1 files changed, 186 insertions, 0 deletions
diff --git a/vendor/rayon/src/iter/collect/consumer.rs b/vendor/rayon/src/iter/collect/consumer.rs
new file mode 100644
index 000000000..acd67dffa
--- /dev/null
+++ b/vendor/rayon/src/iter/collect/consumer.rs
@@ -0,0 +1,186 @@
+use super::super::plumbing::*;
+use crate::SendPtr;
+use std::marker::PhantomData;
+use std::ptr;
+use std::slice;
+
+pub(super) struct CollectConsumer<'c, T: Send> {
+    /// See `CollectResult` for explanation of why this is not a slice
+    start: SendPtr<T>,
+    len: usize,
+    marker: PhantomData<&'c mut T>,
+}
+
+impl<T: Send> CollectConsumer<'_, T> {
+    /// Create a collector for `len` items in the unused capacity of the vector.
+    pub(super) fn appender(vec: &mut Vec<T>, len: usize) -> CollectConsumer<'_, T> {
+        let start = vec.len();
+        assert!(vec.capacity() - start >= len);
+
+        // SAFETY: We already made sure to have the additional space allocated.
+        // The pointer is derived from `Vec` directly, not through a `Deref`,
+        // so it has provenance over the whole allocation.
+        unsafe { CollectConsumer::new(vec.as_mut_ptr().add(start), len) }
+    }
+}
+
+impl<'c, T: Send + 'c> CollectConsumer<'c, T> {
+    /// The target memory is considered uninitialized, and will be
+    /// overwritten without reading or dropping existing values.
+    unsafe fn new(start: *mut T, len: usize) -> Self {
+        CollectConsumer {
+            start: SendPtr(start),
+            len,
+            marker: PhantomData,
+        }
+    }
+}
+
+/// CollectResult represents an initialized part of the target slice.
+///
+/// This is a proxy owner of the elements in the slice; when it drops,
+/// the elements will be dropped, unless its ownership is released before then.
+#[must_use]
+pub(super) struct CollectResult<'c, T> {
+    /// This pointer and length has the same representation as a slice,
+    /// but retains the provenance of the entire array so that we can merge
+    /// these regions together in `CollectReducer`.
+    start: SendPtr<T>,
+    total_len: usize,
+    /// The current initialized length after `start`
+    initialized_len: usize,
+    /// Lifetime invariance guarantees that the data flows from consumer to result,
+    /// especially for the `scope_fn` callback in `Collect::with_consumer`.
+    invariant_lifetime: PhantomData<&'c mut &'c mut [T]>,
+}
+
+unsafe impl<'c, T> Send for CollectResult<'c, T> where T: Send {}
+
+impl<'c, T> CollectResult<'c, T> {
+    /// The current length of the collect result
+    pub(super) fn len(&self) -> usize {
+        self.initialized_len
+    }
+
+    /// Release ownership of the slice of elements, and return the length
+    pub(super) fn release_ownership(mut self) -> usize {
+        let ret = self.initialized_len;
+        self.initialized_len = 0;
+        ret
+    }
+}
+
+impl<'c, T> Drop for CollectResult<'c, T> {
+    fn drop(&mut self) {
+        // Drop the first `self.initialized_len` elements, which have been recorded
+        // to be initialized by the folder.
+        unsafe {
+            ptr::drop_in_place(slice::from_raw_parts_mut(
+                self.start.0,
+                self.initialized_len,
+            ));
+        }
+    }
+}
+
+impl<'c, T: Send + 'c> Consumer<T> for CollectConsumer<'c, T> {
+    type Folder = CollectResult<'c, T>;
+    type Reducer = CollectReducer;
+    type Result = CollectResult<'c, T>;
+
+    fn split_at(self, index: usize) -> (Self, Self, CollectReducer) {
+        let CollectConsumer { start, len, .. } = self;
+
+        // Produce new consumers.
+        // SAFETY: This assert checks that `index` is a valid offset for `start`
+        unsafe {
+            assert!(index <= len);
+            (
+                CollectConsumer::new(start.0, index),
+                CollectConsumer::new(start.0.add(index), len - index),
+                CollectReducer,
+            )
+        }
+    }
+
+    fn into_folder(self) -> Self::Folder {
+        // Create a result/folder that consumes values and writes them
+        // into the region after start. The initial result has length 0.
+        CollectResult {
+            start: self.start,
+            total_len: self.len,
+            initialized_len: 0,
+            invariant_lifetime: PhantomData,
+        }
+    }
+
+    fn full(&self) -> bool {
+        false
+    }
+}
+
+impl<'c, T: Send + 'c> Folder<T> for CollectResult<'c, T> {
+    type Result = Self;
+
+    fn consume(mut self, item: T) -> Self {
+        assert!(
+            self.initialized_len < self.total_len,
+            "too many values pushed to consumer"
+        );
+
+        // SAFETY: The assert above is a bounds check for this write, and we
+        // avoid assignment here so we do not drop an uninitialized T.
+        unsafe {
+            // Write item and increase the initialized length
+            self.start.0.add(self.initialized_len).write(item);
+            self.initialized_len += 1;
+        }
+
+        self
+    }
+
+    fn complete(self) -> Self::Result {
+        // NB: We don't explicitly check that the local writes were complete,
+        // but Collect will assert the total result length in the end.
+        self
+    }
+
+    fn full(&self) -> bool {
+        false
+    }
+}
+
+/// Pretend to be unindexed for `special_collect_into_vec`,
+/// but we should never actually get used that way...
+impl<'c, T: Send + 'c> UnindexedConsumer<T> for CollectConsumer<'c, T> {
+    fn split_off_left(&self) -> Self {
+        unreachable!("CollectConsumer must be indexed!")
+    }
+    fn to_reducer(&self) -> Self::Reducer {
+        CollectReducer
+    }
+}
+
+/// CollectReducer combines adjacent chunks; the result must always
+/// be contiguous so that it is one combined slice.
+pub(super) struct CollectReducer;
+
+impl<'c, T> Reducer<CollectResult<'c, T>> for CollectReducer {
+    fn reduce(
+        self,
+        mut left: CollectResult<'c, T>,
+        right: CollectResult<'c, T>,
+    ) -> CollectResult<'c, T> {
+        // Merge if the CollectResults are adjacent and in left to right order
+        // else: drop the right piece now and total length will end up short in the end,
+        // when the correctness of the collected result is asserted.
+        unsafe {
+            let left_end = left.start.0.add(left.initialized_len);
+            if left_end == right.start.0 {
+                left.total_len += right.total_len;
+                left.initialized_len += right.release_ownership();
+            }
+            left
+        }
+    }
+}