Man Boy Test Written in Zig

manBoyTest.zig

const std = @import("std");

const Frame = struct {
  f: *const fn (frame: *Frame) i32,
  k: *i32 = undefined,
  x1: *Frame = undefined,
  x2: *Frame = undefined,
  x3: *Frame = undefined,
  x4: *Frame = undefined,
  x5: *Frame = undefined,

  pub fn next(f: *Frame, k: *i32, x1: *Frame, x2: *Frame, x3: *Frame, x4: *Frame, x5: *Frame) *Frame {
    f.k = k;
    f.x1 = x1;
    f.x2 = x2;
    f.x3 = x3;
    f.x4 = x4;
    f.x5 = x5;
    return f;
  }
};

fn F(a: *Frame) i32 { return a.k.*; }
 
fn eval(a: *Frame) i32 { return a.f(a); }
 
fn B(a: *Frame) i32 {
  a.k.* -= 1;
  var k: i32 = a.k.*;
  var b = Frame{ .f = B };
  return A(Frame.next(&b, &k, a, a.x1, a.x2, a.x3, a.x4));
}
 
fn A(a: *Frame) i32 {
  if (a.k.* <= 0) { return eval(a.x4) + eval(a.x5); }
  else { return B(a); }
}

pub fn main() !void {
  var k: i32 = 10;
  var zero: i32 = 0;
  var one: i32 = 1;
  var negOne: i32 = -1;

  var a = Frame{ .f = B };
  var f1 = Frame{ .f = F, .k = &one };
  var f0 = Frame{ .f = F, .k = &zero };
  var fn1 = Frame{ .f = F, .k = &negOne };

  std.debug.print("{}\n", .{ A(Frame.next(&a, &k, &f1, &fn1, &fn1, &f1, &f0)) });
}