1 files changed, 75 insertions, 0 deletions

diff --git a/language-web/src/main/js/editor/EditorStore.jsx b/language-web/src/main/js/editor/EditorStore.jsx
new file mode 100644
index 00000000..9c286c28
--- /dev/null
+++ b/language-web/src/main/js/editor/EditorStore.jsx
@@ -0,0 +1,75 @@
+import CodeMirror from 'codemirror';
+import { createAtom, makeAutoObservable, observable } from 'mobx';
+
+export default class EditorStore {
+  atom;
+  /** @type {CodeMirror} */
+  editor = null;
+  /** @type {string} */
+  value = '';
+
+  constructor() {
+    this.atom = createAtom('EditorStore');
+    makeAutoObservable(this, {
+      atom: false,
+      editor: observable.ref,
+    });
+  }
+
+  /**
+   * Attaches a new CodeMirror instance.
+   *
+   * The store will node subscribe to any CodeMirror events. Instead,
+   * the editor component should subscribe to them and relay them to the store.
+   *
+   * @param {CodeMirror} newEditor The new CodeMirror instance
+   */
+  updateEditor(newEditor) {
+    this.editor = newEditor;
+  }
+
+  /**
+   * Updates the contents of the editor.
+   *
+   * @param {string} newValue The new contents of the editor
+   */
+  updateValue(newValue) {
+    this.value = newValue;
+  }
+
+  reportChanged() {
+    this.atom.reportChanged();
+  }
+
+  /**
+   * @returns {boolean} `true` if there is history to undo
+   */
+  get canUndo() {
+    this.atom.reportObserved();
+    if (!this.editor) {
+      return false;
+    }
+    const { undo: undoSize } = this.editor.historySize();
+    return undoSize > 0;
+  }
+
+  undo() {
+    this.editor.undo();
+  }
+
+  /**
+   * @returns {boolean} `true` if there is history to redo
+   */
+  get canRedo() {
+    this.atom.reportObserved();
+    if (!this.editor) {
+      return false;
+    }
+    const { redo: redoSize } = this.editor.historySize();
+    return redoSize > 0;
+  }
+
+  redo() {
+    this.editor.redo();
+  }
+}