Remove container guide.

This isn't really what guides are for, this information belongs in the module-level docs. Fixes #9314.
2025-02-21 11:23:03 +00:00 · 2014-09-08 17:21:34 -04:00 · 2014-09-08 17:21:34 -04:00 · 1b818020a0
commit 1b818020a0
parent 84030fd05a
3 changed files with 3 additions and 418 deletions
--- a/src/doc/guide-container.md
+++ b/src/doc/guide-container.md
@ -1,414 +1,6 @@
 % The Rust Containers and Iterators Guide
-# Containers
+This guide has been removed, with no direct replacement.
-The container traits are defined in the `std::container` module.
+You may enjoy reading the [iterator](std/iter/index.html) and
-
+[collections](std/collections/index.html) documentation.
 ## Unique vectors
 Vectors have `O(1)` indexing, push (to the end) and pop (from the end). Vectors
 are the most common container in Rust, and are flexible enough to fit many use
 cases.
 Vectors can also be sorted and used as efficient lookup tables with the
 `bsearch()` method, if all the elements are inserted at one time and
 deletions are unnecessary.
 ## Maps and sets
 Maps are collections of unique keys with corresponding values, and sets are
 just unique keys without a corresponding value. The `Map` and `Set` traits in
 `std::container` define the basic interface.
 The standard library provides three owned map/set types:
 * `collections::HashMap` and `collections::HashSet`, requiring the keys to
  implement `Eq` and `Hash`
 * `collections::TrieMap` and `collections::TrieSet`, requiring the keys to be `uint`
 * `collections::TreeMap` and `collections::TreeSet`, requiring the keys
  to implement `Ord`
 These maps do not use managed pointers so they can be sent between tasks as
 long as the key and value types are sendable. Neither the key or value type has
 to be copyable.
 The `TrieMap` and `TreeMap` maps are ordered, while `HashMap` uses an arbitrary
 order.
 Each `HashMap` instance has a random 128-bit key to use with a keyed hash,
 making the order of a set of keys in a given hash table randomized. Rust
 provides a [SipHash](https://131002.net/siphash/) implementation for any type
 implementing the `Hash` trait.
 ## Double-ended queues
 The `collections::ringbuf` module implements a double-ended queue with `O(1)`
 amortized inserts and removals from both ends of the container. It also has
 `O(1)` indexing like a vector. The contained elements are not required to be
 copyable, and the queue will be sendable if the contained type is sendable.
 Its interface `Deque` is defined in `collections`.
 The `extra::dlist` module implements a double-ended linked list, also
 implementing the `Deque` trait, with `O(1)` removals and inserts at either end,
 and `O(1)` concatenation.
 ## Priority queues
 The `collections::priority_queue` module implements a queue ordered by a key.  The
 contained elements are not required to be copyable, and the queue will be
 sendable if the contained type is sendable.
 Insertions have `O(log n)` time complexity and checking or popping the largest
 element is `O(1)`. Converting a vector to a priority queue can be done
 in-place, and has `O(n)` complexity. A priority queue can also be converted to
 a sorted vector in-place, allowing it to be used for an `O(n log n)` in-place
 heapsort.
 # Iterators
 ## Iteration protocol
 The iteration protocol is defined by the `Iterator` trait in the
 `std::iter` module. The minimal implementation of the trait is a `next`
 method, yielding the next element from an iterator object:
 ~~~
 /// An infinite stream of zeroes
 struct ZeroStream;
 impl Iterator<int> for ZeroStream {
    fn next(&mut self) -> Option<int> {
        Some(0)
    }
 }
 ~~~
 Reaching the end of the iterator is signalled by returning `None` instead of
 `Some(item)`:
 ~~~
 # fn main() {}
 /// A stream of N zeroes
 struct ZeroStream {
    remaining: uint
 }
 impl ZeroStream {
    fn new(n: uint) -> ZeroStream {
        ZeroStream { remaining: n }
    }
 }
 impl Iterator<int> for ZeroStream {
    fn next(&mut self) -> Option<int> {
        if self.remaining == 0 {
            None
        } else {
            self.remaining -= 1;
            Some(0)
        }
    }
 }
 ~~~
 In general, you cannot rely on the behavior of the `next()` method after it has
 returned `None`. Some iterators may return `None` forever. Others may behave
 differently.
 ## Container iterators
 Containers implement iteration over the contained elements by returning an
 iterator object. For example, for vector slices several iterators are available:
 * `iter()` for immutable references to the elements
 * `mut_iter()` for mutable references to the elements
 * `move_iter()` to move the elements out by-value
 A typical mutable container will implement at least `iter()`, `mut_iter()` and
 `move_iter()`. If it maintains an order, the returned iterators will be
 `DoubleEndedIterator`s, which are described below.
 ### Freezing
 Unlike most other languages with external iterators, Rust has no *iterator
 invalidation*. As long as an iterator is still in scope, the compiler will prevent
 modification of the container through another handle.
 ~~~
 let mut xs = [1i, 2, 3];
 {
    let _it = xs.iter();
    // the vector is frozen for this scope, the compiler will statically
    // prevent modification
 }
 // the vector becomes unfrozen again at the end of the scope
 ~~~
 These semantics are due to most container iterators being implemented with `&`
 and `&mut`.
 ## Iterator adaptors
 The `Iterator` trait provides many common algorithms as default methods. For
 example, the `fold` method will accumulate the items yielded by an `Iterator`
 into a single value:
 ~~~
 let xs = [1i, 9, 2, 3, 14, 12];
 let result = xs.iter().fold(0, |accumulator, item| accumulator - *item);
 assert_eq!(result, -41);
 ~~~
 Most adaptors return an adaptor object implementing the `Iterator` trait itself:
 ~~~
 let xs = [1i, 9, 2, 3, 14, 12];
 let ys = [5i, 2, 1, 8];
 let sum = xs.iter().chain(ys.iter()).fold(0, |a, b| a + *b);
 assert_eq!(sum, 57);
 ~~~
 Some iterator adaptors may return `None` before exhausting the underlying
 iterator. Additionally, if these iterator adaptors are called again after
 returning `None`, they may call their underlying iterator again even if the
 adaptor will continue to return `None` forever. This may not be desired if the
 underlying iterator has side-effects.
 In order to provide a guarantee about behavior once `None` has been returned, an
 iterator adaptor named `fuse()` is provided. This returns an iterator that will
 never call its underlying iterator again once `None` has been returned:
 ~~~
 let xs = [1i,2,3,4,5];
 let mut calls = 0i;
 {
    let it = xs.iter().scan((), |_, x| {
        calls += 1;
        if *x < 3 { Some(x) } else { None }});
    // the iterator will only yield 1 and 2 before returning None
    // If we were to call it 5 times, calls would end up as 5, despite
    // only 2 values being yielded (and therefore 3 unique calls being
    // made). The fuse() adaptor can fix this.
    let mut it = it.fuse();
    it.next();
    it.next();
    it.next();
    it.next();
    it.next();
 }
 assert_eq!(calls, 3);
 ~~~
 ## For loops
 The function `range` (or `range_inclusive`) allows to simply iterate through a given range:
 ~~~
 for i in range(0i, 5) {
  print!("{} ", i) // prints "0 1 2 3 4"
 }
 for i in std::iter::range_inclusive(0i, 5) { // needs explicit import
  print!("{} ", i) // prints "0 1 2 3 4 5"
 }
 ~~~
 The `for` keyword can be used as sugar for iterating through any iterator:
 ~~~
 let xs = [2u, 3, 5, 7, 11, 13, 17];
 // print out all the elements in the vector
 for x in xs.iter() {
    println!("{}", *x)
 }
 // print out all but the first 3 elements in the vector
 for x in xs.iter().skip(3) {
    println!("{}", *x)
 }
 ~~~
 For loops are *often* used with a temporary iterator object, as above. They can
 also advance the state of an iterator in a mutable location:
 ~~~
 let xs = [1i, 2, 3, 4, 5];
 let ys = ["foo", "bar", "baz", "foobar"];
 // create an iterator yielding tuples of elements from both vectors
 let mut it = xs.iter().zip(ys.iter());
 // print out the pairs of elements up to (&3, &"baz")
 for (x, y) in it {
    println!("{} {}", *x, *y);
    if *x == 3 {
        break;
    }
 }
 // yield and print the last pair from the iterator
 println!("last: {}", it.next());
 // the iterator is now fully consumed
 assert!(it.next().is_none());
 ~~~
 ## Conversion
 Iterators offer generic conversion to containers with the `collect` adaptor:
 ~~~
 let xs = [0i, 1, 1, 2, 3, 5, 8];
 let ys = xs.iter().rev().skip(1).map(|&x| x * 2).collect::<Vec<int>>();
 assert_eq!(ys, vec![10, 6, 4, 2, 2, 0]);
 ~~~
 The method requires a type hint for the container type, if the surrounding code
 does not provide sufficient information.
 Containers can provide conversion from iterators through `collect` by
 implementing the `FromIterator` trait. For example, the implementation for
 vectors is as follows:
 ~~~ {.ignore}
 impl<T> FromIterator<T> for Vec<T> {
    fn from_iter<I:Iterator<A>>(mut iterator: I) -> Vec<T> {
        let (lower, _) = iterator.size_hint();
        let mut vector = Vec::with_capacity(lower);
        for element in iterator {
            vector.push(element);
        }
        vector
    }
 }
 ~~~
 ### Size hints
 The `Iterator` trait provides a `size_hint` default method, returning a lower
 bound and optionally on upper bound on the length of the iterator:
 ~~~ {.ignore}
 fn size_hint(&self) -> (uint, Option<uint>) { (0, None) }
 ~~~
 The vector implementation of `FromIterator` from above uses the lower bound
 to pre-allocate enough space to hold the minimum number of elements the
 iterator will yield.
 The default implementation is always correct, but it should be overridden if
 the iterator can provide better information.
 The `ZeroStream` from earlier can provide an exact lower and upper bound:
 ~~~
 # fn main() {}
 /// A stream of N zeroes
 struct ZeroStream {
    remaining: uint
 }
 impl ZeroStream {
    fn new(n: uint) -> ZeroStream {
        ZeroStream { remaining: n }
    }
    fn size_hint(&self) -> (uint, Option<uint>) {
        (self.remaining, Some(self.remaining))
    }
 }
 impl Iterator<int> for ZeroStream {
    fn next(&mut self) -> Option<int> {
        if self.remaining == 0 {
            None
        } else {
            self.remaining -= 1;
            Some(0)
        }
    }
 }
 ~~~
 ## Double-ended iterators
 The `DoubleEndedIterator` trait represents an iterator able to yield elements
 from either end of a range. It inherits from the `Iterator` trait and extends
 it with the `next_back` function.
 A `DoubleEndedIterator` can have its direction changed with the `rev` adaptor,
 returning another `DoubleEndedIterator` with `next` and `next_back` exchanged.
 ~~~
 let xs = [1i, 2, 3, 4, 5, 6];
 let mut it = xs.iter();
 println!("{}", it.next()); // prints `Some(1)`
 println!("{}", it.next()); // prints `Some(2)`
 println!("{}", it.next_back()); // prints `Some(6)`
 // prints `5`, `4` and `3`
 for &x in it.rev() {
    println!("{}", x)
 }
 ~~~
 The `chain`, `map`, `filter`, `filter_map` and `inspect` adaptors are
 `DoubleEndedIterator` implementations if the underlying iterators are.
 ~~~
 let xs = [1i, 2, 3, 4];
 let ys = [5i, 6, 7, 8];
 let mut it = xs.iter().chain(ys.iter()).map(|&x| x * 2);
 println!("{}", it.next()); // prints `Some(2)`
 // prints `16`, `14`, `12`, `10`, `8`, `6`, `4`
 for x in it.rev() {
    println!("{}", x);
 }
 ~~~
 The `reverse_` method is also available for any double-ended iterator yielding
 mutable references. It can be used to reverse a container in-place. Note that
 the trailing underscore is a workaround for issue #5898 and will be removed.
 ~~~
 let mut ys = [1i, 2, 3, 4, 5];
 ys.mut_iter().reverse_();
 assert!(ys == [5i, 4, 3, 2, 1]);
 ~~~
 ## Random-access iterators
 The `RandomAccessIterator` trait represents an iterator offering random access
 to the whole range. The `indexable` method retrieves the number of elements
 accessible with the `idx` method.
 The `chain` adaptor is an implementation of `RandomAccessIterator` if the
 underlying iterators are.
 ~~~
 let xs = [1i, 2, 3, 4, 5];
 let ys = [7i, 9, 11];
 let mut it = xs.iter().chain(ys.iter());
 println!("{}", it.idx(0)); // prints `Some(1)`
 println!("{}", it.idx(5)); // prints `Some(7)`
 println!("{}", it.idx(7)); // prints `Some(11)`
 println!("{}", it.idx(8)); // prints `None`
 // yield two elements from the beginning, and one from the end
 it.next();
 it.next();
 it.next_back();
 println!("{}", it.idx(0)); // prints `Some(3)`
 println!("{}", it.idx(4)); // prints `Some(9)`
 println!("{}", it.idx(6)); // prints `None`
 ~~~
--- a/src/doc/index.md
+++ b/src/doc/index.md
@ -57,7 +57,6 @@ a guide that can help you out:
 * [Strings](guide-strings.html)
 * [Pointers](guide-pointers.html)
 * [References and Lifetimes](guide-lifetimes.html)
 * [Containers and Iterators](guide-container.html)
 * [Tasks and Communication](guide-tasks.html)
 * [Foreign Function Interface](guide-ffi.html)
 * [Writing Unsafe and Low-Level Code](guide-unsafe.html)
--- a/src/libcore/iter.rs
+++ b/src/libcore/iter.rs
@ -56,12 +56,6 @@ loop {
 This `for` loop syntax can be applied to any iterator over any type.
 ## Iteration protocol and more
 More detailed information about iterators can be found in the [container
 guide](http://doc.rust-lang.org/guide-container.html) with
 the rest of the rust manuals.
 */
 use clone::Clone;