Is there a LINQ library for C++? [closed]

Answer 1

Here is my implemention of c++-linq with c++11(in chinese):

http://www.cnblogs.com/cbscan/archive/2012/10/20/2732773.html

It support features like "deferred query","stack based"(use operator new as little as possible),"copy semantic"(so you can iterate a query multitime after backup it), and so on.

It also support dozens of function including "from, select, where, cast ,range, all, any ,cast, average ,contain, count ,first, last, head, tail ,groupBy ,takeUntil, skipUntil ,max, min ,reduce ,unique, sort, random ,intersect, _union".

I think my code is simple enough to understand and extend by anybody selves.

Answer 2

You may take a look at PSade.Oven, a strongly boostified library working on STL ranges and providing a lot LINQ like functions.

Answer 3

This is my solution of template C++ LINQ library.
Source code is here: Boolinq
There are a lot of tests on each feature.
I'm working on it right now.

Any comments?
May be advices?

UPDATE: project moved to https://github.com/k06a/boolinq and now have version 2.0 with only 700 lines of source code :)

Answer 4

Here is another alternative that is simply a wrapper around boost and stl algorithms, and thus you get most of the performance benefits of those implementations.

It works like this:

std::vector<int> xs;
auto count = from(xs)
   .select([](int x){return x*x;})
   .where([](int x){return x > 16;})
   .count();
auto xs2 = from(xs)
   .select([](int x){return x*x;})
   .to<std::vector<int>>();

Note that some methods return a proxy for empty ranges, e.g.

std::vector<int> xs;
auto max = from(xs)
   .select([](int x){return x*x;})
   .where([](int x){return x > 16;})
   .max()
   .value_or(default_max_value);

Feedback is welcome.

Answer 5

I don't think C++ has the compiler sugar to handle things such as lambda expressions, so no, that's not going to happen.