Replace ACE Editor with CodeMirror

.eslintignore

@@ -1,5 +1,4 @@
 app/assets/config/manifest.js
-app/assets/javascripts/ace_editor.js
 app/assets/javascripts/i18n/translations.js
 app/assets/javascripts/types/index.d.ts
 app/assets/javascripts/inputServiceWorker.js

Gemfile

@@ -59,9 +59,6 @@ gem 'builder', '~>3.2.4'
 # generate diffs
 gem 'diff-lcs', '~>1.5'
 
-# code editor
-gem 'ace-rails-ap', '~>4.5'
-
 # auto css prefixer
 gem 'autoprefixer-rails', '~>10.4.13'
 

Gemfile.lock

@@ -1,7 +1,6 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    ace-rails-ap (4.5)
     actioncable (7.0.7.2)
       actionpack (= 7.0.7.2)
       activesupport (= 7.0.7.2)
@@ -517,7 +516,6 @@ PLATFORMS
   x86_64-linux
 
 DEPENDENCIES
-  ace-rails-ap (~> 4.5)
   after_commit_everywhere (~> 1.3.1)
   annotate (~> 3.2.0)
   autoprefixer-rails (~> 10.4.13)

app/assets/config/manifest.js

@@ -1,3 +1,2 @@
 //= link_tree ../images
-//= link ace_editor.js
 //= link_tree ../builds

app/assets/javascripts/coding_scratchpad.ts

@@ -2,14 +2,8 @@ import { Papyros } from "@dodona/papyros";
 import { InputMode } from "@dodona/papyros";
 import { ProgrammingLanguage } from "@dodona/papyros";
 import { themeState } from "state/Theme";
-
-/**
- * Custom interface to not have to add the ace package as dependency
- */
-interface Editor {
-    setValue(v: string): void;
-    getValue(): string;
-}
+import { EditorView } from "@codemirror/view";
+import { setCode } from "editor";
 
 /** Identifiers used in HTML for relevant elements */
 const CODE_EDITOR_PARENT_ID = "scratchpad-editor-wrapper";
@@ -25,7 +19,7 @@ const SUBMIT_TAB_ID = "activity-handin-link";
 function initCodingScratchpad(programmingLanguage: ProgrammingLanguage): void {
     if (Papyros.supportsProgrammingLanguage(programmingLanguage)) {
         let papyros: Papyros | undefined = undefined;
-        let editor: Editor | undefined = undefined;
+        let editor: EditorView | undefined = undefined;
         const closeButton = document.getElementById(CLOSE_BUTTON_ID);
         // To prevent horizontal scrollbar issues, we delay rendering the button
         // until after the page is loaded
@@ -46,14 +40,14 @@ function initCodingScratchpad(programmingLanguage: ProgrammingLanguage): void {
                     });
                 editor ||= window.dodona.editor;
                 if (editor) {
-                    // Shortcut to copy code to ACE editor
+                    // Shortcut to copy code to editor
                     papyros.addButton(
                         {
                             id: CODE_COPY_BUTTON_ID,
                             buttonText: I18n.t("js.coding_scratchpad.copy_code")
                         },
                         () => {
-                            editor.setValue(papyros.getCode());
+                            setCode(editor, papyros.getCode());
                             closeButton.click();
                             // Open submit panel if possible
                             document.getElementById(SUBMIT_TAB_ID)?.click();
@@ -88,7 +82,7 @@ function initCodingScratchpad(programmingLanguage: ProgrammingLanguage): void {
         document.getElementById(OFFCANVAS_ID).addEventListener("shown.bs.offcanvas", () => {
             editor ||= window.dodona.editor;
             if (editor) { // Start with code from the editor, if there is any
-                const editorCode = editor.getValue();
+                const editorCode = editor.state.doc.toString();
                 const currentCode = papyros.getCode();
                 if (!currentCode || // Papyros empty
                     // Neither code areas are empty, but they differ

app/assets/javascripts/editor.ts

@@ -0,0 +1,221 @@
+import { closeBrackets, closeBracketsKeymap } from "@codemirror/autocomplete";
+import { defaultKeymap, history, historyKeymap } from "@codemirror/commands";
+import {
+    bracketMatching,
+    foldGutter,
+    foldKeymap,
+    HighlightStyle,
+    indentOnInput, LanguageDescription,
+    syntaxHighlighting
+} from "@codemirror/language";
+import { languages } from "@codemirror/language-data";
+import {
+    drawSelection,
+    dropCursor,
+    EditorView,
+    highlightActiveLine,
+    highlightActiveLineGutter,
+    highlightSpecialChars,
+    keymap,
+    lineNumbers
+} from "@codemirror/view";
+import { tags } from "@lezer/highlight";
+import { Extension } from "@codemirror/state";
+
+declare type EditorEventHandler = (event: FocusEvent, view: EditorView) => boolean | void;
+
+
+// A custom theme for CodeMirror that applies the same CSS as Rouge does,
+// meaning we can use our existing themes.
+const rougeStyle = HighlightStyle.define([
+    { tag: tags.comment, class: "c" },
+    { tag: tags.lineComment, class: "c" },
+    { tag: tags.blockComment, class: "cm" },
+    { tag: tags.docComment, class: "cs" },
+    { tag: tags.name, class: "n" },
+    { tag: tags.variableName, class: "nv" },
+    { tag: tags.typeName, class: "kt" },
+    { tag: tags.tagName, class: "nt" },
+    { tag: tags.propertyName, class: "py" },
+    { tag: tags.attributeName, class: "na" },
+    { tag: tags.className, class: "nc" },
+    { tag: tags.labelName, class: "nl" },
+    { tag: tags.namespace, class: "nn" },
+    { tag: tags.macroName, class: "n" },
+    { tag: tags.literal, class: "l" },
+    { tag: tags.string, class: "s" },
+    { tag: tags.docString, class: "sd" },
+    { tag: tags.character, class: "sc" },
+    { tag: tags.attributeValue, class: "g" },
+    { tag: tags.number, class: "m" },
+    { tag: tags.integer, class: "mi" },
+    { tag: tags.float, class: "mf" },
+    { tag: tags.bool, class: "l" },
+    { tag: tags.regexp, class: "sr" },
+    { tag: tags.escape, class: "se" },
+    { tag: tags.color, class: "l" },
+    { tag: tags.url, class: "l" },
+    { tag: tags.keyword, class: "k" },
+    { tag: tags.self, class: "k" },
+    { tag: tags.null, class: "l" },
+    { tag: tags.atom, class: "l" },
+    { tag: tags.unit, class: "l" },
+    { tag: tags.modifier, class: "g" },
+    { tag: tags.operatorKeyword, class: "ow" },
+    { tag: tags.controlKeyword, class: "k" },
+    { tag: tags.definitionKeyword, class: "kd" },
+    { tag: tags.moduleKeyword, class: "kn" },
+    { tag: tags.operator, class: "o" },
+    { tag: tags.derefOperator, class: "o" },
+    { tag: tags.arithmeticOperator, class: "o" },
+    { tag: tags.logicOperator, class: "o" },
+    { tag: tags.bitwiseOperator, class: "o" },
+    { tag: tags.compareOperator, class: "o" },
+    { tag: tags.updateOperator, class: "o" },
+    { tag: tags.definitionOperator, class: "o" },
+    { tag: tags.typeOperator, class: "o" },
+    { tag: tags.controlOperator, class: "o" },
+    { tag: tags.punctuation, class: "p" },
+    { tag: tags.separator, class: "dl" },
+    { tag: tags.bracket, class: "p" },
+    { tag: tags.angleBracket, class: "p" },
+    { tag: tags.squareBracket, class: "p" },
+    { tag: tags.paren, class: "p" },
+    { tag: tags.brace, class: "p" },
+    { tag: tags.content, class: "g" },
+    { tag: tags.heading, class: "gh" },
+    { tag: tags.heading1, class: "gu" },
+    { tag: tags.heading2, class: "gu" },
+    { tag: tags.heading3, class: "gu" },
+    { tag: tags.heading4, class: "gu" },
+    { tag: tags.heading5, class: "gu" },
+    { tag: tags.heading6, class: "gu" },
+    { tag: tags.contentSeparator, class: "dl" },
+    { tag: tags.list, class: "p" },
+    { tag: tags.quote, class: "p" },
+    { tag: tags.emphasis, class: "ge" },
+    { tag: tags.strong, class: "gs" },
+    { tag: tags.link, class: "g" },
+    { tag: tags.monospace, class: "go" },
+    { tag: tags.strikethrough, class: "gst" },
+    { tag: tags.inserted, class: "gi" },
+    { tag: tags.deleted, class: "gd" },
+    { tag: tags.changed, class: "g" },
+    { tag: tags.invalid, class: "err" },
+    { tag: tags.meta, class: "c" }
+]);
+
+// Basic, built-in extensions.
+const editorSetup = (() => [
+    lineNumbers(),
+    highlightActiveLineGutter(),
+    highlightSpecialChars(),
+    history(),
+    foldGutter(),
+    drawSelection(),
+    dropCursor(),
+    indentOnInput(),
+    bracketMatching(),
+    closeBrackets(),
+    highlightActiveLine(),
+    keymap.of([
+        ...closeBracketsKeymap,
+        ...defaultKeymap,
+        ...historyKeymap,
+        ...foldKeymap,
+    ]),
+    syntaxHighlighting(rougeStyle, {
+        fallback: true
+    })
+])();
+
+
+// The "@codemirror/language-data" does not support community languages,
+// so we add support for those ourselves.
+const additionalLanguages = [
+    LanguageDescription.of({
+        name: "R",
+        alias: ["rlang"],
+        extensions: ["r"],
+        load() {
+            return import("codemirror-lang-r").then(m => m.r());
+        }
+    }),
+    LanguageDescription.of({
+        name: "Prolog",
+        alias: ["rlang"],
+        extensions: ["pl", "pro", "p"],
+        load() {
+            return import("codemirror-lang-prolog").then(m => m.prolog());
+        }
+    }),
+    LanguageDescription.of({
+        name: "C#",
+        alias: ["csharp", "cs"],
+        extensions: ["cs"],
+        load() {
+            return import("@replit/codemirror-lang-csharp").then(m => m.csharp());
+        }
+    }),
+];
+
+
+async function loadProgrammingLanguage(language: string): Promise<Extension | undefined> {
+    const potentialLanguages = additionalLanguages.concat(languages);
+    const description = LanguageDescription.matchLanguageName(potentialLanguages, language);
+    if (description) {
+        await description.load();
+        return description.support;
+    }
+    console.warn(`${language} is not supported by our editor, falling back to nothing.`);
+}
+
+/**
+ * Set up the code editor.
+ *
+ * @param parent The element to insert the editor into. Existing content will be inserted into the editor.
+ * @param programmingLanguage The programming language of the editor. Will attempt to load language support.
+ * @param focusHandler A callback that will be called when the editor receives focus.
+ */
+export async function configureEditor(parent: Element, programmingLanguage: string, focusHandler: EditorEventHandler): Promise<EditorView> {
+    const existingCode = parent.textContent;
+    // Clear the existing code, as we will put it in CodeMirror.
+    parent.textContent = "";
+    const eventHandlers = EditorView.domEventHandlers({
+        "focus": focusHandler
+    });
+    const languageSupport = await loadProgrammingLanguage(programmingLanguage);
+    const languageExtensions = [];
+    if (languageSupport !== undefined) {
+        languageExtensions.push(languageSupport);
+    }
+    return new EditorView({
+        doc: existingCode,
+        extensions: [
+            // Basic editor functionality
+            editorSetup,
+            // Listen for focus
+            eventHandlers,
+            // Language support
+            ...languageExtensions
+        ],
+        parent: parent
+    });
+}
+
+
+/**
+ * Set the content of a code editor.
+ *
+ * @param editorView The code editor to set the content in.
+ * @param code The code to insert.
+ */
+export function setCode(editorView: EditorView, code: string): void {
+    editorView.dispatch(editorView.state.update({
+        changes: {
+            from: 0,
+            to: editorView.state.doc.length,
+            insert: code,
+        }
+    }));
+}