refactor: move selection to core/location

frontend/app_flowy/packages/appflowy_editor/lib/appflowy_editor.dart

@@ -5,8 +5,8 @@ export 'src/infra/log.dart';
 export 'src/render/style/editor_style.dart';
 export 'src/core/document/node.dart';
 export 'src/core/document/path.dart';
-export 'src/core/selection/position.dart';
+export 'src/core/location/position.dart';
-export 'src/document/selection.dart';
+export 'src/core/location/selection.dart';
 export 'src/document/state_tree.dart';
 export 'src/core/document/text_delta.dart';
 export 'src/core/document/attributes.dart';

frontend/app_flowy/packages/appflowy_editor/lib/src/commands/format_built_in_text.dart

@@ -4,7 +4,7 @@ import 'package:appflowy_editor/src/core/document/attributes.dart';
 import 'package:appflowy_editor/src/document/built_in_attribute_keys.dart';
 import 'package:appflowy_editor/src/core/document/node.dart';
 import 'package:appflowy_editor/src/core/document/path.dart';
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import 'package:appflowy_editor/src/editor_state.dart';
 
 Future<void> formatBuiltInTextAttributes(

frontend/app_flowy/packages/appflowy_editor/lib/src/commands/format_text.dart

@@ -4,7 +4,7 @@ import 'package:appflowy_editor/src/commands/text_command_infra.dart';
 import 'package:appflowy_editor/src/core/document/attributes.dart';
 import 'package:appflowy_editor/src/core/document/node.dart';
 import 'package:appflowy_editor/src/core/document/path.dart';
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import 'package:appflowy_editor/src/editor_state.dart';
 import 'package:appflowy_editor/src/operation/transaction_builder.dart';
 import 'package:flutter/widgets.dart';

frontend/app_flowy/packages/appflowy_editor/lib/src/commands/text_command_infra.dart

@@ -1,6 +1,6 @@
 import 'package:appflowy_editor/src/core/document/node.dart';
 import 'package:appflowy_editor/src/core/document/path.dart';
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import 'package:appflowy_editor/src/editor_state.dart';
 
 // get formatted [TextNode]

frontend/app_flowy/packages/appflowy_editor/lib/src/core/location/position.dart

@@ -0,0 +1,40 @@
+import 'package:appflowy_editor/src/core/document/path.dart';
+
+class Position {
+  final Path path;
+  final int offset;
+
+  Position({
+    required this.path,
+    this.offset = 0,
+  });
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) return true;
+
+    return other is Position &&
+        other.path.equals(path) &&
+        other.offset == offset;
+  }
+
+  @override
+  int get hashCode => Object.hash(offset, Object.hashAll(path));
+
+  @override
+  String toString() => 'path = $path, offset = $offset';
+
+  Position copyWith({Path? path, int? offset}) {
+    return Position(
+      path: path ?? this.path,
+      offset: offset ?? this.offset,
+    );
+  }
+
+  Map<String, dynamic> toJson() {
+    return {
+      'path': path,
+      'offset': offset,
+    };
+  }
+}

frontend/app_flowy/packages/appflowy_editor/lib/src/core/location/selection.dart

@@ -0,0 +1,107 @@
+import 'package:appflowy_editor/src/core/document/path.dart';
+import 'package:appflowy_editor/src/core/location/position.dart';
+
+/// Selection represents the selected area or the cursor area in the editor.
+///
+/// [Selection] is directional.
+///
+/// 1. forward，the end position is before the start position.
+/// 2. backward, the end position is after the start position.
+/// 3. collapsed, the end position is equal to the start position.
+class Selection {
+  /// Create a selection with [start], [end].
+  Selection({
+    required this.start,
+    required this.end,
+  });
+
+  /// Create a selection with [Path], [startOffset] and [endOffset].
+  ///
+  /// The [endOffset] is optional.
+  ///
+  /// This constructor will return a collapsed [Selection] if [endOffset] is null.
+  ///
+  Selection.single({
+    required Path path,
+    required int startOffset,
+    int? endOffset,
+  })  : start = Position(path: path, offset: startOffset),
+        end = Position(path: path, offset: endOffset ?? startOffset);
+
+  /// Create a collapsed selection with [position].
+  Selection.collapsed(Position position)
+      : start = position,
+        end = position;
+
+  final Position start;
+  final Position end;
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) return true;
+
+    return other is Selection && other.start == start && other.end == end;
+  }
+
+  @override
+  int get hashCode => start.hashCode ^ end.hashCode;
+
+  @override
+  String toString() => 'start = $start, end = $end';
+
+  /// Returns a Boolean indicating whether the selection's start and end points
+  /// are at the same position.
+  bool get isCollapsed => start == end;
+
+  /// Returns a Boolean indicating whether the selection's start and end points
+  /// are at the same path.
+  bool get isSingle => start.path.equals(end.path);
+
+  /// Returns a Boolean indicating whether the selection is forward.
+  bool get isForward =>
+      (start.path > end.path) || (isSingle && start.offset > end.offset);
+
+  /// Returns a Boolean indicating whether the selection is backward.
+  bool get isBackward =>
+      (start.path < end.path) || (isSingle && start.offset < end.offset);
+
+  /// Returns a normalized selection that direction is forward.
+  Selection get normalized => isBackward ? copyWith() : reversed.copyWith();
+
+  /// Returns a reversed selection.
+  Selection get reversed => copyWith(start: end, end: start);
+
+  /// Returns the offset in the starting position under the normalized selection.
+  int get startIndex => normalized.start.offset;
+
+  /// Returns the offset in the ending position under the normalized selection.
+  int get endIndex => normalized.end.offset;
+
+  int get length => endIndex - startIndex;
+
+  /// Collapses the current selection to a single point.
+  ///
+  /// If [atStart] is true, the selection will be collapsed to the start point.
+  /// If [atStart] is false, the selection will be collapsed to the end point.
+  Selection collapse({bool atStart = false}) {
+    if (atStart) {
+      return copyWith(end: start);
+    } else {
+      return copyWith(start: end);
+    }
+  }
+
+  Selection copyWith({Position? start, Position? end}) {
+    return Selection(
+      start: start ?? this.start,
+      end: end ?? this.end,
+    );
+  }
+
+  Map<String, dynamic> toJson() {
+    return {
+      'start': start.toJson(),
+      'end': end.toJson(),
+    };
+  }
+}

frontend/app_flowy/packages/appflowy_editor/lib/src/editor_state.dart

@@ -5,7 +5,7 @@ import 'package:appflowy_editor/src/render/style/editor_style.dart';
 import 'package:appflowy_editor/src/service/service.dart';
 import 'package:flutter/material.dart';
 
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import 'package:appflowy_editor/src/document/state_tree.dart';
 import 'package:appflowy_editor/src/operation/operation.dart';
 import 'package:appflowy_editor/src/operation/transaction.dart';

frontend/app_flowy/packages/appflowy_editor/lib/src/extensions/node_extensions.dart

@@ -1,6 +1,6 @@
 import 'package:appflowy_editor/src/core/document/node.dart';
 import 'package:appflowy_editor/src/core/document/path.dart';
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import 'package:appflowy_editor/src/extensions/object_extensions.dart';
 import 'package:appflowy_editor/src/render/selection/selectable.dart';
 import 'package:flutter/material.dart';

frontend/app_flowy/packages/appflowy_editor/lib/src/extensions/text_node_extensions.dart

@@ -1,7 +1,7 @@
 import 'package:appflowy_editor/src/core/document/node.dart';
 import 'package:appflowy_editor/src/core/document/path.dart';
-import 'package:appflowy_editor/src/core/selection/position.dart';
+import 'package:appflowy_editor/src/core/location/position.dart';
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import 'package:appflowy_editor/src/core/document/text_delta.dart';
 import 'package:appflowy_editor/src/document/built_in_attribute_keys.dart';
 

frontend/app_flowy/packages/appflowy_editor/lib/src/operation/transaction.dart

@@ -1,6 +1,6 @@
 import 'dart:collection';
 import 'package:flutter/material.dart';
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import './operation.dart';
 
 /// A [Transaction] has a list of [Operation] objects that will be applied

frontend/app_flowy/packages/appflowy_editor/lib/src/operation/transaction_builder.dart

@@ -4,8 +4,8 @@ import 'dart:math';
 import 'package:appflowy_editor/src/core/document/attributes.dart';
 import 'package:appflowy_editor/src/core/document/node.dart';
 import 'package:appflowy_editor/src/core/document/path.dart';
-import 'package:appflowy_editor/src/core/selection/position.dart';
+import 'package:appflowy_editor/src/core/location/position.dart';
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import 'package:appflowy_editor/src/core/document/text_delta.dart';
 import 'package:appflowy_editor/src/editor_state.dart';
 import 'package:appflowy_editor/src/operation/operation.dart';

frontend/app_flowy/packages/appflowy_editor/lib/src/render/image/image_node_widget.dart

@@ -1,7 +1,7 @@
 import 'package:appflowy_editor/src/extensions/object_extensions.dart';
 import 'package:appflowy_editor/src/core/document/node.dart';
-import 'package:appflowy_editor/src/core/selection/position.dart';
+import 'package:appflowy_editor/src/core/location/position.dart';
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import 'package:appflowy_editor/src/infra/flowy_svg.dart';
 import 'package:appflowy_editor/src/render/selection/selectable.dart';
 import 'package:flutter/material.dart';

frontend/app_flowy/packages/appflowy_editor/lib/src/render/rich_text/default_selectable.dart

@@ -1,5 +1,5 @@
-import 'package:appflowy_editor/src/core/selection/position.dart';
+import 'package:appflowy_editor/src/core/location/position.dart';
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import 'package:appflowy_editor/src/render/selection/selectable.dart';
 import 'package:flutter/material.dart';
 

frontend/app_flowy/packages/appflowy_editor/lib/src/render/rich_text/flowy_rich_text.dart

@@ -7,8 +7,8 @@ import 'package:flutter/rendering.dart';
 
 import 'package:appflowy_editor/src/core/document/node.dart';
 import 'package:appflowy_editor/src/core/document/path.dart';
-import 'package:appflowy_editor/src/core/selection/position.dart';
+import 'package:appflowy_editor/src/core/location/position.dart';
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import 'package:appflowy_editor/src/core/document/text_delta.dart';
 import 'package:appflowy_editor/src/editor_state.dart';
 import 'package:appflowy_editor/src/extensions/url_launcher_extension.dart';

frontend/app_flowy/packages/appflowy_editor/lib/src/render/selection/selectable.dart

@@ -1,5 +1,5 @@
-import 'package:appflowy_editor/src/core/selection/position.dart';
+import 'package:appflowy_editor/src/core/location/position.dart';
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import 'package:flutter/material.dart';
 
 enum CursorStyle {

frontend/app_flowy/packages/appflowy_editor/lib/src/service/default_text_operations/format_rich_text_style.dart

@@ -1,8 +1,8 @@
 import 'package:appflowy_editor/src/core/document/attributes.dart';
 import 'package:appflowy_editor/src/core/document/node.dart';
 import 'package:appflowy_editor/src/core/document/path.dart';
-import 'package:appflowy_editor/src/core/selection/position.dart';
+import 'package:appflowy_editor/src/core/location/position.dart';
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import 'package:appflowy_editor/src/editor_state.dart';
 import 'package:appflowy_editor/src/extensions/text_node_extensions.dart';
 import 'package:appflowy_editor/src/operation/transaction_builder.dart';

frontend/app_flowy/packages/appflowy_editor/lib/src/service/input_service.dart

@@ -4,7 +4,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
 import 'package:appflowy_editor/src/core/document/node.dart';
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import 'package:appflowy_editor/src/editor_state.dart';
 import 'package:appflowy_editor/src/extensions/node_extensions.dart';
 import 'package:appflowy_editor/src/operation/transaction_builder.dart';

frontend/app_flowy/packages/appflowy_editor/lib/src/service/internal_key_event_handlers/arrow_keys_handler.dart

@@ -220,7 +220,7 @@ ShortcutEventHandler cursorEndSelect = (editorState, event) {
 KeyEventResult cursorUp(EditorState editorState, RawKeyEvent event) {
   final nodes = editorState.service.selectionService.currentSelectedNodes;
   final selection =
-      editorState.service.selectionService.currentSelection.value?.normalize;
+      editorState.service.selectionService.currentSelection.value?.normalized;
   if (nodes.isEmpty || selection == null) {
     return KeyEventResult.ignored;
   }
@@ -234,7 +234,7 @@ KeyEventResult cursorUp(EditorState editorState, RawKeyEvent event) {
 KeyEventResult cursorDown(EditorState editorState, RawKeyEvent event) {
   final nodes = editorState.service.selectionService.currentSelectedNodes;
   final selection =
-      editorState.service.selectionService.currentSelection.value?.normalize;
+      editorState.service.selectionService.currentSelection.value?.normalized;
   if (nodes.isEmpty || selection == null) {
     return KeyEventResult.ignored;
   }
@@ -248,7 +248,7 @@ KeyEventResult cursorDown(EditorState editorState, RawKeyEvent event) {
 KeyEventResult cursorLeft(EditorState editorState, RawKeyEvent event) {
   final nodes = editorState.service.selectionService.currentSelectedNodes;
   final selection =
-      editorState.service.selectionService.currentSelection.value?.normalize;
+      editorState.service.selectionService.currentSelection.value?.normalized;
   if (nodes.isEmpty || selection == null) {
     return KeyEventResult.ignored;
   }
@@ -270,7 +270,7 @@ KeyEventResult cursorLeft(EditorState editorState, RawKeyEvent event) {
 KeyEventResult cursorRight(EditorState editorState, RawKeyEvent event) {
   final nodes = editorState.service.selectionService.currentSelectedNodes;
   final selection =
-      editorState.service.selectionService.currentSelection.value?.normalize;
+      editorState.service.selectionService.currentSelection.value?.normalized;
   if (nodes.isEmpty || selection == null) {
     return KeyEventResult.ignored;
   }

frontend/app_flowy/packages/appflowy_editor/lib/src/service/internal_key_event_handlers/copy_paste_handler.dart

@@ -25,7 +25,7 @@ Selection _computeSelectionAfterPasteMultipleNodes(
 }
 
 void _handleCopy(EditorState editorState) async {
-  final selection = editorState.cursorSelection?.normalize;
+  final selection = editorState.cursorSelection?.normalized;
   if (selection == null || selection.isCollapsed) {
     return;
   }
@@ -65,7 +65,7 @@ void _handleCopy(EditorState editorState) async {
 }
 
 void _pasteHTML(EditorState editorState, String html) {
-  final selection = editorState.cursorSelection?.normalize;
+  final selection = editorState.cursorSelection?.normalized;
   if (selection == null) {
     return;
   }
@@ -234,7 +234,7 @@ Delta _lineContentToDelta(String lineContent) {
 }
 
 void _handlePastePlainText(EditorState editorState, String plainText) {
-  final selection = editorState.cursorSelection?.normalize;
+  final selection = editorState.cursorSelection?.normalized;
   if (selection == null) {
     return;
   }
@@ -300,7 +300,7 @@ void _handleCut(EditorState editorState) {
 }
 
 void _deleteSelectedContent(EditorState editorState) {
-  final selection = editorState.cursorSelection?.normalize;
+  final selection = editorState.cursorSelection?.normalized;
   if (selection == null || selection.isCollapsed) {
     return;
   }

frontend/app_flowy/packages/appflowy_editor/lib/src/service/internal_key_event_handlers/number_list_helper.dart

@@ -1,4 +1,4 @@
-import 'package:appflowy_editor/src/document/selection.dart';
+import 'package:appflowy_editor/src/core/location/selection.dart';
 import 'package:appflowy_editor/src/editor_state.dart';
 import 'package:appflowy_editor/src/document/built_in_attribute_keys.dart';
 import 'package:appflowy_editor/src/operation/transaction_builder.dart';