Use immutable when possible

lib/src/models/documents/attribute.dart

@@ -1,6 +1,7 @@
 import 'dart:collection';
 
 import 'package:equatable/equatable.dart';
+import 'package:meta/meta.dart' show immutable;
 import 'package:quiver/core.dart';
 
 enum AttributeScope {
@@ -10,6 +11,7 @@ enum AttributeScope {
   ignore, // attributes that can be ignored
 }
 
+@immutable
 class Attribute<T> extends Equatable {
   const Attribute(
     this.key,

lib/src/models/documents/history.dart

@@ -1,3 +1,5 @@
+import 'package:meta/meta.dart' show immutable;
+
 import '../quill_delta.dart';
 import '../structs/doc_change.dart';
 import '../structs/history_changed.dart';
@@ -12,7 +14,7 @@ class History {
     this.lastRecorded = 0,
   });
 
-  final HistoryStack stack = HistoryStack.empty();
+  final HistoryStack stack = const HistoryStack.empty();
 
   bool get hasUndo => stack.undo.isNotEmpty;
 
@@ -119,10 +121,11 @@ class History {
   }
 }
 
+@immutable
 class HistoryStack {
-  HistoryStack.empty()
-      : undo = [],
-        redo = [];
+  const HistoryStack.empty()
+      : undo = const [],
+        redo = const [];
 
   final List<Delta> undo;
   final List<Delta> redo;

lib/src/models/rules/delete.dart

@@ -1,9 +1,12 @@
+import 'package:meta/meta.dart' show immutable;
+
 import '../documents/attribute.dart';
 import '../documents/nodes/embeddable.dart';
 import '../quill_delta.dart';
 import 'rule.dart';
 
 /// A heuristic rule for delete operations.
+@immutable
 abstract class DeleteRule extends Rule {
   const DeleteRule();
 
@@ -18,6 +21,7 @@ abstract class DeleteRule extends Rule {
   }
 }
 
+@immutable
 class EnsureLastLineBreakDeleteRule extends DeleteRule {
   const EnsureLastLineBreakDeleteRule();
 
@@ -34,6 +38,7 @@ class EnsureLastLineBreakDeleteRule extends DeleteRule {
 
 /// Fallback rule for delete operations which simply deletes specified text
 /// range without any special handling.
+@immutable
 class CatchAllDeleteRule extends DeleteRule {
   const CatchAllDeleteRule();
 
@@ -54,6 +59,7 @@ class CatchAllDeleteRule extends DeleteRule {
 /// This rule makes sure to apply all style attributes of deleted newline
 /// to the next available newline, which may reset any style attributes
 /// already present there.
+@immutable
 class PreserveLineStyleOnMergeRule extends DeleteRule {
   const PreserveLineStyleOnMergeRule();
 
@@ -112,6 +118,7 @@ class PreserveLineStyleOnMergeRule extends DeleteRule {
 /// Prevents user from merging a line containing an embed with other lines.
 /// This rule applies to video, not image.
 /// The rule relates to [InsertEmbedsRule].
+@immutable
 class EnsureEmbedLineRule extends DeleteRule {
   const EnsureEmbedLineRule();
 

lib/src/models/rules/format.dart

@@ -1,8 +1,11 @@
+import 'package:meta/meta.dart' show immutable;
+
 import '../documents/attribute.dart';
 import '../quill_delta.dart';
 import 'rule.dart';
 
 /// A heuristic rule for format (retain) operations.
+@immutable
 abstract class FormatRule extends Rule {
   const FormatRule();
 
@@ -19,6 +22,7 @@ abstract class FormatRule extends Rule {
 
 /// Produces Delta with line-level attributes applied strictly to
 /// newline characters.
+@immutable
 class ResolveLineFormatRule extends FormatRule {
   const ResolveLineFormatRule();
 
@@ -109,6 +113,7 @@ class ResolveLineFormatRule extends FormatRule {
 }
 
 /// Allows updating link format with collapsed selection.
+@immutable
 class FormatLinkAtCaretPositionRule extends FormatRule {
   const FormatLinkAtCaretPositionRule();
 
@@ -148,6 +153,7 @@ class FormatLinkAtCaretPositionRule extends FormatRule {
 
 /// Produces Delta with inline-level attributes applied to all characters
 /// except newlines.
+@immutable
 class ResolveInlineFormatRule extends FormatRule {
   const ResolveInlineFormatRule();
 
@@ -193,6 +199,7 @@ class ResolveInlineFormatRule extends FormatRule {
 }
 
 /// Produces Delta with attributes applied to image leaf node
+@immutable
 class ResolveImageFormatRule extends FormatRule {
   const ResolveImageFormatRule();
 

lib/src/models/rules/insert.dart

@@ -1,3 +1,5 @@
+import 'package:meta/meta.dart' show immutable;
+
 import '../../models/documents/document.dart';
 import '../documents/attribute.dart';
 import '../documents/nodes/embeddable.dart';
@@ -6,6 +8,7 @@ import '../quill_delta.dart';
 import 'rule.dart';
 
 /// A heuristic rule for insert operations.
+@immutable
 abstract class InsertRule extends Rule {
   const InsertRule();
 
@@ -23,6 +26,7 @@ abstract class InsertRule extends Rule {
 ///
 /// This rule ignores scenarios when the line is split on its edge, meaning
 /// a newline is inserted at the beginning or the end of a line.
+@immutable
 class PreserveLineStyleOnSplitRule extends InsertRule {
   const PreserveLineStyleOnSplitRule();
 
@@ -73,6 +77,7 @@ class PreserveLineStyleOnSplitRule extends InsertRule {
 ///   * pasting text containing multiple lines of text in a block
 ///
 /// This rule may also be activated for changes triggered by auto-correct.
+@immutable
 class PreserveBlockStyleOnInsertRule extends InsertRule {
   const PreserveBlockStyleOnInsertRule();
 
@@ -149,6 +154,7 @@ class PreserveBlockStyleOnInsertRule extends InsertRule {
 /// This rule is only applied when the cursor is on the last line of a block.
 /// When the cursor is in the middle of a block we allow adding empty lines
 /// and preserving the block's style.
+@immutable
 class AutoExitBlockRule extends InsertRule {
   const AutoExitBlockRule();
 
@@ -228,6 +234,7 @@ class AutoExitBlockRule extends InsertRule {
 ///
 /// This handles scenarios when a new line is added when at the end of a
 /// heading line. The newly added line should be a regular paragraph.
+@immutable
 class ResetLineFormatOnNewLineRule extends InsertRule {
   const ResetLineFormatOnNewLineRule();
 
@@ -264,6 +271,7 @@ class ResetLineFormatOnNewLineRule extends InsertRule {
 
 /// Handles all format operations which manipulate embeds.
 /// This rule wraps line breaks around video, not image.
+@immutable
 class InsertEmbedsRule extends InsertRule {
   const InsertEmbedsRule();
 
@@ -327,6 +335,7 @@ class InsertEmbedsRule extends InsertRule {
 /// the URL pattern.
 ///
 /// The link attribute is applied as the user types.
+@immutable
 class AutoFormatMultipleLinksRule extends InsertRule {
   const AutoFormatMultipleLinksRule();
 
@@ -355,9 +364,6 @@ class AutoFormatMultipleLinksRule extends InsertRule {
   // https://example.net/
   // URL generator tool (https://www.randomlists.com/urls) is used.
 
-  // TODO: You might want to rename those but everywhere even in
-  // flutter_quill_extensions
-
   static const _oneLineLinkPattern =
       r'^https?:\/\/[\w\-]+(\.[\w\-]+)*(:\d+)?(\/.*)?$';
   static const _detectLinkPattern =
@@ -489,6 +495,7 @@ class AutoFormatMultipleLinksRule extends InsertRule {
 
 /// Applies link format to text segment (which looks like a link) when user
 /// inserts space character after it.
+@immutable
 class AutoFormatLinksRule extends InsertRule {
   const AutoFormatLinksRule();
 
@@ -534,6 +541,7 @@ class AutoFormatLinksRule extends InsertRule {
 }
 
 /// Preserves inline styles when user inserts text inside formatted segment.
+@immutable
 class PreserveInlineStylesRule extends InsertRule {
   const PreserveInlineStylesRule();
 
@@ -585,6 +593,7 @@ class PreserveInlineStylesRule extends InsertRule {
 }
 
 /// Fallback rule which simply inserts text as-is without any special handling.
+@immutable
 class CatchAllInsertRule extends InsertRule {
   const CatchAllInsertRule();
 
@@ -615,6 +624,7 @@ _NextNewLine _getNextNewLine(DeltaIterator iterator) {
   return const _NextNewLine(null, null);
 }
 
+@immutable
 class _NextNewLine {
   const _NextNewLine(this.operation, this.skipped);
 

lib/src/models/rules/rule.dart

@@ -1,3 +1,5 @@
+import 'package:meta/meta.dart' show immutable;
+
 import '../documents/attribute.dart';
 import '../documents/document.dart';
 import '../quill_delta.dart';
@@ -7,6 +9,7 @@ import 'insert.dart';
 
 enum RuleType { insert, delete, format }
 
+@immutable
 abstract class Rule {
   const Rule();
 
@@ -48,24 +51,24 @@ class Rules {
   List<Rule> _customRules = [];
 
   final List<Rule> _rules;
-  static final Rules _instance = Rules([
-    const FormatLinkAtCaretPositionRule(),
-    const ResolveLineFormatRule(),
-    const ResolveInlineFormatRule(),
-    const ResolveImageFormatRule(),
-    const InsertEmbedsRule(),
-    const AutoExitBlockRule(),
-    const PreserveBlockStyleOnInsertRule(),
-    const PreserveLineStyleOnSplitRule(),
-    const ResetLineFormatOnNewLineRule(),
-    const AutoFormatLinksRule(),
-    const AutoFormatMultipleLinksRule(),
-    const PreserveInlineStylesRule(),
-    const CatchAllInsertRule(),
-    const EnsureEmbedLineRule(),
-    const PreserveLineStyleOnMergeRule(),
-    const CatchAllDeleteRule(),
-    const EnsureLastLineBreakDeleteRule()
+  static final Rules _instance = Rules(const [
+    FormatLinkAtCaretPositionRule(),
+    ResolveLineFormatRule(),
+    ResolveInlineFormatRule(),
+    ResolveImageFormatRule(),
+    InsertEmbedsRule(),
+    AutoExitBlockRule(),
+    PreserveBlockStyleOnInsertRule(),
+    PreserveLineStyleOnSplitRule(),
+    ResetLineFormatOnNewLineRule(),
+    AutoFormatLinksRule(),
+    AutoFormatMultipleLinksRule(),
+    PreserveInlineStylesRule(),
+    CatchAllInsertRule(),
+    EnsureEmbedLineRule(),
+    PreserveLineStyleOnMergeRule(),
+    CatchAllDeleteRule(),
+    EnsureLastLineBreakDeleteRule()
   ]);
 
   static Rules getInstance() => _instance;

lib/src/models/structs/history_changed.dart

@@ -1,3 +1,6 @@
+import 'package:meta/meta.dart' show immutable;
+
+@immutable
 class HistoryChanged {
   const HistoryChanged(
     this.changed,

lib/src/models/structs/image_url.dart

@@ -1,3 +1,6 @@
+import 'package:meta/meta.dart' show immutable;
+
+@immutable
 class ImageUrl {
   const ImageUrl(
     this.url,

lib/src/models/structs/link_dialog_action.dart

@@ -1,7 +1,9 @@
-import 'package:flutter/material.dart';
+import 'package:flutter/widgets.dart' show Widget;
+import 'package:meta/meta.dart' show immutable;
 
+@immutable
 class LinkDialogAction {
-  LinkDialogAction({required this.builder});
+  const LinkDialogAction({required this.builder});
 
-  Widget Function(bool canPress, void Function() applyLink) builder;
+  final Widget Function(bool canPress, void Function() applyLink) builder;
 }

lib/src/models/structs/offset_value.dart

@@ -1,5 +1,8 @@
+import 'package:meta/meta.dart' show immutable;
+
+@immutable
 class OffsetValue<T> {
-  OffsetValue(this.offset, this.value, [this.length]);
+  const OffsetValue(this.offset, this.value, [this.length]);
   final int offset;
   final int? length;
   final T value;

lib/src/models/structs/optional_size.dart

@@ -1,4 +1,3 @@
-// ignore_for_file: public_member_api_docs, sort_constructors_first
 import 'package:meta/meta.dart' show immutable;
 
 @immutable

lib/src/models/structs/segment_leaf_node.dart

@@ -1,6 +1,9 @@
+import 'package:meta/meta.dart' show immutable;
+
 import '../documents/nodes/leaf.dart';
 import '../documents/nodes/line.dart';
 
+@immutable
 class SegmentLeafNode {
   const SegmentLeafNode(this.line, this.leaf);
 

lib/src/models/structs/vertical_spacing.dart

@@ -1,3 +1,6 @@
+import 'package:meta/meta.dart' show immutable;
+
+@immutable
 class VerticalSpacing {
   const VerticalSpacing(
     this.top,

lib/src/models/themes/quill_dialog_theme.dart

@@ -1,7 +1,18 @@
-import 'package:flutter/foundation.dart';
-import 'package:flutter/material.dart';
+import 'package:flutter/foundation.dart' show Diagnosticable;
+import 'package:flutter/material.dart'
+    show
+        BoxConstraints,
+        ButtonStyle,
+        Color,
+        EdgeInsets,
+        EdgeInsetsGeometry,
+        ShapeBorder,
+        TextStyle;
+import 'package:meta/meta.dart' show immutable;
 
 /// Used to configure the dialog's look and feel.
+
+@immutable
 class QuillDialogTheme with Diagnosticable {
   const QuillDialogTheme({
     this.buttonTextStyle,

lib/src/models/themes/quill_icon_theme.dart

@@ -1,5 +1,8 @@
-import 'package:flutter/material.dart';
+import 'package:flutter/widgets.dart' show Color;
 
+import 'package:meta/meta.dart' show immutable;
+
+@immutable
 class QuillIconTheme {
   const QuillIconTheme(
       {this.iconSelectedColor,