How can I parse code to build a compiler in Java?

Question

I need to write a compiler. It's homework at the univ. The teacher told us that we can use any API we want to do the parsing of the code, as long as it is a good one. That way we can focus more on the JVM we will generate.

So yes, I'll write a compiler in Java to generate Java.

Do you know any good API for this? Should I use regex? I normally write my own parsers by hand, though it is not advisable in this scenario.

Any help would be appreciated.

Answer 1

I suggest you look at at the source for BeanShell. It has a compiler for Java and is fairly simple to read.

Answer 2

JFlex is a scanner generator which, according to the manual, is designed to work with the parser generator CUP.

One of the main design goals of JFlex was to make interfacing with the free Java parser generator CUP as easy as possibly [sic].

It also has support for BYACC/J, which, as its name suggests, is a port of Berkeley YACC to generate Java code.

I have used JFlex itself and liked it. Howeveer, the project I was doing was simple enough that I wrote the parser by hand, so I don't know how good either CUP or BYACC/J is.

Answer 3

Have a look at JavaCC, a language parser for Java. It's very easy to use and get the hang of

Answer 4

Parser combinators is a good choice. Popular Java implementation is JParsec.

Answer 5

I'd recommend using either a metacompiler like ANTLR, or a simple parser combinator library. Functional Java has a parser combinator API. There's also JParsec. Both of these are based on the Parsec library for Haskell.

Answer 6

http://java-source.net/open-source/parser-generators and http://catalog.compilertools.net/java.html contain catalogs of tools for this. Compare also the Stackoverflow question Alternatives to Regular Expressions.