Cache offset and length in document nodes (#408)

packages/parchment/lib/src/document/attributes.dart

@@ -1,7 +1,6 @@
 import 'dart:math' as math;
 
 import 'package:collection/collection.dart';
-import 'package:quiver/core.dart';
 
 /// Scope of a style attribute, defines context in which an attribute can be
 /// applied.
@@ -254,7 +253,7 @@ class ParchmentAttribute<T> implements ParchmentAttributeBuilder<T> {
   }
 
   @override
-  int get hashCode => hash3(key, scope, value);
+  int get hashCode => Object.hash(key, scope, value);
 
   @override
   String toString() => '$key: $value';
@@ -397,8 +396,9 @@ class ParchmentStyle {
 
   @override
   int get hashCode {
-    final hashes = _data.entries.map((entry) => hash2(entry.key, entry.value));
-    return hashObjects(hashes);
+    final hashes =
+        _data.entries.map((entry) => Object.hash(entry.key, entry.value));
+    return Object.hashAll(hashes);
   }
 
   @override

packages/parchment/lib/src/document/embeds.dart

@@ -1,5 +1,4 @@
 import 'package:collection/collection.dart';
-import 'package:quiver/core.dart';
 
 const _dataEquality = DeepCollectionEquality();
 
@@ -60,12 +59,11 @@ class EmbeddableObject {
 
   @override
   int get hashCode {
-    if (_data.isEmpty) return hash2(type, inline);
+    if (_data.isEmpty) return Object.hash(type, inline);
 
-    final dataHash = hashObjects(
-      _data.entries.map((e) => hash2(e.key, e.value)),
-    );
-    return hash3(type, inline, dataHash);
+    final dataHash =
+        Object.hashAll(_data.entries.map((e) => Object.hash(e.key, e.value)));
+    return Object.hash(type, inline, dataHash);
   }
 
   Map<String, dynamic> toJson() {

packages/parchment/lib/src/document/leaf.dart

@@ -29,6 +29,12 @@ abstract base class LeafNode extends Node with StyledNode {
   Object get value => _value;
   Object _value;
 
+  void _setValue(Object newValue) {
+    _value = newValue;
+    parent.invalidateLength();
+    next?.invalidateOffset();
+  }
+
   /// Splits this leaf node at [index] and returns new node.
   ///
   /// If this is the last node in its list and [index] equals this node's
@@ -48,7 +54,7 @@ abstract base class LeafNode extends Node with StyledNode {
 
     if (this is TextNode) {
       final text = _value as String;
-      _value = text.substring(0, index);
+      _setValue(text.substring(0, index));
       final split = LeafNode(text.substring(index));
       split.applyStyle(style);
       insertAfter(split);
@@ -205,7 +211,7 @@ abstract base class LeafNode extends Node with StyledNode {
       var mergeWith = node.previous as TextNode;
       if (mergeWith.style == node.style) {
         final combinedValue = mergeWith.value + node.value;
-        mergeWith._value = combinedValue;
+        mergeWith._setValue(combinedValue);
         node.unlink();
         node = mergeWith;
       }
@@ -214,7 +220,7 @@ abstract base class LeafNode extends Node with StyledNode {
       var mergeWith = node.next as TextNode;
       if (mergeWith.style == node.style) {
         final combinedValue = node.value + mergeWith.value;
-        node._value = combinedValue;
+        node._setValue(combinedValue);
         mergeWith.unlink();
       }
     }

packages/parchment/lib/src/document/line.dart

@@ -155,7 +155,6 @@ final class LineNode extends ContainerNode<LeafNode> with StyledNode {
   @override
   LeafNode get defaultChild => TextNode();
 
-  // TODO: should be able to cache length and invalidate on any child-related operation
   @override
   int get length => super.length + 1;
 

packages/parchment/lib/src/document/node.dart

@@ -1,5 +1,6 @@
 import 'dart:collection';
 
+import 'package:meta/meta.dart';
 import 'package:parchment_delta/parchment_delta.dart';
 
 import 'attributes.dart';
@@ -33,24 +34,32 @@ abstract base class Node extends LinkedListEntry<Node> {
   /// `null`.
   bool get mounted => _parent != null;
 
+  int? _offsetCache;
+
   /// Offset in characters of this node relative to [parent] node.
   ///
   /// To get offset of this node in the document see [documentOffset].
   int get offset {
-    if (isFirst) return 0;
+    if (_offsetCache != null) return _offsetCache!;
+
+    if (isFirst) return _offsetCache = 0;
     var offset = 0;
     var node = this;
     do {
       node = node.previous!;
       offset += node.length;
     } while (!node.isFirst);
-    return offset;
+    return _offsetCache = offset;
   }
 
+  int? _documentOffsetCache;
+
   /// Offset in characters of this node in the document.
   int get documentOffset {
+    if (_documentOffsetCache != null) return _documentOffsetCache!;
+
     final parentOffset = (_parent is! RootNode) ? _parent!.documentOffset : 0;
-    return parentOffset + offset;
+    return _documentOffsetCache = parentOffset + offset;
   }
 
   /// Returns `true` if this node contains character at specified [offset] in
@@ -86,20 +95,40 @@ abstract base class Node extends LinkedListEntry<Node> {
     assert(entry._parent == null && _parent != null);
     entry._parent = _parent;
     super.insertBefore(entry);
+    _parent?.invalidateLength();
+    invalidateOffset();
   }
 
   @override
   void insertAfter(Node entry) {
     assert(entry._parent == null && _parent != null);
     entry._parent = _parent;
     super.insertAfter(entry);
+    parent?.invalidateLength();
+    entry.invalidateOffset();
   }
 
   @override
   void unlink() {
     assert(_parent != null);
+    final oldParent = _parent;
+    final oldNext = next;
     _parent = null;
     super.unlink();
+    oldNext?.invalidateOffset();
+    oldParent?.invalidateLength();
+  }
+
+  @mustCallSuper
+  void invalidateOffset() {
+    _offsetCache = null;
+    invalidateDocumentOffset();
+    next?.invalidateOffset();
+  }
+
+  @mustCallSuper
+  void invalidateDocumentOffset() {
+    _documentOffsetCache = null;
   }
 }
 
@@ -163,20 +192,29 @@ abstract base class ContainerNode<T extends Node> extends Node {
     assert(node._parent == null);
     node._parent = this;
     _children.add(node);
+    node.invalidateOffset();
+    invalidateLength();
   }
 
   /// Adds [node] to the beginning of this container children list.
   void addFirst(T node) {
     assert(node._parent == null);
     node._parent = this;
     _children.addFirst(node);
+    node.invalidateOffset();
+    invalidateLength();
   }
 
   /// Removes [node] from this container.
   void remove(T node) {
     assert(node._parent == this);
     node._parent = null;
-    _children.remove(node);
+    final oldNext = node.next;
+    final removed = _children.remove(node);
+    if (removed) {
+      invalidateLength();
+      oldNext?.invalidateOffset();
+    }
   }
 
   /// Moves children of this node to [newParent].
@@ -222,10 +260,13 @@ abstract base class ContainerNode<T extends Node> extends Node {
   @override
   String toPlainText() => children.map((child) => child.toPlainText()).join();
 
+  int? _length;
+
   /// Content length of this node's children. To get number of children in this
   /// node use [childCount].
   @override
-  int get length => _children.fold(0, (current, node) => current + node.length);
+  int get length => _length ??=
+      _children.fold<int>(0, (current, node) => current + node.length);
 
   @override
   void insert(int index, Object data, ParchmentStyle? style) {
@@ -258,6 +299,20 @@ abstract base class ContainerNode<T extends Node> extends Node {
 
   @override
   String toString() => _children.join('\n');
+
+  @override
+  void invalidateDocumentOffset() {
+    super.invalidateDocumentOffset();
+    for (var child in children) {
+      child.invalidateDocumentOffset();
+    }
+  }
+
+  void invalidateLength() {
+    _length = null;
+    next?.invalidateOffset();
+    parent?.invalidateLength();
+  }
 }
 
 /// Mixin used by nodes that wish to implement [StyledNode] interface.

packages/parchment/pubspec.yaml

@@ -11,9 +11,9 @@ environment:
 dependencies:
   collection: ^1.18.0
   parchment_delta: ^1.0.0
-  quiver: ^3.2.1
   html: ^0.15.4
+  meta: ^1.12.0
 
 dev_dependencies:
-  test: ^1.25.5
+  test: ^1.25.8
   lints: ^4.0.0

packages/parchment/test/document/leaf_test.dart

@@ -96,8 +96,10 @@ void main() {
     test('insert in formatted node', () {
       line.retain(0, 6, boldStyle);
       expect(line.childCount, 2);
+      expect(line.children.last.offset, 6);
       line.insert(3, 'don', null);
       expect(line.childCount, 4);
+      expect(line.children.last.offset, 9);
       final b = boldStyle.toJson();
       expect(
         line.children.elementAt(0).toDelta(),

packages/parchment/test/document/line_test.dart

@@ -59,7 +59,10 @@ void main() {
       root.retain(0, 4, boldStyle);
       root.retain(16, 6, boldStyle);
       final line = root.first as LineNode;
+      final lastTextSegment = line.children.last;
+      expect(lastTextSegment.offset, 16);
       final newLine = line.splitAt(10);
+      expect(lastTextSegment.offset, 6);
       expect(line.toPlainText(), 'This house\n');
       expect(newLine.toPlainText(), ' is a circus\n');
     });
@@ -124,10 +127,17 @@ void main() {
     });
 
     test('format line', () {
-      root.insert(0, 'Hello world', null);
+      root.insert(0, 'Hello world\n', null);
+      root.insert(12, 'Second headline\n', null);
       root.retain(11, 1, h1Style);
       root.retain(11, 1, rightStyle);
 
+      final secondHeadline = root.first.next!;
+      expect(secondHeadline.offset, 12);
+
+      root.retain(27, 1, ParchmentStyle().merge(ParchmentAttribute.cl));
+      expect(secondHeadline.offset, 0);
+
       final line = root.first as LineNode;
       expect(line, hasLength(12));
 

packages/parchment/test/document/node_test.dart

@@ -23,11 +23,20 @@ void main() {
     });
 
     test('documentOffset', () {
-      root.insert(0, 'First line\nSecond line', null);
-      final line = root.children.last as LineNode;
-      final text = line.first as TextNode;
-      expect(line.documentOffset, 11);
-      expect(text.documentOffset, 11);
+      root.insert(0, 'First line\nSecond line\nThird line', null);
+      final secondLine = root.children.first.next as LineNode;
+      final thirdLine = root.children.last as LineNode;
+      expect(thirdLine.documentOffset, 23);
+      secondLine.insert(6, ' styled', ParchmentStyle.fromJson({'b': true}));
+      final styledText = secondLine.first.next as TextNode;
+      final lastText = secondLine.last as TextNode;
+      expect(secondLine.documentOffset, 11);
+      expect(thirdLine.documentOffset, 30);
+      expect(styledText.documentOffset, 17);
+      expect(lastText.documentOffset, 24);
+      secondLine.remove(styledText);
+      expect(lastText.documentOffset, 17);
+      expect(thirdLine.documentOffset, 23);
     });
 
     test('containsOffset', () {