From ba19b93aa3bf3f65e3c85271ee33d4391422cf3f Mon Sep 17 00:00:00 2001
From: Martin Heistermann <git@mheistermann.de>
Date: Tue, 21 May 2019 16:27:39 +0200
Subject: [PATCH] implement/improve mesh assignment

---
 src/OpenVolumeMesh/Core/BaseProperty.hh      |  5 +++
 src/OpenVolumeMesh/Core/GeometryKernel.hh    |  5 +++
 src/OpenVolumeMesh/Core/PropertyPtr.hh       |  2 ++
 src/OpenVolumeMesh/Core/PropertyPtrT_impl.hh |  7 ++++
 src/OpenVolumeMesh/Core/ResourceManager.cc   | 34 +++++++++++++++++---
 src/OpenVolumeMesh/Core/TopologyKernel.hh    |  3 ++
 6 files changed, 51 insertions(+), 5 deletions(-)

diff --git a/src/OpenVolumeMesh/Core/BaseProperty.hh b/src/OpenVolumeMesh/Core/BaseProperty.hh
index 71e99ee..4c39c97 100644
--- a/src/OpenVolumeMesh/Core/BaseProperty.hh
+++ b/src/OpenVolumeMesh/Core/BaseProperty.hh
@@ -62,6 +62,7 @@ public:
 
     BaseProperty& operator=(const BaseProperty& _cpy) = delete;
 
+
     virtual ~BaseProperty() {}
 
     virtual const std::string& name() const = 0;
@@ -92,6 +93,10 @@ public:
 
 protected:
 
+    /// Copy data from other property. `other` MUST point to an object with the same type as `this`!
+    /// Currently no type check is performed.
+    virtual void assign_values_from(const BaseProperty *other) = 0;
+
     virtual void delete_multiple_entries(const std::vector<bool>& _tags) = 0;
 
     virtual void resize(size_t /*_size*/) = 0;
diff --git a/src/OpenVolumeMesh/Core/GeometryKernel.hh b/src/OpenVolumeMesh/Core/GeometryKernel.hh
index 8541a00..ab8f85d 100644
--- a/src/OpenVolumeMesh/Core/GeometryKernel.hh
+++ b/src/OpenVolumeMesh/Core/GeometryKernel.hh
@@ -64,6 +64,11 @@ public:
     /// Destructor
     ~GeometryKernel() = default;
 
+    template<class OtherTopoKernel>
+    void assign(const GeometryKernel<VecT, OtherTopoKernel> *other) {
+        TopologyKernelT::assign(other);
+        other->clone_vertices(vertices_);
+    }
 
     /// Override of empty add_vertex function
     virtual VertexHandle add_vertex() { return add_vertex(VecT()); }
diff --git a/src/OpenVolumeMesh/Core/PropertyPtr.hh b/src/OpenVolumeMesh/Core/PropertyPtr.hh
index 1c5d408..6c8840c 100644
--- a/src/OpenVolumeMesh/Core/PropertyPtr.hh
+++ b/src/OpenVolumeMesh/Core/PropertyPtr.hh
@@ -115,6 +115,8 @@ public:
 
 protected:
 
+    void assign_values_from(const BaseProperty *other) override;
+
     virtual void delete_multiple_entries(const std::vector<bool>& _tags);
 
     virtual void resize(size_t _size);
diff --git a/src/OpenVolumeMesh/Core/PropertyPtrT_impl.hh b/src/OpenVolumeMesh/Core/PropertyPtrT_impl.hh
index e240e15..6bcfb70 100644
--- a/src/OpenVolumeMesh/Core/PropertyPtrT_impl.hh
+++ b/src/OpenVolumeMesh/Core/PropertyPtrT_impl.hh
@@ -59,6 +59,13 @@ PropertyPtr<PropT,Entity>::~PropertyPtr() {
     }
 }
 
+template <class PropT, typename Entity>
+void PropertyPtr<PropT,Entity>::assign_values_from(const BaseProperty *other) {
+    auto _other = static_cast<const PropertyPtr<PropT,Entity>*>(other);
+    // FIXME: would be nice to perform a type check here
+    ptr::shared_ptr<PropT>::get()->data_vector() = _other->get()->data_vector();
+}
+
 template <class PropT, typename Entity>
 void PropertyPtr<PropT,Entity>::resize(size_t _size) {
     ptr::shared_ptr<PropT>::get()->resize(_size);
diff --git a/src/OpenVolumeMesh/Core/ResourceManager.cc b/src/OpenVolumeMesh/Core/ResourceManager.cc
index fa8a90e..0772678 100644
--- a/src/OpenVolumeMesh/Core/ResourceManager.cc
+++ b/src/OpenVolumeMesh/Core/ResourceManager.cc
@@ -51,11 +51,34 @@ ResourceManager& ResourceManager::operator=(const ResourceManager &other)
     if (this == &other)
         return *this;
 
-    auto cloneProps = [this](const Properties &src, Properties &dest) {
-        dest.reserve(src.size());
-        for (BaseProperty *bp: src) {
-            dest.push_back(bp->clone(*this, bp->handle()));
+    auto cloneProps = [this](const Properties &src, Properties &dest)
+    {
+        // If possible, re-use existing properties instead of copying
+        // everything blindly.
+        // This way, references to properties of `this` do not expire
+        // if a corresponding property exists in `other`, e.g. attributes.
+        Properties out;
+        out.reserve(src.size());
+        for (BaseProperty *srcprop: src) {
+            bool found = false;
+            for (auto it = dest.begin(); it != dest.end(); ++it) {
+                auto dstprop = *it;
+                if (dstprop->name() == srcprop->name())
+                {
+                    // TODO: type check
+                    out.push_back(dstprop);
+                    dest.erase(it);
+                    dstprop->assign_values_from(srcprop);
+                    found = true;
+                    break;
+                }
+            }
+            if (!found) {
+                out.push_back(srcprop->clone(*this, OpenVolumeMeshHandle(-1)));
+            }
         }
+        updatePropHandles(out);
+        dest = std::move(out);
     };
     cloneProps(other.vertex_props_,   vertex_props_);
     cloneProps(other.edge_props_,     edge_props_);
@@ -72,7 +95,8 @@ ResourceManager& ResourceManager::operator=(ResourceManager &&other)
     if (this == &other)
         return *this;
 
-    auto moveProps = [this](Properties &&src, Properties &dest) {
+    auto moveProps = [this](Properties &&src, Properties &dest){
+        // TODO: check for existing properties and move data contents instead of Property classes
         dest = std::move(src);
         for (auto prop: dest) {
             prop->setResMan(this);
diff --git a/src/OpenVolumeMesh/Core/TopologyKernel.hh b/src/OpenVolumeMesh/Core/TopologyKernel.hh
index 8fde79a..f638ce5 100644
--- a/src/OpenVolumeMesh/Core/TopologyKernel.hh
+++ b/src/OpenVolumeMesh/Core/TopologyKernel.hh
@@ -62,6 +62,9 @@ public:
 
     TopologyKernel& operator=(const TopologyKernel&) = default;
 
+    void assign(const TopologyKernel *other) {
+        *this = *other;
+    }
 
     /*
      * Defines and constants
-- 
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