Int within ranges

[nrgyzer]

> On Mon, 13 Jun 2011 14:52:24 -0400, nrgyzer <nrgyzer at gmail.com>
wrote:
> >> On Mon, 13 Jun 2011 12:15:40 -0400, nrgyzer <nrgyzer at gmail.com>
> > wrote:
> >> > Hi there,
> >> >
> >> > is there any possibility to get a sliced array from another
array
> >> > between two ranges like:
> >> >
> >> > int[uint] myArray;
> >> > myArray[10] = 1000;
> >> > myArray[20] = 2000;
> >> > myArray[30] = 3000;
> >> > myArray[40] = 4000;
> >> > myArray[50] = 5000;
> >> >
> >> > int[] newArray = myArray[>= 20 .. <= 40]; // not able to do
this
> >> > writeln(newArray); // should print [2000, 3000, 4000]
> >> >
> >> > Is there any way to do this?
> >> import dcollections.TreeMap;
> >> auto myArray = new TreeMap!(uint, int);
> >> myArray[10] = 1000;
> >> myArray[20] = 2000;
> >> myArray[30] = 3000;
> >> myArray[40] = 4000;
> >> myArray[50] = 5000;
> >> // this is a little kludgy, but necessary since you require <= 40
> >> auto c = myArray.elemAt(40);
> >> c.popFront();
> >> int newArray = array(myArray[20..c]);
> >> Note two things:
> >> 1. int[uint] is a hash, and so has no particular order.
Therefore,
> > there
> >> is no guarantee of iteration order, or that a range of such a
> > container
> >> (if one existed) would be properly constructed with two keys.  A
> > TreeMap,
> >> or RedBlackTree, is sorted, and so the order is guaranteed.
> >> 2. dcollections.TreeMap is implemented with the same collection
as
> >> std.container.RedBlackTree, so you could potentially do the same
> > thing
> >> with it.  But the dcollections.TreeMap API is more polished.
> >> -Steve
> >
> > Exactly what I'm looking for, but how can I realize that it also
> > gives me the elements when the key doesn't exists like:
> >
> > import std.range;
> > import dcollections.TreeMap;
> >
> > auto myArray = new TreeMap!(uint, int);
> >
> > myArray[10] = 1000;
> > myArray[20] = 2000;
> > myArray[30] = 3000;
> > myArray[45] = 4500;
> > myArray[50] = 5000;
> >
> > auto c = myArray.elemAt(40);
> > c.popFront();
> > int[] newArray = array(myArray[20..c]);
> > writeln(newArray);
> >
> > This will throw an exception because element 40 doesn't exist. Is
> > there any possibility to get the element 20 and 30 from this map?
> It might be useful to have elemAt return an empty range that is
located at
> the place the element *would* be.
> When this code was first written, in order to detect whether elemAt
found
> your element, you compared it to container.end (similar to C++'s
STL).
> But now that cursors are tiny ranges, and have an empty property, I
can
> use that to indicate the element wasn't exactly found.  So I can
change
> the semantics to find the place the element *would* be.
> myArray[20..41];
> and it will find all elements >= 20 and < 41, regardless of whether
20 and
> 41 were valid elements.
> Hm... can you post this as an enhancement to dcollections so it's
not
> forgotten?
> http://www.dsource.org/projects/dcollections/newticket
> -Steve

Thanks! I created a new ticket... by the way - is there any bug in
DMD 2.053 by using my own opCmp? The following code throws me an
HiddenFuncException:

private import std.stdio : writeln;

class Example {

	int pId;

	this(int id) {

		pId = id;

	}

	int opCmp(ref Example other) {

		return pId - other.pId;

	}

}

int main(string[] args) {

	Example[] exps;
	exps ~= new Example(1);
	exps ~= new Example(2);
	writeln(exps.sort);

	return 1;

}