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Also I’m slightly confused by this example.
for_tree(string x = ""; x.size() <= 8; x : {x+"a", x+"b", x+"c"}){
print(x);
}
So, our “next node” operation is to concatenate to x. Won’t we either have to have a method for modifying x to go “up” a node, or we’ll have to keep a record of what x was upon entering each node? Like in this example we’ll end up with x=“aaaaaaaa” and then go up a node, over to a “b” node, and get x=“aaaaaaaab”, right?
The author said it could be implemented recursively, so a call with x="aaaaaaa" would call three more functions with x="aaaaaaaa", "aaaaaaab" and "aaaaaaac". you never need to go up a node
I think the intention is that you keep a record of what x is in the current node, and at every node above the current node. In the recursive implementation which the author describes as equivalent, these values are kept in the stack.
Well, it doesn't need to be any worse than the stack-based implementation of a recursive tree traversal, and it can't be significantly better. You have to store that state somewhere.
Perhaps it can be optimized to be a little better than the recursive version, depending on how much overhead your language uses for a stack frame that it won't need for this special case.
> This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Also I’m slightly confused by this example.
}So, our “next node” operation is to concatenate to x. Won’t we either have to have a method for modifying x to go “up” a node, or we’ll have to keep a record of what x was upon entering each node? Like in this example we’ll end up with x=“aaaaaaaa” and then go up a node, over to a “b” node, and get x=“aaaaaaaab”, right?