efficient and safe way to iterate on associative array?

[Minas Mina via Digitalmars-d-learn]

On Friday, 4 March 2016 at 13:53:22 UTC, aki wrote:
> Is it okay to modify associative array while iterating it?
>
> import std.stdio;
>
> void main() {
> 	string[string] hash = [ "k1":"v1", "k2":"v2" ];
> 	auto r = hash.byKeyValue();
> 	while(!r.empty) {
> 		auto key = r.front.key;
> 		auto value = r.front.value;
> 		r.popFront();
> 		writefln("key=%s, value=%s", key, value);
> 		// may not modify 'hash' here ?
> 		hash = null;
> 	}
> }
>
> I guess probably it's not.
> Then, my question is are there an efficient and safe way to 
> iterate on an associative array even if there are possibility 
> to be modified while iterating?
> I'm writing interpreter and want to make my language to be 
> safe; even malicious script cannot fall it in 'core dump' 
> state. It is okay if it causes undefined behavior like throw or 
> instant exit from loop, but not crash.
>
> Thanks, Aki.

I think what you can do is extract its contents to an array, 
iterate it and modify it as you like, and then insert back to 
another associative array. I don't think it's efficient but I 
don't know if it's possible to do something else.