now.
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let len = self.len();
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unsafe {
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self.set_len(0);
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let start = self.as_mut_ptr();
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for i in 0..len {
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let p = start.add(i);
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ptr::write(p, f(ptr::read(p)));
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}
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self.set_len(len);
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}
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self
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}
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}
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impl<T> IdFunctor for Box<[T]> {
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type Inner = T;
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#[inline]
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fn map_id<F>(self, f: F) -> Self
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where
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F: FnMut(Self::Inner) -> Self::Inner,
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{
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Vec::from(self).map_id(f).into()
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}
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}
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impl<I: Idx, T> IdFunctor for IndexVec<I, T> {
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type Inner = T;
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#[inline]
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fn map_id<F>(self, f: F) -> Self
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where
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F: FnMut(Self::Inner) -> Self::Inner,
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{
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IndexVec::from_raw(self.raw.map_id(f))
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}
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}
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