Adding documentation to subexp.js

src/js/parser/javascript/subexp.js

@@ -1,9 +1,14 @@
+// Subexp nodes are for expressions inside of parenthesis. It is rendered as a
+// labeled box around the contained expression if a label is required.
+
 import _ from 'lodash';
 
 export default {
   type: 'subexp',
 
   definedProperties: {
+    // Default anchor is overridden to move it down to account for the group
+    // label and outline box.
     _anchor: {
       get: function() {
         var anchor = this.regexp.getBBox(),
@@ -24,37 +29,38 @@ export default {
     '?!': 'negative lookahead'
   },
 
+  // Renders the subexp into the currently set container.
   _render() {
-    // NOTE: this.label() MUST be called here, in _render and before any child
+    // **NOTE:** `this.label()` **MUST** be called here, in _render, and before
-    // nodes are rendered. This is to keep the group numbers in the correct
+    // any child nodes are rendered. This is to keep the group numbers in the
-    // order.
+    // correct order.
     var label = this.label();
 
+    // Render the contained regexp.
     return this.regexp.render(this.container.group())
       .then(() => {
+        // Create the labeled box around the regexp.
         return this.renderLabeledBox(label, this.regexp, {
           padding: 10
         });
       });
   },
 
+  // Returns the label for the subexpression.
   label() {
-    if (typeof this._label === 'undefined') {
     if (_.has(this.labelMap, this.properties.capture.textValue)) {
-        this._label = this.labelMap[this.properties.capture.textValue];
+      return this.labelMap[this.properties.capture.textValue];
     } else {
-        this._label = 'group #' + (this.state.groupCounter++);
+      return `group #${this.state.groupCounter++}`;
     }
-    }
-
-    return this._label;
   },
 
   setup() {
-    // NOTE: DO NOT call this.label() in setup. It will lead to groups being
+    // **NOTE:** **DO NOT** call `this.label()` in setup. It will lead to
-    // numbered in reverse order
+    // groups being numbered in reverse order.
     this.regexp = this.properties.regexp;
 
+    // If there is no need for a label, then proxy to the nested regexp.
     if (this.properties.capture.textValue == '?:') {
       this.proxy = this.regexp;
     }