Use keypress event to enter text

Use EditState to maintain editor state

Move reading of activeSections off cursor, onto EditState

Ensure that cursorDidChange event fires when active sections change

Ensure cursor change callbacks do not fire before rendering

src/js/editor/edit-state.js

@@ -0,0 +1,59 @@
+import { contains, isArrayEqual } from 'mobiledoc-kit/utils/array-utils';
+
+export default class EditState {
+  constructor(editor) {
+    this.editor = editor;
+    this._activeMarkups = [];
+    this._activeSections = [];
+  }
+
+  get activeSections() {
+    let { editor: { range, post } } = this;
+    if (range.isBlank) {
+      return [];
+    } else {
+      return post.sections.readRange(range.head.section, range.tail.section);
+    }
+  }
+
+  get activeMarkups() {
+    let { editor: { cursor, post, range } } = this;
+
+    if (!cursor.hasCursor()) {
+      return [];
+    } else if (!this._activeMarkups) {
+      this._activeMarkups = post.markupsInRange(range);
+    }
+
+    return this._activeMarkups;
+  }
+
+  toggleMarkupState(markup) {
+    if (contains(this.activeMarkups, markup)) {
+      this._removeActiveMarkup(markup);
+    } else {
+      this._addActiveMarkup(markup);
+    }
+  }
+
+  /**
+   * @return {Boolean} Whether the markups after reset have changed
+   */
+  resetActiveMarkups() {
+    let prevMarkups = this._activeMarkups || [];
+    delete this._activeMarkups;
+    let markups = this.activeMarkups || [];
+
+    let didChange = !isArrayEqual(prevMarkups, markups);
+    return didChange;
+  }
+
+  _removeActiveMarkup(markup) {
+    let index = this._activeMarkups.indexOf(markup);
+    this._activeMarkups.splice(index, 1);
+  }
+
+  _addActiveMarkup(markup) {
+    this._activeMarkups.push(markup);
+  }
+}