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use super::{BacktrackingState, BacktrackingIterator};
use std::sync::{Arc, RwLock, Mutex};
static EXPECT_RW: &'static str = "The read-write lock on the history has been poisoned by a thread panic!";
static EXPECT_MUTEX: &'static str = "The mutual exclusion lock on the iterator has been poisoned by a thread panic!";
impl<'item, Iter> From<Iter> for ConcurrentReferencingBacktrackingIterator<'item, Iter> where Iter: Iterator, Iter: 'item {
fn from(iterator: Iter) -> Self {
ConcurrentReferencingBacktrackingIterator {
item_marker: std::marker::PhantomData,
iterator: Arc::new(Mutex::new(iterator)),
backtracking_vec: Arc::new(RwLock::new(vec![])),
position: 0,
}
}
}
pub struct ConcurrentReferencingBacktrackingIterator<'item, Iter> where Iter: Iterator, Iter: 'item {
item_marker: std::marker::PhantomData<&'item Iter::Item>,
iterator: Arc<Mutex<Iter>>,
backtracking_vec: Arc<RwLock<Vec<Iter::Item>>>,
position: usize,
}
impl<'item, Iter> Clone for ConcurrentReferencingBacktrackingIterator<'item, Iter> where Iter: Iterator, Iter: 'item {
fn clone(&self) -> Self {
ConcurrentReferencingBacktrackingIterator {
item_marker: std::marker::PhantomData,
iterator: self.iterator.clone(),
backtracking_vec: self.backtracking_vec.clone(),
position: self.position,
}
}
}
impl<'item, Iter> Iterator for ConcurrentReferencingBacktrackingIterator<'item, Iter> where Iter: Iterator, Iter: 'item {
type Item = &'item Iter::Item;
fn next(&mut self) -> Option<&'item Iter::Item> {
macro_rules! unsafe_backtracking_index {
($index:expr) => {
unsafe {
&*(&self.backtracking_vec.read().expect(EXPECT_RW)[$index] as *const Iter::Item)
}
};
}
use crate::{Backtracking, Progressing};
if self.position >= self.backtracking_vec.read().expect(EXPECT_RW).len() {
if let Some(val) = self.iterator.lock().expect(EXPECT_MUTEX).next() {
self.backtracking_vec.write().expect(EXPECT_RW).push(val);
self.position = self.position + 1;
Some(unsafe_backtracking_index!(self.backtracking_vec.read().expect(EXPECT_RW).len() - 1))
} else {
None
}
} else {
let old_position = self.position;
self.position = self.position + 1;
Some(unsafe_backtracking_index!(old_position))
}
}
}
impl<'item, Iter> BacktrackingIterator for ConcurrentReferencingBacktrackingIterator<'item, Iter> where Iter: Iterator, Iter: 'item {
type RefPoint = usize;
fn get_ref_point(&self) -> usize {
self.position
}
fn get_oldest_point(&self) -> usize {
0_usize
}
fn backtrack(&mut self, position: usize) {
self.position = position;
}
}
impl<Iter> From<Iter> for ConcurrentCopyingBacktrackingIterator<Iter> where Iter: Iterator, Iter::Item: Clone {
fn from(iterator: Iter) -> Self {
ConcurrentCopyingBacktrackingIterator {
iterator: Arc::new(Mutex::new(iterator)),
backtracking_vec: Arc::new(RwLock::new(vec![])),
position: 0,
}
}
}
pub struct ConcurrentCopyingBacktrackingIterator<Iter> where Iter: Iterator, Iter::Item: Clone {
iterator: Arc<Mutex<Iter>>,
backtracking_vec: Arc<RwLock<Vec<Iter::Item>>>,
position: usize,
}
impl<Iter> Clone for ConcurrentCopyingBacktrackingIterator<Iter> where Iter: Iterator, Iter::Item: Clone {
fn clone(&self) -> Self {
ConcurrentCopyingBacktrackingIterator {
iterator: self.iterator.clone(),
backtracking_vec: self.backtracking_vec.clone(),
position: self.position,
}
}
}
impl<Iter> Iterator for ConcurrentCopyingBacktrackingIterator<Iter> where Iter: Iterator, Iter::Item: Clone {
type Item = Iter::Item;
fn next(&mut self) -> Option<Iter::Item> {
use crate::{Backtracking, Progressing};
if self.position >= self.backtracking_vec.read().expect(EXPECT_RW).len() {
if let Some(val) = self.iterator.lock().expect(EXPECT_MUTEX).next() {
self.backtracking_vec.write().expect(EXPECT_RW).push(val.clone());
self.position = self.position + 1;
Some(val)
} else {
None
}
} else {
let old_position = self.position;
self.position = self.position + 1;
Some(self.backtracking_vec.read().expect(EXPECT_RW)[old_position].clone())
}
}
}
impl<Iter> BacktrackingIterator for ConcurrentCopyingBacktrackingIterator<Iter> where Iter: Iterator, Iter::Item: Clone {
type RefPoint = usize;
fn get_ref_point(&self) -> usize {
self.position
}
fn get_oldest_point(&self) -> usize {
0_usize
}
fn backtrack(&mut self, position: usize) {
self.position = position;
}
}
#[cfg(test)]
mod tests {
#[test]
fn many_iter_test() {
use matches::{matches};
let bt_con_iter = crate::concurrent::ConcurrentReferencingBacktrackingIterator::from(1..1000);
for _ in 1..3 {
let mut bt_iter = bt_con_iter.clone();
for expected in 1..1000 {
assert!(matches!(bt_iter.next(), Some(&i) if i == expected))
}
}
}
#[test]
fn many_iter_clone_test() {
use matches::{matches};
let bt_con_iter = crate::concurrent::ConcurrentCopyingBacktrackingIterator::from(1..1000);
for _ in 1..3 {
let mut bt_iter = bt_con_iter.clone();
for expected in 1..1000 {
assert!(matches!(bt_iter.next(), Some(i) if i == expected))
}
}
}
#[test]
fn dont_need_clone_test() {
use matches::{matches};
struct Uncloneable {};
let uncloneables = vec![Uncloneable {}];
let mut bt_con_iter = crate::concurrent::ConcurrentReferencingBacktrackingIterator::from(uncloneables.into_iter());
assert!(matches!(bt_con_iter.next(), Some(&Uncloneable {})))
}
}