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/*
* meli - melib crate.
*
* Copyright 2019 Manos Pitsidianakis
*
* This file is part of meli.
*
* meli is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* meli is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with meli. If not, see <http://www.gnu.org/licenses/>.
*/
use std::iter::{Extend, FromIterator};
use std::ops::Index;
const STACK_VEC_CAPACITY: usize = 32;
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
pub struct StackVec<T: Default + Copy + std::fmt::Debug> {
len: usize,
array: [T; STACK_VEC_CAPACITY],
heap_vec: Vec<T>,
}
impl<T: Default + Copy + std::fmt::Debug> StackVec<T> {
pub fn new() -> Self {
StackVec {
len: 0,
array: [T::default(); STACK_VEC_CAPACITY],
heap_vec: Vec::new(),
}
}
pub fn push(&mut self, ind: T) {
if self.len == self.array.len() {
if self.heap_vec.is_empty() {
self.heap_vec.reserve(STACK_VEC_CAPACITY);
for _ in 0..STACK_VEC_CAPACITY {
self.heap_vec.push(T::default());
}
}
self.heap_vec[0..STACK_VEC_CAPACITY].copy_from_slice(&self.array);
self.heap_vec.push(ind);
} else if self.len > self.array.len() {
self.heap_vec.push(ind);
} else {
self.array[self.len] = ind;
}
self.len += 1;
}
pub fn pop(&mut self) -> Option<T> {
if self.len == 0 {
return None;
}
if self.len > self.array.len() {
self.len -= 1;
self.heap_vec.pop()
} else {
let ret = self.array[self.len - 1];
self.len -= 1;
Some(ret)
}
}
pub fn len(&self) -> usize {
self.len
}
pub fn is_empty(&self) -> bool {
self.len == 0
}
pub fn iter(&self) -> StackVecIter<T> {
StackVecIter {
stack: &self,
range: 0..self.len,
}
}
pub fn remove(&mut self, i: usize) -> T {
if self.len > self.array.len() {
self.len -= 1;
self.heap_vec.remove(i)
} else {
let ret = std::mem::replace(&mut self.array[i], T::default());
self.len -= 1;
for i in i..self.len {
self.array[i] = self.array[i + 1];
}
ret
}
}
pub fn set(&mut self, i: usize, val: T) {
debug_assert!(i < self.len);
if self.len > self.array.len() {
self.heap_vec[i] = val;
if i < self.array.len() {
self.array[i] = val;
}
} else {
self.array[i] = val;
}
}
pub fn clear(&mut self) {
self.len = 0;
}
}
pub struct StackVecIter<'a, T: Default + Copy + std::fmt::Debug> {
stack: &'a StackVec<T>,
range: std::ops::Range<usize>,
}
impl<'a, T: Default + Copy + std::fmt::Debug> Iterator for StackVecIter<'a, T> {
type Item = &'a T;
fn next(&mut self) -> Option<&'a T> {
if self.range.len() == 0 {
None
} else {
let idx = self.range.start;
self.range.start += 1;
Some(&self.stack[idx])
}
}
}
impl<'a, T: Default + Copy + std::fmt::Debug> std::iter::DoubleEndedIterator
for StackVecIter<'a, T>
{
fn next_back(&mut self) -> Option<&'a T> {
if self.range.len() == 0 {
None
} else {
let idx = self.range.end - 1;
self.range.end -= 1;
Some(&self.stack[idx])
}
}
}
impl<T: Default + Copy + std::fmt::Debug> Index<usize> for StackVec<T> {
type Output = T;
fn index(&self, idx: usize) -> &T {
if self.len > self.array.len() {
&self.heap_vec[idx]
} else {
&self.array[idx]
}
}
}
impl<T: Default + Copy + std::fmt::Debug> Extend<T> for StackVec<T> {
fn extend<I>(&mut self, iter: I)
where
I: IntoIterator<Item = T>,
{
for elem in iter {
self.push(elem);
}
}
}
impl<T: Default + Copy + std::fmt::Debug> FromIterator<T> for StackVec<T> {
fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self {
let mut c = StackVec::new();
for i in iter {
c.push(i);
}
c
}
}
pub struct StackVecIterOwned<T: Default + Copy + std::fmt::Debug>(StackVec<T>);
impl<T: Default + Copy + std::fmt::Debug> IntoIterator for StackVec<T> {
type Item = T;
type IntoIter = StackVecIterOwned<T>;
fn into_iter(self) -> Self::IntoIter {
StackVecIterOwned(self)
}
}
impl<'a, T: Default + Copy + std::fmt::Debug> IntoIterator for &'a StackVec<T> {
type Item = &'a T;
type IntoIter = StackVecIter<'a, T>;
fn into_iter(self) -> Self::IntoIter {
self.iter()
}
}
impl<T: Default + Copy + std::fmt::Debug> Iterator for StackVecIterOwned<T> {
type Item = T;
fn next(&mut self) -> Option<T> {
if self.0.is_empty() {
None
} else {
Some(self.0.remove(0))
}
}
}
impl<T: Default + Copy + std::fmt::Debug> std::iter::DoubleEndedIterator for StackVecIterOwned<T> {
fn next_back(&mut self) -> Option<T> {
if self.0.is_empty() {
None
} else {
self.0.pop()
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_stackvec() {
let mut stack = StackVec::from_iter(0..4 * STACK_VEC_CAPACITY);
let mut ctr = 0;
assert!(stack.iter().all(|&x| {
let ret = x == ctr;
ctr += 1;
ret
}));
for _ in 0..(3 * STACK_VEC_CAPACITY) + 1 {
stack.pop();
}
ctr = 0;
assert!(stack.iter().all(|&x| {
let ret = x == ctr;
ctr += 1;
ret
}));
}
}