From b4312c9492445a6a3e3baabebbc4451f89b8bd0e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bla=C5=BE=20Hrastnik?= <blaz@mxxn.io>
Date: Tue, 16 Feb 2021 11:03:36 +0900
Subject: [PATCH] transaction: Use builder methods to generate compact
changesets.
---
helix-core/src/syntax.rs | 58 ++++++++---------
helix-core/src/transaction.rs | 117 ++++++++++++++++++++++------------
2 files changed, 106 insertions(+), 69 deletions(-)
diff --git a/helix-core/src/syntax.rs b/helix-core/src/syntax.rs
index 70d42c47..861cda0c 100644
--- a/helix-core/src/syntax.rs
+++ b/helix-core/src/syntax.rs
@@ -451,7 +451,7 @@ impl LanguageLayer {
Delete(i) | Retain(i) => *i,
Insert(_) => 0,
};
- let old_end = old_pos + len;
+ let mut old_end = old_pos + len;
match change {
Retain(_) => {
@@ -467,10 +467,27 @@ impl LanguageLayer {
// let line_start_byte = line_to_byte()
// Position::new(line, line_start_byte - byte)
- // a subsequent ins means a replace, consume it
- if let Some(Insert(s)) = iter.peek() {
+ // deletion
+ edits.push(tree_sitter::InputEdit {
+ start_byte, // old_pos to byte
+ old_end_byte, // old_end to byte
+ new_end_byte: start_byte, // old_pos to byte
+ start_position, // old pos to coords
+ old_end_position, // old_end to coords
+ new_end_position: start_position, // old pos to coords
+ });
+ }
+ Insert(s) => {
+ let (start_byte, start_position) = point_at_pos(&old_text, old_pos);
+
+ let ins = s.chars().count();
+
+ // a subsequent delete means a replace, consume it
+ if let Some(Delete(len)) = iter.peek() {
+ old_end = old_pos + len;
+ let (old_end_byte, old_end_position) = point_at_pos(&old_text, old_end);
+
iter.next();
- let ins = s.chars().count();
// replacement
edits.push(tree_sitter::InputEdit {
@@ -481,34 +498,17 @@ impl LanguageLayer {
old_end_position, // old_end to coords
new_end_position: traverse(start_position, s), // old pos + chars, newlines matter too (iter over)
});
-
- new_pos += ins;
} else {
- // deletion
+ // insert
edits.push(tree_sitter::InputEdit {
- start_byte, // old_pos to byte
- old_end_byte, // old_end to byte
- new_end_byte: start_byte, // old_pos to byte
- start_position, // old pos to coords
- old_end_position, // old_end to coords
- new_end_position: start_position, // old pos to coords
+ start_byte, // old_pos to byte
+ old_end_byte: start_byte, // same
+ new_end_byte: start_byte + s.len(), // old_pos + s.len()
+ start_position, // old pos to coords
+ old_end_position: start_position, // same
+ new_end_position: traverse(start_position, s), // old pos + chars, newlines matter too (iter over)
});
- };
- }
- Insert(s) => {
- let (start_byte, start_position) = point_at_pos(&old_text, old_pos);
-
- let ins = s.chars().count();
-
- // insert
- edits.push(tree_sitter::InputEdit {
- start_byte, // old_pos to byte
- old_end_byte: start_byte, // same
- new_end_byte: start_byte + s.len(), // old_pos + s.len()
- start_position, // old pos to coords
- old_end_position: start_position, // same
- new_end_position: traverse(start_position, s), // old pos + chars, newlines matter too (iter over)
- });
+ }
new_pos += ins;
}
diff --git a/helix-core/src/transaction.rs b/helix-core/src/transaction.rs
index 25a1a762..359eb2ee 100644
--- a/helix-core/src/transaction.rs
+++ b/helix-core/src/transaction.rs
@@ -63,6 +63,56 @@ impl ChangeSet {
len
}
+ // Changeset builder operations: delete/insert/retain
+ fn delete(&mut self, n: usize) {
+ use Operation::*;
+ if n == 0 {
+ return;
+ }
+
+ if let Some(Delete(count)) = self.changes.last_mut() {
+ *count += n;
+ } else {
+ self.changes.push(Delete(n));
+ }
+ }
+
+ fn insert(&mut self, fragment: Tendril) {
+ use Operation::*;
+
+ if fragment.is_empty() {
+ return;
+ }
+
+ let new_last = match self.changes.as_mut_slice() {
+ [.., Insert(prev)] => {
+ prev.push_tendril(&fragment);
+ return;
+ }
+ [.., Insert(prev), Delete(_)] => {
+ prev.push_tendril(&fragment);
+ return;
+ }
+ [.., last @ Delete(_)] => std::mem::replace(last, Insert(fragment)),
+ _ => Insert(fragment),
+ };
+
+ self.changes.push(new_last);
+ }
+
+ fn retain(&mut self, n: usize) {
+ use Operation::*;
+ if n == 0 {
+ return;
+ }
+
+ if let Some(Retain(count)) = self.changes.last_mut() {
+ *count += n;
+ } else {
+ self.changes.push(Retain(n));
+ }
+ }
+
/// Combine two changesets together.
/// In other words, If `this` goes `docA` → `docB` and `other` represents `docB` → `docC`, the
/// returned value will represent the change `docA` → `docC`.
@@ -77,7 +127,10 @@ impl ChangeSet {
let mut head_a = changes_a.next();
let mut head_b = changes_b.next();
- let mut changes: Vec<Operation> = Vec::with_capacity(len); // TODO: max(a, b), shrink_to_fit() afterwards
+ let mut changes = Self {
+ len: self.len,
+ changes: Vec::with_capacity(len), // TODO: max(a, b), shrink_to_fit() afterwards
+ };
loop {
use std::cmp::Ordering;
@@ -88,37 +141,31 @@ impl ChangeSet {
break;
}
// deletion in A
- (Some(change @ Delete(..)), b) => {
- changes.push(change);
+ (Some(Delete(i)), b) => {
+ changes.delete(i);
head_a = changes_a.next();
head_b = b;
}
// insertion in B
(a, Some(Insert(current))) => {
- // merge onto previous insert if possible
- // TODO: do these as operations on a changeset
- if let Some(Insert(prev)) = changes.last_mut() {
- prev.push_tendril(¤t);
- } else {
- changes.push(Insert(current));
- }
+ changes.insert(current);
head_a = a;
head_b = changes_b.next();
}
(None, _) | (_, None) => return unreachable!(),
(Some(Retain(i)), Some(Retain(j))) => match i.cmp(&j) {
Ordering::Less => {
- changes.push(Retain(i));
+ changes.retain(i);
head_a = changes_a.next();
head_b = Some(Retain(j - i));
}
Ordering::Equal => {
- changes.push(Retain(i));
+ changes.retain(i);
head_a = changes_a.next();
head_b = changes_b.next();
}
Ordering::Greater => {
- changes.push(Retain(j));
+ changes.retain(j);
head_a = Some(Retain(i - j));
head_b = changes_b.next();
}
@@ -147,12 +194,12 @@ impl ChangeSet {
let len = s.chars().count();
match len.cmp(&j) {
Ordering::Less => {
- changes.push(Insert(s));
+ changes.insert(s);
head_a = changes_a.next();
head_b = Some(Retain(j - len));
}
Ordering::Equal => {
- changes.push(Insert(s));
+ changes.insert(s);
head_a = changes_a.next();
head_b = changes_b.next();
}
@@ -160,7 +207,7 @@ impl ChangeSet {
// figure out the byte index of the truncated string end
let (pos, _) = s.char_indices().nth(j).unwrap();
let pos = pos as u32;
- changes.push(Insert(s.subtendril(0, pos)));
+ changes.insert(s.subtendril(0, pos));
head_a = Some(Insert(s.subtendril(pos, s.len() as u32 - pos)));
head_b = changes_b.next();
}
@@ -168,17 +215,17 @@ impl ChangeSet {
}
(Some(Retain(i)), Some(Delete(j))) => match i.cmp(&j) {
Ordering::Less => {
- changes.push(Delete(i));
+ changes.delete(i);
head_a = changes_a.next();
head_b = Some(Delete(j - i));
}
Ordering::Equal => {
- changes.push(Delete(j));
+ changes.delete(j);
head_a = changes_a.next();
head_b = changes_b.next();
}
Ordering::Greater => {
- changes.push(Delete(j));
+ changes.delete(j);
head_a = Some(Retain(i - j));
head_b = changes_b.next();
}
@@ -186,10 +233,7 @@ impl ChangeSet {
};
}
- Self {
- len: self.len,
- changes,
- }
+ changes
}
/// Given another change set starting in the same document, maps this
@@ -421,37 +465,29 @@ impl Transaction {
I: IntoIterator<Item = Change> + ExactSizeIterator,
{
let len = state.doc.len_chars();
- let mut acc = Vec::with_capacity(2 * changes.len() + 1);
+ let acc = Vec::with_capacity(2 * changes.len() + 1);
+ let mut changeset = ChangeSet { changes: acc, len };
// TODO: verify ranges are ordered and not overlapping or change will panic.
let mut last = 0;
for (from, to, tendril) in changes {
// Retain from last "to" to current "from"
- if from - last > 0 {
- acc.push(Operation::Retain(from - last));
- }
+ changeset.retain(from - last);
let span = to - from;
match tendril {
Some(text) => {
- if span > 0 {
- acc.push(Operation::Delete(span));
- }
- acc.push(Operation::Insert(text));
+ changeset.delete(span);
+ changeset.insert(text);
}
- None if span > 0 => acc.push(Operation::Delete(span)),
- // empty delete is useless
- None => (),
+ None => changeset.delete(span),
}
last = to;
}
- let span = len - last;
- if span > 0 {
- acc.push(Operation::Retain(span));
- }
+ changeset.retain(len - last);
- Self::from(ChangeSet { changes: acc, len })
+ Self::from(changeset)
}
/// Generate a transaction with a change per selection range.
@@ -591,7 +627,7 @@ mod test {
}
#[test]
- fn insert_composition() {
+ fn optimized_composition() {
let mut state = State::new("".into());
let t1 = Transaction::insert(&state, Tendril::from_char('h'));
t1.apply(&mut state);
@@ -620,5 +656,6 @@ mod test {
use Operation::*;
assert_eq!(changes.changes, &[Insert("hello".into())]);
+ // instead of insert h, insert e, insert l, insert l, insert o
}
}