1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349
//! Finger Trees
//! [![Build Status](https://travis-ci.org/aslpavel/fingertree-rs.svg?branch=master)](https://travis-ci.org/aslpavel/fingertree-rs)
//! [![Coverage Status](https://coveralls.io/repos/github/aslpavel/fingertree-rs/badge.svg?branch=master)](https://coveralls.io/github/aslpavel/fingertree-rs?branch=master)
//!
//! Finger trees is a functional representation of persistent sequences
//! supporting access to the ends in amortized constant time, and concatenation
//! and splitting in time logarithmic in the size of the smaller piece. It also
//! has [`split`](struct.FingerTree.html#method.split) operation defined in general
//! form, which can be used to implement sequence, priority queue, search tree,
//! priority search queue and more datastructures.
//!
//! ## Links:
//! - Original paper: [Finger Trees: A Simple General-purpose Data Structure](http://www.staff.city.ac.uk/~ross/papers/FingerTree.html)
//! - Wikipedia article: [FingerTree](https://en.wikipedia.org/wiki/Finger_tree)
//!
//! ## Notes:
//! - This implementation does not use non-regular recursive types as implementation
//! described in the paper. As rust's monomorphization does not play well with such types.
//! - Implmentation abstracts over reference counted types `Rc/Arc`. Using type family trick.
//! - Uses strict spine in implementation.
//! - Iterator returns cloned value, and in general this implementation assumes that value
//! stored in a tree is cheaply clonable, if it is not you can always put it in a `Rc/Arc` or
//! anything else.
//!
//! ## Examples:
//! ```rust
//! # use std::iter::FromIterator;
//! use fingertrees::measure::Size;
//! use fingertrees::monoid::Sum;
//! use fingertrees::{FingerTree, Measured, RcRefs};
//!
//! // construct `Rc` based finger tree with `Size` measure
//! let ft: FingerTree<RcRefs, _> = vec!["one", "two", "three", "four", "five"]
//! .into_iter()
//! .map(Size)
//! .collect();
//! assert_eq!(ft.measure(), Sum(5));
//!
//! // split with predicate
//! let (left, right) = ft.split(|measure| *measure > Sum(2));
//! assert_eq!(left.measure(), Sum(2));
//! assert_eq!(Vec::from_iter(&left), vec![Size("one"), Size("two")]);
//! assert_eq!(right.measure(), Sum(3));
//! assert_eq!(Vec::from_iter(&right), vec![Size("three"), Size("four"), Size("five")]);
//!
//! // concatinate
//! assert_eq!(ft, left + right);
//!
//! // push values
//! assert_eq!(
//! ft.push_left(Size("left")).push_right(Size("right")),
//! vec!["left", "one", "two", "three", "four", "five", "right"]
//! .into_iter()
//! .map(Size)
//! .collect(),
//! );
//! ```
#![deny(missing_docs)]
#![deny(warnings)]
mod digit;
mod iter;
pub mod measure;
pub mod monoid;
mod node;
mod reference;
mod tree;
#[cfg(test)]
mod test;
pub use crate::measure::Measured;
pub use crate::monoid::Monoid;
pub use crate::node::NodeInner;
pub use crate::reference::{ArcRefs, RcRefs, Ref, Refs};
pub use crate::tree::TreeInner;
pub mod rc {
//! `Rc` based implementation of `FingerTree`
/// FingerTree based on `Rc` references
pub type FingerTree<V> = super::FingerTree<super::RcRefs, V>;
}
pub mod sync {
//! `Arc` based implementation of `FingerTree`
/// FingerTree based on `Arc` references
///
/// This implementation becomes `{Send|Sync}` if `V: Send + Sync, V::Measure: Send + Sync`
pub type FingerTree<V> = super::FingerTree<super::ArcRefs, V>;
}
use std::fmt;
use std::iter::FromIterator;
use std::ops::Add;
use crate::iter::Iter;
use crate::node::Node;
use crate::tree::Tree;
/// FingerTree implemenetation
///
/// FingerTree is parametrized by two type parpameters
/// - `R` - type family trick which determines type of references used in
/// implementation. This crate implementes [`ArcRefs`](enum.ArcRefs.html) which is based
/// on `Arc` atomic reference counter, and [`RcRefs`](enum.RcRefs.html) which is based
/// on `Rc`.
/// - `V` - value type which must be measurable and cheaply clonable.
pub struct FingerTree<R, V>
where
R: Refs<V>,
V: Measured,
{
pub(crate) rec: Tree<R, V>,
}
impl<R, V> Clone for FingerTree<R, V>
where
R: Refs<V>,
V: Measured,
{
fn clone(&self) -> Self {
FingerTree {
rec: self.rec.clone(),
}
}
}
impl<R, V> FingerTree<R, V>
where
R: Refs<V>,
V: Measured,
{
/// Constructs a new, empty `FingerTree`
///
/// Complexity: `O(1)`
pub fn new() -> Self {
FingerTree { rec: Tree::empty() }
}
/// Returns `true` if finger tree is empty
///
/// Complexity: `O(1)`
pub fn is_empty(&self) -> bool {
match self.rec {
Tree::Empty => true,
_ => false,
}
}
/// Creates new tree with value prepended to the left side of the tree
///
/// Amortized complexity: `O(1)`
pub fn push_left(&self, value: V) -> Self {
FingerTree {
rec: self.rec.push_left(Node::leaf(value)),
}
}
/// Creates new tree with value prepended to the right side of the tree
///
/// Amortized complexity: `O(1)`
pub fn push_right(&self, value: V) -> Self {
FingerTree {
rec: self.rec.push_right(Node::leaf(value)),
}
}
/// Destrutures tree into a tuple with first element of it containing first
/// element from the left side of the tree, and second element contains tree
/// with reset of the elements
///
/// Amortized complexity: `O(1)`
pub fn view_left(&self) -> Option<(V, Self)> {
let (head, tail) = self.rec.view_left()?;
match head.as_ref() {
NodeInner::Leaf(value) => Some((value.clone(), FingerTree { rec: tail })),
_ => panic!("not leaf returned from to level finger-tree"),
}
}
/// Destrutures tree into a tuple with first element of it containing first
/// element from the left side of the tree, and second element contains tree
/// with reset of the elements
///
/// Amortized complexity: `O(1)`
pub fn view_right(&self) -> Option<(V, Self)> {
let (head, tail) = self.rec.view_right()?;
match head.as_ref() {
NodeInner::Leaf(value) => Some((value.clone(), FingerTree { rec: tail })),
_ => panic!("not leaf returned from to level finger-tree"),
}
}
/// Destructures tree into two three, using provided predicate.
///
/// Predicate must be monotinic function accepting accumulated measure of elments
/// and changing its value from `true` to `false`. This function basically behave
/// as if we would iterate all elements from left to right, and accumlating measure
/// of all iterated elements, calling predicate on this accumulated value and once
/// its value flips from `true` to `false` we stop iteration and form two threes
/// from already iterated elements and the rest of the elements.
///
/// Complexity: `O(ln(N))`
pub fn split<F>(&self, mut pred: F) -> (FingerTree<R, V>, FingerTree<R, V>)
where
F: FnMut(&V::Measure) -> bool,
{
if self.is_empty() {
(Self::new(), Self::new())
} else if (&mut pred)(&self.measure()) {
let (l, x, r) = self.rec.split(&V::Measure::unit(), &mut pred);
(
FingerTree { rec: l },
FingerTree {
rec: r.push_left(x),
},
)
} else {
(self.clone(), Self::new())
}
}
/// Construct new finger tree wich is concatination of `self` and `other`
///
/// Complexity: `O(ln(N))`
pub fn concat(&self, other: &Self) -> Self {
FingerTree {
rec: Tree::concat(&self.rec, &mut ::std::iter::empty(), &other.rec),
}
}
/// Double ended iterator visiting all elements of the tree from left to right
pub fn iter(&self) -> Iter<R, V> {
Iter::new(self)
}
}
impl<R, V> Measured for FingerTree<R, V>
where
R: Refs<V>,
V: Measured,
{
type Measure = V::Measure;
fn measure(&self) -> Self::Measure {
self.rec.measure()
}
}
impl<'a, 'b, R, V> Add<&'b FingerTree<R, V>> for &'a FingerTree<R, V>
where
R: Refs<V>,
V: Measured,
{
type Output = FingerTree<R, V>;
fn add(self, other: &'b FingerTree<R, V>) -> Self::Output {
self.concat(other)
}
}
impl<R, V> Add<FingerTree<R, V>> for FingerTree<R, V>
where
R: Refs<V>,
V: Measured,
{
type Output = FingerTree<R, V>;
fn add(self, other: Self) -> Self::Output {
self.concat(&other)
}
}
impl<R, V> PartialEq for FingerTree<R, V>
where
R: Refs<V>,
V: Measured + PartialEq,
{
fn eq(&self, other: &FingerTree<R, V>) -> bool {
self.iter().zip(other).all(|(a, b)| a == b)
}
}
impl<R, V> Eq for FingerTree<R, V>
where
R: Refs<V>,
V: Measured + Eq,
{
}
impl<'a, R, V> IntoIterator for &'a FingerTree<R, V>
where
R: Refs<V>,
V: Measured,
{
type Item = V;
type IntoIter = Iter<R, V>;
fn into_iter(self) -> Self::IntoIter {
self.iter()
}
}
impl<R, V> IntoIterator for FingerTree<R, V>
where
R: Refs<V>,
V: Measured,
{
type Item = V;
type IntoIter = Iter<R, V>;
fn into_iter(self) -> Self::IntoIter {
self.iter()
}
}
impl<R, V> FromIterator<V> for FingerTree<R, V>
where
R: Refs<V>,
V: Measured,
{
fn from_iter<I: IntoIterator<Item = V>>(iter: I) -> Self {
iter.into_iter()
.fold(FingerTree::new(), |ft, item| ft.push_right(item))
}
}
impl<R, V> fmt::Debug for FingerTree<R, V>
where
R: Refs<V>,
V: Measured + fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "FingerTree")?;
f.debug_list().entries(self.iter()).finish()
}
}
impl<R, V> Default for FingerTree<R, V>
where
R: Refs<V>,
V: Measured,
{
fn default() -> Self {
FingerTree::new()
}
}