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use std::ops::RangeBounds;
use super::*;
use generic_btree::rle::{CanRemove, TryInsert};
impl<V: DeltaValue, Attr> DeltaItem<V, Attr> {
/// Including the delete length
pub fn delta_len(&self) -> usize {
match self {
DeltaItem::Retain { len, .. } => *len,
DeltaItem::Replace {
value,
attr: _,
delete,
} => value.rle_len() + delete,
}
}
/// The real length of the item in the delta, excluding the delete length
pub fn data_len(&self) -> usize {
match self {
DeltaItem::Retain { len, .. } => *len,
DeltaItem::Replace { value, .. } => value.rle_len(),
}
}
pub fn new_insert(value: V, attr: Attr) -> Self {
DeltaItem::Replace {
value,
attr,
delete: 0,
}
}
}
impl<V: DeltaValue, Attr: Default> DeltaItem<V, Attr> {
pub fn new_delete(len: usize) -> Self {
DeltaItem::Replace {
value: Default::default(),
attr: Default::default(),
delete: len,
}
}
}
impl<V: DeltaValue, Attr> HasLength for DeltaItem<V, Attr> {
/// This would treat the len of the Delete as 0
fn rle_len(&self) -> usize {
self.delta_len()
}
}
impl<V: Mergeable, Attr: PartialEq> Mergeable for DeltaItem<V, Attr> {
fn can_merge(&self, rhs: &Self) -> bool {
match (self, rhs) {
(DeltaItem::Retain { attr: attr1, .. }, DeltaItem::Retain { attr: attr2, .. }) => {
attr1 == attr2
}
(
DeltaItem::Replace {
value: value1,
attr: attr1,
delete: _del1,
},
DeltaItem::Replace {
value: value2,
attr: attr2,
delete: _del2,
},
) => value1.can_merge(value2) && attr1 == attr2,
_ => false,
}
}
fn merge_right(&mut self, rhs: &Self) {
match (self, rhs) {
(DeltaItem::Retain { len: len1, .. }, DeltaItem::Retain { len: len2, .. }) => {
*len1 += len2
}
(
DeltaItem::Replace {
value: value1,
delete: del1,
..
},
DeltaItem::Replace {
value: value2,
delete: del2,
..
},
) => {
value1.merge_right(value2);
*del1 += *del2;
}
_ => unreachable!(),
}
}
fn merge_left(&mut self, left: &Self) {
match (self, left) {
(DeltaItem::Retain { len: len1, .. }, DeltaItem::Retain { len: len2, .. }) => {
*len1 += len2
}
(
DeltaItem::Replace {
value: value1,
delete: del1,
..
},
DeltaItem::Replace {
value: value2,
delete: del2,
..
},
) => {
value1.merge_left(value2);
*del1 += del2;
}
_ => unreachable!(),
}
}
}
impl<V: DeltaValue, Attr: DeltaAttr> Sliceable for DeltaItem<V, Attr> {
fn _slice(&self, range: std::ops::Range<usize>) -> Self {
assert!(range.end <= self.rle_len());
match self {
DeltaItem::Retain { len, attr } => {
assert!(range.end <= *len);
DeltaItem::Retain {
len: range.len(),
attr: attr.clone(),
}
}
DeltaItem::Replace {
value,
attr,
delete,
} => {
if range.end <= value.rle_len() {
let value = value._slice(range.clone());
DeltaItem::Replace {
value,
attr: attr.clone(),
delete: 0,
}
} else if range.start >= value.rle_len() {
debug_assert!(range.end <= delete + value.rle_len());
debug_assert!(range.len() <= *delete);
DeltaItem::new_delete(range.len())
} else {
let delete_len = range.end - value.rle_len();
debug_assert!(delete_len <= *delete);
let value = value._slice(range.start..value.rle_len());
DeltaItem::Replace {
delete: delete_len,
value,
attr: attr.clone(),
}
}
}
}
}
/// slice in-place
#[inline(always)]
fn slice_(&mut self, range: impl RangeBounds<usize>) {
*self = self.slice(range);
}
fn split(&mut self, pos: usize) -> Self {
match self {
DeltaItem::Retain { len, attr } => {
let right_len = *len - pos;
*len = pos;
DeltaItem::Retain {
len: right_len,
attr: attr.clone(),
}
}
DeltaItem::Replace {
value,
attr,
delete,
} => {
if pos < value.rle_len() {
let right = value.split(pos);
let right_delete = *delete;
*delete = 0;
DeltaItem::Replace {
value: right,
attr: attr.clone(),
delete: right_delete,
}
} else {
let right_len = value.rle_len() + *delete - pos;
let right = DeltaItem::new_delete(right_len);
*delete -= right_len;
right
}
}
}
}
/// Update the slice in the given range.
/// This method may split `self` into two or three parts.
/// If so, it will make `self` the leftmost part and return the next split parts.
///
/// # Example
///
/// If `self.rle_len() == 10`, `self.update(1..5)` will split self into three parts and update the middle part.
/// It returns the middle and the right part.
fn update_with_split(
&mut self,
range: impl RangeBounds<usize>,
f: impl FnOnce(&mut Self),
) -> (Option<Self>, Option<Self>) {
let start = match range.start_bound() {
std::ops::Bound::Included(x) => *x,
std::ops::Bound::Excluded(x) => x + 1,
std::ops::Bound::Unbounded => 0,
};
let end = match range.end_bound() {
std::ops::Bound::Included(x) => x + 1,
std::ops::Bound::Excluded(x) => *x,
std::ops::Bound::Unbounded => self.rle_len(),
};
match (start == 0, end == self.rle_len()) {
(true, true) => {
f(self);
(None, None)
}
(true, false) => {
let right = self.split(end);
f(self);
if self.can_merge(&right) {
self.merge_right(&right);
(None, None)
} else {
(Some(right), None)
}
}
(false, true) => {
let mut right = self.split(start);
f(&mut right);
if self.can_merge(&right) {
self.merge_right(&right);
(None, None)
} else {
(Some(right), None)
}
}
(false, false) => {
let right = self.split(end);
let mut middle = self.split(start);
f(&mut middle);
if middle.can_remove() {
if self.can_merge(&right) {
self.merge_right(&right);
(None, None)
} else {
(Some(right), None)
}
} else if middle.can_merge(&right) {
middle.merge_right(&right);
if self.can_merge(&middle) {
self.merge_right(&middle);
(None, None)
} else {
(Some(middle), None)
}
} else if self.can_merge(&middle) {
self.merge_right(&middle);
(Some(right), None)
} else {
(Some(middle), Some(right))
}
}
}
}
}
impl<V: DeltaValue, Attr: Clone + PartialEq + Debug> TryInsert for DeltaItem<V, Attr> {
fn try_insert(&mut self, pos: usize, elem: Self) -> Result<(), Self>
where
Self: Sized,
{
match (self, elem) {
(
DeltaItem::Retain { len, attr },
DeltaItem::Retain {
len: len_b,
attr: attr_b,
},
) => {
if attr == &attr_b {
*len += len_b;
Ok(())
} else {
Err(DeltaItem::Retain {
len: len_b,
attr: attr_b,
})
}
}
(
DeltaItem::Replace {
value: l_value,
attr: l_attr,
delete: l_delete,
},
DeltaItem::Replace {
value: r_value,
attr: r_attr,
delete: r_delete,
},
) => {
if l_value.rle_len() == 0 && r_value.rle_len() == 0 {
*l_delete += r_delete;
return Ok(());
}
if l_attr == &r_attr {
match l_value.try_insert(pos, r_value) {
Ok(_) => {
*l_delete += r_delete;
return Ok(());
}
Err(r_value) => {
return Err(DeltaItem::Replace {
value: r_value,
attr: r_attr,
delete: r_delete,
})
}
}
}
Err(DeltaItem::Replace {
value: r_value,
attr: r_attr,
delete: r_delete,
})
}
(_, a) => Err(a),
}
}
}
impl<V: DeltaValue, Attr: Clone> CanRemove for DeltaItem<V, Attr> {
fn can_remove(&self) -> bool {
match self {
DeltaItem::Retain { len, .. } => *len == 0,
DeltaItem::Replace {
value,
attr: _,
delete,
} => value.rle_len() == 0 && *delete == 0,
}
}
}
impl<V: DeltaValue, Attr: DeltaAttr> Default for DeltaItem<V, Attr> {
fn default() -> Self {
DeltaItem::Retain {
len: 0,
attr: Default::default(),
}
}
}
impl<V: DeltaValue, Attr: DeltaAttr> DeltaValue for DeltaItem<V, Attr> {}