On Thursday, 3 December 2015 at 23:42:31 UTC, Nordlöw wrote:
On Thursday, 3 December 2015 at 21:40:05 UTC, Jim Barnett wrote:
Thanks for reading.
My version slightly adjusted version:
/** Returns: If range is a palindrome larger than $(D
minLength).
See also:
http://forum.dlang.org/thread/dlfeiszyweafpjioc...@forum.dlang.org#post-vpzuaqxvtdpzpeuorxdl:40forum.dlang.org
See also:
https://stackoverflow.com/questions/21849580/equality-operator-in-favour-of-std-range-equal
TODO: Test graphemes in `string` and `wstring`.
*/
bool isSymmetric(R)(R range, size_t minLength = 0) // TODO good
value for minLength?
if (isBidirectionalRange!(R))
{
static if (isRandomAccessRange!R) // arrays excluding
`char[]` and `wchar[]`
{
if (range.length < minLength) { return false; }
}
size_t i = 0;
while (!range.empty)
{
import std.range.primitives: front, back, popFront,
popBack;
if (range.front != range.back) return false;
range.popFront(); i++;
if (range.empty) break;
range.popBack(); i++;
}
return i >= minLength;
}
unittest
{
assert(`dallassallad`.isSymmetric);
assert(!`ab`.isSymmetric);
assert(`a`.isSymmetric);
assert(`åäå`.isSymmetric);
assert(`áá`.isSymmetric);
assert(`åäå`.isSymmetric(3));
assert(!`åäå`.isSymmetric(4));
assert(``.isSymmetric);
assert([1, 2, 2, 1].isSymmetric);
assert(![1, 2, 2, 1].isSymmetric(5));
}
alias isPalindrome = isSymmetric;
Interesting solution... probably worth some future analysis for
me...
The `import` statement inside the `for`-loop kind of smells to me.
It's a little more generalized than I was looking for, but
interesting. Your code is also searching for a threshold of
symmetry. I haven't encountered a problem like that personally,
but it's interesting and makes me think.
I appreciate your response.
