From e2502e5b16c2a685a8b9dcdac7f837bb8a3390fb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philipp=20M=C3=B6ller?= <bootsarehax@googlemail.com>
Date: Fri, 16 Nov 2012 22:05:10 +0100
Subject: [PATCH] Add circulator concepts and a (not useful) test-case.

---
 .../CGAL/Circulator/Circulator_concepts.h     | 95 +++++++++++++++++++
 .../Circulator/circulator_concept_checks.cpp  | 32 +++++++
 2 files changed, 127 insertions(+)
 create mode 100644 Circulator/include/CGAL/Circulator/Circulator_concepts.h
 create mode 100644 Circulator/test/Circulator/circulator_concept_checks.cpp

diff --git a/Circulator/include/CGAL/Circulator/Circulator_concepts.h b/Circulator/include/CGAL/Circulator/Circulator_concepts.h
new file mode 100644
index 00000000000..99525c52da0
--- /dev/null
+++ b/Circulator/include/CGAL/Circulator/Circulator_concepts.h
@@ -0,0 +1,95 @@
+#ifndef CGAL_CIRCULATOR_CONCEPTS_H
+#define CGAL_CIRCULATOR_CONCEPTS_H
+
+#include <boost/concept/assert.hpp>
+#include <boost/concept_check.hpp>
+#include <boost/concept/detail/concept_def.hpp>
+
+#include <iterator>
+
+#include <CGAL/circulator_bases.h>
+
+namespace CGAL { namespace Concepts {
+
+// N.B.: there is no such concept as Circulator as it is immaterial
+template <typename C>
+struct ForwardCirculator 
+  : boost::Assignable<C>, boost::DefaultConstructible<C>
+  , boost::CopyConstructible<C> 
+{
+  // for some odd reason circulators have no associated traits
+  typedef typename C::value_type value_type;
+  typedef typename C::reference reference;
+  typedef typename C::pointer pointer;
+  typedef typename C::difference_type difference_type;
+  // odd name but useful for compatibility
+  typedef typename C::iterator_category iterator_category;
+
+  // this requirement ought to be a mistake because it breaks
+  // compatibility with iterators
+  // typedef typename C::size_type size_type;
+
+  BOOST_CONCEPT_USAGE(ForwardCirculator)
+  {
+    BOOST_CONCEPT_ASSERT((boost::SignedInteger<difference_type>));
+    BOOST_CONCEPT_ASSERT((boost::Convertible<iterator_category, CGAL::Forward_circulator_tag>));
+    
+    boost::require_boolean_expr(a == NULL);
+    boost::require_boolean_expr(a != NULL);
+    ++a;
+    a++;
+    (void)*a; // suppress unused warning, don't check the return type
+              // to allow for proxies
+  }
+private:
+  C a;
+};
+
+template<typename C>
+struct BidirectionalCirculator
+  : ForwardCirculator<C>
+{
+  BOOST_CONCEPT_USAGE(BidirectionalCirculator)
+  {
+    BOOST_CONCEPT_ASSERT((boost::Convertible<typename C::iterator_category, CGAL::Bidirectional_circulator_tag>));
+    --a;
+    a--;
+  }
+private:
+  C a;
+};
+
+template<typename C>
+struct RandomAccessCirculator
+  : BidirectionalCirculator<C>
+{
+  BOOST_CONCEPT_USAGE(RandomAccessCirculator)
+  {
+    BOOST_CONCEPT_ASSERT((boost::Convertible<typename C::iterator_category, CGAL::Random_access_circulator_tag>));
+    c += n; // addition
+    c = c + n; c = n + c;
+    c -= n; // subtraction
+    c = c - n; 
+    n = c - b; // difference
+    (void)c[n]; // operator[]
+
+    c.min_circulator(); // minimum
+  }
+private:
+  C c, b;
+  C i;
+  typename C::difference_type n;
+};
+
+} // Concept
+} // CGAL
+
+
+
+#include <boost/concept/detail/concept_undef.hpp>
+
+
+#endif /* CGAL_CIRCULATOR_CONCEPTS_H */
+
+
+
diff --git a/Circulator/test/Circulator/circulator_concept_checks.cpp b/Circulator/test/Circulator/circulator_concept_checks.cpp
new file mode 100644
index 00000000000..69615405e5b
--- /dev/null
+++ b/Circulator/test/Circulator/circulator_concept_checks.cpp
@@ -0,0 +1,32 @@
+#include <vector>
+#include <list>
+
+#include <boost/concept/assert.hpp>
+
+#include <CGAL/circulator.h>
+#include <CGAL/Circulator/Circulator_concepts.h>
+
+int main()
+{
+  // test Circulator_from_container
+  typedef CGAL::Circulator_from_container< std::vector<int> > Circulator_from_vec;
+  typedef CGAL::Circulator_from_container< std::list<int> > Circulator_from_list;
+
+  // neither of the container adaptors passes the checks for tag
+  // convertibility
+  
+  // BOOST_CONCEPT_ASSERT((CGAL::Concepts::RandomAccessCirculator<Circulator_from_vec>));
+  // BOOST_CONCEPT_ASSERT((CGAL::Concepts::BidirectionalCirculator<Circulator_from_list>));
+
+  typedef CGAL::Circulator_from_iterator<int*> Circulator_from_intp;
+  typedef CGAL::Circulator_from_iterator<std::vector<int>::iterator> Circulator_from_veci;
+  typedef CGAL::Circulator_from_iterator<std::list<int>::iterator> Circulator_from_listi;
+
+  // same as above
+  // BOOST_CONCEPT_ASSERT((CGAL::Concepts::RandomAccessCirculator<Circulator_from_intp>));
+  // BOOST_CONCEPT_ASSERT((CGAL::Concepts::RandomAccessCirculator<Circulator_from_veci>));
+  // BOOST_CONCEPT_ASSERT((CGAL::Concepts::BidirectionalCirculator<Circulator_from_listi>));
+  
+
+  return 0;
+}