leonrd / lpegj

Port of LPEG 0.10.1 to Java, and bindings for LuaJ.

LPEG/J

This is a straight port of the LPEG compiler and virtual machine to Java. It also includes a binding to LuaJ, so Lua scripts running under LuaJ can use it as if it were LPEG 0.10.1 (with require "lpegj.luaj.lpeg"), with the caveats below.

Caveats

• LuaJ does not have a 100% faithful implementation of arithmetic metamethods, so things like 1 - p where p is a pattern do not work; use lpeg.P(1) - p. Things like p + 1 work, though. The file test.lua has been adjusted accordingly.

• Almost no optimizations yet in the generated patterns, just the simplest identities

• NO VERIFIER, so you may write patterns that hang and the compiler will not detect it

• A lot of sanity checking that LPEG does to detect erroneous patterns and captures is missing

As a rule of thumb, if it works in LPEG it should work in LPEG/J, and if it does not work in LPEG it may give a spurious result in LPEG/J. Plans are to do the verifier first, then sanity checking, and the funky optimizations last.

License

The license is the same as Lua.