ENH: free/nullify of PtrList and UPtrList

- Allows clearing or freeing pointers without touching the underlying
  list size. Was previously only for PtrDynList, but now available on
  UPtrList, PtrList as well.

- add transfer() method to PtrDynList to avoid potential slicing.

src/OpenFOAM/containers/PtrLists/PtrDynList/PtrDynList.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2018-2022 OpenCFD Ltd.
+    Copyright (C) 2018-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -126,9 +126,6 @@ public:
 
     // Edit
 
-        //- Delete the allocated entries, but retain the list size.
-        using PtrList<T>::free;
-
         //- Squeeze out intermediate nullptr entries in the list of pointers
         //- and adjust the addressable size accordingly.
         //  \return the number of non-null entries
@@ -138,6 +135,13 @@ public:
         template<int AnySizeMin>
         inline void swap(PtrDynList<T, AnySizeMin>& other);
 
+        //- Transfer contents of the argument PtrList into this.
+        inline void transfer(PtrList<T>& list);
+
+        //- Transfer contents of any sized PtrDynList into this.
+        template<int AnySizeMin>
+        inline void transfer(PtrDynList<T, AnySizeMin>& list);
+
         //- Construct an element at the end of the list,
         //- return reference to the new list element
         template<class... Args>

src/OpenFOAM/containers/PtrLists/PtrDynList/PtrDynListI.H

@@ -216,6 +216,44 @@ inline void Foam::PtrDynList<T, SizeMin>::swap
 }
 
 
+template<class T, int SizeMin>
+inline void Foam::PtrDynList<T, SizeMin>::transfer(PtrList<T>& other)
+{
+    if
+    (
+        static_cast<const PtrList<T>*>(this)
+     == static_cast<const PtrList<T>*>(&other)
+    )
+    {
+        return;  // Self assignment is a no-op
+    }
+
+    UPtrList<T>::swap(other);
+    other.clear();
+}
+
+
+template<class T, int SizeMin>
+template<int AnySizeMin>
+inline void Foam::PtrDynList<T, SizeMin>::transfer
+(
+    PtrDynList<T, AnySizeMin>& other
+)
+{
+    if
+    (
+        static_cast<const PtrList<T>*>(this)
+     == static_cast<const PtrList<T>*>(&other)
+    )
+    {
+        return;  // Self assignment is a no-op
+    }
+
+    this->swap(other);
+    other.clear();
+}
+
+
 template<class T, int SizeMin>
 template<class... Args>
 inline T& Foam::PtrDynList<T, SizeMin>::emplace_back(Args&&... args)

src/OpenFOAM/containers/PtrLists/PtrList/PtrList.H

@@ -78,8 +78,6 @@ protected:
         template<class INew>
         void readIstream(Istream& is, const INew& inew);
 
-        //- Delete the allocated entries, but retain the list size.
-        inline void free();
 
 public:
 
@@ -142,6 +140,9 @@ public:
         //- Clear the PtrList. Delete allocated entries and set size to zero.
         inline void clear();
 
+        //- Free memory and nullify all entries. Does not change the list size.
+        inline void free();
+
         //- Adjust size of PtrList.
         //  New entries are initialized to nullptr, removed entries are deleted
         void resize(const label newLen);

src/OpenFOAM/containers/PtrLists/PtrList/PtrListI.H

@@ -30,15 +30,6 @@ License
 #include "refPtr.H"
 #include "tmp.H"
 
-// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
-
-template<class T>
-inline void Foam::PtrList<T>::free()
-{
-    (this->ptrs_).free(); // free old pointers
-}
-
-
 // * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * * //
 
 template<class T>
@@ -96,11 +87,18 @@ inline Foam::PtrList<T>::PtrList
 template<class T>
 inline void Foam::PtrList<T>::clear()
 {
-    (this->ptrs_).free(); // free old pointers
+    (this->ptrs_).free();  // Free and nullify old pointers
     UPtrList<T>::clear();
 }
 
 
+template<class T>
+inline void Foam::PtrList<T>::free()
+{
+    (this->ptrs_).free();  // Free and nullify old pointers
+}
+
+
 template<class T>
 template<class... Args>
 inline T& Foam::PtrList<T>::emplace_back(Args&&... args)
@@ -260,7 +258,12 @@ inline Foam::autoPtr<T> Foam::PtrList<T>::release(const label i)
 template<class T>
 inline void Foam::PtrList<T>::transfer(PtrList<T>& list)
 {
-    (this->ptrs_).free(); // free old pointers
+    if (this == &list)
+    {
+        return;  // Self-assignment is a no-op
+    }
+
+    (this->ptrs_).free();  // Free and nullify old pointers
     UPtrList<T>::transfer(list);
 }
 

src/OpenFOAM/containers/PtrLists/UPtrList/UPtrList.H

@@ -295,6 +295,9 @@ public:
         //- Set list size to zero.
         inline void clear();
 
+        //- Nullify all entries. Does not change the list size.
+        inline void free();
+
         //- Change the size of the list.
         //  New entries are initialized to nullptr.
         inline void resize(const label newLen);

src/OpenFOAM/containers/PtrLists/UPtrList/UPtrListI.H

@@ -205,6 +205,13 @@ inline void Foam::UPtrList<T>::clear()
 }
 
 
+template<class T>
+inline void Foam::UPtrList<T>::free()
+{
+    ptrs_.setNull();
+}
+
+
 template<class T>
 inline void Foam::UPtrList<T>::swap(UPtrList<T>& list)
 {

src/OpenFOAM/meshes/polyMesh/mapPolyMesh/mapDistribute/mapDistributeBaseTemplates.C

@@ -191,7 +191,7 @@ void Foam::mapDistributeBase::send
 
     // Set up receives from neighbours
 
-    recvFields.clear();
+    recvFields.free();
     recvFields.resize(nProcs);
 
     for (const int domain : UPstream::allProcs(comm))
@@ -219,7 +219,7 @@ void Foam::mapDistributeBase::send
 
     // Set up sends to neighbours
 
-    sendFields.clear();
+    recvFields.free();
     sendFields.resize(nProcs);
 
     for (const int domain : UPstream::allProcs(comm))

src/OpenFOAM/meshes/polyMesh/polyBoundaryMesh/polyBoundaryMesh.C

@@ -206,6 +206,13 @@ Foam::polyBoundaryMesh::polyBoundaryMesh
 
 // * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
+void Foam::polyBoundaryMesh::clear()
+{
+    polyPatchList::clear();
+    clearAddressing();
+}
+
+
 void Foam::polyBoundaryMesh::clearGeom()
 {
     polyPatchList& patches = *this;
@@ -219,9 +226,9 @@ void Foam::polyBoundaryMesh::clearGeom()
 
 void Foam::polyBoundaryMesh::clearAddressing()
 {
-    neighbourEdgesPtr_.clear();
+    neighbourEdgesPtr_.reset(nullptr);
-    patchIDPtr_.clear();
+    patchIDPtr_.reset(nullptr);
-    groupIDsPtr_.clear();
+    groupIDsPtr_.reset(nullptr);
 
     polyPatchList& patches = *this;
 
@@ -493,7 +500,7 @@ void Foam::polyBoundaryMesh::setGroup
     const labelUList& patchIDs
 )
 {
-    groupIDsPtr_.clear();
+    groupIDsPtr_.reset(nullptr);
 
     polyPatchList& patches = *this;
 
@@ -1179,9 +1186,9 @@ void Foam::polyBoundaryMesh::movePoints(const pointField& p)
 
 void Foam::polyBoundaryMesh::updateMesh()
 {
-    neighbourEdgesPtr_.clear();
+    neighbourEdgesPtr_.reset(nullptr);
-    patchIDPtr_.clear();
+    patchIDPtr_.reset(nullptr);
-    groupIDsPtr_.clear();
+    groupIDsPtr_.reset(nullptr);
 
     PstreamBuffers pBufs(Pstream::defaultCommsType);
 

src/OpenFOAM/meshes/polyMesh/polyBoundaryMesh/polyBoundaryMesh.H

@@ -94,23 +94,24 @@ class polyBoundaryMesh
         //- Read if IOobject flags set. Return true if read.
         bool readContents(const bool allowReadIfPresent);
 
-        //- No copy construct
-        polyBoundaryMesh(const polyBoundaryMesh&) = delete;
-
-        //- No copy assignment
-        void operator=(const polyBoundaryMesh&) = delete;
-
-
 public:
 
     //- Declare friendship with polyMesh
     friend class polyMesh;
 
-
     //- Runtime type information
     TypeName("polyBoundaryMesh");
 
 
+    // Generated Methods
+
+        //- No copy construct
+        polyBoundaryMesh(const polyBoundaryMesh&) = delete;
+
+        //- No copy assignment
+        void operator=(const polyBoundaryMesh&) = delete;
+
+
     // Constructors
 
         //- Read constructor given IOobject and a polyMesh reference
@@ -142,15 +143,17 @@ public:
     ~polyBoundaryMesh() = default;
 
 
+    // Member Functions
+
+        //- Clear the patch list and all demand-driven data
+        void clear();
+
         //- Clear geometry at this level and at patches
         void clearGeom();
 
         //- Clear addressing at this level and at patches
         void clearAddressing();
 
-
-    // Member Functions
-
         //- Return the mesh reference
         const polyMesh& mesh() const noexcept
         {

src/OpenFOAM/meshes/polyMesh/polyMeshClear.C

@@ -40,9 +40,7 @@ void Foam::polyMesh::removeBoundary()
 {
     DebugInFunction << "Removing boundary patches." << endl;
 
-    // Remove the point zones
     boundary_.clear();
-    boundary_.setSize(0);
 
     clearOut();
 }

src/OpenFOAM/meshes/polyMesh/polyMeshIO.C

@@ -212,7 +212,7 @@ Foam::polyMesh::readUpdateState Foam::polyMesh::readUpdate()
                 << "unexpected consequences.  Proceed with care." << endl;
 
             boundary_.clear();
-            boundary_.setSize(newBoundary.size());
+            boundary_.resize(newBoundary.size());
 
             forAll(newBoundary, patchi)
             {

src/dynamicMesh/boundaryMesh/boundaryMesh.C

@@ -462,8 +462,7 @@ void Foam::boundaryMesh::clearOut()
 void Foam::boundaryMesh::read(const polyMesh& mesh)
 {
     patches_.clear();
-
+    patches_.resize(mesh.boundaryMesh().size());
-    patches_.setSize(mesh.boundaryMesh().size());
 
     // Number of boundary faces
     const label nBFaces = mesh.nBoundaryFaces();
@@ -630,7 +629,7 @@ void Foam::boundaryMesh::readTriSurface(const fileName& fName)
         // There are as many surface patches as region numbers in triangles
         // so use the surface patches
 
-        patches_.setSize(surfPatches.size());
+        patches_.resize(surfPatches.size());
 
         // Take over patches, setting size to 0 for now.
         forAll(surfPatches, patchi)
@@ -655,7 +654,7 @@ void Foam::boundaryMesh::readTriSurface(const fileName& fName)
     {
         // There are not enough surface patches. Make up my own.
 
-        patches_.setSize(regionToBoundaryPatch.size());
+        patches_.resize(regionToBoundaryPatch.size());
 
         forAll(patches_, patchi)
         {
@@ -1627,9 +1626,7 @@ void Foam::boundaryMesh::deletePatch(const word& patchName)
         newPatches.set(patchi - 1, patches_[patchi].clone());
     }
 
-    patches_.clear();
+    patches_ = std::move(newPatches);
-
-    patches_ = newPatches;
 
     if (debug)
     {

src/finiteArea/faMesh/faBoundaryMesh/faBoundaryMesh.C

@@ -176,6 +176,15 @@ Foam::faBoundaryMesh::faBoundaryMesh
 {}
 
 
+// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
+
+void Foam::faBoundaryMesh::clear()
+{
+    faPatchList::clear();
+    groupIDsPtr_.reset(nullptr);
+}
+
+
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 void Foam::faBoundaryMesh::calcGeometry()

src/finiteArea/faMesh/faBoundaryMesh/faBoundaryMesh.H

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2016-2017 Wikki Ltd
-    Copyright (C) 2018-2022 OpenCFD Ltd.
+    Copyright (C) 2018-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -90,12 +90,6 @@ class faBoundaryMesh
         //- Read if IOobject flags set. Return true if read.
         bool readContents(const bool allowReadIfPresent);
 
-        //- No copy construct
-        faBoundaryMesh(const faBoundaryMesh&) = delete;
-
-        //- No copy assignment
-        void operator=(const faBoundaryMesh&) = delete;
-
 
 public:
 
@@ -103,6 +97,15 @@ public:
     TypeName("faBoundaryMesh");
 
 
+    // Generated Methods
+
+        //- No copy construct
+        faBoundaryMesh(const faBoundaryMesh&) = delete;
+
+        //- No copy assignment
+        void operator=(const faBoundaryMesh&) = delete;
+
+
     // Constructors
 
         //- Construct from faMesh
@@ -127,6 +130,9 @@ public:
 
     // Member Functions
 
+        //- Clear the patch list and all demand-driven data
+        void clear();
+
         //- Return the mesh reference
         const faMesh& mesh() const noexcept
         {

src/sampling/sampledSet/sampledSets/sampledSets.C

@@ -155,7 +155,7 @@ void Foam::sampledSets::gatherAllSets()
 
     const PtrList<sampledSet>& localSets = *this;
 
-    gatheredSets_.clear();
+    gatheredSets_.free();
     gatheredSets_.resize(localSets.size());
     gatheredSorting_.resize_nocopy(localSets.size());
     globalIndices_.resize_nocopy(localSets.size());