Introducing the Diff Editor

Make sure we dispose the instance model

Return either instance or editor from 'use'

Should be useful for chaining

Make sure the model exists before disposing

Introduced the DiffEditor

Abstracted 'createModel' into a static fn

Allow creation of instances without a model

This is useful for the cases when an extension implements
some custom model generation mechanism (for example with
some decorators)

Correct disposal of the DiffEditor models

Prettified the Editor Lite module

app/assets/javascripts/editor/editor_lite.js

@@ -6,7 +6,7 @@ import { registerLanguages } from '~/ide/utils';
 import { joinPaths } from '~/lib/utils/url_utility';
 import { uuids } from '~/diffs/utils/uuids';
 import { clearDomElement } from './utils';
-import { EDITOR_LITE_INSTANCE_ERROR_NO_EL, URI_PREFIX, EDITOR_READY_EVENT } from './constants';
+import { EDITOR_LITE_INSTANCE_ERROR_NO_EL, URI_PREFIX, EDITOR_READY_EVENT, EDITOR_TYPE_DIFF } from './constants';
 
 export default class EditorLite {
   constructor(options = {}) {
@@ -102,17 +102,28 @@ export default class EditorLite {
       });
   }
 
-  static createEditorModel({ blobPath, blobContent, blobGlobalId, instance } = {}) {
-    let model = null;
+  static createEditorModel({
+    blobPath = '',
+    blobContent = '',
+    originalBlobContent = null,
+    blobGlobalId = uuids()[0],
+    instance = null,
+  } = {}) {
     if (!instance) {
       return null;
     }
     const uriFilePath = joinPaths(URI_PREFIX, blobGlobalId, blobPath);
-    const uri = Uri.file(uriFilePath);
-    const existingModel = monacoEditor.getModel(uri);
-    model = existingModel || monacoEditor.createModel(blobContent, undefined, uri);
+    const existingModel = monacoEditor.getModel(uriFilePath);
+    const model =
+      existingModel || monacoEditor.createModel(blobContent, undefined, Uri.file(uriFilePath));
+    if (originalBlobContent === null) {
       instance.setModel(model);
-    return model;
+    } else {
+      instance.setModel({
+        original: monacoEditor.createModel(originalBlobContent, undefined, Uri.file(uriFilePath)),
+        modified: model,
+      });
+    }
   }
 
   /**
@@ -128,33 +139,76 @@ export default class EditorLite {
     el = undefined,
     blobPath = '',
     blobContent = '',
+    originalBlobContent = '',
     blobGlobalId = uuids()[0],
     extensions = [],
+    diff = false,
     ...instanceOptions
   } = {}) {
     EditorLite.prepareInstance(el);
 
-    const instance = monacoEditor.create(el, {
+    let instance;
+
+    if (!diff) {
+      instance = monacoEditor.create(el, {
         ...this.options,
         ...instanceOptions,
       });
+      if (instanceOptions.model !== null) {
+        EditorLite.createEditorModel({ blobGlobalId, blobPath, blobContent, instance });
+      }
+    } else {
+      instance = monacoEditor.createDiffEditor(el, {
+        ...this.options,
+        ...instanceOptions,
+      });
+      if (instanceOptions.model !== null) {
+        EditorLite.createEditorModel({
+          blobGlobalId,
+          originalBlobContent,
+          blobPath,
+          blobContent,
+          instance,
+        });
+      }
+    }
 
-    const model = EditorLite.createEditorModel({ blobGlobalId, blobPath, blobContent, instance });
+    Object.assign(instance, {
+      updateModelLanguage: (path) => EditorLite.updateModelLanguage(path, instance),
+      use: (args) => this.use(args, instance),
+    });
 
     instance.onDidDispose(() => {
       const index = this.instances.findIndex((inst) => inst === instance);
       this.instances.splice(index, 1);
-      model.dispose();
+      const instanceModel = instance.getModel();
+      if (instanceModel) {
+        if (instance.getEditorType() === EDITOR_TYPE_DIFF) {
+          const { original, modified } = instanceModel;
+          if (original) {
+            original.dispose();
+          }
+          if (modified) {
+            modified.dispose();
+          }
+        } else {
+          instanceModel.dispose();
+        }
+      }
     });
-    instance.updateModelLanguage = (path) => EditorLite.updateModelLanguage(path, instance);
-    instance.use = (args) => this.use(args, instance);
-
     EditorLite.manageDefaultExtensions(instance, el, extensions);
 
     this.instances.push(instance);
     return instance;
   }
 
+  createDiffInstance(args) {
+    this.createInstance({
+      ...args,
+      diff: true,
+    });
+  }
+
   dispose() {
     this.instances.forEach((instance) => instance.dispose());
   }
@@ -168,10 +222,11 @@ export default class EditorLite {
     };
     if (instance) {
       initExtensions(instance);
-    } else {
+      return instance;
+    }
     this.instances.forEach((inst) => {
       initExtensions(inst);
     });
-    }
+    return this;
   }
 }