C++ LINQ copy constructor demo. This is a modified version of CppLinq.Mini.cpp to include a call to `first` in [mrage__visual_cpp_bug_repro](https://cpplinq.codeplex.com/SourceControl/changeset/359ffa38b853c0113589b5cb69ff05d36e375a6a). It also includes an corresponding call to std::find_if. Only the call to first invokes the copy constructor of…

gistfile1.txt

// ----------------------------------------------------------------------------------------------
// Copyright (c) Mårten Rånge.
// ----------------------------------------------------------------------------------------------
// This source code is subject to terms and conditions of the Microsoft Public License. A 
// copy of the license can be found in the License.html file at the root of this distribution. 
// If you cannot locate the  Microsoft Public License, please send an email to 
// dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound 
//  by the terms of the Microsoft Public License.
// ----------------------------------------------------------------------------------------------
// You must not remove this notice, or any other, from this software.
// ----------------------------------------------------------------------------------------------
#include "stdafx.h"
// ----------------------------------------------------------------------------------------------
#include "../CppLinq/cpplinq.hpp"

int copyConstructorCalls;

class A
{
    public: int i;
    public: explicit A(int i): i(i) {}
    public: A(A const& a): i(a.i) { ++copyConstructorCalls; }
};

// ----------------------------------------------------------------------------------------------
int main (int argc, char* args[])
{
    using namespace cpplinq;
    std::vector<A> as;
    as.reserve(4);
    as.emplace_back(2);
    as.emplace_back(3);
    as.emplace_back(4);
    as.emplace_back(5);
    auto begin = as.begin();
    auto end = as.end();
    printf("Setup CC: %d\r\n", copyConstructorCalls); copyConstructorCalls = 0;

    auto result = from_iterators (begin, end)
        >> skip (1)
        >> select ([] (A const& a) {return a.i < 5 ? a.i : 0;})
        >> sum ()
        ;
    printf ("%d\r\n", result);
    printf("Select CC: %d\r\n", copyConstructorCalls); copyConstructorCalls = 0;

    A const& resultFromFirst  = from_iterators(begin, end) >> skip(1) >> first( [] (A const& a) {return a.i < 5;} );
    printf ("%d\r\n", resultFromFirst.i);
    printf("First CC: %d\r\n", copyConstructorCalls); copyConstructorCalls = 0;

    A const& resultFromFindIf = *std::find_if(begin + 1, end, [] (A const& a) {return a.i < 5;});
    printf ("%d\r\n", resultFromFindIf.i);
    printf("find_if CC: %d\r\n", copyConstructorCalls); copyConstructorCalls = 0;

    return 0;
}
// ----------------------------------------------------------------------------------------------