On Tue, 21 May 2013 18:00:07 -0400, bearophile <bearophileh...@lycos.com>
wrote:
Sometimes I have need a simple function like this, related to
std.string.squeeze:
// Must keep the original order of the items.
// Slow implementation that shows the semantics.
T[] noDupes(T)(in T[] s) {
import std.algorithm: canFind;
T[] result;
foreach (T c; s)
if (!result.canFind(c))
result ~= c;
return result;
}
void main() {
import std.string: squeeze;
assert("AAAA".noDupes == "A");
assert("AAAA".squeeze == "A");
assert("ABAC".noDupes == "ABC");
assert("ABAC".squeeze == "ABAC");
}
Do you know if this function (or a simple way to implement it) already
in Phobos?
This seems to work for ASCII strings, but the conversion to array is
required (I think because writeln may re-evaluate the range's front more
than once):
Should be O(n), but doesn't really get around the memory allocation. You
could probably write a custom range that does this properly (doesn't set
present until popFront is called):
import std.algorithm;
import std.array;
import std.stdio;
void main()
{
bool present[256];
// writes "ABC"
writeln(array("ABAC".filter!((a){scope(exit) present[a] = true; return
!present[a];})));
}
Kind of a violation of how a range should work, front should be the same
across multiple calls! But it does the trick :)
-Steve
