is_contained() convenience function

[Alexander_Droste]

Summary

This patch adds a convenience is_contained() function
which checks if an element exists in a container.

This patch was originally part of http://reviews.llvm.org/D12761.

[Alexander_Droste]

• changed name to is_contained() because contains() caused name conflicts
• adapted the style of other functions in STLExtras.h

• @david: I hope its ok that I added you as a reviewer. Googling for 'stlextras llvm reviewer' you

were the first author that appeared.

[dblaikie]

Benjamin and I were just discussing a similar piece of code to this in a
review

I think we were settling on something like "any_of(R, is_equal<>(E))" but
I'm OK adding something like "contains" or "is_contained" (contains seems
like the right name, but might be too often used elsewhere to be
convenient?)

Benjamin - any thoughts/preferences here?

[Alexander_Droste]

• changed implementation to std::equal_to<> style

[dblaikie]

I think in the last review I/we were just suggesting to use any_of +
equal_to directly & skip adding this extra construct entirely.

In any case, std::equal_to is a C++14 feature, so we probably can't use it
in LLVM & the suggestion/discussion was about whether we could/should just
implement one in LLVM (llvm::equal_to). But you also make a good point
about equal_to needing a parameter/binding, blah blah - Ben: thoughts on
that? Still nice if we have to use bind too? Could/should we make another
function object to handle that more easily (the general case of a stateful
unary equal_to, I mean)?

[Alexander_Droste]

@benjamin : I think your expertise is needed. :)

[bkramer]

I personally dislike bind. I thought there was a a way to use std::equal_to without manually binding, but apparently there isn't, so adding is_contained is fine with me. Preferably with std::find as it avoids a confusing bind.

[Alexander_Droste]

• reverted implementation, in order to be based on find instead of any_of/std::equal_to<E>()

[Alexander_Droste]

• removed whitespace:

bool is_contained(R && Range,..
->
bool is_contained(R &&Range,..

[Alexander_Droste]

Hi,

as it seems, this patch has not been committed yet.
https://github.com/llvm-mirror/llvm/blob/master/include/llvm/ADT/STLExtras.h
I have no commit access. Can someone commit this for me?

llvm/trunk/include/llvm/ADT/STLExtras.h

 
 /// Provide wrappers to std::remove_if which take ranges instead of having to
 /// pass begin/end explicitly.
 template<typename R, class UnaryPredicate>
 auto remove_if(R &&Range, UnaryPredicate &&P) -> decltype(Range.begin()) {
   return std::remove_if(Range.begin(), Range.end(), P);
 }
 
+/// Wrapper function around std::find to detect if an element exists
+/// in a container.
+template <typename R, typename E>
+bool is_contained(R &&Range, const E &Element) {
+  return std::find(Range.begin(), Range.end(), Element) != Range.end();
+}
+
 //===----------------------------------------------------------------------===//
 //     Extra additions to <memory>
 //===----------------------------------------------------------------------===//
 
 // Implement make_unique according to N3656.
 
 /// \brief Constructs a `new T()` with the given args and returns a
 ///        `unique_ptr<T>` which owns the object.