A simple memoization with AspectJ, for golden ratio calculation.

GoldenRatio.java

package tests.recursive;

public class GoldenRation {
    public static long fib(int n) {
        if (n <= 1) return n;
        else return fib(n-1) + fib(n-2);
    }
    
    public static double goldenratio(int n){
    	return fib(n+1)*Math.pow(fib(n),-1);
    }

    public static void main(String[] args) {
        int N = Integer.parseInt(args[0]);
        for (int i = 2; i <= N; i++)
            System.out.println(i + ": " + goldenratio(i));
    }

}

MemoizeAspect.aj

package tests.recursive;

import java.util.HashMap;

public aspect MemoizeAspect {
	HashMap<Integer, Long> mem = new HashMap<Integer, Long>();
	
	pointcut RecPointcut(Integer num) : execution (long fib(*)) && args(num);
	
	long around (Integer num) : RecPointcut(num)
	{
		long ret;
		if(mem.containsKey(num))
			ret = mem.get(num);
		else
		{
			ret = proceed(num);
			mem.put(num, ret);
		}
		return ret;
	}
}