On 6/23/15 8:12 AM, Baz wrote:
On Tuesday, 23 June 2015 at 11:22:31 UTC, Steven Schveighoffer wrote:
On 6/23/15 1:51 AM, jkpl wrote:
On Tuesday, 23 June 2015 at 05:16:23 UTC, Assembly wrote:
[...]
* Option 1/
if most of the time you have to insert at the beginning, then start
reading from the end and append to the end, so that the existing block
has not to be moved. You just have to add val at the end.
* Option 2/
better way to move the whole block (this can be done with memmove too).
---
void push(T val)
{
buffer.length += 1;
buffer[1..$] = buffer[0..$-1];
This will fail.
http://dlang.org/arrays.html#overlapping-copying
I will note, dcollections had a deque, which allowed insertion at the
front in O(1) (amortized) time. It basically worked by having 2 arrays
front to front.
according to the C library, memmove handle overlapps, you mismatch with
memcpy which does not.
The above is not memmove, it's slice assignment, which is specifically
illegal for overlaps:
$ cat testsliceassign.d
void buffer[100];
void main()
{
buffer[1..$] = buffer[0..$-1];
}
$ dmd testsliceassign.d
$ ./testsliceassign
object.Error@(0): Overlapping arrays in copy: 98 byte(s) overlap of 99
-Steve
