testFunctorHolder.cpp

#include <functional>
 
#include "DGtal/base/FunctorHolder.h"
#include "DGtal/base/Common.h"
#include "DGtal/base/CUnaryFunctor.h"
 
#include "DGtalCatch.h"
 
using namespace DGtal;
using namespace DGtal::functors;
using namespace std;

// Functor and functions
 
struct Functor
{
  double cst;
 
  explicit Functor(double c) : cst(c) {}
  inline double operator() (double v) const { return v + cst; }
};
 
double add(double v)
{
  return v + 1.5;
}
 

// Test cases
 
TEST_CASE( "Holding a lambda", "[lambda]" )
{
  double cst = 1.5;
 
  // Holding an unary lambda by mutable lvalue
  {
    auto fn = [&cst] (double v) { return v + cst; };
    auto holder = holdFunctor(fn);
    BOOST_CONCEPT_ASSERT(( boost::Assignable<decltype(holder)> ));
    BOOST_CONCEPT_ASSERT(( concepts::CUnaryFunctor<decltype(holder), double, double> ));
    REQUIRE( holder(0.5) == 2.0 );
    auto holder2 = holder;
    REQUIRE( holder2(0.5) == 2.0 );
  }
 
  // Holding an unary lambda by constant lvalue
  {
    const auto fn = [&cst] (double v) { return v + cst; };
    auto holder = holdFunctor(fn);
    BOOST_CONCEPT_ASSERT(( boost::Assignable<decltype(holder)> ));
    BOOST_CONCEPT_ASSERT(( concepts::CUnaryFunctor<decltype(holder), double, double> ));
    REQUIRE( holder(0.5) == 2.0 );
    auto holder2 = holder;
    REQUIRE( holder2(0.5) == 2.0 );
  }
 
  // Holding an unary lambda by rvalue
  {
    auto holder = holdFunctor( [&cst] (double v) { return v + cst; } );
    BOOST_CONCEPT_ASSERT(( boost::Assignable<decltype(holder)> ));
    BOOST_CONCEPT_ASSERT(( concepts::CUnaryFunctor<decltype(holder), double, double> ));
    REQUIRE( holder(0.5) == 2.0 );
    auto holder2 = holder;
    REQUIRE( holder2(0.5) == 2.0 );
  }
 
  // Holding an unary mutable lambda by rvalue
  {
    auto holder = holdFunctor( [cst] (double v) mutable { return v + cst; } );
    BOOST_CONCEPT_ASSERT(( boost::Assignable<decltype(holder)> ));
    BOOST_CONCEPT_ASSERT(( concepts::CUnaryFunctor<decltype(holder), double, double> ));
    REQUIRE( holder(0.5) == 2.0 );
    auto holder2 = holder;
    REQUIRE( holder2(0.5) == 2.0 );
  }
 
  // Holding a binary lambda by rvalue
  {
    auto holder = holdFunctor( [] (double v, double c) { return v + c; } );
    BOOST_CONCEPT_ASSERT(( boost::Assignable<decltype(holder)> ));
    REQUIRE( holder(0.5, 1.5) == 2.0 );
    auto holder2 = holder;
    REQUIRE( holder2(0.5, 1.5) == 2.0 );
  }
}
 
TEST_CASE( "Holding a functor", "[functor]" )
{
  double cst = 1.5;
 
  // Holding an unary functor by mutable lvalue
  {
    auto fn = Functor(cst);
    auto holder = holdFunctor(fn);
    BOOST_CONCEPT_ASSERT(( boost::Assignable<decltype(holder)> ));
    BOOST_CONCEPT_ASSERT(( concepts::CUnaryFunctor<decltype(holder), double, double> ));
    REQUIRE( holder(0.5) == 2.0 );
    auto holder2 = holder;
    REQUIRE( holder2(0.5) == 2.0 );
  }
 
  // Holding an unary functor by constant lvalue
  {
    const auto fn = Functor(cst);
    auto holder = holdFunctor(fn);
    BOOST_CONCEPT_ASSERT(( boost::Assignable<decltype(holder)> ));
    BOOST_CONCEPT_ASSERT(( concepts::CUnaryFunctor<decltype(holder), double, double> ));
    REQUIRE( holder(0.5) == 2.0 );
    auto holder2 = holder;
    REQUIRE( holder2(0.5) == 2.0 );
  }
 
  // Holding an unary functor by rvalue
  {
    auto holder = holdFunctor( Functor(cst) );
    BOOST_CONCEPT_ASSERT(( boost::Assignable<decltype(holder)> ));
    BOOST_CONCEPT_ASSERT(( concepts::CUnaryFunctor<decltype(holder), double, double> ));
    REQUIRE( holder(0.5) == 2.0 );
    auto holder2 = holder;
    REQUIRE( holder2(0.5) == 2.0 );
  }
}
 
TEST_CASE( "Holding a function", "[function]" )
{
  // Holding a function by reference
  {
    auto holder = holdFunctor( add );
    BOOST_CONCEPT_ASSERT(( boost::Assignable<decltype(holder)> ));
    BOOST_CONCEPT_ASSERT(( concepts::CUnaryFunctor<decltype(holder), double, double> ));
    REQUIRE( holder(0.5) == 2.0 );
    auto holder2 = holder;
    REQUIRE( holder2(0.5) == 2.0 );
  }
 
  // Holding a function by address
  {
    auto holder = holdFunctor( &add );
    BOOST_CONCEPT_ASSERT(( boost::Assignable<decltype(holder)> ));
    BOOST_CONCEPT_ASSERT(( concepts::CUnaryFunctor<decltype(holder), double, double> ));
    REQUIRE( holder(0.5) == 2.0 );
    auto holder2 = holder;
    REQUIRE( holder2(0.5) == 2.0 );
  }
}
 
TEST_CASE( "Holding a std::function", "[std::function]" )
{
  double cst = 1.5;
 
  // Holding a std::function
  std::function<double(double)> fn = Functor(cst);
  auto holder = holdFunctor( fn );
  BOOST_CONCEPT_ASSERT(( boost::Assignable<decltype(holder)> ));
  BOOST_CONCEPT_ASSERT(( concepts::CUnaryFunctor<decltype(holder), double, double> ));
  REQUIRE( holder(0.5) == 2.0 );
  auto holder2 = holder;
  REQUIRE( holder2(0.5) == 2.0 );
}