Re: Shifting values within an array

[Steven Schveighoffer]

On Tue, 10 Aug 2010 09:01:28 -0400, Chris Williams <a...@seanet.com> wrote:
I would like to be able to do something like this:

class A {
        int i;
}

int main() {
        A[] list;

        for (uint L = 0; L < 3; L++) {
                for (uint L2 = 0; L2 < 3; L2++) {
                        uint index = L + L2;

                        uint copyAmount = list.length - index;
                        list.length = list.length + 1;
			if (copyAmount > 0) {  // Move data after index one slot later to  
make room
                                A[] sliceFrom = list[index .. (index + 
copyAmount)];
                                A[] sliceTo = list[(index + 1) .. (index + 1 + 
copyAmount)];
                                sliceTo[] = sliceFrom[];
                        }
                        list[index] = new A();
                        list[index].i = index;
                }
        }

        return 0;
}

I have a running implementation which uses C's memmove(), but I gather  
that this isn't a safe means to do it as the garbage collector
might run while the references to the object are being manipulated. Is  
there a way to do this outside of a loop?

I think memmove should be fine.  All thread stacks are scanned during GC  
cycles, so there is no danger of having one element get collected.  I  
think memmove will not copy half a reference anyways.

-Steve