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use super::*;
struct DeltaReplace<'a, V, Attr> {
value: &'a V,
attr: &'a Attr,
delete: usize,
}
impl<V: DeltaValue, Attr: DeltaAttr> DeltaRope<V, Attr> {
pub fn compose(&mut self, other: &Self) {
// TODO: Need to implement a slow mode that is guaranteed to be correct, then we can fuzz on it
if self.is_empty() {
*self = other.clone();
return;
}
// trace!("Composing {:#?}\n{:#?}", &self, &other);
let mut index = 0;
let mut push_rest = false;
for item in other.iter() {
if index >= self.len() {
self.push_retain(index - self.len(), Attr::default());
push_rest = true;
}
if push_rest {
self.push(item.clone());
continue;
}
match item {
DeltaItem::Retain { len, attr } => {
if self.len() < index + len {
self.push_retain(index + len - self.len(), Default::default());
}
if !attr.attr_is_empty() {
self.update_attr_in_range(index..index + len, attr);
}
index += len;
}
DeltaItem::Replace {
value: this_value,
attr: this_attr,
delete,
} => {
self._compose_replace(
DeltaReplace {
value: this_value,
attr: this_attr,
delete: *delete,
},
&mut index,
);
}
}
}
// trace!("Composed {:#?}", &self);
}
pub fn delete(&mut self, mut index: usize, len: usize) {
self._compose_replace(
DeltaReplace {
value: &Default::default(),
attr: &Default::default(),
delete: len,
},
&mut index,
);
}
fn _compose_replace(
&mut self,
delta_replace_item @ DeltaReplace {
value: this_value,
attr: this_attr,
delete,
}: DeltaReplace<V, Attr>,
index: &mut usize,
) {
let mut should_insert = this_value.rle_len() > 0;
let mut left_del_len = delete;
if *index > self.len() {
self.push_retain(*index - self.len(), Attr::default());
}
if delete > 0 && *index != self.len() {
let range = *index..(*index + left_del_len).min(self.len());
let from = self.tree.query::<LengthFinder>(&range.start).unwrap();
let to = self.tree.query::<LengthFinder>(&range.end).unwrap();
if from.cursor.leaf == to.cursor.leaf {
self._replace_on_single_leaf(from, to, left_del_len, delta_replace_item);
should_insert = false;
left_del_len = 0;
} else {
self._replace_batch_leaves(from, to, &mut left_del_len);
}
}
if left_del_len > 0 || should_insert {
let replace = DeltaItem::Replace {
value: if should_insert {
this_value.clone()
} else {
Default::default()
},
attr: if should_insert {
this_attr.clone()
} else {
Default::default()
},
delete: left_del_len,
};
self.insert_values(*index, [replace]);
}
*index += this_value.rle_len();
}
fn _replace_batch_leaves(
&mut self,
from: generic_btree::QueryResult,
to: generic_btree::QueryResult,
left_del_len: &mut usize,
) {
self.tree.update(from.cursor..to.cursor, &mut |item| {
// This method will split the leaf node before calling this closure.
// So it's guaranteed that the item is contained in the range.
if *left_del_len == 0 {
return None;
}
match item {
DeltaItem::Retain { len, .. } => {
assert!(*len <= *left_del_len);
*left_del_len -= *len;
let diff = -(*len as isize);
*item = DeltaItem::Replace {
delete: *len,
value: Default::default(),
attr: Default::default(),
};
Some(Len {
data_len: diff,
delta_len: 0,
})
}
DeltaItem::Replace { value, attr, .. } => {
if *left_del_len >= value.rle_len() {
let diff = value.rle_len() as isize;
*left_del_len -= value.rle_len();
*value = Default::default();
*attr = Default::default();
Some(Len {
data_len: -diff,
delta_len: -diff,
})
} else {
unreachable!()
}
}
}
});
}
fn _replace_on_single_leaf(
&mut self,
from: generic_btree::QueryResult,
to: generic_btree::QueryResult,
left_del_len: usize,
DeltaReplace {
value: this_value,
attr: this_attr,
delete: _,
}: DeltaReplace<V, Attr>,
) {
self.tree.update_leaf(from.cursor.leaf, |item| match item {
DeltaItem::Retain {
len: retain_len, ..
} => {
let start = from.cursor.offset;
let end = to.cursor.offset;
debug_assert!(end <= *retain_len);
let (l, r) = item.update_with_split(start..end, |item| {
*item = DeltaItem::Replace {
delete: left_del_len,
value: this_value.clone(),
attr: this_attr.clone(),
};
});
(true, l, r)
}
DeltaItem::Replace { value, delete, .. } => {
let start = from.cursor.offset;
let end = to.cursor.offset;
let value_len = value.rle_len();
let value_start = start.min(value_len);
let value_end = value_len.min(end);
{
// We need to remove the part of value that is between start and end.
// If the range is out of the bounds of the value, we record extra deletions
// on the `delete` field of this item.
let left = left_del_len.saturating_sub(value_end - value_start);
*delete += left;
}
let (l, r) = item.update_with_split(value_start..value_end, |item| {
*item = DeltaItem::Replace {
value: this_value.clone(),
attr: this_attr.clone(),
delete: 0,
};
});
(true, l, r)
}
});
}
}