ENH: additional methods for globalIndex

- const version of offsets().

- empty() method to test for empty offsets, or zero overall size

- reset() methods for reseting the sizes. For example, when the context
  has shifted slightly.

- localStart() methods, similar to localSize() methods

STYLE: make globalIndex single parameter constructors explicit

src/OpenFOAM/meshes/polyMesh/globalMeshData/globalIndex.C

@@ -3,7 +3,7 @@
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
     \\  /    A nd           | Copyright (C) 2011-2016 OpenFOAM Foundation
-     \\/     M anipulation  |
+     \\/     M anipulation  | Copyright (C) 2018 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -27,18 +27,27 @@ License
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
-Foam::globalIndex::globalIndex
+Foam::globalIndex::globalIndex(Istream& is)
+{
+    is >> offsets_;
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+void Foam::globalIndex::reset
 (
     const label localSize,
     const int tag,
     const label comm,
     const bool parallel
 )
-:
-    offsets_(Pstream::nProcs(comm)+1)
 {
-    labelList localSizes(Pstream::nProcs(comm), 0);
+    offsets_.resize(Pstream::nProcs(comm)+1);
+
+    labelList localSizes(Pstream::nProcs(comm), Zero);
     localSizes[Pstream::myProcNo(comm)] = localSize;
+
     if (parallel)
     {
         Pstream::gatherList(localSizes, tag, comm);
@@ -47,9 +56,9 @@ Foam::globalIndex::globalIndex
 
     label offset = 0;
     offsets_[0] = 0;
-    for (label proci = 0; proci < Pstream::nProcs(comm); proci++)
+    for (label proci = 0; proci < Pstream::nProcs(comm); ++proci)
     {
-        label oldOffset = offset;
+        const label oldOffset = offset;
         offset += localSizes[proci];
 
         if (offset < oldOffset)
@@ -65,20 +74,21 @@ Foam::globalIndex::globalIndex
 }
 
 
-Foam::globalIndex::globalIndex(const label localSize)
+void Foam::globalIndex::reset(const label localSize)
-:
-    offsets_(Pstream::nProcs()+1)
 {
-    labelList localSizes(Pstream::nProcs(), 0);
+    offsets_.resize(Pstream::nProcs()+1);
+
+    labelList localSizes(Pstream::nProcs(), Zero);
     localSizes[Pstream::myProcNo()] = localSize;
+
     Pstream::gatherList(localSizes, Pstream::msgType());
     Pstream::scatterList(localSizes, Pstream::msgType());
 
     label offset = 0;
     offsets_[0] = 0;
-    for (label proci = 0; proci < Pstream::nProcs(); proci++)
+    for (label proci = 0; proci < Pstream::nProcs(); ++proci)
     {
-        label oldOffset = offset;
+        const label oldOffset = offset;
         offset += localSizes[proci];
 
         if (offset < oldOffset)
@@ -94,12 +104,6 @@ Foam::globalIndex::globalIndex(const label localSize)
 }
 
 
-Foam::globalIndex::globalIndex(Istream& is)
-{
-    is >> offsets_;
-}
-
-
 // * * * * * * * * * * * * * * * Friend Operators  * * * * * * * * * * * * * //
 
 Foam::Istream& Foam::operator>>(Istream& is, globalIndex& gi)

src/OpenFOAM/meshes/polyMesh/globalMeshData/globalIndex.H

@@ -3,7 +3,7 @@
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
     \\  /    A nd           | Copyright (C) 2011-2017 OpenFOAM Foundation
-     \\/     M anipulation  |
+     \\/     M anipulation  | Copyright (C) 2018 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -78,11 +78,11 @@ public:
 
         //- Construct from local max size.
         //  Does communication with default communicator and message tag.
-        globalIndex(const label localSize);
+        inline explicit globalIndex(const label localSize);
 
         //- Construct from local max size.
         //  Does communication with given communicator and message tag
-        globalIndex
+        inline globalIndex
         (
             const label localSize,
             const int tag,
@@ -91,10 +91,10 @@ public:
         );
 
         //- Copy construct from list of labels
-        inline globalIndex(const labelUList& offsets);
+        inline explicit globalIndex(const labelUList& offsets);
 
         //- Move construct from list of labels
-        inline globalIndex(labelList&& offsets);
+        inline explicit globalIndex(labelList&& offsets);
 
         //- Construct from Istream
         globalIndex(Istream& is);
@@ -102,14 +102,38 @@ public:
 
     // Member Functions
 
-        // Edit
+        //- Check for null constructed or global sum == 0
+        inline bool empty() const;
 
-            //- Change after construction
+        //- Const-access to the offsets
-            inline labelList& offsets();
+        inline const labelList& offsets() const;
+
+
+    // Edit
+
+        //- Write-access to the offsets, for changing after construction
+        inline labelList& offsets();
+
+        //- Reset from local size.
+        //  Does communication with default communicator and message tag.
+        void reset(const label localSize);
+
+        //- Reset from local size.
+        //  Does communication with given communicator and message tag
+        void reset
+        (
+            const label localSize,
+            const int tag,
+            const label comm,
+            const bool parallel     // use parallel comms
+        );
 
 
         // Queries relating to my processor (using world communicator)
 
+            //- My local start
+            inline label localStart() const;
+
             //- My local size
             inline label localSize() const;
 
@@ -132,6 +156,12 @@ public:
             //- Global sum of localSizes
             inline label size() const;
 
+            //- Start of proci data
+            inline label offset(const label proci) const;
+
+            //- Start of proci data
+            inline label localStart(const label proci) const;
+
             //- Size of proci data
             inline label localSize(const label proci) const;
 
@@ -150,9 +180,6 @@ public:
             //- Which processor does global come from? Binary search.
             inline label whichProcID(const label i) const;
 
-            //- Start of proci data
-            inline label offset(const label proci) const;
-
 
         // Other
 

src/OpenFOAM/meshes/polyMesh/globalMeshData/globalIndexI.H

@@ -28,6 +28,28 @@ License
 
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
+inline Foam::globalIndex::globalIndex(const label localSize)
+:
+    globalIndex()
+{
+    reset(localSize);
+}
+
+
+inline Foam::globalIndex::globalIndex
+(
+    const label localSize,
+    const int tag,
+    const label comm,
+    const bool parallel
+)
+:
+    globalIndex()
+{
+    reset(localSize, tag, comm, parallel);
+}
+
+
 inline Foam::globalIndex::globalIndex(const labelUList& offsets)
 :
     offsets_(offsets)
@@ -42,6 +64,18 @@ inline Foam::globalIndex::globalIndex(labelList&& offsets)
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
+inline bool Foam::globalIndex::empty() const
+{
+    return offsets_.empty() || offsets_.last() == 0;
+}
+
+
+inline const Foam::labelList& Foam::globalIndex::offsets() const
+{
+    return offsets_;
+}
+
+
 inline Foam::labelList& Foam::globalIndex::offsets()
 {
     return offsets_;
@@ -54,6 +88,18 @@ inline Foam::label Foam::globalIndex::offset(const label proci) const
 }
 
 
+inline Foam::label Foam::globalIndex::localStart(const label proci) const
+{
+    return offsets_[proci];
+}
+
+
+inline Foam::label Foam::globalIndex::localStart() const
+{
+    return localStart(Pstream::myProcNo());
+}
+
+
 inline Foam::label Foam::globalIndex::localSize(const label proci) const
 {
     return offsets_[proci+1] - offsets_[proci];