Refactored code to improve readability and maintainability

<!-- Thank you for proposing a contribution to StringTemplate! (Please make sure your PR is in a branch other than dev or master and also make sure that you derive this branch from dev.) As of 4.3.2, StringTemplate uses the Linux Foundation's Developer Certificate of Origin, DCO, version 1.1. See either https://developercertificate.org/ or file contributors-cert-of-origin.txt in the main directory. Each commit requires a "signature", which is simple as using `-s` (not `-S`) to the git commit command: git commit -s -m 'This is my commit message' Github's pull request process enforces the sig and gives instructions on how to fix any commits that lack the sig. See https://github.com/apps/dco for more info. No signature is required in this file (unlike the previous StringTemplate contributor's certificate of origin.) --> Hello, I'm just starting my journey contributing to open-source projects and I've refactored certain methods and classes for better maintainability and/or readability. Kindly let me know how it goes. Thanks!