The worst D code you'll ever see

[H. S. Teoh]

On Tue, Jan 15, 2019 at 10:55:02AM +0000, bauss via Digitalmars-d wrote:
> I think I just wrote the worst D code in existence.
> 
> https://www.reddit.com/r/badcode/comments/aftpcf/bad_code_coding_challenge_2_primes_between_x_and_y/ee41he6/
> 
> What it does is find prime numbers between X and Y and adds them to an
> array.
> 
> It's part of a coding challenge to write bad code, but figured I'd
> share here.
> 
> It's rare I see D used in contests, so I figured I would use it for
> this one.
> 
> Enjoy the cringe.

It may be bad code, but it will not make me cringe until it looks like
an IOCCC entry.  For example (in C):

	#include <stdio.h>
	#include <stdlib.h>
	#include <time.h>


	/* Defines */

	#ifndef NO_STTY
	#define S1 system("stty cbreak -echo")||
	#define S2 system("stty sane")||
	#else
	#define S1
	#define S2
	#endif

	#define A(i) (((q*)R(8))[i])
	#define B p(b)
	#define C p(&a)
	#define H(i) sscanf(A(i),"%ld",&R(i+11))&0 ||
	#define P q*
	#define M(a,b) main((i)(a),(P)(b))

	#define p(x) ((i*)(x))
	#define D T(B-C,C-B)
	#define T(x,y) ((a&1)*((i)(x))+(~a&1)*((i)(y)))
	#define R(x) (*(B+x))
	#define q char*
	#define Q(x) ((q)(x))
	#define W(x,y) ((B[x]=(i)(y))&0)||
	#define BS (w*l*h)
	#define do(x,y) (a-x||y)&&
	#define f(x) M(x,b)
	#define if(p,q,r,s) ((p)&&!(q)||(s))&&(r)||
	#define i long
	#define I (int)

	#define while(x,y,z) do(x, y && !(z) && f(a))
	#define for(s,i,x,y,z,Z) W(i,x)f(s)||Z) && while(s,R(i)-y,z||W(i,R(i)+1)0)(s
	#define return return do
	#define w R(12)
	#define l R(13)
	#define h R(14)
	#define X(i) (R(i)%w)
	#define Y(i) ((R(i)%(w*l))/w)

	#define Z(i) (R(i)/(w*l))
	#define pr !printf
	#define switch(x) (W(32+R(15),R(32+x+R(15))) W(32+x+R(15),0) (B[15]+=x)|1)
	#define case(k,x,y) R(a)==k && x && switch(y) && f(13)||
	#define TL(i) R(32+R(i))


	/* Main program */

	int main(int a, P b) {
		return(1>>1^1, M(6+!!M(5,C),C))

		do(
			13,
			pr("\x1b[;H")||

			for(14,4,0,BS,!X(4)&&pr(
				"%*s",
				I(l-Y(4)),
				""
			)

			||

			if(TL(4),pr(
				"%*ld",I
				R(31),
				TL(4)),0,
				pr("%*.*s",I
				R(31),
				I R(31),"#####")
			)
			if(X(4)==w-1 , pr("\n"),0 , pr("%*s", I(l+1), "")) (
				(R(4)+1)%(w*l)==0 && l>1)&&
				pr("\n"),0))
				do(
					1&~1,
					pr("Syntax: %s <x> <y> [<z>]\n", b[0])||f(15)
				)((a&~1)

				-6||D>>12
				&&(*(p(T(C,b))+8)=*p(Q(b)+(Q(&b)-Q(C)))
			)
				
			&&(*(p(T(C,b))+9) = *p(b))&&M(
				8,T(C,b))
			||

			f( a) )&&do(
				8,
				if(R(9)&1,H(1)H(
					2 ) 0,W(14,
					l)W(13,1)0,
					H(1
				)

				H(2)
				H(3)
				0)(srand(time(0)),0
			) ||for(9,4, 0,BS, f(16)

		|| W(R(4)+32,R(0))!R(0) && W(15,R(4) )0,
		
		W(
			31,
			snprintf(A(0),1,"%ld",BS))
			S1 pr("\x1b[2J") ||
				f(13)
			||
		
			f(18) ||
				f(15)
			))

			do(
				16,W(0,rand()%BS
			) W(1,0)

			for(17, 5, 0,R(4),! (
				TL(
					5)-R(0))&&! (
					W(1,1)
					W(5,R(4)-1)
					0),R(1)&&f(16))
				)

				do(
					18,W(0,0
				) for(19,4,0,BS, TL(4)-(R(4)+1)
				
				%BS&& (
					W(0,1)
					W(4,BS-1
				) 0)||0,!R(0) &&

				pr(
					"You win!\n"
				)
				||
				R(0)&& (
					W(a,getchar())
					case('i',
						0<Z(15),
						-w*l)
					case('j',
						0<X(15),
						-1)
					case('k',
						Z(15)<h-1,
						w*l)
					case('l',
						X(15)<w-1,
						1)
					case('n',
						Y(15)<l-1,
						w)
					case('o',
						0<Y(15),-w
				)
				R(a)=='q'&&!
				
				pr(
					"You lose :-)\n"
				)
				&&f(15)||f(a))
			)
		)

		do(
			15,S2 
			(exit(0),a)
		) (a-5||C<p(b));
	}

Exercise for the reader: figure out how this code works.

(Hint: it's much worse than it looks. And I do mean MUCH worse. You
won't even begin to appreciate just how nasty this code is until you've
unravelled the first several layers of obfuscation. (And no, running it
through the preprocessor first does not make it any more readable -- in
fact, quite the opposite. :-P))

One of these days, I might take a shot at doing this in D... Be afraid,
be very afraid! :-D


T

-- 
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