http://d.puremagic.com/issues/show_bug.cgi?id=4489
Dmitry Olshansky <dmitry.o...@gmail.com> changed:
What |Removed |Added
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CC| |dmitry.o...@gmail.com
--- Comment #3 from Dmitry Olshansky <dmitry.o...@gmail.com> 2012-09-28
11:27:53 PDT ---
Actually the culprit is the final step and not the simmingly complicated
packing of parameters into a range. I'm talking of this one:
private void insertInPlaceImpl(T, Range)(ref T[] array, size_t pos, Range
stuff)
if(isInputRange!Range &&
(is(ElementType!Range : T) ||
isSomeString!(T[]) && is(ElementType!Range : dchar)))
{
auto app = appender!(T[])();
app.put(array[0 .. pos]);
app.put(stuff);
app.put(array[pos .. $]);
array = app.data;
}
I'm actually surprized that there is no other specialization but surely there
was was one. Basically the thing above allocates an appender and does up to 3
resizes (1 per each put).
To taste waters I tried this:
static if(hasLength!Range)
{
import core.stdc.string;
immutable to_insert = stuff.length;
immutable len = array.length;
T* ptr = array.ptr+pos;
array.length += to_insert;
memmove(ptr+to_insert, ptr, (len-pos)*T.sizeof);
//TODO: need to blit T.init over vacant places if T.__dtor exists?
copy(stuff, array[pos..pos+to_insert]);
}
else
{// Generic implementation
auto app = appender!(T[])();
app.put(array[0 .. pos]);
app.put(stuff);
app.put(array[pos .. $]);
array = app.data;
}
And for inserting at front the numbers were
23387
23599
For inserting at i-th (last) index I got:
58
92
These last ones were not very stable but indicate that the this packing into a
range also adds up.
I'll get myself busy with pull request since I was adding this packing thingy.
Still no idea when and how the underlying insertInPlaceImpl become 'create a
copy and return'. Sorry wasn't on my watch :)
Back when I last touched it, it looked like this:
void insertInPlaceImpl(T, Range)(ref T[] array, size_t pos, Range stuff)
static if(hasLength!Range &&
is(ElementEncodingType!Range : T) &&
!is(T == const T) &&
!is(T == immutable T))
{
immutable
delta = stuff.length,
oldLength = array.length,
newLength = oldLength + delta;
// Reallocate the array to make space for new content
array = (cast(T*) core.memory.GC.realloc(array.ptr,
newLength * array[0].sizeof))[0 .. newLength];
assert(array.length == newLength);
// Move data in pos .. pos + stuff.length to the end of the array
foreach_reverse (i; pos .. oldLength)
{
// This will be guaranteed to not throw
move(array[i], array[i + delta]);
}
// Copy stuff into array
copy(stuff, array[pos .. pos + stuff.length]);
}
else
{
auto app = appender!(T[])();
app.put(array[0 .. pos]);
app.put(stuff);
app.put(array[pos .. $]);
array = app.data;
}
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