Adding documentation to charset.js

src/js/parser/javascript/charset.js

@@ -1,9 +1,17 @@
+// Charset nodes are used for `[abc1-9]` regular expression syntax. It is
+// rendered as a labeled box with each literal, escape, and range rendering
+// handled by the nested node(s).
+
 import util from '../../util.js';
 import _ from 'lodash';
+
 export default {
   type: 'charset',
 
   definedProperties: {
+    // Default anchor is overridden to move it down so that it connects at the
+    // middle of the box that wraps all of the charset parts, instead of the
+    // middle of the container, which would take the label into account.
     _anchor: {
       get: function() {
         var matrix = this.transform().localMatrix;
@@ -15,17 +23,21 @@ export default {
     }
   },
 
+  // Renders the charset into the currently set container.
   _render() {
     this.partContainer = this.container.group();
 
+    // Renders each part of the charset into the part container.
     return Promise.all(_.map(this.elements, part => {
       return part.render(this.partContainer.group());
     }))
       .then(() => {
+        // Space the parts of the charset vertically in the part container.
         util.spaceVertically(this.elements, {
           padding: 5
         });
 
+        // Label the part container.
         return this.renderLabeledBox(this.label, this.partContainer, {
           padding: 5
         });
@@ -33,11 +45,24 @@ export default {
   },
 
   setup() {
+    // The label for the charset will be:
+    // - "One of:" for charsets of the form: `[abc]`.
+    // - "None of:" for charsets of the form: `[^abc]`.
     this.label = (this.properties.invert.textValue === '^') ? 'None of:' : 'One of:';
+
+    // Removes any duplicate parts from the charset. This is based on the type
+    // and text value of the part, so `[aa]` will have only one item, but
+    // `[a\x61]` will contain two since the first matches "a" and the second
+    // matches 0x61 (even though both are an "a").
     this.elements = _.unique(this.properties.parts.elements, part => {
       return `${part.type}:${part.textValue}`;
     });
 
+    // Include a warning for charsets that attempt to match `\c` followed by
+    // any character other than A-Z (case insensitive). Charsets like `[\c@]`
+    // behave differently in different browsers. Some match the character
+    // reference by the control charater escape, others match "\", "c", or "@",
+    // and some do not appear to match anything.
     if (this.textValue.match(/\\c[^a-zA-Z]/)) {
       this.state.warnings.push(`The character set "${this.textValue}" contains the \\c escape followed by a character other than A-Z. This can lead to different behavior depending on browser. The representation here is the most common interpretation.`);
     }