diff options
Diffstat (limited to 'src/liballoc')
| -rw-r--r-- | src/liballoc/prelude/v1.rs | 1 | ||||
| -rw-r--r-- | src/liballoc/slice.rs | 129 | ||||
| -rw-r--r-- | src/liballoc/str.rs | 14 | ||||
| -rw-r--r-- | src/liballoc/tests/vec.rs | 109 | ||||
| -rw-r--r-- | src/liballoc/vec.rs | 69 |
5 files changed, 245 insertions, 77 deletions
diff --git a/src/liballoc/prelude/v1.rs b/src/liballoc/prelude/v1.rs index b6b01395ad6..3cb285bf049 100644 --- a/src/liballoc/prelude/v1.rs +++ b/src/liballoc/prelude/v1.rs @@ -6,6 +6,5 @@ #[unstable(feature = "alloc_prelude", issue = "58935")] pub use crate::borrow::ToOwned; #[unstable(feature = "alloc_prelude", issue = "58935")] pub use crate::boxed::Box; -#[unstable(feature = "alloc_prelude", issue = "58935")] pub use crate::slice::SliceConcatExt; #[unstable(feature = "alloc_prelude", issue = "58935")] pub use crate::string::{String, ToString}; #[unstable(feature = "alloc_prelude", issue = "58935")] pub use crate::vec::Vec; diff --git a/src/liballoc/slice.rs b/src/liballoc/slice.rs index f7b0a5e703c..bc4ae167984 100644 --- a/src/liballoc/slice.rs +++ b/src/liballoc/slice.rs @@ -484,6 +484,56 @@ impl<T> [T] { } buf } + + /// Flattens a slice of `T` into a single value `Self::Output`. + /// + /// # Examples + /// + /// ``` + /// assert_eq!(["hello", "world"].concat(), "helloworld"); + /// assert_eq!([[1, 2], [3, 4]].concat(), [1, 2, 3, 4]); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn concat<Separator: ?Sized>(&self) -> T::Output + where T: SliceConcat<Separator> + { + SliceConcat::concat(self) + } + + /// Flattens a slice of `T` into a single value `Self::Output`, placing a + /// given separator between each. + /// + /// # Examples + /// + /// ``` + /// assert_eq!(["hello", "world"].join(" "), "hello world"); + /// assert_eq!([[1, 2], [3, 4]].join(&0), [1, 2, 0, 3, 4]); + /// ``` + #[stable(feature = "rename_connect_to_join", since = "1.3.0")] + pub fn join<Separator: ?Sized>(&self, sep: &Separator) -> T::Output + where T: SliceConcat<Separator> + { + SliceConcat::join(self, sep) + } + + /// Flattens a slice of `T` into a single value `Self::Output`, placing a + /// given separator between each. + /// + /// # Examples + /// + /// ``` + /// # #![allow(deprecated)] + /// assert_eq!(["hello", "world"].connect(" "), "hello world"); + /// assert_eq!([[1, 2], [3, 4]].connect(&0), [1, 2, 0, 3, 4]); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_deprecated(since = "1.3.0", reason = "renamed to join")] + pub fn connect<Separator: ?Sized>(&self, sep: &Separator) -> T::Output + where T: SliceConcat<Separator> + { + SliceConcat::join(self, sep) + } + } #[lang = "slice_u8_alloc"] @@ -527,87 +577,46 @@ impl [u8] { //////////////////////////////////////////////////////////////////////////////// // Extension traits for slices over specific kinds of data //////////////////////////////////////////////////////////////////////////////// -#[unstable(feature = "slice_concat_ext", - reason = "trait should not have to exist", - issue = "27747")] -/// An extension trait for concatenating slices -/// -/// While this trait is unstable, the methods are stable. `SliceConcatExt` is -/// included in the [standard library prelude], so you can use [`join()`] and -/// [`concat()`] as if they existed on `[T]` itself. -/// -/// [standard library prelude]: ../../std/prelude/index.html -/// [`join()`]: #tymethod.join -/// [`concat()`]: #tymethod.concat -pub trait SliceConcatExt<T: ?Sized> { - #[unstable(feature = "slice_concat_ext", - reason = "trait should not have to exist", - issue = "27747")] + +/// Helper trait for [`[T]::concat`](../../std/primitive.slice.html#method.concat) +/// and [`[T]::join`](../../std/primitive.slice.html#method.join) +#[unstable(feature = "slice_concat_trait", issue = "27747")] +pub trait SliceConcat<Separator: ?Sized>: Sized { + #[unstable(feature = "slice_concat_trait", issue = "27747")] /// The resulting type after concatenation type Output; - /// Flattens a slice of `T` into a single value `Self::Output`. - /// - /// # Examples - /// - /// ``` - /// assert_eq!(["hello", "world"].concat(), "helloworld"); - /// assert_eq!([[1, 2], [3, 4]].concat(), [1, 2, 3, 4]); - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - fn concat(&self) -> Self::Output; - - /// Flattens a slice of `T` into a single value `Self::Output`, placing a - /// given separator between each. - /// - /// # Examples - /// - /// ``` - /// assert_eq!(["hello", "world"].join(" "), "hello world"); - /// assert_eq!([[1, 2], [3, 4]].join(&0), [1, 2, 0, 3, 4]); - /// ``` - #[stable(feature = "rename_connect_to_join", since = "1.3.0")] - fn join(&self, sep: &T) -> Self::Output; + /// Implementation of [`[T]::concat`](../../std/primitive.slice.html#method.concat) + #[unstable(feature = "slice_concat_trait", issue = "27747")] + fn concat(slice: &[Self]) -> Self::Output; - /// Flattens a slice of `T` into a single value `Self::Output`, placing a - /// given separator between each. - /// - /// # Examples - /// - /// ``` - /// # #![allow(deprecated)] - /// assert_eq!(["hello", "world"].connect(" "), "hello world"); - /// assert_eq!([[1, 2], [3, 4]].connect(&0), [1, 2, 0, 3, 4]); - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - #[rustc_deprecated(since = "1.3.0", reason = "renamed to join")] - fn connect(&self, sep: &T) -> Self::Output { - self.join(sep) - } + /// Implementation of [`[T]::join`](../../std/primitive.slice.html#method.join) + #[unstable(feature = "slice_concat_trait", issue = "27747")] + fn join(slice: &[Self], sep: &Separator) -> Self::Output; } #[unstable(feature = "slice_concat_ext", reason = "trait should not have to exist", issue = "27747")] -impl<T: Clone, V: Borrow<[T]>> SliceConcatExt<T> for [V] { +impl<T: Clone, V: Borrow<[T]>> SliceConcat<T> for V { type Output = Vec<T>; - fn concat(&self) -> Vec<T> { - let size = self.iter().map(|slice| slice.borrow().len()).sum(); + fn concat(slice: &[Self]) -> Vec<T> { + let size = slice.iter().map(|slice| slice.borrow().len()).sum(); let mut result = Vec::with_capacity(size); - for v in self { + for v in slice { result.extend_from_slice(v.borrow()) } result } - fn join(&self, sep: &T) -> Vec<T> { - let mut iter = self.iter(); + fn join(slice: &[Self], sep: &T) -> Vec<T> { + let mut iter = slice.iter(); let first = match iter.next() { Some(first) => first, None => return vec![], }; - let size = self.iter().map(|slice| slice.borrow().len()).sum::<usize>() + self.len() - 1; + let size = slice.iter().map(|slice| slice.borrow().len()).sum::<usize>() + slice.len() - 1; let mut result = Vec::with_capacity(size); result.extend_from_slice(first.borrow()); diff --git a/src/liballoc/str.rs b/src/liballoc/str.rs index 70a93157c9e..37a1046d094 100644 --- a/src/liballoc/str.rs +++ b/src/liballoc/str.rs @@ -37,7 +37,7 @@ use core::unicode::conversions; use crate::borrow::ToOwned; use crate::boxed::Box; -use crate::slice::{SliceConcatExt, SliceIndex}; +use crate::slice::{SliceConcat, SliceIndex}; use crate::string::String; use crate::vec::Vec; @@ -74,16 +74,16 @@ pub use core::str::{EscapeDebug, EscapeDefault, EscapeUnicode}; #[unstable(feature = "slice_concat_ext", reason = "trait should not have to exist", issue = "27747")] -impl<S: Borrow<str>> SliceConcatExt<str> for [S] { +impl<S: Borrow<str>> SliceConcat<str> for S { type Output = String; - fn concat(&self) -> String { - self.join("") + fn concat(slice: &[Self]) -> String { + Self::join(slice, "") } - fn join(&self, sep: &str) -> String { + fn join(slice: &[Self], sep: &str) -> String { unsafe { - String::from_utf8_unchecked( join_generic_copy(self, sep.as_bytes()) ) + String::from_utf8_unchecked( join_generic_copy(slice, sep.as_bytes()) ) } } } @@ -126,7 +126,7 @@ macro_rules! copy_slice_and_advance { // Optimized join implementation that works for both Vec<T> (T: Copy) and String's inner vec // Currently (2018-05-13) there is a bug with type inference and specialization (see issue #36262) -// For this reason SliceConcatExt<T> is not specialized for T: Copy and SliceConcatExt<str> is the +// For this reason SliceConcat<T> is not specialized for T: Copy and SliceConcat<str> is the // only user of this function. It is left in place for the time when that is fixed. // // the bounds for String-join are S: Borrow<str> and for Vec-join Borrow<[T]> diff --git a/src/liballoc/tests/vec.rs b/src/liballoc/tests/vec.rs index e0c724f557b..6e8ffe18522 100644 --- a/src/liballoc/tests/vec.rs +++ b/src/liballoc/tests/vec.rs @@ -945,6 +945,115 @@ fn drain_filter_complex() { } #[test] +#[cfg(not(miri))] // Miri does not support catching panics +fn drain_filter_consumed_panic() { + use std::rc::Rc; + use std::sync::Mutex; + + struct Check { + index: usize, + drop_counts: Rc<Mutex<Vec<usize>>>, + }; + + impl Drop for Check { + fn drop(&mut self) { + self.drop_counts.lock().unwrap()[self.index] += 1; + println!("drop: {}", self.index); + } + } + + let check_count = 10; + let drop_counts = Rc::new(Mutex::new(vec![0_usize; check_count])); + let mut data: Vec<Check> = (0..check_count) + .map(|index| Check { index, drop_counts: Rc::clone(&drop_counts) }) + .collect(); + + let _ = std::panic::catch_unwind(move || { + let filter = |c: &mut Check| { + if c.index == 2 { + panic!("panic at index: {}", c.index); + } + // Verify that if the filter could panic again on another element + // that it would not cause a double panic and all elements of the + // vec would still be dropped exactly once. + if c.index == 4 { + panic!("panic at index: {}", c.index); + } + c.index < 6 + }; + let drain = data.drain_filter(filter); + + // NOTE: The DrainFilter is explictly consumed + drain.for_each(drop); + }); + + let drop_counts = drop_counts.lock().unwrap(); + assert_eq!(check_count, drop_counts.len()); + + for (index, count) in drop_counts.iter().cloned().enumerate() { + assert_eq!(1, count, "unexpected drop count at index: {} (count: {})", index, count); + } +} + +#[test] +#[cfg(not(miri))] // Miri does not support catching panics +fn drain_filter_unconsumed_panic() { + use std::rc::Rc; + use std::sync::Mutex; + + struct Check { + index: usize, + drop_counts: Rc<Mutex<Vec<usize>>>, + }; + + impl Drop for Check { + fn drop(&mut self) { + self.drop_counts.lock().unwrap()[self.index] += 1; + println!("drop: {}", self.index); + } + } + + let check_count = 10; + let drop_counts = Rc::new(Mutex::new(vec![0_usize; check_count])); + let mut data: Vec<Check> = (0..check_count) + .map(|index| Check { index, drop_counts: Rc::clone(&drop_counts) }) + .collect(); + + let _ = std::panic::catch_unwind(move || { + let filter = |c: &mut Check| { + if c.index == 2 { + panic!("panic at index: {}", c.index); + } + // Verify that if the filter could panic again on another element + // that it would not cause a double panic and all elements of the + // vec would still be dropped exactly once. + if c.index == 4 { + panic!("panic at index: {}", c.index); + } + c.index < 6 + }; + let _drain = data.drain_filter(filter); + + // NOTE: The DrainFilter is dropped without being consumed + }); + + let drop_counts = drop_counts.lock().unwrap(); + assert_eq!(check_count, drop_counts.len()); + + for (index, count) in drop_counts.iter().cloned().enumerate() { + assert_eq!(1, count, "unexpected drop count at index: {} (count: {})", index, count); + } +} + +#[test] +fn drain_filter_unconsumed() { + let mut vec = vec![1, 2, 3, 4]; + let drain = vec.drain_filter(|&mut x| x % 2 != 0); + drop(drain); + assert_eq!(vec, [2, 4]); +} + +#[test] fn test_reserve_exact() { // This is all the same as test_reserve diff --git a/src/liballoc/vec.rs b/src/liballoc/vec.rs index c0544d7469c..173946b312a 100644 --- a/src/liballoc/vec.rs +++ b/src/liballoc/vec.rs @@ -2152,6 +2152,7 @@ impl<T> Vec<T> { del: 0, old_len, pred: filter, + panic_flag: false, } } } @@ -2779,10 +2780,20 @@ pub struct DrainFilter<'a, T, F> where F: FnMut(&mut T) -> bool, { vec: &'a mut Vec<T>, + /// The index of the item that will be inspected by the next call to `next`. idx: usize, + /// The number of items that have been drained (removed) thus far. del: usize, + /// The original length of `vec` prior to draining. old_len: usize, + /// The filter test predicate. pred: F, + /// A flag that indicates a panic has occured in the filter test prodicate. + /// This is used as a hint in the drop implmentation to prevent consumption + /// of the remainder of the `DrainFilter`. Any unprocessed items will be + /// backshifted in the `vec`, but no further items will be dropped or + /// tested by the filter predicate. + panic_flag: bool, } #[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")] @@ -2793,20 +2804,23 @@ impl<T, F> Iterator for DrainFilter<'_, T, F> fn next(&mut self) -> Option<T> { unsafe { - while self.idx != self.old_len { + while self.idx < self.old_len { let i = self.idx; - self.idx += 1; let v = slice::from_raw_parts_mut(self.vec.as_mut_ptr(), self.old_len); - if (self.pred)(&mut v[i]) { + self.panic_flag = true; + let drained = (self.pred)(&mut v[i]); + self.panic_flag = false; + // Update the index *after* the predicate is called. If the index + // is updated prior and the predicate panics, the element at this + // index would be leaked. + self.idx += 1; + if drained { self.del += 1; return Some(ptr::read(&v[i])); } else if self.del > 0 { let del = self.del; let src: *const T = &v[i]; let dst: *mut T = &mut v[i - del]; - // This is safe because self.vec has length 0 - // thus its elements will not have Drop::drop - // called on them in the event of a panic. ptr::copy_nonoverlapping(src, dst, 1); } } @@ -2824,9 +2838,46 @@ impl<T, F> Drop for DrainFilter<'_, T, F> where F: FnMut(&mut T) -> bool, { fn drop(&mut self) { - self.for_each(drop); - unsafe { - self.vec.set_len(self.old_len - self.del); + struct BackshiftOnDrop<'a, 'b, T, F> + where + F: FnMut(&mut T) -> bool, + { + drain: &'b mut DrainFilter<'a, T, F>, + } + + impl<'a, 'b, T, F> Drop for BackshiftOnDrop<'a, 'b, T, F> + where + F: FnMut(&mut T) -> bool + { + fn drop(&mut self) { + unsafe { + if self.drain.idx < self.drain.old_len && self.drain.del > 0 { + // This is a pretty messed up state, and there isn't really an + // obviously right thing to do. We don't want to keep trying + // to execute `pred`, so we just backshift all the unprocessed + // elements and tell the vec that they still exist. The backshift + // is required to prevent a double-drop of the last successfully + // drained item prior to a panic in the predicate. + let ptr = self.drain.vec.as_mut_ptr(); + let src = ptr.add(self.drain.idx); + let dst = src.sub(self.drain.del); + let tail_len = self.drain.old_len - self.drain.idx; + src.copy_to(dst, tail_len); + } + self.drain.vec.set_len(self.drain.old_len - self.drain.del); + } + } + } + + let backshift = BackshiftOnDrop { + drain: self + }; + + // Attempt to consume any remaining elements if the filter predicate + // has not yet panicked. We'll backshift any remaining elements + // whether we've already panicked or if the consumption here panics. + if !backshift.drain.panic_flag { + backshift.drain.for_each(drop); } } } |