17600c1ea7
Add iterator method .rfold(init, function); the reverse of fold rfold is the reverse version of fold. Fold allows iterators to implement a different (non-resumable) internal iteration when it is more efficient than the external iteration implemented through the next method. (Common examples are VecDeque and .chain()). Introduce rfold() so that the same customization is available for reverse iteration. This is achieved by both adding the method, and by having the Rev\<I> adaptor connect Rev::rfold → I::fold and Rev::fold → I::rfold. On the surface, rfold(..) is just .rev().fold(..), but the special case implementations allow a data structure specific fold to be used through for example .iter().rev(); we thus have gains even for users never calling exactly rfold themselves.
272 lines
8.4 KiB
Rust
272 lines
8.4 KiB
Rust
// Copyright 2014-2017 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! # The Rust core allocation and collections library
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//!
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//! This library provides smart pointers and collections for managing
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//! heap-allocated values.
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//!
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//! This library, like libcore, is not intended for general usage, but rather as
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//! a building block of other libraries. The types and interfaces in this
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//! library are reexported through the [standard library](../std/index.html),
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//! and should not be used through this library.
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//!
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//! ## Boxed values
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//!
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//! The [`Box`](boxed/index.html) type is a smart pointer type. There can
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//! only be one owner of a `Box`, and the owner can decide to mutate the
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//! contents, which live on the heap.
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//!
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//! This type can be sent among threads efficiently as the size of a `Box` value
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//! is the same as that of a pointer. Tree-like data structures are often built
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//! with boxes because each node often has only one owner, the parent.
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//!
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//! ## Reference counted pointers
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//!
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//! The [`Rc`](rc/index.html) type is a non-threadsafe reference-counted pointer
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//! type intended for sharing memory within a thread. An `Rc` pointer wraps a
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//! type, `T`, and only allows access to `&T`, a shared reference.
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//!
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//! This type is useful when inherited mutability (such as using `Box`) is too
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//! constraining for an application, and is often paired with the `Cell` or
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//! `RefCell` types in order to allow mutation.
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//!
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//! ## Atomically reference counted pointers
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//!
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//! The [`Arc`](arc/index.html) type is the threadsafe equivalent of the `Rc`
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//! type. It provides all the same functionality of `Rc`, except it requires
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//! that the contained type `T` is shareable. Additionally, `Arc<T>` is itself
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//! sendable while `Rc<T>` is not.
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//!
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//! This type allows for shared access to the contained data, and is often
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//! paired with synchronization primitives such as mutexes to allow mutation of
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//! shared resources.
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//!
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//! ## Collections
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//!
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//! Implementations of the most common general purpose data structures are
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//! defined in this library. They are reexported through the
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//! [standard collections library](../std/collections/index.html).
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//!
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//! ## Heap interfaces
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//!
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//! The [`heap`](heap/index.html) module defines the low-level interface to the
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//! default global allocator. It is not compatible with the libc allocator API.
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#![allow(unused_attributes)]
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#![unstable(feature = "alloc",
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reason = "this library is unlikely to be stabilized in its current \
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form or name",
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issue = "27783")]
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#![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
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html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
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html_root_url = "https://doc.rust-lang.org/nightly/",
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issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
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test(no_crate_inject, attr(allow(unused_variables), deny(warnings))))]
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#![no_std]
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#![needs_allocator]
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#![deny(warnings)]
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#![deny(missing_debug_implementations)]
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#![cfg_attr(test, allow(deprecated))] // rand
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#![cfg_attr(test, feature(placement_in))]
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#![cfg_attr(not(test), feature(core_float))]
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#![cfg_attr(not(test), feature(exact_size_is_empty))]
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#![cfg_attr(not(test), feature(slice_rotate))]
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#![cfg_attr(not(test), feature(generator_trait))]
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#![cfg_attr(test, feature(rand, test))]
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#![feature(allow_internal_unstable)]
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#![feature(box_patterns)]
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#![feature(box_syntax)]
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#![feature(cfg_target_has_atomic)]
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#![feature(coerce_unsized)]
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#![feature(const_fn)]
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#![feature(core_intrinsics)]
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#![feature(custom_attribute)]
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#![feature(dropck_eyepatch)]
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#![feature(exact_size_is_empty)]
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#![feature(fmt_internals)]
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#![feature(fundamental)]
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#![feature(fused)]
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#![feature(generic_param_attrs)]
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#![feature(i128_type)]
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#![feature(inclusive_range)]
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#![feature(iter_rfold)]
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#![feature(lang_items)]
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#![feature(needs_allocator)]
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#![feature(nonzero)]
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#![feature(offset_to)]
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#![feature(optin_builtin_traits)]
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#![feature(pattern)]
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#![feature(placement_in_syntax)]
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#![feature(placement_new_protocol)]
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#![feature(rustc_attrs)]
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#![feature(shared)]
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#![feature(slice_get_slice)]
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#![feature(slice_patterns)]
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#![feature(slice_rsplit)]
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#![feature(specialization)]
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#![feature(staged_api)]
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#![feature(str_internals)]
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#![feature(trusted_len)]
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#![feature(unboxed_closures)]
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#![feature(unicode)]
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#![feature(unique)]
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#![feature(unsize)]
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#![feature(allocator_internals)]
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#![cfg_attr(not(test), feature(fused, fn_traits, placement_new_protocol, swap_with_slice, i128))]
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#![cfg_attr(test, feature(test, box_heap))]
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// Allow testing this library
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#[cfg(test)]
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#[macro_use]
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extern crate std;
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#[cfg(test)]
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extern crate test;
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extern crate std_unicode;
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// Module with internal macros used by other modules (needs to be included before other modules).
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#[macro_use]
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mod macros;
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// Allocator trait and helper struct definitions
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pub mod allocator;
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// Heaps provided for low-level allocation strategies
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pub mod heap;
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// Primitive types using the heaps above
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// Need to conditionally define the mod from `boxed.rs` to avoid
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// duplicating the lang-items when building in test cfg; but also need
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// to allow code to have `use boxed::HEAP;`
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// and `use boxed::Box;` declarations.
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#[cfg(not(test))]
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pub mod boxed;
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#[cfg(test)]
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mod boxed {
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pub use std::boxed::{Box, IntermediateBox, HEAP};
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}
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#[cfg(test)]
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mod boxed_test;
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#[cfg(target_has_atomic = "ptr")]
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pub mod arc;
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pub mod rc;
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pub mod raw_vec;
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// collections modules
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pub mod binary_heap;
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mod btree;
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pub mod borrow;
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pub mod fmt;
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pub mod linked_list;
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pub mod range;
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pub mod slice;
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pub mod str;
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pub mod string;
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pub mod vec;
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pub mod vec_deque;
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#[stable(feature = "rust1", since = "1.0.0")]
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pub mod btree_map {
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//! A map based on a B-Tree.
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#[stable(feature = "rust1", since = "1.0.0")]
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pub use btree::map::*;
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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pub mod btree_set {
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//! A set based on a B-Tree.
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#[stable(feature = "rust1", since = "1.0.0")]
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pub use btree::set::*;
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}
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#[cfg(not(test))]
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mod std {
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pub use core::ops; // RangeFull
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}
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/// An endpoint of a range of keys.
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///
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/// # Examples
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///
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/// `Bound`s are range endpoints:
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///
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/// ```
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/// #![feature(collections_range)]
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///
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/// use std::collections::range::RangeArgument;
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/// use std::collections::Bound::*;
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///
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/// assert_eq!((..100).start(), Unbounded);
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/// assert_eq!((1..12).start(), Included(&1));
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/// assert_eq!((1..12).end(), Excluded(&12));
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/// ```
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///
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/// Using a tuple of `Bound`s as an argument to [`BTreeMap::range`].
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/// Note that in most cases, it's better to use range syntax (`1..5`) instead.
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///
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/// ```
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/// use std::collections::BTreeMap;
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/// use std::collections::Bound::{Excluded, Included, Unbounded};
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///
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/// let mut map = BTreeMap::new();
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/// map.insert(3, "a");
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/// map.insert(5, "b");
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/// map.insert(8, "c");
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///
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/// for (key, value) in map.range((Excluded(3), Included(8))) {
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/// println!("{}: {}", key, value);
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/// }
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///
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/// assert_eq!(Some((&3, &"a")), map.range((Unbounded, Included(5))).next());
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/// ```
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///
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/// [`BTreeMap::range`]: btree_map/struct.BTreeMap.html#method.range
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#[stable(feature = "collections_bound", since = "1.17.0")]
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#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
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pub enum Bound<T> {
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/// An inclusive bound.
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#[stable(feature = "collections_bound", since = "1.17.0")]
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Included(#[stable(feature = "collections_bound", since = "1.17.0")] T),
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/// An exclusive bound.
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#[stable(feature = "collections_bound", since = "1.17.0")]
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Excluded(#[stable(feature = "collections_bound", since = "1.17.0")] T),
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/// An infinite endpoint. Indicates that there is no bound in this direction.
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#[stable(feature = "collections_bound", since = "1.17.0")]
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Unbounded,
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}
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/// An intermediate trait for specialization of `Extend`.
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#[doc(hidden)]
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trait SpecExtend<I: IntoIterator> {
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/// Extends `self` with the contents of the given iterator.
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fn spec_extend(&mut self, iter: I);
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}
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#[doc(no_inline)]
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pub use binary_heap::BinaryHeap;
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#[doc(no_inline)]
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pub use btree_map::BTreeMap;
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#[doc(no_inline)]
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pub use btree_set::BTreeSet;
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#[doc(no_inline)]
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pub use linked_list::LinkedList;
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#[doc(no_inline)]
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pub use vec_deque::VecDeque;
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#[doc(no_inline)]
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pub use string::String;
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#[doc(no_inline)]
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pub use vec::Vec;
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