Output now uses CodeMirror editor

src/web/utils/editorUtils.mjs

@@ -0,0 +1,28 @@
+/**
+ * CodeMirror utilities that are relevant to both the input and output
+ *
+ * @author n1474335 [n1474335@gmail.com]
+ * @copyright Crown Copyright 2022
+ * @license Apache-2.0
+ */
+
+
+/**
+ * Override for rendering special characters.
+ * Should mirror the toDOM function in
+ * https://github.com/codemirror/view/blob/main/src/special-chars.ts#L150
+ * But reverts the replacement of line feeds with newline control pictures.
+ * @param {number} code
+ * @param {string} desc
+ * @param {string} placeholder
+ * @returns {element}
+ */
+export function renderSpecialChar(code, desc, placeholder) {
+    const s = document.createElement("span");
+    // CodeMirror changes 0x0a to "NL" instead of "LF". We change it back.
+    s.textContent = code === 0x0a ? "\u240a" : placeholder;
+    s.title = desc;
+    s.setAttribute("aria-label", desc);
+    s.className = "cm-specialChar";
+    return s;
+}