On Tue, 04 Oct 2011 03:22:35 -0400, Jacob Carlborg <[email protected]> wrote:
On 2011-10-04 07:21, Robert Jacques wrote:
[snip]
Actually it does not need to be part of the public API when I think
about it. I can move it into Serializer. Array would still need to be
public since both Serailzer and Archive need access to it and the
package attribute doesn't work very well.
Regarding design, I agree, although I'd go one further and define Array
as a public type inside the Serializer class. However, this concept of
an 'Array' is fundamentally flawed. Consider:
auto c = a[1..3];
auto cArr = Array(c.ptr,c.length,4);
assert(!cArr.isSliceOf(bArr));
assert(!bArr.isSliceOf(cArr));
Any suggestion how to fix this, how to properly detect if an array is a
slice of some other array?
Well, there are two problems. First, there is an API issue: When you pass an
aliased array to the archiver, you must pass both an array and a slice of that
array.
Second, is detection. The comparison operator I suggested below covers this
issue. Just remember that with a loop based approach, you can't terminate the
search early: you have to check all existing arrays for possible matches.
// and
b ~= 5;
bArr = Array(b.ptr, b.length, 4);
assert(!bArr.isSliceOf(aArr));
Appending to "b" will reallocate "b" making it a regular array and not a
slice:
b ~= 5;
b[] = 100;
assert(a == [0, 1, 2, 3, 4]);
"a" is not modified and the assert passes.
I'm sorry, you're right. In my mind b extended to the end of the a array, for
some reason. However, if you do define b to extend to the end of the a array,
then it can append without allocating:
auto a = [0, 1, 2, 3, 4];
auto b = a[2 .. $];
b ~= 5;
assert(b[0]==2);
a[2] = 10;
assert(b[0]==10);
So please don't dismiss this point.
[snip]
Would this something similar to:
https://github.com/jacob-carlborg/orange/blob/master/orange/serialization/Serializer.d#L1520
?
I'm not sure, that routine seems to be filtering pointers between those with
aliases and those without aliases, which would be similar in effect to:
if( auto node = arr.ptr in setOfAliases ) {} else {}
What is the advantage with using a tree? Is the advantage that you loop
over the elements once in the pseudo-code compared to that I loop over
them twice, as in:
https://github.com/jacob-carlborg/orange/blob/master/orange/serialization/Serializer.d#L1495
?
Primarily, it's O(N logN) vs O(N^2). Also, it solves the isSliceOf problem we
discussed above and puts arrays and objects into the same framework, as objects
containing fixed sized arrays can have slices.
