CODEWITHSUNDEEP
c++c++11vectorgecode
Krishna
Krishna

Reputation: 1362

Unable to initialize Gecode's `IntSet` from `Vector`

As per the Gecode documentation "Modelling and Programming with Gecode", an IntVar can be created with IntSet

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This is also confirmed by Gecode's reference for IntVar at https://www.gecode.org/doc/6.2.0/reference/classGecode_1_1IntVar.html

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And an IntSet can be created using a vector<int> as per https://www.gecode.org/doc/6.2.0/reference/classGecode_1_1IntSet.html

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But the following code

std::vector<int> values = {2, 4, 6, 8};
IntVar i;

Class() : i(*this, IntSet(values)) {
}

gives me an error message that looks something like this

In file included from $GECODE_HOME/include/gecode/int.hh:356,
                 from bla.cc:3:
$GECODE_HOME/include/gecode/int/int-set-1.hpp: In instantiation of ‘static void Gecode::IntSetInit<I>::init(Gecode::IntSet&, I&) [with I = std::vector<int>]’:
$GECODE_HOME/include/gecode/int/int-set-1.hpp:87:24:   required from ‘Gecode::IntSet::IntSet(I&) [with I = std::vector<int>]’
bla.cc:14:35:   required from here
$GECODE_HOME/include/gecode/int/int-set-1.hpp:61:15: error: no match for call to ‘(std::vector<int>) ()’
   61 |       while (i()) {
      |              ~^~
$GECODE_HOME/include/gecode/int/int-set-1.hpp:62:22: error: ‘class std::vector<int>’ has no member named ‘min’
   62 |         d[n].min = i.min(); d[n].max = i.max(); size += i.width();
      |                    ~~^~~
$GECODE_HOME/include/gecode/int/int-set-1.hpp:62:42: error: ‘class std::vector<int>’ has no member named ‘max’
   62 |         d[n].min = i.min(); d[n].max = i.max(); size += i.width();
      |                                        ~~^~~
$GECODE_HOME/include/gecode/int/int-set-1.hpp:62:59: error: ‘class std::vector<int>’ has no member named ‘width’
   62 |         d[n].min = i.min(); d[n].max = i.max(); size += i.width();
      |                                                         ~~^~~~~
$GECODE_HOME/include/gecode/int/int-set-1.hpp:63:14: error: no match for ‘operator++’ (operand type is ‘std::vector<int>’)
   63 |         ++n; ++i;
      |              ^~~

Full code

#include <vector>

#include <gecode/int.hh>
#include <gecode/search.hh>
#include <gecode/minimodel.hh>

using namespace Gecode;

class Class : public Space {
public:
  std::vector<int> values = {2, 4, 6, 8};
  IntVar i;

  Class() : i(*this, IntSet(values)) {

  }

  // search support
  Class(Class& s) : Space(s) {
    i.update(*this, s.i);
  }

  virtual Space* copy(void) {
    return new Class(*this);
  }

  // print solution
  void print() {
    std::cout << i << "\n";
  }
};


int main(int argc, char* argv[]) {
    Class* c = new Class;
    DFS<Class> e(c);
    delete c;
    while (Class* s = e.next()) {
      s->print(); delete s;
    }

    return 0;
}

Command to compile

g++ -std=c++20 -O3 -I $GECODE_HOME/include -L$GECODE_HOME/lib -lgecodesearch -lgecodeminimodel -lgecodeint -lgecodekernel -lgecodesupport bla.cc

What am I missing here? Do I misunderstand something?

Upvotes: 1

Views: 54

Answers (1)

3CxEZiVlQ
3CxEZiVlQ

Reputation: 38508

The vector is bound to the constructor template <typename I> IntSet::IntSet(I&), you seem to expect the specialized constructor template <> IntSet::IntSet(const std::vector<int>& r). Make the vector const: const std::vector<int> values = {2, 4, 6, 8};.

See the minimized example for your case: https://godbolt.org/z/Gd8Enjfr4

See the example with the const vector: https://godbolt.org/z/dTshKrPPb

Upvotes: 2

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