src/main/java/org/luaj/vm3/LuaFunction.java

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package org.luaj.vm3;

/** 
 * Base class for functions implemented in Java. 
 * <p>
 * Direct subclass include {@link LibFunction} which is the base class for 
 * all built-in library functions coded in Java, 
 * and {@link LuaClosure}, which represents a lua closure 
 * whose bytecode is interpreted when the function is invoked.    
 * @see LuaValue
 * @see LibFunction
 * @see LuaClosure
 */
abstract public class LuaFunction extends LuaValue {

	/** Shared static metatable for all functions and closures. */
	public static LuaValue s_metatable;

	public int type() {
		return TFUNCTION;
	}

	public String typename() {
		return "function";
	}

	public boolean isfunction() {
		return true;
	}

	public LuaFunction checkfunction() {
		return this;
	}

	public LuaFunction optfunction(LuaFunction defval) {
		return this;
	}

	public LuaValue getmetatable() {
		return s_metatable;
	}

	public String tojstring() {
		return "function: " + classnamestub();
	}

	public LuaString strvalue() {
		return valueOf(tojstring());
	}

	/** Return the last part of the class name, to be used as a function name in tojstring and elsewhere. 
	 * @return String naming the last part of the class name after the last dot (.) or dollar sign ($).
	 */
	public String classnamestub() {
		String s = getClass().getName();
		return s.substring(Math.max(s.lastIndexOf('.'), s.lastIndexOf('$')) + 1);
	}

	/** Return a human-readable name for this function.  Returns the last part of the class name by default.
	 * Is overridden by LuaClosure to return the source file and line, and by LibFunctions to return the name.
	 * @return common name for this function.  */
	public String name() {
		return classnamestub();
	}
}