Help me write "saveAll"

[monarch_dodra]

On Friday, 21 December 2012 at 20:38:34 UTC, Joshua Niehus wrote:
> On Friday, 21 December 2012 at 17:01:14 UTC, monarch_dodra 
> wrote:
>> There are a lot of algorithms in std.algorithm that operate on 
>> "foo(Range, Needles...)(Range range, Needles needles)".
>>
>> Needles can be anything, in particular, either an "element" or 
>> a "range".
>>
>> The thing is that every now and then, you want to save the 
>> entirety of (the ranges) inside needles. EG, I want to be able 
>> to write:
>> foo(range, needles.saveAll);
>> [...snip...]
>> Any thought on how do get this working?
>> size_t r = startsWith!pred(haystack, needles.saveAll);
>
> Sorry if im misunderstanding, but doesn't filter do this?
> Example:
> import std.stdio, std.algorithm, std.range;
> void main() {
>     auto x = [
>         [1, 2, 3],
>         [4, 5, 6],
>         [7, 8, 9],
>         [10, 11, 12]
>     ];
>                 //haystack               // needle          // 
> needle
>     auto y = x.filter!(a => (a == [4, 5, 6] || a == [7, 8, 
> 9])).array;
>     y.writeln;
> }

I think there may be some misunderstanding. It's more like this;

//----
[1, 2, 3, 4].find(4, 7, [1, 3], [2, 3]);
//----
Here, as you can see, the 4 needles are:
4: Element
7: Element
[1, 3]: Range
[2, 3]: Range

In your example, you are just comparing elements: The elements 
themselves happen to be ranges, but that is irrelevant in the 
iteration scheme, they remain *elements* in the search.

In my example, Filter can't operate the Needle "[1, 3]", because 
it contains multiple elements.