Am 22.08.2010 21:45, schrieb bearophile:
(...)
import std.stdio: writeln;
import std.typecons: Tuple, tuple;
import std.traits: ReturnType, ParameterTypeTuple;
struct Memoize(alias F) {
ReturnType!F opCall(ParameterTypeTuple!F args) {
alias ReturnType!F ResultType;
static ResultType[Tuple!(ParameterTypeTuple!F)] cache;
auto ptr = tuple(args) in cache;
if (ptr == null) {
auto result = F(args);
cache[tuple(args)] = result;
return result;
} else {
return *ptr;
}
}
}
pure int fib(int n) {
if (n< 2)
return n;
return fib(n - 1) + fib(n - 2);
}
void main() {
pure int delegate(int n) cfib_impl;
Memoize!cfib_impl cfib;
cfib_impl = (int n) {
if (n< 2)
return n;
return cfib(n - 1) + cfib(n - 2);
};
enum int N = 40;
writeln("fib(", N, ") = ", fib(N));
writeln("cfib(", N, ") = ", cfib(N));
}
Bye,
bearophile
I see; I should use template magic. Oh, and I used Tuple the wrong way
beacuse I've never used it before.
Thanks
Mafi
