follow up PR #9274 "Mesh_3 - speedup protecting balls placement"

Mesh_3/include/CGAL/Mesh_3/Protect_edges_sizing_field.h

@@ -73,22 +73,25 @@
 #include <optional>
 #include <ostream>
 #include <set>
-#include <sstream>
 #include <stack>
 #include <string>
 #include <tuple>
 #include <type_traits>
 #include <utility>
 #include <vector>
 
+// std::ostringstream is used in assertion messages and debug messages
+#include <sstream> // IWYU pragma: keep
+
 namespace CGAL {
 namespace Mesh_3 {
 namespace internal {
 
-const double min_intersection_factor = .4; // (1-alpha)
-const double weight_modifier = .81; //0.9025;//0.81;
-const double distance_divisor = 2.1;
-const int max_nb_vertices_to_reevaluate_size = 10;
+inline constexpr double min_intersection_factor = .4; // (1-alpha)
+inline constexpr double distance_modifier = .9;
+inline constexpr double weight_modifier = distance_modifier * distance_modifier;
+inline constexpr double distance_divisor = 2.1;
+inline constexpr int max_nb_vertices_to_reevaluate_size = 10;
 
 // for the origins of `refine_balls_max_nb_of_loops`, that dates from the
 // very beginning of this file:
@@ -741,7 +744,7 @@ class Protect_edges_sizing_field
         auto pos = corners_on_curves_.find(Corner_and_curve_index(corner_index, curve_index));
         CGAL_assertion_msg(pos != corners_on_curves_.end(),
                            std::invoke([&] {
-                             std::stringstream ss;
+                             std::ostringstream ss;
                              ss.copyfmt(std::cerr);
                              ss << "position_on_curve(v=" << IO::oformat(v, With_point_tag{})
                                 << " (corner index: " << corner_index
@@ -868,9 +871,6 @@ void
 Protect_edges_sizing_field<C3T3, MD, Sf, Df>::
 operator()(const bool refine)
 {
-  // TODO: that caching of iterators should not be the responsibility of the
-  // domain, but of the Protect_edges_sizing_field class. -- LR, 2026-02-16
-
   // This class is only meant to be used with non-periodic triangulations
   CGAL_assertion(!(std::is_same_v<typename Tr::Periodic_tag, CGAL::Tag_true>));
 
@@ -1418,7 +1418,7 @@ insert_balls_on_edges()
         insert_balls(vp, vq, curve_index, CGAL::POSITIVE, Emptyset_iterator());
       }
       set_treated(curve_index);
-//      std::stringstream s;
+//      std::ostringstream s;
 //      s << "dump-mesh-curve-" << curve_index << ".binary.cgal";
 //      debug_dump_c3t3(s.str(), c3t3_);
     }
@@ -1486,7 +1486,7 @@ insert_balls(const Vertex_handle& vp,
 
 #if ! defined(CGAL_NO_PRECONDITIONS)
   if(sp < minimal_size_) {
-    std::stringstream msg;
+    std::ostringstream msg;
     msg.precision(17);
     msg << "Error: the mesh sizing field is smaller than minimal size ";
     msg << " at point (" << cp(vp_wp) << ")!";

Mesh_3/include/CGAL/Mesh_3/Slivers_exuder.h

@@ -48,7 +48,6 @@
 #include <limits>
 #include <map>
 #include <optional>
-#include <type_traits>
 #include <utility>
 #include <vector>