Added first embed: horizontal rule

packages/notus/analysis_options.yaml

 analyzer:
-  strong-mode: true
   language:
     enableSuperMixins: true
 

packages/notus/lib/notus.dart

 export 'src/document/leaf.dart';
 export 'src/document/line.dart';
 export 'src/document/node.dart';
-export 'src/embed.dart';
 export 'src/heuristics.dart';
 export 'src/heuristics/delete_rules.dart';
 export 'src/heuristics/format_rules.dart';

packages/notus/lib/src/document.dart

 import 'document/leaf.dart';
 import 'document/line.dart';
 import 'document/node.dart';
-import 'embed.dart';
 import 'heuristics.dart';
 
 /// Source of a [NotusChange].
     _controller.close();
   }
 
-  /// Inserts [value] in this document at specified [index]. Value must be a
-  /// [String] or an instance of [NotusEmbed].
+  /// Inserts [text] in this document at specified [index].
   ///
   /// This method applies heuristic rules before modifying this document and
   /// produces a [NotusChange] with source set to [ChangeSource.local].
   ///
   /// Returns an instance of [Delta] actually composed into this document.
-  Delta insert(int index, dynamic value) {
+  Delta insert(int index, String text) {
     assert(index >= 0);
-    assert(value is String || value is NotusEmbed,
-        'Value must be a string or a NotusEmbed.');
-    Delta change;
-    if (value is String) {
-      assert(value.isNotEmpty);
-      value = _sanitizeString(value);
-      if (value.isEmpty) return new Delta();
-      change = _heuristics.applyInsertRules(this, index, value);
-    } else {
-      NotusEmbed embed = value;
-      change = _heuristics.applyEmbedRules(this, index, embed.attribute);
-    }
+    assert(text.isNotEmpty);
+    text = _sanitizeString(text);
+    if (text.isEmpty) return new Delta();
+    final change = _heuristics.applyInsertRules(this, index, text);
     compose(change, ChangeSource.local);
     return change;
   }
     assert(index >= 0 && length > 0);
     // TODO: need a heuristic rule to ensure last line-break.
     final change = _heuristics.applyDeleteRules(this, index, length);
-    // Delete rules are allowed to prevent the edit so it may be empty.
     if (change.isNotEmpty) {
+      // Delete rules are allowed to prevent the edit so it may be empty.
       compose(change, ChangeSource.local);
     }
     return change;
   }
 
-  /// Replaces [length] of characters starting at [index] with [value]. Value
-  /// must be a [String] or an instance of [NotusEmbed].
+  /// Replaces [length] of characters starting at [index] [text].
   ///
   /// This method applies heuristic rules before modifying this document and
   /// produces a [NotusChange] with source set to [ChangeSource.local].
   ///
   /// Returns an instance of [Delta] actually composed into this document.
-  Delta replace(int index, int length, dynamic value) {
-    assert(index >= 0 && (value.isNotEmpty || length > 0),
-        'With index $index, length $length and text "$value"');
-    assert(value is String || value is NotusEmbed,
-        'Value must be a string or a NotusEmbed.');
-
-    final hasInsert =
-        (value is NotusEmbed || (value is String && value.isNotEmpty));
+  Delta replace(int index, int length, String text) {
+    assert(index >= 0 && (text.isNotEmpty || length > 0),
+        'With index $index, length $length and text "$text"');
     Delta delta = new Delta();
-
     // We have to compose before applying delete rules
     // Otherwise delete would be operating on stale document snapshot.
-    if (hasInsert) {
-      delta = insert(index, value);
+    if (text.isNotEmpty) {
+      delta = insert(index, text);
       index = delta.transformPosition(index);
     }
 
     return delta;
   }
 
-  /// Formats portion of this document with specified [attribute].
+  /// Formats segment of this document with specified [attribute].
   ///
   /// Applies heuristic rules before modifying this document and
   /// produces a [NotusChange] with source set to [ChangeSource.local].
   /// unchanged and no [NotusChange] is published to [changes] stream.
   Delta format(int index, int length, NotusAttribute attribute) {
     assert(index >= 0 && length >= 0 && attribute != null);
-    Delta change;
-    if (attribute is EmbedAttribute) {
-      assert(length == 1);
-      change = _heuristics.applyEmbedRules(this, index, attribute);
-    } else {
-      change = _heuristics.applyFormatRules(this, index, length, attribute);
-    }
+    final change = _heuristics.applyFormatRules(this, index, length, attribute);
     if (change.isNotEmpty) {
       compose(change, ChangeSource.local);
     }

packages/notus/lib/src/embed.dart

-import 'document/attributes.dart';
-
-abstract class NotusEmbed {
-  NotusAttribute get attribute;
-}
-
-class HorizontalRuleEmbed implements NotusEmbed {
-  const HorizontalRuleEmbed();
-
-  @override
-  NotusAttribute<Map<String, dynamic>> get attribute =>
-      NotusAttribute.embed.horizontalRule;
-}
-
-class ImageEmbed implements NotusEmbed {
-  const ImageEmbed(this.source) : assert(source != null);
-  final String source;
-
-  @override
-  NotusAttribute get attribute => NotusAttribute.embed.image(source);
-}

packages/notus/lib/src/heuristics.dart

 import 'package:quill_delta/quill_delta.dart';
 
 import 'heuristics/delete_rules.dart';
-import 'heuristics/embed_rules.dart';
 import 'heuristics/format_rules.dart';
 import 'heuristics/insert_rules.dart';
 
   /// Default set of heuristic rules.
   static const NotusHeuristics fallback = NotusHeuristics(
     formatRules: [
+      FormatEmbedsRule(),
       FormatLinkAtCaretPositionRule(),
       ResolveLineFormatRule(),
       ResolveInlineFormatRule(),
       PreserveLineStyleOnMergeRule(),
       CatchAllDeleteRule(),
     ],
-    embedRules: [
-      FormatEmbedsRule(),
-    ],
   );
 
   const NotusHeuristics({
     this.formatRules,
     this.insertRules,
     this.deleteRules,
-    this.embedRules,
   });
 
   /// List of format rules in this registry.
   /// List of delete rules in this registry.
   final List<DeleteRule> deleteRules;
 
-  /// List of embed rules in this registry.
-  final List<EmbedRule> embedRules;
-
   /// Applies heuristic rules to specified insert operation based on current
   /// state of Notus [document].
   Delta applyInsertRules(NotusDocument document, int index, String insert) {
     throw new StateError(
         'Failed to apply delete heuristic rules: none applied.');
   }
-
-  /// Applies heuristic rules to specified embed operation based on current
-  /// state of [document].
-  Delta applyEmbedRules(
-      NotusDocument document, int index, EmbedAttribute embed) {
-    final delta = document.toDelta();
-    for (var rule in embedRules) {
-      final result = rule.apply(delta, index, embed);
-      if (result != null) return result..trim();
-    }
-    throw new StateError(
-        'Failed to apply embed heuristic rules: none applied.');
-  }
 }

packages/notus/lib/src/heuristics/embed_rules.dart

-// Copyright (c) 2018, the Zefyr project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-import 'package:quill_delta/quill_delta.dart';
-import 'package:notus/notus.dart';
-
-/// A heuristic rule for embed operations.
-abstract class EmbedRule {
-  /// Constant constructor allows subclasses to declare constant constructors.
-  const EmbedRule();
-
-  /// Applies heuristic rule to an embed operation on a [document] and returns
-  /// resulting [Delta].
-  Delta apply(Delta document, int index, EmbedAttribute embed);
-}
-
-/// Handles all operations which manipulate embeds.
-class FormatEmbedsRule extends EmbedRule {
-  const FormatEmbedsRule();
-
-  @override
-  Delta apply(Delta document, int index, EmbedAttribute embed) {
-    final iter = new DeltaIterator(document);
-    final previous = iter.skip(index);
-
-    final target = iter.next();
-    Delta result = new Delta()..retain(index);
-    if (target.length == 1 && target.data == EmbedNode.kPlainTextPlaceholder) {
-      assert(() {
-        final style = NotusStyle.fromJson(target.attributes);
-        return style.single.key == NotusAttribute.embed.key;
-      }());
-
-      // There is already embed here, simply update its style.
-      return result..retain(1, embed.toJson());
-    } else {
-      // Target is not an embed, need to insert.
-      // Embeds can be inserted only into an empty line.
-
-      // Check if [index] is on an empty line already.
-      final isNewlineBefore = previous == null || previous.data.endsWith('\n');
-      final isNewlineAfter = target.data.startsWith('\n');
-      final isOnEmptyLine = isNewlineBefore && isNewlineAfter;
-      if (isOnEmptyLine) {
-        return result..insert(EmbedNode.kPlainTextPlaceholder, embed.toJson());
-      }
-      // We are on a non-empty line, split it (preserving style if needed)
-      // and insert our embed.
-      final lineStyle = _getLineStyle(iter, target);
-      if (!isNewlineBefore) {
-        result..insert('\n', lineStyle);
-      }
-      result..insert(EmbedNode.kPlainTextPlaceholder, embed.toJson());
-      if (!isNewlineAfter) {
-        result..insert('\n');
-      }
-      return result;
-    }
-//
-//    if (embed == NotusAttribute.embed.unset) {
-//      // Convert into a delete operation.
-//      return result..delete(1);
-//    } else {
-//      return result..retain(1, embed.toJson());
-//    }
-  }
-
-  Map<String, dynamic> _getLineStyle(
-      DeltaIterator iterator, Operation current) {
-    if (current.data.indexOf('\n') >= 0) {
-      return current.attributes;
-    }
-    // Continue looking for line-break.
-    Map<String, dynamic> attributes;
-    while (iterator.hasNext) {
-      final op = iterator.next();
-      int lf = op.data.indexOf('\n');
-      if (lf >= 0) {
-        attributes = op.attributes;
-        break;
-      }
-    }
-    return attributes;
-  }
-}

packages/notus/lib/src/heuristics/format_rules.dart

     return result;
   }
 }
+
+/// Handles all format operations which manipulate embeds.
+class FormatEmbedsRule extends FormatRule {
+  const FormatEmbedsRule();
+
+  @override
+  Delta apply(Delta document, int index, int length, NotusAttribute attribute) {
+    // We are only interested in embed attributes
+    if (attribute is! EmbedAttribute) return null;
+    EmbedAttribute embed = attribute;
+
+    if (length == 1 && embed.isUnset) {
+      // Remove the embed.
+      return new Delta()
+        ..retain(index)
+        ..delete(length);
+    } else {
+      // If length is 0 we treat it as an insert at specified [index].
+      // If length is non-zero we treat it as a replace of selected range
+      // with the embed.
+      assert(!embed.isUnset);
+      return _insertEmbed(document, index, length, embed);
+    }
+  }
+
+  Delta _insertEmbed(
+      Delta document, int index, int length, EmbedAttribute embed) {
+    Delta result = new Delta()..retain(index);
+    final iter = new DeltaIterator(document);
+    final previous = iter.skip(index);
+    iter.skip(length); // ignore deleted part.
+    final target = iter.next();
+
+    // Check if [index] is on an empty line already.
+    final isNewlineBefore = previous == null || previous.data.endsWith('\n');
+    final isNewlineAfter = target.data.startsWith('\n');
+    final isOnEmptyLine = isNewlineBefore && isNewlineAfter;
+    if (isOnEmptyLine) {
+      return result..insert(EmbedNode.kPlainTextPlaceholder, embed.toJson());
+    }
+    // We are on a non-empty line, split it (preserving style if needed)
+    // and insert our embed.
+    final lineStyle = _getLineStyle(iter, target);
+    if (!isNewlineBefore) {
+      result..insert('\n', lineStyle);
+    }
+    result..insert(EmbedNode.kPlainTextPlaceholder, embed.toJson());
+    if (!isNewlineAfter) {
+      result..insert('\n');
+    }
+    result.delete(length);
+    return result;
+  }
+
+  Map<String, dynamic> _getLineStyle(
+      DeltaIterator iterator, Operation current) {
+    if (current.data.indexOf('\n') >= 0) {
+      return current.attributes;
+    }
+    // Continue looking for line-break.
+    Map<String, dynamic> attributes;
+    while (iterator.hasNext) {
+      final op = iterator.next();
+      int lf = op.data.indexOf('\n');
+      if (lf >= 0) {
+        attributes = op.attributes;
+        break;
+      }
+    }
+    return attributes;
+  }
+}

packages/notus/test/document_test.dart

 
     test('insert embed after line-break', () {
       final doc = dartconfDoc();
-      doc.insert(9, const HorizontalRuleEmbed());
+      doc.format(9, 0, NotusAttribute.embed.horizontalRule);
       expect(doc.root.children, hasLength(3));
       expect(doc.root.first.toPlainText(), 'DartConf\n');
       expect(doc.root.last.toPlainText(), 'Los Angeles\n');
 
     test('insert embed before line-break', () {
       final doc = dartconfDoc();
-      doc.insert(8, const HorizontalRuleEmbed());
+      doc.format(8, 0, NotusAttribute.embed.horizontalRule);
       expect(doc.root.children, hasLength(3));
       expect(doc.root.first.toPlainText(), 'DartConf\n');
       expect(doc.root.last.toPlainText(), 'Los Angeles\n');
 
     test('insert embed in the middle of a line', () {
       final doc = dartconfDoc();
-      doc.insert(4, const HorizontalRuleEmbed());
+      doc.format(4, 0, NotusAttribute.embed.horizontalRule);
       expect(doc.root.children, hasLength(4));
       expect(doc.root.children.elementAt(0).toPlainText(), 'Dart\n');
       expect(doc.root.children.elementAt(1).toPlainText(),
 
     test('delete embed', () {
       final doc = dartconfDoc();
-      doc.insert(8, const HorizontalRuleEmbed());
+      doc.format(8, 0, NotusAttribute.embed.horizontalRule);
       expect(doc.root.children, hasLength(3));
       doc.delete(9, 1);
       expect(doc.root.children, hasLength(3));
 
     test('insert text before embed', () {
       final doc = dartconfDoc();
-      doc.insert(8, const HorizontalRuleEmbed());
+      doc.format(8, 0, NotusAttribute.embed.horizontalRule);
       expect(doc.root.children, hasLength(3));
       doc.insert(9, 'text');
       expect(doc.root.children, hasLength(4));
 
     test('insert text after embed', () {
       final doc = dartconfDoc();
-      doc.insert(8, const HorizontalRuleEmbed());
+      doc.format(8, 0, NotusAttribute.embed.horizontalRule);
       expect(doc.root.children, hasLength(3));
       doc.insert(10, 'text');
       expect(doc.root.children, hasLength(4));
           '${EmbedNode.kPlainTextPlaceholder}\n');
       expect(doc.root.children.elementAt(2).toPlainText(), 'text\n');
     });
+
+    test('replace text with embed', () {
+      final doc = dartconfDoc();
+      doc.format(4, 4, NotusAttribute.embed.horizontalRule);
+      expect(doc.root.children, hasLength(3));
+      expect(doc.root.children.elementAt(0).toPlainText(), 'Dart\n');
+      expect(doc.root.children.elementAt(1).toPlainText(),
+          '${EmbedNode.kPlainTextPlaceholder}\n');
+      expect(doc.root.children.elementAt(2).toPlainText(), 'Los Angeles\n');
+    });
   });
 }

packages/zefyr/lib/src/widgets/horizontal_rule.dart

 }
 
 class RenderHorizontalRule extends RenderBox implements RenderEditableBox {
-  static const kPaddingBottom = 16.0;
+  static const kPaddingBottom = 24.0;
   static const kWidth = 3.0;
 
   RenderHorizontalRule({

packages/zefyr/lib/src/widgets/toolbar.dart

   numberList,
   code,
   quote,
+  horizontalRule,
   hideKeyboard,
   close,
   confirm,
   ZefyrToolbarAction.bulletList: NotusAttribute.block.bulletList,
   ZefyrToolbarAction.numberList: NotusAttribute.block.numberList,
   ZefyrToolbarAction.code: NotusAttribute.block.code,
-  ZefyrToolbarAction.quote: NotusAttribute.block.quote
+  ZefyrToolbarAction.quote: NotusAttribute.block.quote,
+  ZefyrToolbarAction.horizontalRule: NotusAttribute.embed.horizontalRule,
 };
 
 /// Allows customizing appearance of [ZefyrToolbar].
       buildButton(context, ZefyrToolbarAction.numberList),
       buildButton(context, ZefyrToolbarAction.quote),
       buildButton(context, ZefyrToolbarAction.code),
+      buildButton(context, ZefyrToolbarAction.horizontalRule),
     ];
     return buttons;
   }
     ZefyrToolbarAction.numberList: Icons.format_list_numbered,
     ZefyrToolbarAction.code: Icons.code,
     ZefyrToolbarAction.quote: Icons.format_quote,
+    ZefyrToolbarAction.horizontalRule: Icons.remove,
     ZefyrToolbarAction.hideKeyboard: Icons.keyboard_hide,
     ZefyrToolbarAction.close: Icons.close,
     ZefyrToolbarAction.confirm: Icons.check,