Introduced the Source Editor Instance module

This is the part of a large effort of refactoring Source Editor

Changelog: added

app/assets/javascripts/editor/constants.js

 import { DEFAULT_DEBOUNCE_AND_THROTTLE_MS } from '~/lib/utils/constants';
 import { s__ } from '~/locale';
 
-export const SOURCE_EDITOR_INSTANCE_ERROR_NO_EL = s__(
-  'SourceEditor|"el" parameter is required for createInstance()',
-);
-
 export const URI_PREFIX = 'gitlab';
 export const CONTENT_UPDATE_DEBOUNCE = DEFAULT_DEBOUNCE_AND_THROTTLE_MS;
 
-export const ERROR_INSTANCE_REQUIRED_FOR_EXTENSION = s__(
-  'SourceEditor|Source Editor instance is required to set up an extension.',
-);
-
 export const EDITOR_READY_EVENT = 'editor-ready';
 
 export const EDITOR_TYPE_CODE = 'vs.editor.ICodeEditor';
@@ -20,9 +12,31 @@ export const EDITOR_TYPE_DIFF = 'vs.editor.IDiffEditor';
 export const EDITOR_CODE_INSTANCE_FN = 'createInstance';
 export const EDITOR_DIFF_INSTANCE_FN = 'createDiffInstance';
 
+export const SOURCE_EDITOR_INSTANCE_ERROR_NO_EL = s__(
+  'SourceEditor|"el" parameter is required for createInstance()',
+);
+export const ERROR_INSTANCE_REQUIRED_FOR_EXTENSION = s__(
+  'SourceEditor|Source Editor instance is required to set up an extension.',
+);
 export const EDITOR_EXTENSION_DEFINITION_ERROR = s__(
   'SourceEditor|Extension definition should be either a class or a function',
 );
+export const EDITOR_EXTENSION_NO_DEFINITION_ERROR = s__(
+  'SourceEditor|`definition` property is expected on the extension.',
+);
+export const EDITOR_EXTENSION_DEFINITION_TYPE_ERROR = s__(
+  'SourceEditor|Extension definition should be either class, function, or an Array of definitions.',
+);
+export const EDITOR_EXTENSION_NOT_SPECIFIED_FOR_UNUSE_ERROR = s__(
+  'SourceEditor|No extension for unuse has been specified.',
+);
+export const EDITOR_EXTENSION_NOT_REGISTERED_ERROR = s__('SourceEditor|%{name} is not registered.');
+export const EDITOR_EXTENSION_NAMING_CONFLICT_ERROR = s__(
+  'SourceEditor|Name conflict for "%{prop}()" method.',
+);
+export const EDITOR_EXTENSION_STORE_IS_MISSING_ERROR = s__(
+  'SourceEditor|Extensions Store is required to check for an extension.',
+);
 
 //
 // EXTENSIONS' CONSTANTS

app/assets/javascripts/editor/source_editor_extension.js

@@ -12,6 +12,6 @@ export default class EditorExtension {
   }
 
   get api() {
-    return this.obj.provides();
+    return this.obj.provides && this.obj.provides();
   }
 }

app/assets/javascripts/editor/source_editor_instance.js

+/**
+ * @module source_editor_instance
+ */
+
+/**
+ * A Source Editor Extension definition
+ * @typedef {Object} SourceEditorExtensionDefinition
+ * @property {Object} definition
+ * @property {Object} setupOptions
+ */
+
+/**
+ * A Source Editor Extension
+ * @typedef {Object} SourceEditorExtension
+ * @property {Object} obj
+ * @property {Object} api
+ */
+
+import { isEqual } from 'lodash';
+import { editor as monacoEditor } from 'monaco-editor';
+import { getBlobLanguage } from '~/editor/utils';
+import { logError } from '~/lib/logger';
+import { sprintf } from '~/locale';
+import EditorExtension from './source_editor_extension';
+import {
+  EDITOR_EXTENSION_DEFINITION_TYPE_ERROR,
+  EDITOR_EXTENSION_NAMING_CONFLICT_ERROR,
+  EDITOR_EXTENSION_NO_DEFINITION_ERROR,
+  EDITOR_EXTENSION_NOT_REGISTERED_ERROR,
+  EDITOR_EXTENSION_NOT_SPECIFIED_FOR_UNUSE_ERROR,
+  EDITOR_EXTENSION_STORE_IS_MISSING_ERROR,
+} from './constants';
+
+const utils = {
+  removeExtFromMethod: (method, extensionName, container) => {
+    if (!container) {
+      return;
+    }
+    if (Object.prototype.hasOwnProperty.call(container, method)) {
+      // eslint-disable-next-line no-param-reassign
+      delete container[method];
+    }
+  },
+
+  getStoredExtension: (extensionsStore, name) => {
+    if (!extensionsStore) {
+      logError(EDITOR_EXTENSION_STORE_IS_MISSING_ERROR);
+      return undefined;
+    }
+    return extensionsStore.get(name);
+  },
+};
+
+/** Class representing a Source Editor Instance */
+export default class EditorInstance {
+  constructor(rootInstance = {}, extensionsStore = new Map()) {
+    /** The methods provided by extensions. */
+    this.methods = {};
+
+    const seInstance = this;
+    const getHandler = {
+      get(target, prop, receiver) {
+        const methodExtension =
+          Object.prototype.hasOwnProperty.call(seInstance.methods, prop) &&
+          seInstance.methods[prop];
+        if (methodExtension) {
+          const extension = extensionsStore.get(methodExtension);
+
+          return (...args) => {
+            return extension.api[prop].call(seInstance, ...args, receiver);
+          };
+        }
+        return seInstance[prop]
+          ? Reflect.get(seInstance, prop, receiver)
+          : Reflect.get(target, prop, receiver);
+      },
+      set(target, prop, value) {
+        Object.assign(seInstance, {
+          [prop]: value,
+        });
+        return true;
+      },
+    };
+    const instProxy = new Proxy(rootInstance, getHandler);
+
+    /**
+     * Main entry point to apply an extension to the instance
+     * @param {SourceEditorExtensionDefinition}
+     */
+    this.use = EditorInstance.useUnuse.bind(instProxy, extensionsStore, this.useExtension);
+
+    /**
+     * Main entry point to un-use an extension and remove it from the instance
+     * @param {SourceEditorExtension}
+     */
+    this.unuse = EditorInstance.useUnuse.bind(instProxy, extensionsStore, this.unuseExtension);
+
+    return instProxy;
+  }
+
+  static useUnuse(extensionsStore, fn, extensions) {
+    if (Array.isArray(extensions)) {
+      if (!extensions.length) {
+        return fn.call(this, extensionsStore, undefined);
+      }
+      const exts = new Array(extensions.length);
+      extensions.forEach((ext, i) => {
+        exts[i] = fn.call(this, extensionsStore, ext);
+      });
+      return exts;
+    }
+    return fn.call(this, extensionsStore, extensions);
+  }
+
+  //
+  // REGISTERING NEW EXTENSION
+  //
+  useExtension(extensionsStore, extensionDefinition = {}) {
+    const { definition } = extensionDefinition;
+    if (!definition) {
+      throw new Error(EDITOR_EXTENSION_NO_DEFINITION_ERROR);
+    }
+    if (typeof definition !== 'function') {
+      throw new Error(EDITOR_EXTENSION_DEFINITION_TYPE_ERROR);
+    }
+
+    // Existing Extension Path
+    const existingExt = utils.getStoredExtension(extensionsStore, definition.name);
+    if (existingExt) {
+      if (isEqual(extensionDefinition.setupOptions, existingExt.setupOptions)) {
+        return existingExt;
+      }
+      this.unuseExtension(extensionsStore, existingExt);
+    }
+
+    // New Extension Path
+    const extension = new EditorExtension(extensionDefinition);
+    const { name, setupOptions, obj: extensionObj } = extension;
+    if (extensionObj.onSetup) {
+      extensionObj.onSetup(setupOptions, this);
+    }
+    if (extensionsStore) {
+      this.registerExtension(name, extension, extensionsStore);
+    }
+    this.registerExtensionMethods(name, extension);
+    return extension;
+  }
+
+  registerExtension(name, extension, extensionsStore) {
+    const hasExtensionRegistered =
+      extensionsStore.has(name) &&
+      isEqual(extension.setupOptions, extensionsStore.get(name).setupOptions);
+    if (hasExtensionRegistered) {
+      return;
+    }
+    extensionsStore.set(name, extension);
+    const { obj: extensionObj } = extension;
+    if (extensionObj.onUse) {
+      extensionObj.onUse(this);
+    }
+  }
+
+  registerExtensionMethods(name, extension) {
+    const { api } = extension;
+
+    if (!api) {
+      return;
+    }
+
+    Object.keys(api).forEach((prop) => {
+      if (this[prop]) {
+        logError(sprintf(EDITOR_EXTENSION_NAMING_CONFLICT_ERROR, { prop }));
+      } else {
+        this.methods[prop] = name;
+      }
+    }, this);
+  }
+
+  //
+  // UNREGISTERING AN EXTENSION
+  //
+  unuseExtension(extensionsStore, extension) {
+    if (!extension) {
+      throw new Error(EDITOR_EXTENSION_NOT_SPECIFIED_FOR_UNUSE_ERROR);
+    }
+    const { name } = extension;
+    const existingExt = utils.getStoredExtension(extensionsStore, name);
+    if (!existingExt) {
+      throw new Error(sprintf(EDITOR_EXTENSION_NOT_REGISTERED_ERROR, { name }));
+    }
+    const { obj: extensionObj } = existingExt;
+    if (extensionObj.onBeforeUnuse) {
+      extensionObj.onBeforeUnuse(this);
+    }
+    this.unregisterExtensionMethods(name, existingExt);
+    if (extensionObj.onUnuse) {
+      extensionObj.onUnuse(this);
+    }
+  }
+
+  unregisterExtensionMethods(name, extension) {
+    const { api } = extension;
+    if (!api) {
+      return;
+    }
+    Object.keys(api).forEach((method) => {
+      utils.removeExtFromMethod(method, name, this.methods);
+    });
+  }
+
+  /**
+   * PUBLIC API OF AN INSTANCE
+   */
+
+  /**
+   * Updates model language based on the path
+   * @param {String} path - blob path
+   */
+  updateModelLanguage(path) {
+    const lang = getBlobLanguage(path);
+    const model = this.getModel();
+    // return monacoEditor.setModelLanguage(model, lang);
+    monacoEditor.setModelLanguage(model, lang);
+  }
+
+  /**
+   * Get the methods returned by extensions.
+   * @returns {Array}
+   */
+  get extensionsAPI() {
+    return Object.keys(this.methods);
+  }
+}

locale/gitlab.pot

@@ -32697,12 +32697,30 @@ msgstr ""
 msgid "SourceEditor|\"el\" parameter is required for createInstance()"
 msgstr ""
 
+msgid "SourceEditor|%{name} is not registered."
+msgstr ""
+
 msgid "SourceEditor|Extension definition should be either a class or a function"
 msgstr ""
 
+msgid "SourceEditor|Extension definition should be either class, function, or an Array of definitions."
+msgstr ""
+
+msgid "SourceEditor|Extensions Store is required to check for an extension."
+msgstr ""
+
+msgid "SourceEditor|Name conflict for \"%{prop}()\" method."
+msgstr ""
+
+msgid "SourceEditor|No extension for unuse has been specified."
+msgstr ""
+
 msgid "SourceEditor|Source Editor instance is required to set up an extension."
 msgstr ""
 
+msgid "SourceEditor|`definition` property is expected on the extension."
+msgstr ""
+
 msgid "Sourcegraph"
 msgstr ""
 

spec/frontend/editor/helpers.js

+export class MyClassExtension {
+  // eslint-disable-next-line class-methods-use-this
+  provides() {
+    return {
+      shared: () => 'extension',
+      classExtMethod: () => 'class own method',
+    };
+  }
+}
+
+export function MyFnExtension() {
+  return {
+    fnExtMethod: () => 'fn own method',
+    provides: () => {
+      return {
+        fnExtMethod: () => 'class own method',
+      };
+    },
+  };
+}
+
+export const MyConstExt = () => {
+  return {
+    provides: () => {
+      return {
+        constExtMethod: () => 'const own method',
+      };
+    },
+  };
+};
+
+export const conflictingExtensions = {
+  WithInstanceExt: () => {
+    return {
+      provides: () => {
+        return {
+          use: () => 'A conflict with instance',
+          ownMethod: () => 'Non-conflicting method',
+        };
+      },
+    };
+  },
+  WithAnotherExt: () => {
+    return {
+      provides: () => {
+        return {
+          shared: () => 'A conflict with extension',
+          ownMethod: () => 'Non-conflicting method',
+        };
+      },
+    };
+  },
+};

spec/frontend/editor/source_editor_extension_spec.js

 import EditorExtension from '~/editor/source_editor_extension';
 import { EDITOR_EXTENSION_DEFINITION_ERROR } from '~/editor/constants';
-
-class MyClassExtension {
-  // eslint-disable-next-line class-methods-use-this
-  provides() {
-    return {
-      shared: () => 'extension',
-      classExtMethod: () => 'class own method',
-    };
-  }
-}
-
-function MyFnExtension() {
-  return {
-    fnExtMethod: () => 'fn own method',
-    provides: () => {
-      return {
-        shared: () => 'extension',
-      };
-    },
-  };
-}
-
-const MyConstExt = () => {
-  return {
-    provides: () => {
-      return {
-        shared: () => 'extension',
-        constExtMethod: () => 'const own method',
-      };
-    },
-  };
-};
+import * as helpers from './helpers';
 
 describe('Editor Extension', () => {
   const dummyObj = { foo: 'bar' };
@@ -53,15 +22,15 @@ describe('Editor Extension', () => {
 
   it.each`
     definition                  | setupOptions | expectedName
-    ${MyClassExtension} | ${undefined} | ${'MyClassExtension'}
-    ${MyClassExtension} | ${{}}        | ${'MyClassExtension'}
-    ${MyClassExtension} | ${dummyObj}  | ${'MyClassExtension'}
-    ${MyFnExtension}    | ${undefined} | ${'MyFnExtension'}
-    ${MyFnExtension}    | ${{}}        | ${'MyFnExtension'}
-    ${MyFnExtension}    | ${dummyObj}  | ${'MyFnExtension'}
-    ${MyConstExt}       | ${undefined} | ${'MyConstExt'}
-    ${MyConstExt}       | ${{}}        | ${'MyConstExt'}
-    ${MyConstExt}       | ${dummyObj}  | ${'MyConstExt'}
+    ${helpers.MyClassExtension} | ${undefined} | ${'MyClassExtension'}
+    ${helpers.MyClassExtension} | ${{}}        | ${'MyClassExtension'}
+    ${helpers.MyClassExtension} | ${dummyObj}  | ${'MyClassExtension'}
+    ${helpers.MyFnExtension}    | ${undefined} | ${'MyFnExtension'}
+    ${helpers.MyFnExtension}    | ${{}}        | ${'MyFnExtension'}
+    ${helpers.MyFnExtension}    | ${dummyObj}  | ${'MyFnExtension'}
+    ${helpers.MyConstExt}       | ${undefined} | ${'MyConstExt'}
+    ${helpers.MyConstExt}       | ${{}}        | ${'MyConstExt'}
+    ${helpers.MyConstExt}       | ${dummyObj}  | ${'MyConstExt'}
   `(
     'correctly creates extension for definition = $definition and setupOptions = $setupOptions',
     ({ definition, setupOptions, expectedName }) => {
@@ -82,9 +51,9 @@ describe('Editor Extension', () => {
   describe('api', () => {
     it.each`
       definition                  | expectedKeys
-      ${MyClassExtension} | ${['shared', 'classExtMethod']}
-      ${MyFnExtension}    | ${['shared']}
-      ${MyConstExt}       | ${['shared', 'constExtMethod']}
+      ${helpers.MyClassExtension} | ${['shared', 'classExtMethod']}
+      ${helpers.MyFnExtension}    | ${['fnExtMethod']}
+      ${helpers.MyConstExt}       | ${['constExtMethod']}
     `('correctly returns API for $definition', ({ definition, expectedKeys }) => {
       const extension = new EditorExtension({ definition });
       const expectedApi = Object.fromEntries(