Update a few comments and add profile script

Author: gregjacobs

package.json

@@ -22,6 +22,7 @@
         "lint": "eslint src tests scripts",
         "lint:fix": "npm run lint -- --fix",
         "prepublishOnly": "npm-run-all build test",
+        "profile": "node --inspect --require ts-node/register benchmarks/profile.ts",
         "start": "webpack serve --open",
         "test": "npm-run-all test:unit test:integration",
         "test:ci": "npm-run-all coverage test:integration",

src/parser/parse-matches.ts

@@ -1164,17 +1164,11 @@ function captureMatchIfValidAndRemove(context: ParseMatchesContext, stateMachine
         case StateMachineType.Url: {
             // We don't want to accidentally match a URL that is preceded by an
             // '@' character, which would be an email address
-            const charBeforeUrlMatch = text.charAt(stateMachine.startIdx - 1);
-            if (charBeforeUrlMatch === '@') {
+            const charBeforeUrlMatch = text.charCodeAt(stateMachine.startIdx - 1);
+            if (charBeforeUrlMatch === Char.AtSign /* '@' */) {
                 return;
             }
 
-            // For the purpose of this parser, we've generalized 'www'
-            // matches as part of 'tld' matches. However, for backward
-            // compatibility, we distinguish beween TLD matches and matches
-            // that begin with 'www.' so that users may turn off 'www'
-            // matches. As such, we need to correct for that now if the
-            // URL begins with 'www.'
             switch (stateMachine.matchType) {
                 case UrlStateMachineMatchType.Scheme: {
                     // Autolinker accepts many characters in a url's scheme (like `fake://test.com`).

src/parser/uri-utils.ts

@@ -205,6 +205,8 @@ export function isValidTldMatch(url: string): boolean {
 }
 
 // Regular expression to confirm a valid IPv4 address (ex: '192.168.0.1')
+// TODO: encode this into the state machine so that we don't need to run this
+//       regexp separately to confirm the match
 const ipV4Re =
     /^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/;