Add comments describing what the pre/post processor functions do

lib/preprocessors/glimmer.js

@@ -9,6 +9,21 @@ const util = require('ember-template-imports/src/util');
 const TRANSFORM_CACHE = new Map();
 const TEXT_CACHE = new Map();
 
+/**
+ * This function is responsible for running the embedded templates transform
+ * from ember-template-imports.
+ *
+ * It takes a gjs or gts file and converts <template> tags to their
+ * intermediary (private) format.
+ *
+ * This is needed so that eslint knows what variables accessed within the template
+ * are missing or accessed within the JS scope, because
+ * part of the output includes a snippet that looks like:
+ *
+ * `, { strictMode: true, scope: () => ({on,noop}) })]
+ *
+ * So if on and noop are not present in the JS, we will have an error to work with
+ */
 function gjs(text, filename) {
   const isGlimmerFile = filename.endsWith('.gjs') || filename.endsWith('.gts');
 
@@ -21,6 +36,11 @@ function gjs(text, filename) {
     ];
   }
 
+  /**
+   * If the file is already processed, we don't need to process it again.
+   *
+   * a file will not have a TEMPLATE_TAG_PLACEHOLDER unless it has been processed
+   */
   if (text.includes(util.TEMPLATE_TAG_PLACEHOLDER)) {
     return [
       {
@@ -61,6 +81,12 @@ function gjs(text, filename) {
   ];
 }
 
+/**
+ * This function is for mapping back from the intermediary (private) format
+ * back to gjs/gts / <template> so that we can appropriatly display errors
+ * or warnings in the correct location in the original source file in the user's
+ * editor.
+ */
 function mapRange(messages, filename) {
   const transformed = TRANSFORM_CACHE.get(filename);
   const original = TEXT_CACHE.get(filename);