Java method for compiling Lua code with the LuaJ interpreter

Question

http://luaj.org/luaj/README.html

I'm using Luaj to run Lua code in a Java application. I'm getting some really slow results, so I want to try to compile the code before running it to calculate the actual proccesing time of a Lua script.

The problem is - Luaj does show an example how to compile Lua source to Lua or Java bytecode through the command prompt, but it doesn't show me the lines to compile a Lua script with a Java application.

It only shows how to compile AND run a Lua script:

import org.luaj.vm2.*;
import org.luaj.vm2.lib.jse.*;

String script = "examples/lua/hello.lua";
LuaValue _G = JsePlatform.standardGlobals();
_G.get("dofile").call( LuaValue.valueOf(script) );

I want to find the code that would only compile Lua to Lua or Java bytecode and would output a bytecode file.

Answer 1

LuaJ contains a Lua to bytecode compiler. So you can just look at the source code. I have extracted the most relevant portion here.

private void processScript( InputStream script, String chunkname, OutputStream out ) throws IOException {
    try {
        // create the chunk
        Prototype chunk = LuaC.instance.compile(script, chunkname);

        // list the chunk
        if (list)
            Print.printCode(chunk);

        // write out the chunk
        if (!parseonly) {
            DumpState.dump(chunk, out, stripdebug, numberformat, littleendian);
        }

    } catch ( Exception e ) {
        e.printStackTrace( System.err );
    } finally {
        script.close();
    }
}

Keep in mind that you can only really rely on byte code being compatible with the implementation of Lua that produced it.