On Monday, 30 January 2017 at 11:03:52 UTC, Profile Anaysis wrote:
I need to yield from a complex recursive function too allow
visualizing what it is doing.
e.g., if it is a tree searching algorithm, I'd like to yield
for each node so that the current state can be shown visually.
I realize that there are several ways to do this but D a yield
version without additional threads would be optimal. I don't
need concurrency or speed, just simple.
Sounds like opApply (external iteration) may well be the way to
go.
It is a great tool to separate (possibly complex) iteration logic
from (possibly complex) instance processing logic.
Here is a random recipe:
https://www.sociomantic.com/blog/2010/06/opapply-recipe
An example:
-----
import std.stdio;
class Node {
int value;
Node left, right;
this (int value_) {value = value_;}
}
struct InOrderViewer {
Node root;
int opApply (int delegate (Node) process) {
void recur (Node cur) {
if (cur is null) return;
recur (cur.left);
process (cur); // use return value here to allow break in
foreach
recur (cur.right);
}
recur (root);
return 0;
}
}
void main () {
auto v1 = new Node (1);
auto v2 = new Node (2);
auto v3 = new Node (3);
auto v4 = new Node (4);
auto v5 = new Node (5);
v2.left = v1;
v2.right = v5;
v5.left = v3;
v3.right = v4;
foreach (node; InOrderViewer (v2)) {
writeln (node.value ^^ 2); // 1 4 9 16 25
}
}
-----
Ivan Kazmenko.
