Reflections on isPalindrome

[Peter Alexander via Digitalmars-d-learn]

On Friday, 24 October 2014 at 21:56:20 UTC, Nordlöw wrote:
> bool isPalindrome(R)(in R range) @safe pure

Aside: for templates, just let the compiler infer @safe and pure. 
You don't know whether the range operations on R are pure or not.

As for the actual algorithm, there's no need for the random 
access version, and you bidirectional version does twice as much 
as necessary:

Just do:

while (!range.empty)
{
   if (range.front != range.back) return false;
   range.popFront();
   if (range.empty) break;
   range.popBack();
}
return true;

This automatically handles narrow strings.


> Further, I would like to extend isPalindrome() with a minimum 
> length argument minLength that for string and wstring does
>
> import std.uni: byDchar;
> range.byDchar.array.length >= minLength.
>
> AFAIK this will however prevent my algorithm from being 
> single-pass right?

I'm not sure what you are saying here, but hopefully the above 
code obviates this anyway.