xPad Pro is a simple text editor without formatting, but with some extra functions. In addition to opening text files, it's also very useful for breaking the formatting of text copied from other apps.
Selecting the desired language, it will be recognized in the text. At the same time the text will be colored and the parts of code enabled the grouping will be indicated by the "boxtree" (squares with plus and minus symbols). This app is a great way to edit your project file without loading the entire native frameworks each time.