Hi all,

I'm trying to find out a solution to implement a generic tree or array container whose nodes
can either be elements or a subtree (or sub-array).

Pretty much like you can do in Python:

l = [1, 2, [1, 2, 3], 4]

l is a list of (integers or list of integers).

Any idea on how to do that?

Thanks.

On Monday, 26 October 2015 at 18:46:45 UTC, Dandyvica wrote:
> Hi all,
>
> I'm trying to find out a solution to implement a generic tree or array container whose nodes
> can either be elements or a subtree (or sub-array).
>
> Pretty much like you can do in Python:
>
> l = [1, 2, [1, 2, 3], 4]
>
> l is a list of (integers or list of integers).
>
> Any idea on how to do that?
>
> Thanks.

It's a bit more involved than in Python as D is not a dynamically typed language.

import std.typecons;
import std.stdio;

struct Tree(T)
{
	T payload;
	Tree!T[] children;
}

Tree!T tree(T)(T payload, Tree!T[] children...)
{
	return Tree!T(payload, children.dup);
}

//Convenience overload because typeof(null)
//does not implicitly convert to Tree!T[]
Tree!T tree(T)(T payload, typeof(null))
{
	return Tree!T(payload, null);
}

void printTree(T)(Tree!T tree)
{
	writeln(tree.payload);
	foreach (child; tree.children)
	{
		printTree(child);
	}
}

void main()
{
	auto intTree = tree(0,
		           tree(1,
		               tree(2)),
			   tree(3,
			       tree(4,
			           tree(5))),
			   tree(6,
			       tree(7)));

	printTree(intTree);
}

Otherwise, you an use std.variant.Variant or std.variant.Algebraic.

On Monday, 26 October 2015 at 19:26:08 UTC, Meta wrote:
> On Monday, 26 October 2015 at 18:46:45 UTC, Dandyvica wrote:
>> Hi all,
>>
>> I'm trying to find out a solution to implement a generic tree or array container whose nodes
>> can either be elements or a subtree (or sub-array).
>>
>> Pretty much like you can do in Python:
>>
>> l = [1, 2, [1, 2, 3], 4]
>>
>> l is a list of (integers or list of integers).
>>
>> Any idea on how to do that?
>>
>> Thanks.
>
> It's a bit more involved than in Python as D is not a dynamically typed language.
>
> import std.typecons;
> import std.stdio;
>
> struct Tree(T)
> {
> 	T payload;
> 	Tree!T[] children;
> }
>
> Tree!T tree(T)(T payload, Tree!T[] children...)
> {
> 	return Tree!T(payload, children.dup);
> }
>
> //Convenience overload because typeof(null)
> //does not implicitly convert to Tree!T[]
> Tree!T tree(T)(T payload, typeof(null))
> {
> 	return Tree!T(payload, null);
> }
>
> void printTree(T)(Tree!T tree)
> {
> 	writeln(tree.payload);
> 	foreach (child; tree.children)
> 	{
> 		printTree(child);
> 	}
> }
>
> void main()
> {
> 	auto intTree = tree(0,
> 		           tree(1,
> 		               tree(2)),
> 			   tree(3,
> 			       tree(4,
> 			           tree(5))),
> 			   tree(6,
> 			       tree(7)));
>
> 	printTree(intTree);
> }
>
> Otherwise, you an use std.variant.Variant or std.variant.Algebraic.

Thanks Meta, great idea.

But does I'd like to have something like dynamic arrays and be able to do this:

class A(T) { T _v; this(T v) { _v = v; }  }

auto myContainer = MyContainerArray!(A!int)();

myContainer ~= new A!int(1);
myContainer ~= new A!int(2);

auto myInnerContainer = MyContainerArray!(A!int)();
myInnerContainer ~= new A!int(3);
myInnerContainer ~= new A!int(4);

myContainer ~= myInnerContainer;
myContainer ~= new A!int(5);

I don't know if your implementation allows this?

On Monday, 26 October 2015 at 20:53:18 UTC, Dandyvica wrote:
> Thanks Meta, great idea.
>
> But does I'd like to have something like dynamic arrays and be able to do this:
>
> class A(T) { T _v; this(T v) { _v = v; }  }
>
> auto myContainer = MyContainerArray!(A!int)();
>
> myContainer ~= new A!int(1);
> myContainer ~= new A!int(2);
>
> auto myInnerContainer = MyContainerArray!(A!int)();
> myInnerContainer ~= new A!int(3);
> myInnerContainer ~= new A!int(4);
>
> myContainer ~= myInnerContainer;
> myContainer ~= new A!int(5);
>
> I don't know if your implementation allows this?

There is a Red Black Tree implement in std.container.rbtree (http://dlang.org/phobos/std_container_rbtree.html). I'm not sure if it supports the concatenation operator or not, though.