Can PMD be customized to fully support a new language?

Question

Can PMD be customized to fully support a new language, in a reasonable amount of time. I mean I know that technically almost anything can be done, but im wondering if this can be done in a reasonable amount of time? E.g. < 2 weeks

This page mentions how to write a CPD parser http://pmd.sourceforge.net/cpd-parser-howto.html

But is this just for copy / paste detection? Does writing a CPD parser give me full support of PMD in terms of rile sets?

Answer 1

I would guess not, but I'm not a PMD expert (and I have my own bias, check my bio).

The issues are:

• Can you define a syntax for my langauge quickly (maybe, depending on how good you are, how messy the language is, and the strength of the parsing machinery offered by PMD)
• Can you define the semantics of my language so that "semantic checks" provided by PMD work. You have to do this, because syntax tells you (and a tool) literally nothing about semantic of the syntax. I would guess that the PMD tool 'semantic checks' are pretty wired into the precise details of Java; if you language matched java perfectly, this would be zero work. But it doesn't, or you wouldn't be asking the question. And langauge semantics differences, even minor ones, cause discontinuous changes to the interpreation of the code. Before you get to doing even "serious" semantics, you're likely to have to build a symbol table mapping identifiers in the code to declarations (and the "semantic" type) for those symbols. Based on tool infrastructure I work with, this step alone takes 1-2 months for a real language.
• Lastly, you are likely to have to code special PMD checks that are specific to your langauge. That takes time and energy, too.

I build generic compiler-type machinery (parsers, flow analyzers, style/error checkers) and get asked the equivalent of this question all the time WRT to our machinery. We try to have a lot of machinery available, try to make it easy to integrate new langauges, and we've been working on trying to make this "convenient and fast" for 15+ years. Its still not convenient, and there's no way to do this with our tools in a few weeks. I doubt PMD is better.