diff options
Diffstat (limited to 'compiler/rustc_data_structures/src')
| -rw-r--r-- | compiler/rustc_data_structures/src/map_in_place.rs | 127 | ||||
| -rw-r--r-- | compiler/rustc_data_structures/src/thin_vec.rs | 45 |
2 files changed, 94 insertions, 78 deletions
diff --git a/compiler/rustc_data_structures/src/map_in_place.rs b/compiler/rustc_data_structures/src/map_in_place.rs index 874de03d37a..d912211443a 100644 --- a/compiler/rustc_data_structures/src/map_in_place.rs +++ b/compiler/rustc_data_structures/src/map_in_place.rs @@ -1,3 +1,4 @@ +use crate::thin_vec::ThinVec; use smallvec::{Array, SmallVec}; use std::ptr; @@ -15,94 +16,64 @@ pub trait MapInPlace<T>: Sized { I: IntoIterator<Item = T>; } -impl<T> MapInPlace<T> for Vec<T> { - fn flat_map_in_place<F, I>(&mut self, mut f: F) - where - F: FnMut(T) -> I, - I: IntoIterator<Item = T>, - { - let mut read_i = 0; - let mut write_i = 0; - unsafe { - let mut old_len = self.len(); - self.set_len(0); // make sure we just leak elements in case of panic +// The implementation of this method is syntactically identical for all the +// different vector types. +macro_rules! flat_map_in_place { + () => { + fn flat_map_in_place<F, I>(&mut self, mut f: F) + where + F: FnMut(T) -> I, + I: IntoIterator<Item = T>, + { + let mut read_i = 0; + let mut write_i = 0; + unsafe { + let mut old_len = self.len(); + self.set_len(0); // make sure we just leak elements in case of panic - while read_i < old_len { - // move the read_i'th item out of the vector and map it - // to an iterator - let e = ptr::read(self.as_ptr().add(read_i)); - let iter = f(e).into_iter(); - read_i += 1; + while read_i < old_len { + // move the read_i'th item out of the vector and map it + // to an iterator + let e = ptr::read(self.as_ptr().add(read_i)); + let iter = f(e).into_iter(); + read_i += 1; - for e in iter { - if write_i < read_i { - ptr::write(self.as_mut_ptr().add(write_i), e); - write_i += 1; - } else { - // If this is reached we ran out of space - // in the middle of the vector. - // However, the vector is in a valid state here, - // so we just do a somewhat inefficient insert. - self.set_len(old_len); - self.insert(write_i, e); + for e in iter { + if write_i < read_i { + ptr::write(self.as_mut_ptr().add(write_i), e); + write_i += 1; + } else { + // If this is reached we ran out of space + // in the middle of the vector. + // However, the vector is in a valid state here, + // so we just do a somewhat inefficient insert. + self.set_len(old_len); + self.insert(write_i, e); - old_len = self.len(); - self.set_len(0); + old_len = self.len(); + self.set_len(0); - read_i += 1; - write_i += 1; + read_i += 1; + write_i += 1; + } } } - } - // write_i tracks the number of actually written new items. - self.set_len(write_i); + // write_i tracks the number of actually written new items. + self.set_len(write_i); + } } - } + }; } -impl<T, A: Array<Item = T>> MapInPlace<T> for SmallVec<A> { - fn flat_map_in_place<F, I>(&mut self, mut f: F) - where - F: FnMut(T) -> I, - I: IntoIterator<Item = T>, - { - let mut read_i = 0; - let mut write_i = 0; - unsafe { - let mut old_len = self.len(); - self.set_len(0); // make sure we just leak elements in case of panic - - while read_i < old_len { - // move the read_i'th item out of the vector and map it - // to an iterator - let e = ptr::read(self.as_ptr().add(read_i)); - let iter = f(e).into_iter(); - read_i += 1; - - for e in iter { - if write_i < read_i { - ptr::write(self.as_mut_ptr().add(write_i), e); - write_i += 1; - } else { - // If this is reached we ran out of space - // in the middle of the vector. - // However, the vector is in a valid state here, - // so we just do a somewhat inefficient insert. - self.set_len(old_len); - self.insert(write_i, e); - - old_len = self.len(); - self.set_len(0); +impl<T> MapInPlace<T> for Vec<T> { + flat_map_in_place!(); +} - read_i += 1; - write_i += 1; - } - } - } +impl<T, A: Array<Item = T>> MapInPlace<T> for SmallVec<A> { + flat_map_in_place!(); +} - // write_i tracks the number of actually written new items. - self.set_len(write_i); - } - } +impl<T> MapInPlace<T> for ThinVec<T> { + flat_map_in_place!(); } diff --git a/compiler/rustc_data_structures/src/thin_vec.rs b/compiler/rustc_data_structures/src/thin_vec.rs index 716259142d1..fce42e709ab 100644 --- a/compiler/rustc_data_structures/src/thin_vec.rs +++ b/compiler/rustc_data_structures/src/thin_vec.rs @@ -27,6 +27,51 @@ impl<T> ThinVec<T> { ThinVec(None) => *self = vec![item].into(), } } + + /// Note: if `set_len(0)` is called on a non-empty `ThinVec`, it will + /// remain in the `Some` form. This is required for some code sequences + /// (such as the one in `flat_map_in_place`) that call `set_len(0)` before + /// an operation that might panic, and then call `set_len(n)` again + /// afterwards. + pub unsafe fn set_len(&mut self, new_len: usize) { + match *self { + ThinVec(None) => { + // A prerequisite of `Vec::set_len` is that `new_len` must be + // less than or equal to capacity(). The same applies here. + if new_len != 0 { + panic!("unsafe ThinVec::set_len({})", new_len); + } + } + ThinVec(Some(ref mut vec)) => vec.set_len(new_len), + } + } + + pub fn insert(&mut self, index: usize, value: T) { + match *self { + ThinVec(None) => { + if index == 0 { + *self = vec![value].into(); + } else { + panic!("invalid ThinVec::insert"); + } + } + ThinVec(Some(ref mut vec)) => vec.insert(index, value), + } + } + + pub fn remove(&mut self, index: usize) -> T { + match self { + ThinVec(None) => panic!("invalid ThinVec::remove"), + ThinVec(Some(vec)) => vec.remove(index), + } + } + + pub fn as_slice(&self) -> &[T] { + match self { + ThinVec(None) => &[], + ThinVec(Some(vec)) => vec.as_slice(), + } + } } impl<T> From<Vec<T>> for ThinVec<T> { |