ENH: FixedList empty(), size(), max_size() now constexpr static (#1160)

- this allows their use as templates parameters

applications/test/FixedList/Test-FixedList.C

@@ -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) 2019 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -68,6 +68,36 @@ Ostream& printInfo
 }
 
 
+template<class T, unsigned N>
+void compileInfo()
+{
+    // Info<< typeid(decltype(FixedList<T, N>)).name() << nl;
+
+    // Info<< "  holds: "
+    // << typeid(decltype(FixedList<T, N>::value_type())).name() << nl;
+
+    Info<< "max_size:"
+        << FixedList<T, N>::max_size() << nl;
+}
+
+
+template<class FixedListType>
+typename std::enable_if
+<(FixedListType::max_size() == 2), bool>::type
+is_pair()
+{
+     return true;
+}
+
+
+template<class FixedListType>
+typename std::enable_if<(FixedListType::max_size() != 2), std::string>::type
+is_pair()
+{
+     return "not really at all";
+}
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 //  Main program:
 
@@ -86,6 +116,18 @@ int main(int argc, char *argv[])
         args.found("default") || args.options().empty();
 
 
+    typedef FixedList<scalar,2> scalar2Type;
+    typedef FixedList<label,3>  label3Type;
+
+    // Compile-time info
+
+    compileInfo<label, 5>();
+
+    Info<< "pair: " << is_pair<scalar2Type>() << nl;
+    Info<< "pair: " << is_pair<label3Type>() << nl;
+
+    Info<< "max_size:" << scalar2Type::max_size() << nl;
+
     if (defaultTests || args.found("iter"))
     {
         Info<< nl

src/OpenFOAM/containers/Lists/FixedList/FixedList.H

@@ -90,7 +90,7 @@ protected:
     // Protected Member Functions
 
         //- True if there are two or more entries and all entries have
-        //  identical values.
+        //- identical values.
         inline bool uniform() const;
 
         //- Write the FixedList with its compound type
@@ -99,7 +99,7 @@ protected:
 
 public:
 
-    // STL type definitions
+    // STL Type Definitions
 
         //- The value type the FixedList contains
         typedef T value_type;
@@ -197,16 +197,16 @@ public:
         //  This can be used (with caution) when interfacing with C code
         inline T* data();
 
-        //- Return the first element of the list
+        //- The first element of the list, position [0]
         inline T& first();
 
-        //- Return first element of the list
+        //- The first element of the list, position [0]
         inline const T& first() const;
 
-        //- Return the last element of the list
+        //- The last element of the list, position [N-1]
         inline T& last();
 
-        //- Return the last element of the list
+        //- The last element of the list, position [N-1]
         inline const T& last() const;
 
 
@@ -279,7 +279,7 @@ public:
         inline void transfer(FixedList<T, N>& list);
 
 
-    // Member operators
+    // Member Operators
 
         //- Return element of FixedList
         inline T& operator[](const label i);
@@ -357,22 +357,22 @@ public:
         inline const_reverse_iterator rend() const;
 
 
-    // STL member functions
+    // STL Member Functions
 
-        //- Return the number of elements in the FixedList
-        inline label size() const;
+        //- Always false since zero-sized FixedList is compile-time disabled.
+        static constexpr bool empty() noexcept { return !N; }
 
-        //- Return size of the largest possible FixedList
-        inline label max_size() const;
+        //- Return the number of elements in the FixedList
+        static constexpr label size() noexcept { return N; }
 
-        //- Always false since zero-sized FixedList is compile-time disabled.
-        inline bool empty() const;
+        //- The dimensioned size (template parameter N) of the FixedList
+        static constexpr unsigned max_size() noexcept { return N; }
 
         //- Swap lists by swapping the content of the individual list elements
         inline void swap(FixedList<T, N>& list);
 
 
-    // STL member operators
+    // STL Member Operators
 
         //- Equality operation on FixedLists of the same type.
         //  Returns true when the FixedLists are element-wise equal

src/OpenFOAM/containers/Lists/FixedList/FixedListI.H

@@ -548,27 +548,6 @@ Foam::FixedList<T, N>::crend() const
 }
 
 
-template<class T, unsigned N>
-inline Foam::label Foam::FixedList<T, N>::size() const
-{
-    return N;
-}
-
-
-template<class T, unsigned N>
-inline Foam::label Foam::FixedList<T, N>::max_size() const
-{
-    return N;
-}
-
-
-template<class T, unsigned N>
-inline bool Foam::FixedList<T, N>::empty() const
-{
-    return false;
-}
-
-
 // * * * * * * * * * * * * * * * Global Functions  * * * * * * * * * * * * * //
 
 template<class T, unsigned N>