// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! A simple map based on a vector for small integer keys. Space requirements
//! are O(highest integer key).
#![allow(missing_docs)]
use self::Entry::*;
use std::cmp::max;
use std::fmt;
use std::hash::{Hash, Hasher};
use std::iter::{Enumerate, FilterMap, FromIterator, Map};
use std::mem::{replace, swap};
use std::ops::{Index, IndexMut};
use std::{slice, vec};
use std::vec::Vec;
/// A map optimized for small integer keys.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
///
/// let mut months = VecMap::new();
/// months.insert(1, "Jan");
/// months.insert(2, "Feb");
/// months.insert(3, "Mar");
///
/// if !months.contains_key(&12) {
/// println!("The end is near!");
/// }
///
/// assert_eq!(months.get(&1), Some(&"Jan"));
///
/// if let Some(value) = months.get_mut(&3) {
/// *value = "Venus";
/// }
///
/// assert_eq!(months.get(&3), Some(&"Venus"));
///
/// // Print out all months
/// for (key, value) in months.iter() {
/// println!("month {} is {}", key, value);
/// }
///
/// months.clear();
/// assert!(months.is_empty());
/// ```
pub struct VecMap<V> {
v: Vec<Option<V>>,
}
/// A view into a single entry in a map, which may either be vacant or occupied.
pub enum Entry<'a, V: 'a> {
/// A vacant Entry
Vacant(VacantEntry<'a, V>),
/// An occupied Entry
Occupied(OccupiedEntry<'a, V>),
}
/// A vacant Entry.
pub struct VacantEntry<'a, V: 'a> {
map: &'a mut VecMap<V>,
index: usize,
}
/// An occupied Entry.
pub struct OccupiedEntry<'a, V: 'a> {
map: &'a mut VecMap<V>,
index: usize,
}
impl<V> Default for VecMap<V> {
#[inline]
fn default() -> VecMap<V> {
VecMap::new()
}
}
impl<V: Clone> Clone for VecMap<V> {
#[inline]
fn clone(&self) -> VecMap<V> {
VecMap { v: self.v.clone() }
}
#[inline]
fn clone_from(&mut self, source: &VecMap<V>) {
self.v.clone_from(&source.v);
}
}
impl<V: Hash> Hash for VecMap<V> {
fn hash<H: Hasher>(&self, state: &mut H) {
// In order to not traverse the `VecMap` twice, count the elements
// during iteration.
let mut count: usize = 0;
for elt in self {
elt.hash(state);
count += 1;
}
count.hash(state);
}
}
impl<V> VecMap<V> {
/// Creates an empty `VecMap`.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
/// let mut map: VecMap<&str> = VecMap::new();
/// ```
pub fn new() -> VecMap<V> {
VecMap { v: vec![] }
}
/// Creates an empty `VecMap` with space for at least `capacity`
/// elements before resizing.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
/// let mut map: VecMap<&str> = VecMap::with_capacity(10);
/// ```
pub fn with_capacity(capacity: usize) -> VecMap<V> {
VecMap {
v: Vec::with_capacity(capacity),
}
}
/// Returns the number of elements the `VecMap` can hold without
/// reallocating.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
/// let map: VecMap<String> = VecMap::with_capacity(10);
/// assert!(map.capacity() >= 10);
/// ```
#[inline]
pub fn capacity(&self) -> usize {
self.v.capacity()
}
/// Reserves capacity for the given `VecMap` to contain `len` distinct keys.
/// In the case of `VecMap` this means reallocations will not occur as long
/// as all inserted keys are less than `len`.
///
/// The collection may reserve more space to avoid frequent reallocations.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
/// let mut map: VecMap<&str> = VecMap::new();
/// map.reserve_len(10);
/// assert!(map.capacity() >= 10);
/// ```
pub fn reserve_len(&mut self, len: usize) {
let cur_len = self.v.len();
if len >= cur_len {
self.v.reserve(len - cur_len);
}
}
/// Reserves the minimum capacity for the given `VecMap` to contain `len` distinct keys.
/// In the case of `VecMap` this means reallocations will not occur as long as all inserted
/// keys are less than `len`.
///
/// Note that the allocator may give the collection more space than it requests.
/// Therefore capacity cannot be relied upon to be precisely minimal. Prefer
/// `reserve_len` if future insertions are expected.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
/// let mut map: VecMap<&str> = VecMap::new();
/// map.reserve_len_exact(10);
/// assert!(map.capacity() >= 10);
/// ```
pub fn reserve_len_exact(&mut self, len: usize) {
let cur_len = self.v.len();
if len >= cur_len {
self.v.reserve_exact(len - cur_len);
}
}
/// Returns an iterator visiting all keys in ascending order of the keys.
/// The iterator's element type is `usize`.
pub fn keys<'r>(&'r self) -> Keys<'r, V> {
fn first<A, B>((a, _): (A, B)) -> A {
a
}
let first: fn((usize, &'r V)) -> usize = first; // coerce to fn pointer
Keys {
iter: self.iter().map(first),
}
}
/// Returns an iterator visiting all values in ascending order of the keys.
/// The iterator's element type is `&'r V`.
pub fn values<'r>(&'r self) -> Values<'r, V> {
fn second<A, B>((_, b): (A, B)) -> B {
b
}
let second: fn((usize, &'r V)) -> &'r V = second; // coerce to fn pointer
Values {
iter: self.iter().map(second),
}
}
/// Returns an iterator visiting all key-value pairs in ascending order of the keys.
/// The iterator's element type is `(usize, &'r V)`.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
///
/// let mut map = VecMap::new();
/// map.insert(1, "a");
/// map.insert(3, "c");
/// map.insert(2, "b");
///
/// // Print `1: a` then `2: b` then `3: c`
/// for (key, value) in map.iter() {
/// println!("{}: {}", key, value);
/// }
/// ```
pub fn iter<'r>(&'r self) -> Iter<'r, V> {
Iter {
front: 0,
back: self.v.len(),
iter: self.v.iter(),
}
}
/// Returns an iterator visiting all key-value pairs in ascending order of the keys,
/// with mutable references to the values.
/// The iterator's element type is `(usize, &'r mut V)`.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
///
/// let mut map = VecMap::new();
/// map.insert(1, "a");
/// map.insert(2, "b");
/// map.insert(3, "c");
///
/// for (key, value) in map.iter_mut() {
/// *value = "x";
/// }
///
/// for (key, value) in map.iter() {
/// assert_eq!(value, &"x");
/// }
/// ```
pub fn iter_mut<'r>(&'r mut self) -> IterMut<'r, V> {
IterMut {
front: 0,
back: self.v.len(),
iter: self.v.iter_mut(),
}
}
/// Splits the collection into two at the given key.
///
/// Returns a newly allocated `Self`. `self` contains elements `[0, at)`,
/// and the returned `Self` contains elements `[at, max_key)`.
///
/// Note that the capacity of `self` does not change.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
///
/// let mut a = VecMap::new();
/// a.insert(1, "a");
/// a.insert(2, "b");
/// a.insert(3, "c");
/// a.insert(4, "d");
///
/// let b = a.split_off(3);
///
/// assert_eq!(a[1], "a");
/// assert_eq!(a[2], "b");
///
/// assert_eq!(b[3], "c");
/// assert_eq!(b[4], "d");
/// ```
pub fn split_off(&mut self, at: usize) -> Self {
let mut other = VecMap::new();
if at == 0 {
// Move all elements to other
swap(self, &mut other);
return other;
} else if at >= self.v.len() {
// No elements to copy
return other;
}
// Look up the index of the first non-None item
let first_index = self.v.iter().position(|el| el.is_some());
let start_index = match first_index {
Some(index) => max(at, index),
None => {
// self has no elements
return other;
}
};
// Fill the new VecMap with `None`s until `start_index`
other.v.extend((0..start_index).map(|_| None));
// Move elements beginning with `start_index` from `self` into `other`
other
.v
.extend(self.v[start_index..].iter_mut().map(|el| el.take()));
other
}
/// Returns the number of elements in the map.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
///
/// let mut a = VecMap::new();
/// assert_eq!(a.len(), 0);
/// a.insert(1, "a");
/// assert_eq!(a.len(), 1);
/// ```
pub fn len(&self) -> usize {
self.v.iter().filter(|elt| elt.is_some()).count()
}
/// Returns true if the map contains no elements.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
///
/// let mut a = VecMap::new();
/// assert!(a.is_empty());
/// a.insert(1, "a");
/// assert!(!a.is_empty());
/// ```
pub fn is_empty(&self) -> bool {
self.v.iter().all(|elt| elt.is_none())
}
/// Clears the map, removing all key-value pairs.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
///
/// let mut a = VecMap::new();
/// a.insert(1, "a");
/// a.clear();
/// assert!(a.is_empty());
/// ```
pub fn clear(&mut self) {
self.v.clear()
}
/// Returns a reference to the value corresponding to the key.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
///
/// let mut map = VecMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.get(&1), Some(&"a"));
/// assert_eq!(map.get(&2), None);
/// ```
pub fn get(&self, key: &usize) -> Option<&V> {
if *key < self.v.len() {
match self.v[*key] {
Some(ref value) => Some(value),
None => None,
}
} else {
None
}
}
/// Returns true if the map contains a value for the specified key.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
///
/// let mut map = VecMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.contains_key(&1), true);
/// assert_eq!(map.contains_key(&2), false);
/// ```
#[inline]
pub fn contains_key(&self, key: &usize) -> bool {
self.get(key).is_some()
}
/// Returns a mutable reference to the value corresponding to the key.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
///
/// let mut map = VecMap::new();
/// map.insert(1, "a");
/// if let Some(x) = map.get_mut(&1) {
/// *x = "b";
/// }
/// assert_eq!(map[1], "b");
/// ```
pub fn get_mut(&mut self, key: &usize) -> Option<&mut V> {
if *key < self.v.len() {
match *(&mut self.v[*key]) {
Some(ref mut value) => Some(value),
None => None,
}
} else {
None
}
}
/// Inserts a key-value pair into the map. If the key already had a value
/// present in the map, that value is returned. Otherwise, `None` is returned.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
///
/// let mut map = VecMap::new();
/// assert_eq!(map.insert(37, "a"), None);
/// assert_eq!(map.is_empty(), false);
///
/// map.insert(37, "b");
/// assert_eq!(map.insert(37, "c"), Some("b"));
/// assert_eq!(map[37], "c");
/// ```
pub fn insert(&mut self, key: usize, value: V) -> Option<V> {
let len = self.v.len();
if len <= key {
self.v.extend((0..key - len + 1).map(|_| None));
}
replace(&mut self.v[key], Some(value))
}
/// Removes a key from the map, returning the value at the key if the key
/// was previously in the map.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
///
/// let mut map = VecMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.remove(&1), Some("a"));
/// assert_eq!(map.remove(&1), None);
/// ```
pub fn remove(&mut self, key: &usize) -> Option<V> {
if *key >= self.v.len() {
return None;
}
let result = &mut self.v[*key];
result.take()
}
/// Gets the given key's corresponding entry in the map for in-place manipulation.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
///
/// let mut count: VecMap<u32> = VecMap::new();
///
/// // count the number of occurrences of numbers in the vec
/// for x in vec![1, 2, 1, 2, 3, 4, 1, 2, 4] {
/// *count.entry(x).or_insert(0) += 1;
/// }
///
/// assert_eq!(count[1], 3);
/// ```
pub fn entry(&mut self, key: usize) -> Entry<V> {
// FIXME(Gankro): this is basically the dumbest implementation of
// entry possible, because weird non-lexical borrows issues make it
// completely insane to do any other way. That said, Entry is a border-line
// useless construct on VecMap, so it's hardly a big loss.
if self.contains_key(&key) {
Occupied(OccupiedEntry {
map: self,
index: key,
})
} else {
Vacant(VacantEntry {
map: self,
index: key,
})
}
}
}
impl<'a, V> Entry<'a, V> {
/// Returns a mutable reference to the entry if occupied, or the VacantEntry if vacant
pub fn get(self) -> Result<&'a mut V, VacantEntry<'a, V>> {
match self {
Occupied(entry) => Ok(entry.into_mut()),
Vacant(entry) => Err(entry),
}
}
/// Ensures a value is in the entry by inserting the default if empty, and returns
/// a mutable reference to the value in the entry.
pub fn or_insert(self, default: V) -> &'a mut V {
match self {
Occupied(entry) => entry.into_mut(),
Vacant(entry) => entry.insert(default),
}
}
/// Ensures a value is in the entry by inserting the result of the default function if empty,
/// and returns a mutable reference to the value in the entry.
pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V {
match self {
Occupied(entry) => entry.into_mut(),
Vacant(entry) => entry.insert(default()),
}
}
}
impl<'a, V> VacantEntry<'a, V> {
/// Sets the value of the entry with the VacantEntry's key,
/// and returns a mutable reference to it.
pub fn insert(self, value: V) -> &'a mut V {
let index = self.index;
let _ = self.map.insert(index, value);
&mut self.map[index]
}
}
impl<'a, V> OccupiedEntry<'a, V> {
/// Gets a reference to the value in the entry.
pub fn get(&self) -> &V {
let index = self.index;
&self.map[index]
}
/// Gets a mutable reference to the value in the entry.
pub fn get_mut(&mut self) -> &mut V {
let index = self.index;
&mut self.map[index]
}
/// Converts the entry into a mutable reference to its value.
pub fn into_mut(self) -> &'a mut V {
let index = self.index;
&mut self.map[index]
}
/// Sets the value of the entry with the OccupiedEntry's key,
/// and returns the entry's old value.
pub fn insert(&mut self, value: V) -> V {
let index = self.index;
self.map.insert(index, value).unwrap()
}
/// Takes the value of the entry out of the map, and returns it.
pub fn remove(self) -> V {
let index = self.index;
self.map.remove(&index).unwrap()
}
}
impl<V: fmt::Debug> fmt::Debug for VecMap<V> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
try!(write!(f, "{{"));
for (i, (k, v)) in self.iter().enumerate() {
if i != 0 {
try!(write!(f, ", "));
}
try!(write!(f, "{}: {:?}", k, *v));
}
write!(f, "}}")
}
}
impl<V> FromIterator<(usize, V)> for VecMap<V> {
fn from_iter<I: IntoIterator<Item = (usize, V)>>(iter: I) -> VecMap<V> {
let mut map = VecMap::new();
map.extend(iter);
map
}
}
impl<T> IntoIterator for VecMap<T> {
type Item = (usize, T);
type IntoIter = IntoIter<T>;
/// Returns an iterator visiting all key-value pairs in ascending order of
/// the keys, consuming the original `VecMap`.
/// The iterator's element type is `(usize, &'r V)`.
///
/// # Examples
///
/// ```
/// # #![feature(collections)]
/// use std::collections::VecMap;
///
/// let mut map = VecMap::new();
/// map.insert(1, "a");
/// map.insert(3, "c");
/// map.insert(2, "b");
///
/// let vec: Vec<(usize, &str)> = map.into_iter().collect();
///
/// assert_eq!(vec, [(1, "a"), (2, "b"), (3, "c")]);
/// ```
fn into_iter(self) -> IntoIter<T> {
fn filter<A>((i, v): (usize, Option<A>)) -> Option<(usize, A)> {
v.map(|v| (i, v))
}
let filter: fn((usize, Option<T>)) -> Option<(usize, T)> = filter; // coerce to fn ptr
IntoIter {
iter: self.v.into_iter().enumerate().filter_map(filter),
}
}
}
impl<'a, T> IntoIterator for &'a VecMap<T> {
type Item = (usize, &'a T);
type IntoIter = Iter<'a, T>;
fn into_iter(self) -> Iter<'a, T> {
self.iter()
}
}
impl<'a, T> IntoIterator for &'a mut VecMap<T> {
type Item = (usize, &'a mut T);
type IntoIter = IterMut<'a, T>;
fn into_iter(self) -> IterMut<'a, T> {
self.iter_mut()
}
}
impl<V> Extend<(usize, V)> for VecMap<V> {
fn extend<I: IntoIterator<Item = (usize, V)>>(&mut self, iter: I) {
for (k, v) in iter {
let _ = self.insert(k, v);
}
}
}
impl<V> Index<usize> for VecMap<V> {
type Output = V;
#[inline]
fn index<'a>(&'a self, i: usize) -> &'a V {
self.get(&i).expect("key not present")
}
}
impl<'a, V> Index<&'a usize> for VecMap<V> {
type Output = V;
#[inline]
fn index(&self, i: &usize) -> &V {
self.get(i).expect("key not present")
}
}
impl<V> IndexMut<usize> for VecMap<V> {
#[inline]
fn index_mut(&mut self, i: usize) -> &mut V {
self.get_mut(&i).expect("key not present")
}
}
impl<'a, V> IndexMut<&'a usize> for VecMap<V> {
#[inline]
fn index_mut(&mut self, i: &usize) -> &mut V {
self.get_mut(i).expect("key not present")
}
}
macro_rules! iterator {
(impl $name:ident -> $elem:ty, $($getter:ident),+) => {
impl<'a, V> Iterator for $name<'a, V> {
type Item = $elem;
#[inline]
fn next(&mut self) -> Option<$elem> {
while self.front < self.back {
match self.iter.next() {
Some(elem) => {
match elem$(. $getter ())+ {
Some(x) => {
let index = self.front;
self.front += 1;
return Some((index, x));
},
None => {},
}
}
_ => ()
}
self.front += 1;
}
None
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
(0, Some(self.back - self.front))
}
}
}
}
macro_rules! double_ended_iterator {
(impl $name:ident -> $elem:ty, $($getter:ident),+) => {
impl<'a, V> DoubleEndedIterator for $name<'a, V> {
#[inline]
fn next_back(&mut self) -> Option<$elem> {
while self.front < self.back {
match self.iter.next_back() {
Some(elem) => {
match elem$(. $getter ())+ {
Some(x) => {
self.back -= 1;
return Some((self.back, x));
},
None => {},
}
}
_ => ()
}
self.back -= 1;
}
None
}
}
}
}
/// An iterator over the key-value pairs of a map.
pub struct Iter<'a, V: 'a> {
front: usize,
back: usize,
iter: slice::Iter<'a, Option<V>>,
}
// FIXME(#19839) Remove in favor of `#[derive(Clone)]`
impl<'a, V> Clone for Iter<'a, V> {
fn clone(&self) -> Iter<'a, V> {
Iter {
front: self.front,
back: self.back,
iter: self.iter.clone(),
}
}
}
iterator! { impl Iter -> (usize, &'a V), as_ref }
double_ended_iterator! { impl Iter -> (usize, &'a V), as_ref }
/// An iterator over the key-value pairs of a map, with the
/// values being mutable.
pub struct IterMut<'a, V: 'a> {
front: usize,
back: usize,
iter: slice::IterMut<'a, Option<V>>,
}
iterator! { impl IterMut -> (usize, &'a mut V), as_mut }
double_ended_iterator! { impl IterMut -> (usize, &'a mut V), as_mut }
/// An iterator over the keys of a map.
pub struct Keys<'a, V: 'a> {
iter: Map<Iter<'a, V>, fn((usize, &'a V)) -> usize>,
}
// FIXME(#19839) Remove in favor of `#[derive(Clone)]`
impl<'a, V> Clone for Keys<'a, V> {
fn clone(&self) -> Keys<'a, V> {
Keys {
iter: self.iter.clone(),
}
}
}
/// An iterator over the values of a map.
pub struct Values<'a, V: 'a> {
iter: Map<Iter<'a, V>, fn((usize, &'a V)) -> &'a V>,
}
// FIXME(#19839) Remove in favor of `#[derive(Clone)]`
impl<'a, V> Clone for Values<'a, V> {
fn clone(&self) -> Values<'a, V> {
Values {
iter: self.iter.clone(),
}
}
}
/// A consuming iterator over the key-value pairs of a map.
pub struct IntoIter<V> {
iter: FilterMap<
Enumerate<vec::IntoIter<Option<V>>>,
fn((usize, Option<V>)) -> Option<(usize, V)>,
>,
}
impl<'a, V> Iterator for Keys<'a, V> {
type Item = usize;
fn next(&mut self) -> Option<usize> {
self.iter.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
impl<'a, V> DoubleEndedIterator for Keys<'a, V> {
fn next_back(&mut self) -> Option<usize> {
self.iter.next_back()
}
}
impl<'a, V> Iterator for Values<'a, V> {
type Item = &'a V;
fn next(&mut self) -> Option<(&'a V)> {
self.iter.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
impl<'a, V> DoubleEndedIterator for Values<'a, V> {
fn next_back(&mut self) -> Option<(&'a V)> {
self.iter.next_back()
}
}
impl<V> Iterator for IntoIter<V> {
type Item = (usize, V);
fn next(&mut self) -> Option<(usize, V)> {
self.iter.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
impl<V> DoubleEndedIterator for IntoIter<V> {
fn next_back(&mut self) -> Option<(usize, V)> {
self.iter.next_back()
}
}