lumiera_/tests/library/util-foreach-test.cpp

/*
  UtilForeach(Test)  -  helpers to perform something for each element

   Copyright (C)
     2009,            Hermann Vosseler <Ichthyostega@web.de>

  **Lumiera** is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by the
  Free Software Foundation; either version 2 of the License, or (at your
  option) any later version. See the file COPYING for further details.

* *****************************************************************/

/** @file util-foreach-test.cpp
 ** unit test \ref UtilForeach_test
 */


#include "lib/test/run.hpp"
#include "lib/util-foreach.hpp"
#include "lib/iter-adapter.hpp"


#include <boost/lexical_cast.hpp>
#include <functional>
#include <iostream>
#include <vector>


using ::Test;

using util::for_each;
using util::has_any;
using util::and_all;

using boost::lexical_cast;
using std::function;
using std::ref;
using std::cout;
using std::endl;


namespace util {
namespace test {
  
  typedef std::vector<int> VecI;
  typedef lib::RangeIter<VecI::iterator> RangeI;
  
  
  
  namespace{ // Test data and operations
    
    // Placeholder for argument in bind-expressions
    std::_Placeholder<1> _1;
    
    
    VecI
    buildTestNumberz (uint count)
    {
      VecI numbers;
      numbers.reserve(count);
      while (count)
        numbers.push_back(count--);
      
      return numbers;
    }
    
    
    /* == functions to bind and invoke == */
    bool
    plainFunc (int i)
    {
      cout <<':'<< i;
      return i;
    }
    
    bool
    function1 (int i, int j)
    {
      return plainFunc(i+j);
    }
    
    bool
    function2 (int i, int j, int& k)
    {
      k += i + j;
      return plainFunc(k);
    }
    
    
#define _NL_ cout << endl;
#define ANNOUNCE(_LABEL_) cout << "---:" << STRINGIFY(_LABEL_) << endl;
    
  } // (End) test data and operations
  
  
  
  /*****************************************************************//**
   * @test Invoking an operation for each element of a collection.
   *       Covers the various flavours of these convenience helpers:
   *       They might operate either on a STL container (providing
   *       \c begin() and \c end() functions), or at a "Lumiera
   *       Forward Iterator", which is incremented and dereferenced
   *       for each value it yields, until exhaustion.
   *       
   *       Moreover for each of these cases, there are additional
   *       overloads allowing to create a bind-expression on-the fly.
   *       As a further variation of this scheme, an predicate can be
   *       evaluated for each element, either with universal quantisation
   *       (results are && combined), or with existential quantisation.
   */
  class UtilForeach_test : public Test
    {
      uint NUM_ELMS{0};
      
      virtual void
      run (Arg arg)
        {
          NUM_ELMS = firstVal (arg, 10);
          VecI container = buildTestNumberz (NUM_ELMS);
          RangeI iterator(container.begin(), container.end());
          
          check_foreach_plain (container);
          check_foreach_plain (iterator);
          
          check_foreach_bind (container);
          check_foreach_bind (iterator);
          
          check_foreach_bind_const (container);
          
          check_foreach_memFun (container);
          check_foreach_memFun (iterator);
          
          check_foreach_lambda (container);
          check_foreach_lambda (iterator);
          
          check_existence_quant (container);
          check_existence_quant (iterator);
          
          CHECK (int(NUM_ELMS) ==container[0]);
          
          check_ref_argument_bind (container);
          CHECK (int(NUM_ELMS) ==container[0]);
          
          check_ref_argument_bind (iterator);
          CHECK (90+int(NUM_ELMS) ==container[0]);
          // changes got propagated through the iterator
          
          check_wrapped_container_passing(container);
          
          check_invoke_on_each ();
        }
      
      
      /** @test invoke a simple free function, given
       *        as reference, function pointer or functor.
       *        The invoked test function will print its argument
       */
      template<typename CO>
      void
      check_foreach_plain (CO coll)
        {
          ANNOUNCE (check_foreach_plain);
          function<bool(int)> func(plainFunc);
          
          for_each (coll, plainFunc);      _NL_
          for_each (coll, &plainFunc);     _NL_
          for_each (coll, func);           _NL_
          
          and_all (coll, plainFunc);       _NL_
          and_all (coll, &plainFunc);      _NL_
          and_all (coll, func);            _NL_
          
          has_any (coll, plainFunc);       _NL_
          has_any (coll, &plainFunc);      _NL_
          has_any (coll, func);            _NL_
        }
      
      
      /** @test bind additional parameters on-the-fly,
       *        including the possibility to use a placeholder
       *        to denote the position of the variable parameter */
      template<typename CO>
      void
      check_foreach_bind (CO coll)
        {
          ANNOUNCE (check_foreach_bind);
          function<bool(int,int)>     fun1(function1);
          
          for_each (coll, function1, 10, _1 );               _NL_
          for_each (coll, &function1,10, _1 );               _NL_
          for_each (coll, fun1,      10, _1 );               _NL_
          
          and_all (coll, function1,  10, _1 );               _NL_
          and_all (coll, &function1, 10, _1 );               _NL_
          and_all (coll, fun1,       10, _1 );               _NL_
          
          has_any (coll, function1,  10, _1 );               _NL_
          has_any (coll, &function1, 10, _1 );               _NL_
          has_any (coll, fun1,       10, _1 );               _NL_
          
          for_each (coll, function1, _1, _1 );               _NL_
          for_each (coll, &function1,_1, _1 );               _NL_
          for_each (coll, fun1,      _1, _1 );               _NL_
          
          and_all (coll, function1,  _1, _1 );               _NL_
          and_all (coll, &function1, _1, _1 );               _NL_
          and_all (coll, fun1,       _1, _1 );               _NL_
          
          has_any (coll, function1,  _1, _1 );               _NL_
          has_any (coll, &function1, _1, _1 );               _NL_
          has_any (coll, fun1,       _1, _1 );               _NL_
          
        //does not compile.....
       // for_each (coll, function1, 10, 20, _1 );
      //  for_each (coll, function1, _1, _2 );
     //   for_each (coll, function1, 10 );
        }
      
      
      /** @test under some circumstances, it is even possible
       *        to take a ref to the data in the input sequence,
       *        or to a summation variable. In the example performed here,
       *        the function to be applied takes the 3rd argument by reference
       *        and assigns the sum of first and second argument to this parameter.
       *        If we us a bind variable at that position, we end up assigning
       *        by reference to the values contained in the collection.
       *  @note in case of invoking this test with a Lumiera Forward Iterator,
       *        the changes go through to the original container, in spite of
       *        passing the iterator by value. This behaviour is correct, as
       *        an iterator is an reference-like object
       */
      template<typename CO>
      void
      check_ref_argument_bind (CO coll)
        {
          ANNOUNCE (assign_to_input);
          function<bool(int,int,int&)> fun2(function2);
          
          for_each (coll, function2, 5, 5, _1 );             _NL_
          for_each (coll, &function2,5, 5, _1 );             _NL_
          
          and_all (coll, function2,  5, 5, _1 );             _NL_
          and_all (coll, &function2, 5, 5, _1 );             _NL_
          
          has_any (coll, function2,  5, 5, _1 );             _NL_
          has_any (coll, &function2, 5, 5, _1 );             _NL_
          
          // note: in C++11, the reference parameters are passed through
          // even when wrapping the function or function pointer into a function object,
          for_each (coll,fun2,       5, 5, _1 );             _NL_
          and_all (coll, fun2,       5, 5, _1 );             _NL_
          has_any (coll, fun2,       5, 5, _1 );             _NL_
          // at that point we have added 9 * (5+5) to the value at position zero.
          // (note that the has_any only evaluates the function once)
          
          
          // the following test assigns the sum via the ref argument to a local variable.
          int sum=0;
          ANNOUNCE (assign_to_var);
          for_each (coll, function2, -10, _1, ref(sum) );    _NL_
          for_each (coll, &function2,-10, _1, ref(sum) );    _NL_
          for_each (coll, fun2,      -10, _1, ref(sum) );    _NL_
          cout << "sum=" << sum << endl;
          
          sum=0;
          and_all (coll, function2,  -10, _1, ref(sum) );    _NL_
          and_all (coll, &function2, -10, _1, ref(sum) );    _NL_
          and_all (coll, fun2,       -10, _1, ref(sum) );    _NL_
          cout << "sum=" << sum << endl;
          
          sum=0;
          has_any (coll, function2,  -10, _1, ref(sum) );    _NL_
          has_any (coll, &function2, -10, _1, ref(sum) );    _NL_
          has_any (coll, fun2,       -10, _1, ref(sum) );    _NL_
          cout << "sum=" << sum << endl;
        }
      
      
      /** @test the input sequence can be also taken
       *        from a const container (for iterators this
       *        obviously doesn't make sense  */
      template<typename CO>
      void
      check_foreach_bind_const (CO const& coll)
        {
          ANNOUNCE (check_foreach_bind_const);
          
          for_each (coll,function1,  10, _1 );               _NL_
          and_all (coll, function1,  10, _1 );               _NL_
          has_any (coll, function1,  10, _1 );               _NL_
          
          for_each (coll,function1,  _1, _1 );               _NL_
          and_all (coll, function1,  _1, _1 );               _NL_
          has_any (coll, function1,  _1, _1 );               _NL_
          
          int sum=0;
          
          for_each (coll,function2,  _1, _1, ref(sum) );     _NL_
          and_all (coll, function2,  _1, _1, ref(sum) );     _NL_
          has_any (coll, function2,  _1, _1, ref(sum) );     _NL_
        }
      
      
      
      struct Dummy
        {
          int sum_;
          
          bool
          fun (int i)
            {
              sum_ += i;
              return plainFunc (sum_);
            }
        };
      
      /** @test bind a member function to be invoked for each element */
      template<typename CO>
      void
      check_foreach_memFun (CO coll)
        {
          ANNOUNCE (check_foreach_memFun);
          
          Dummy dummy;
          dummy.sum_ = 0;
          
          for_each (coll, &Dummy::fun, dummy,  _1 );         _NL_
          and_all  (coll, &Dummy::fun, dummy,  _1 );         _NL_
          has_any  (coll, &Dummy::fun, dummy,  _1 );         _NL_
          
          for_each (coll, &Dummy::fun, &dummy, _1 );         _NL_
          and_all  (coll, &Dummy::fun, &dummy, _1 );         _NL_
          has_any  (coll, &Dummy::fun, &dummy, _1 );         _NL_
          
          cout << "sum=" << dummy.sum_ << endl;
        }
      
      
      /** @test use lambda-expressions, to be invoked for each element */
      template<typename CO>
      void
      check_foreach_lambda (CO coll)
        {
          ANNOUNCE (check_foreach_lambda);
          uint sum(0);
          
          for_each (coll, [&sum] (uint entry) { sum += entry; });
          
          CHECK (sum == (NUM_ELMS+1) * NUM_ELMS/2);
          
          CHECK (!and_all  (coll, [] (uint elm) { return elm - 1; }));
          CHECK ( has_any  (coll, [] (uint elm) { return elm + 1; }));
        }
      
      
      /** @test verify the logic of universal and existential quantisation.
       *        Using lambda expressions as predicates */
      template<typename CO>
      void
      check_existence_quant (CO coll)
        {
          ANNOUNCE (check_existence_quant);
          
          CHECK ( and_all (coll, [] (uint elm) { return 0 < elm; }));
          CHECK (!and_all (coll, [] (uint elm) { return 1 < elm; }));
          
          CHECK ( has_any (coll, []    (uint elm) { return 0 < elm; }));
          CHECK ( has_any (coll, [this](uint elm) { return elm == NUM_ELMS; }));
          CHECK (!has_any (coll, [this](uint elm) { return elm >  NUM_ELMS; }));
        }
      
      
      struct TestElm
        {
          uint n_;
          TestElm(uint i) : n_(i) {}
          
          bool operation() { return plainFunc (n_); }
        };
      
      
      /** @test the binding can also be used to \em dispatch an operation
       *        on each element within a object collection: here the parameter
       *        is used as \c this pointer to specify the object instance */
      void
      check_invoke_on_each ()
        {
          ANNOUNCE (check_invoke_on_each);
          
          std::vector<TestElm> elms;
          for (uint i=0; i<6; ++i)
            elms.push_back (TestElm(i));
          
          std::vector<TestElm*> elmPtrs;
          for (uint i=0; i<6; ++i)
            elmPtrs.push_back (& elms[i]);
          
          // fed the element pointer as "this" pointer of the member function
          for_each (elmPtrs, &TestElm::operation, _1 );      _NL_
          and_all  (elmPtrs, &TestElm::operation, _1 );      _NL_
          has_any  (elmPtrs, &TestElm::operation, _1 );      _NL_
          
          // the same works with copies of the elements as well...
          for_each (elms, &TestElm::operation, _1 );         _NL_
          and_all  (elms, &TestElm::operation, _1 );         _NL_
          has_any  (elms, &TestElm::operation, _1 );         _NL_
          
          // note: it seems not to be possible to create a binder, which takes the "*this"-Argument by ref
        }
      
      
      /** @test pass the collection to be iterated in various ways
       *        - anonymous temporary
       *        - smart pointer
       *        - pointer
       *        - const&
       *  @note We do modifications using a lambda expression with a
       *        side-effect. The container passed in is always modified,
       *        disregarding const! (In case of the anonymous temporary
       *        the modifications get discarded after reaching the end
       *        of the for_each expression
       */
      void
      check_wrapped_container_passing (VecI coll)
        {
          ANNOUNCE (wrapped_container_passing);
          
#define SHOW_CONTAINER for_each (coll, plainFunc);           _NL_
          
          int counter = NUM_ELMS;
          auto assign_and_decrement = [&] (int& entry)
                                          {
                                            entry = counter--;
                                          };
          
          // use a const reference to pass the container...
          VecI const& passByConstRef (coll);
          
          for_each (passByConstRef,             assign_and_decrement );
          
          SHOW_CONTAINER
          // indeed got modifications into the original container!
          CHECK (0 == counter);
          
          // passing anonymous temporary
          for_each (buildTestNumberz(NUM_ELMS), assign_and_decrement );
          
          // passing a smart-ptr managed copy
          std::shared_ptr<VecI> bySmartPtr (new VecI (coll));
          
          for_each (bySmartPtr,                 assign_and_decrement );
          
          // both didn't influence the original container
          SHOW_CONTAINER
          CHECK (-2*int(NUM_ELMS)   == counter);
          CHECK (bySmartPtr->back() == counter+1);
          
          // passing the container by pointer is also possible
          const VecI * const passByConstPointer (&coll);
          
          for_each (passByConstPointer,         assign_and_decrement );
          SHOW_CONTAINER
          // ...and does indeed influence the original container
        }
      
    };
  
  
  
  
  LAUNCHER (UtilForeach_test, "unit common");
  
  
}} // namespace util::test