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package org.luaj.vm2.lib;
import org.luaj.vm2.LuaValue;
import org.luaj.vm2.Varargs;
/** Abstract base class for Java function implementations that takes varaiable arguments and
* returns multiple return values.
*
* Subclasses need only implement {@link LuaValue#invoke(Varargs)} to complete this class,
* simplifying development.
* All other uses of {@link #call(LuaValue)}, {@link #invoke()},etc,
* are routed through this method by this class,
* converting arguments to {@linnk Varargs} and
* dropping or extending return values with {@code nil} values as required.
*
* If between one and three arguments are required, and only one return value is returned,
* {@link ZeroArgFunction}, {@link OneArgFunction}, {@link TwoArgFunction}, or {@link ThreeArgFunction}.
*
* See {@link LibFunction} for more information on implementation libraries and library functions.
* @see #invoke(Varargs)
* @see LibFunction
* @see ZeroArgFunction
* @see OneArgFunction
* @see TwoArgFunction
* @see ThreeArgFunction
*/
abstract public class VarArgFunction extends LibFunction {
public VarArgFunction() {
}
public LuaValue call() {
return invoke(NONE).arg1();
}
public LuaValue call(LuaValue arg) {
return invoke(arg).arg1();
}
public LuaValue call(LuaValue arg1, LuaValue arg2) {
return invoke(varargsOf(arg1,arg2)).arg1();
}
public LuaValue call(LuaValue arg1, LuaValue arg2, LuaValue arg3) {
return invoke(varargsOf(arg1,arg2,arg3)).arg1();
}
/**
* Subclass responsibility.
* May not have expected behavior for tail calls.
* Should not be used if:
* - function has a possibility of returning a TailcallVarargs
* @param args the arguments to the function call.
*/
public Varargs invoke(Varargs args) {
return onInvoke(args).eval();
}
public Varargs onInvoke(Varargs args) {
return invoke(args);
}
}