From f646ee786cc05f2416b246cd9c82771300941f06 Mon Sep 17 00:00:00 2001
From: Menelaos Karavelas <menelaos.karavelas@gmail.com>
Date: Tue, 24 Feb 2015 15:28:03 +0200
Subject: [PATCH] [algorithms][is_valid] add the following free functions: *
 bool is_valid(geometry, string) * bool is_valid(geometry, visitor) * bool
 is_valid(geometry, failure value)

---
 .../algorithms/detail/is_valid/interface.hpp  | 53 +++++++++++++++++--
 1 file changed, 49 insertions(+), 4 deletions(-)

diff --git a/include/boost/geometry/algorithms/detail/is_valid/interface.hpp b/include/boost/geometry/algorithms/detail/is_valid/interface.hpp
index 49e78181f..1c1972856 100644
--- a/include/boost/geometry/algorithms/detail/is_valid/interface.hpp
+++ b/include/boost/geometry/algorithms/detail/is_valid/interface.hpp
@@ -10,6 +10,9 @@
 #ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_IS_VALID_INTERFACE_HPP
 #define BOOST_GEOMETRY_ALGORITHMS_DETAIL_IS_VALID_INTERFACE_HPP
 
+#include <sstream>
+#include <string>
+
 #include <boost/variant/apply_visitor.hpp>
 #include <boost/variant/static_visitor.hpp>
 #include <boost/variant/variant_fwd.hpp>
@@ -18,6 +21,8 @@
 
 #include <boost/geometry/algorithms/dispatch/is_valid.hpp>
 #include <boost/geometry/policies/is_valid/default_policy.hpp>
+#include <boost/geometry/policies/is_valid/failing_reason_policy.hpp>
+#include <boost/geometry/policies/is_valid/failure_type_policy.hpp>
 
 
 namespace boost { namespace geometry
@@ -67,6 +72,14 @@ struct is_valid<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> >
 } // namespace resolve_variant
 
 
+// Undocumented for now
+template <typename Geometry, typename VisitPolicy>
+inline bool is_valid(Geometry const& geometry, VisitPolicy& visitor)
+{
+    return resolve_variant::is_valid<Geometry>::apply(geometry, visitor);
+}
+
+
 /*!
 \brief \brief_check{is valid (in the OGC sense)}
 \ingroup is_valid
@@ -81,10 +94,42 @@ template <typename Geometry>
 inline bool is_valid(Geometry const& geometry)
 {
     is_valid_default_policy<> policy_visitor;
-    return resolve_variant::is_valid
-        <
-            Geometry
-        >::apply(geometry, policy_visitor);
+    return is_valid(geometry, policy_visitor);
+}
+
+
+// Undocumented for now
+template <typename Geometry>
+inline bool is_valid(Geometry const& geometry, validity_failure_type& failure)
+{
+    failure_type_policy<> policy_visitor;
+    bool result = is_valid(geometry, policy_visitor);
+    failure = policy_visitor.failure();
+    return result;
+}
+
+
+/*!
+\brief \brief_check{is valid (in the OGC sense)}
+\ingroup is_valid
+\tparam Geometry \tparam_geometry
+\param geometry \param_geometry
+\param message A string containing a message stating if the geometry
+is valid or not, and if not valid a reason why
+\return \return_check{is valid (in the OGC sense), with one exception:
+multi-geometries with no elements are considered valid}
+
+\qbk{distinguish,with message}
+\qbk{[include reference/algorithms/is_valid_with_message.qbk]}
+*/
+template <typename Geometry>
+inline bool is_valid(Geometry const& geometry, std::string& message)
+{
+    std::ostringstream stream;
+    failing_reason_policy<> policy_visitor(stream);
+    bool result = is_valid(geometry, policy_visitor);
+    message = stream.str();
+    return result;
 }