ENH: add identity(IntRange) and Istream operator for common types

- provides consistency with identity(label, label) and looks more
  familiar than using labelRange::labels()

- relocates labelRange IO operators to IntRange

ENH: make sliceRange interators random access

STYLE: scalarRanges::match() instead of predicate operator

applications/test/IntRange/Test-IntRange.C

@@ -20,6 +20,7 @@ Description
 #include "argList.H"
 #include "labelPair.H"
 #include "IntRange.H"
+#include "StringStream.H"
 
 using namespace Foam;
 
@@ -66,12 +67,22 @@ int main(int argc, char *argv[])
 
     typedef IntRange<int> intRange;
 
-    Info<< "Default construct int(32): " << IntRange<int32_t>() << nl
+    Info<< "Default construct int32_t: " << IntRange<int32_t>() << nl
-        << "Default construct int(64): " << IntRange<int64_t>() << nl;
+        << "Default construct int64_t: " << IntRange<int64_t>() << nl;
 
     Info<< "  one: " << intRange(10) << nl
         << "  two: " << intRange(5, 10) << nl;
 
+    // Read from stream
+    {
+        IStringStream is("(10 100)");
+        intRange range;
+
+        is >> range;
+
+        Info<< "From stream int32_t: " << range << nl;
+    }
+
     for
     (
         const labelPair& pr

applications/test/labelRanges/Test-labelRanges.C

@@ -70,6 +70,11 @@ int main(int argc, char *argv[])
         labelRange::debug = 1;
     }
 
+    {
+        labelRange range(5, 10);
+        Info<< "identity: " << identity(range) << nl;
+    }
+
     {
         Info<<"test sorting" << endl;
         DynamicList<labelRange> list1(10);

applications/test/sliceRange/Test-sliceRange.C

@@ -94,6 +94,42 @@ void printInfo(const sliceCoeffs& coeffs)
 }
 
 
+void printForLoop(const sliceRange& range)
+{
+    Info<< "for " << range << nl
+        << "  >";
+
+    for (const label val : range)
+    {
+        Info<< ' ' << val;
+    }
+
+    Info<< nl;
+}
+
+
+template<class IteratorType>
+void printIteratorTest(IteratorType& iter)
+{
+    const auto iter2 = (iter - 5);
+    const auto iter3 = (iter + 5);
+
+    // Info<< typeid(iter).name() << nl;
+
+    Info<< "begin: " << *iter++;
+    Info<< " next: " << *iter;
+    Info<< " next: " << *(++iter);
+    Info<< " [5]: " << iter[5];
+    Info<< " +10: " << *(iter + 10);
+    Info<< " -10: " << *(iter - 10);
+    Info<< nl;
+
+    Info<< "compare: " << *iter2 << " and " << *iter3 << nl;
+    Info<< "   == " << (iter2 == iter3) << nl;
+    Info<< "   <  " << (iter2 < iter3) << nl;
+}
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 //  Main program:
 
@@ -119,12 +155,25 @@ int main(int argc, char *argv[])
         printInfo(coeffs);
     }
 
+    // Some iterator tests
+    {
+        const sliceRange range(25, 8, 3);
+
+        auto iter1 = range.begin();
+        Info<< nl << "Forward iterator for " << range << nl;
+        printIteratorTest(iter1);
+
+        auto iter2 = range.rbegin();
+        Info<< nl << "Reverse iterator for " << range << nl;
+        printIteratorTest(iter2);
+    }
+
 
     // Generator
     {
         sliceRange range(25, 8, 3);
 
-        Info<< "Generator for " << range << nl;
+        Info<< nl << "Generator for " << range << nl;
 
         auto gen = range.generator();
 
@@ -216,6 +265,16 @@ int main(int argc, char *argv[])
             << " = " << flatOutput(list1) << nl;
     }
 
+
+    // For loops
+    {
+        Info<< nl << "Test for loops" << nl;
+
+        printForLoop(sliceRange(25, 8, -2));
+        printForLoop(sliceRange(10, 3, 0));
+        printForLoop(sliceRange(10, 3, 2));
+    }
+
     Info<< "\nEnd\n" << endl;
 
     return 0;

src/OpenFOAM/db/Time/timeSelector.C

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2018 OpenCFD Ltd.
+    Copyright (C) 2018-2020 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -49,7 +49,7 @@ Foam::timeSelector::timeSelector(const std::string& str)
 
 bool Foam::timeSelector::selected(const instant& value) const
 {
-    return scalarRanges::operator()(value.value());
+    return scalarRanges::match(value.value());
 }
 
 

src/OpenFOAM/primitives/ranges/IntRange/IntRange.H

@@ -42,7 +42,7 @@ SourceFiles
 #ifndef IntRange_H
 #define IntRange_H
 
-#include <cstdint>
+#include "labelFwd.H"
 #include <iterator>
 #include <type_traits>
 
@@ -52,7 +52,9 @@ namespace Foam
 {
 
 // Forward Declarations
+class Istream;
 class Ostream;
+template<class T> class List;
 
 /*---------------------------------------------------------------------------*\
                           Class IntRange Declaration
@@ -71,6 +73,7 @@ class IntRange
         //- The length of the interval
         IntType size_;
 
+
 protected:
 
     // Protected Member Functions
@@ -200,6 +203,42 @@ public:
         explicit operator bool() const noexcept { return bool(size_); }
 
 
+    // Bidirectional input iterators (const)
+
+        //- Return const_iterator to a position within the range,
+        //- with bounds checking.
+        //  \return iterator at the requested position, or end() for
+        //      out-of-bounds
+        inline const_iterator at(const IntType i) const;
+
+        //- A const_iterator set to the beginning of the range
+        inline const_iterator begin() const;
+
+        //- A const_iterator set to the beginning of the range
+        inline const_iterator cbegin() const;
+
+        //- A const_iterator set to 1 beyond the end of the range.
+        inline const_iterator cend() const;
+
+        //- A const_iterator set to 1 beyond the end of the range.
+        inline const_iterator end() const;
+
+
+    // Bidirectional reverse input iterators (const)
+
+        //- A const_reverse_iterator set to 1 before the end of range
+        inline const_reverse_iterator rbegin() const;
+
+        //- A const_reverse_iterator set to 1 before the end of range
+        inline const_reverse_iterator crbegin() const;
+
+        //- A const_reverse_iterator set to 1 before the begin of range
+        inline const_reverse_iterator rend() const;
+
+        //- A const_reverse_iterator set to 1 before the begin of range
+        inline const_reverse_iterator crend() const;
+
+
     // Iterators
 
         //- Random-access input iterator with const access
@@ -422,50 +461,39 @@ public:
                 return !(*this < iter);
             }
         };
-
-
-    // Bidirectional input iterators (const)
-
-        //- Return const_iterator to a position within the range,
-        //- with bounds checking.
-        //  \return iterator at the requested position, or end() for
-        //      out-of-bounds
-        inline const_iterator at(const IntType i) const;
-
-        //- A const_iterator set to the beginning of the range
-        inline const_iterator begin() const;
-
-        //- A const_iterator set to the beginning of the range
-        inline const_iterator cbegin() const;
-
-        //- A const_iterator set to 1 beyond the end of the range.
-        inline const_iterator cend() const;
-
-        //- A const_iterator set to 1 beyond the end of the range.
-        inline const_iterator end() const;
-
-
-    // Bidirectional reverse input iterators (const)
-
-        //- A const_reverse_iterator set to 1 before the end of range
-        inline const_reverse_iterator rbegin() const;
-
-        //- A const_reverse_iterator set to 1 before the end of range
-        inline const_reverse_iterator crbegin() const;
-
-        //- A const_reverse_iterator set to 1 before the begin of range
-        inline const_reverse_iterator rend() const;
-
-        //- A const_reverse_iterator set to 1 before the begin of range
-        inline const_reverse_iterator crend() const;
 };
 
 
+// * * * * * * * * * * * * * * * Global Functions  * * * * * * * * * * * * * //
+
+// Identity function for common integer types
+
+//- Identity map from an int32_t IntRange
+List<label> identity(const IntRange<int32_t>& range);
+
+#if defined(WM_LABEL_SIZE) && (WM_LABEL_SIZE >= 64)
+//- Identity map from an int64_t IntRange
+List<label> identity(const IntRange<int64_t>& range);
+#endif
+
+
 // * * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * //
 
+// Input operators for common integer types
+
+//- Read IntRange from Istream as bracketed (start size) tuple, no checks
+Istream& operator>>(Istream& os, IntRange<int32_t>& range);
+
+//- Read IntRange from Istream as bracketed (start size) tuple, no checks
+Istream& operator>>(Istream& os, IntRange<int64_t>& range);
+
+
 // Output operators for common integer types
 
+//- Write IntRange to Ostream as bracketed (start size) tuple
 Ostream& operator<<(Ostream& os, const IntRange<int32_t>& range);
+
+//- Write IntRange to Ostream as bracketed (start size) tuple
 Ostream& operator<<(Ostream& os, const IntRange<int64_t>& range);
 
 

src/OpenFOAM/primitives/ranges/IntRange/IntRanges.C

@@ -25,15 +25,32 @@ License
 
 \*---------------------------------------------------------------------------*/
 
-#include "label.H"
 #include "token.H"
+#include "List.H"
+#include "Istream.H"
 #include "Ostream.H"
+#include <numeric>
 
 // * * * * * * * * * * * * * * * Local Functions * * * * * * * * * * * * * * //
 
 namespace Foam
 {
-#if 0
+
+    template<class T>
+    inline static List<label> makeIdentity(const IntRange<T>& range)
+    {
+        if (range.size() < 0)
+        {
+            // Skip this check?
+            return List<label>();
+        }
+
+        List<label> result(range.size());
+        std::iota(result.begin(), result.end(), range.start());
+
+        return result;
+    }
+
     template<class T>
     inline static Istream& input(Istream& is, IntRange<T>& range)
     {
@@ -44,7 +61,6 @@ namespace Foam
         is.check(FUNCTION_NAME);
         return is;
     }
-#endif
 
     template<class T>
     inline static Ostream& output(Ostream& os, const IntRange<T>& range)
@@ -56,12 +72,28 @@ namespace Foam
         os.check(FUNCTION_NAME);
         return os;
     }
+
+} // End namespace Foam
+
+
+// * * * * * * * * * * * * * * * Global Functions  * * * * * * * * * * * * * //
+
+Foam::List<Foam::label> Foam::identity(const IntRange<int32_t>& range)
+{
+    return makeIdentity(range);
 }
 
 
+#if defined(WM_LABEL_SIZE) && (WM_LABEL_SIZE >= 64)
+Foam::List<Foam::label> Foam::identity(const IntRange<int64_t>& range)
+{
+    return makeIdentity(range);
+}
+#endif
+
+
 // * * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * //
 
-#if 0
 Foam::Istream& Foam::operator>>(Istream& is, IntRange<int32_t>& range)
 {
     return input(is, range);
@@ -72,7 +104,6 @@ Foam::Istream& Foam::operator>>(Istream& is, IntRange<int64_t>& range)
 {
     return input(is, range);
 }
-#endif
 
 
 Foam::Ostream& Foam::operator<<(Ostream& os, const IntRange<int32_t>& range)

src/OpenFOAM/primitives/ranges/labelRange/labelRange.C

@@ -27,9 +27,8 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "labelRange.H"
-#include "MinMax.H"
 #include "List.H"
-#include "token.H"
+#include "MinMax.H"
 #include <numeric>
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
@@ -66,8 +65,9 @@ Foam::labelRange::labelRange(Istream& is)
 
 Foam::List<Foam::label> Foam::labelRange::labels() const
 {
-    if (size() <= 0)
+    if (size() < 0)
     {
+        // Skip this check?
         return List<label>();
     }
 
@@ -196,28 +196,4 @@ Foam::labelRange Foam::labelRange::subset0(const label size) const
 }
 
 
-// * * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * //
-
-Foam::Istream& Foam::operator>>(Istream& is, labelRange& range)
-{
-    is.readBegin("labelRange");
-    is >> range.start() >> range.size();
-    is.readEnd("labelRange");
-
-    is.check(FUNCTION_NAME);
-    return is;
-}
-
-
-Foam::Ostream& Foam::operator<<(Ostream& os, const labelRange& range)
-{
-    os  << token::BEGIN_LIST
-        << range.start() << token::SPACE << range.size()
-        << token::END_LIST;
-
-    os.check(FUNCTION_NAME);
-    return os;
-}
-
-
 // ************************************************************************* //

src/OpenFOAM/primitives/ranges/labelRange/labelRange.H

@@ -35,10 +35,10 @@ SourceFiles
     labelRangeI.H
 
 \*---------------------------------------------------------------------------*/
+
 #ifndef labelRange_H
 #define labelRange_H
 
-#include "label.H"
 #include "IntRange.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -47,9 +47,6 @@ namespace Foam
 {
 
 // Forward Declarations
-class Istream;
-class Ostream;
-template<class T> class List;
 template<class T> class MinMax;
 
 /*---------------------------------------------------------------------------*\
@@ -151,7 +148,8 @@ public:
 
     // Other
 
-        //- Return list of labels corresponding to the range
+        //- Return list of labels corresponding to the range.
+        //  Same as Foam::identity()
         List<label> labels() const;
 
         //- Return true if the ranges overlap.
@@ -187,7 +185,7 @@ public:
 };
 
 
-// Global Functions
+// * * * * * * * * * * * * * * * Global Functions  * * * * * * * * * * * * * //
 
 //- Conversion/extraction to labelRange operation (functor).
 //  Specializations shall provide a corresponding \c operator().
@@ -205,15 +203,6 @@ public:
 template<class> struct labelRangeOp;
 
 
-// IOstream Operators
-
-//- Read labelRange from Istream as (start size) tuple, no checks
-Istream& operator>>(Istream& is, labelRange& range);
-
-//- Write labelRange to Ostream as (start size) tuple
-Ostream& operator<<(Ostream& os, const labelRange& range);
-
-
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace Foam

src/OpenFOAM/primitives/ranges/sliceRange/sliceRange.H

@@ -58,9 +58,7 @@ template<class T, unsigned N> class FixedList;
 
 class sliceRange
 {
-protected:
+    // Private Data
-
-    // Protected Data
 
         //- The start of the interval
         label start_;
@@ -177,15 +175,13 @@ public:
         //- Return const_iterator to a position within the range,
         //- with bounds checking.
         //  \return iterator at the requested position, or end() for
-        //      out of bounds
+        //      out-of-bounds
         inline const_iterator at(const label i) const;
 
         //- A const_iterator set to the beginning of the range
-        //  The value returned is guaranteed to be the same as start()
         inline const_iterator begin() const;
 
         //- A const_iterator set to the beginning of the range
-        //  The value returned is guaranteed to be the same as start()
         inline const_iterator cbegin() const;
 
         //- A const_iterator set to 1 beyond the end of the range.
@@ -232,7 +228,7 @@ public:
             //- Default construct with zero value and stride = 1
             inline constexpr indexer() noexcept;
 
-            //- Construct with specified value and stride,
+            //- Construct with specified value and stride
             inline constexpr indexer
             (
                 const label val,
@@ -242,6 +238,18 @@ public:
 
         // Member Functions
 
+            //- The current value
+            constexpr label value() const noexcept { return value_; }
+
+            //- The stride
+            constexpr label stride() const noexcept { return stride_; }
+
+            //- Value with offset
+            constexpr label value(const label n) const noexcept
+            {
+                return value_ + (n * stride_);
+            }
+
             //- Decrement value
             void prev() noexcept { value_ -= stride_; }
 
@@ -254,12 +262,6 @@ public:
             //- Increase value
             void next(const label n) noexcept { value_ += (n * stride_); }
 
-            //- Test for equality of values, ignore stride
-            constexpr bool equals(const indexer& other) const noexcept
-            {
-                return (value_ == other.value_);
-            }
-
 
         // Member Operators
 
@@ -269,7 +271,7 @@ public:
             //- Apply a postfix increment and return the current value.
             //  This operator definition is required for a generator -
             //  see std::generate()
-            inline label operator()();
+            inline label operator()() noexcept;
         };
 
 
@@ -281,7 +283,7 @@ public:
         public:
 
             // STL definitions (as per std::iterator)
-            typedef std::bidirectional_iterator_tag iterator_category;
+            typedef std::random_access_iterator_tag iterator_category;
 
 
         // Constructors
@@ -292,28 +294,81 @@ public:
 
         // Member Operators
 
+            //- Offset dereference operator
+            inline constexpr label operator[](const label n) const noexcept;
+
             //- Prefix increment
             inline const_iterator& operator++() noexcept;
 
-            //- Arbitrary increment
+            //- Postfix increment
-            inline const_iterator& operator+=(const label n) noexcept;
+            inline const_iterator operator++(int) noexcept;
 
             //- Prefix decrement
             inline const_iterator& operator--() noexcept;
 
+            //- Postfix decrement
+            inline const_iterator operator--(int) noexcept;
+
+            //- Arbitrary increment
+            inline const_iterator& operator+=(const label n) noexcept;
+
             //- Arbitrary decrement
             inline const_iterator& operator-=(const label n) noexcept;
 
-            //- Test for equality of values, ignore stride
+            //- Return iterator with offset
-            constexpr bool operator==(const const_iterator& iter) const noexcept
+            inline constexpr const_iterator operator+
+            (
+                const label n
+            ) const noexcept;
+
+            //- Return iterator with offset
+            inline constexpr const_iterator operator-
+            (
+                const label n
+            ) const noexcept;
+
+            //- Difference operator
+            inline constexpr label operator-
+            (
+                const const_iterator& iter
+            ) const noexcept;
+
+
+        // Comparison
+
+            //- Test for equality of values (ignore stride)
+            inline constexpr bool operator==(const const_iterator& iter)
+            const noexcept;
+
+            //- Compare less-than values (ignore stride)
+            inline constexpr bool operator<(const const_iterator& iter)
+            const noexcept;
+
+
+        // Derived comparisons
+
+            constexpr bool operator!=(const const_iterator& iter)
+            const noexcept
             {
-                return equals(iter);
+                return !(*this == iter);
             }
 
-            //- Test for inequality of values, ignore stride
+            constexpr bool operator<=(const const_iterator& iter)
-            constexpr bool operator!=(const const_iterator& iter) const noexcept
+            const noexcept
             {
-                return !equals(iter);
+                return !(iter < *this);
+            }
+
+            constexpr bool operator>(const const_iterator& iter)
+            const noexcept
+            {
+                return (iter < *this);
+            }
+
+            constexpr bool operator>=(const const_iterator& iter)
+            const noexcept
+            {
+                return !(*this < iter);
             }
         };
 
@@ -326,7 +381,7 @@ public:
         public:
 
             // STL definitions (as per std::iterator)
-            typedef std::bidirectional_iterator_tag iterator_category;
+            typedef std::random_access_iterator_tag iterator_category;
 
 
         // Constructors
@@ -337,30 +392,81 @@ public:
 
         // Member Operators
 
+            //- Offset dereference operator
+            inline constexpr label operator[](const label n) const noexcept;
+
             //- Prefix increment
             inline const_reverse_iterator& operator++() noexcept;
 
-            //- Arbitrary increment
+            //- Postfix increment
-            inline const_reverse_iterator& operator+=(const label n) noexcept;
+            inline const_reverse_iterator operator++(int) noexcept;
 
             //- Prefix decrement
             inline const_reverse_iterator& operator--() noexcept;
 
+            //- Postfix decrement
+            inline const_reverse_iterator operator--(int) noexcept;
+
+            //- Arbitrary increment
+            inline const_reverse_iterator& operator+=(const label n) noexcept;
+
             //- Arbitrary decrement
             inline const_reverse_iterator& operator-=(const label n) noexcept;
 
-            //- Test for equality of values (not stride)
+            //- Return iterator with offset
-            constexpr bool operator==(const const_reverse_iterator& iter)
+            inline constexpr const_reverse_iterator operator+
-            const noexcept
+            (
-            {
+                const label n
-                return equals(iter);
+            ) const noexcept;
-            }
+
+            //- Return iterator with offset
+            inline constexpr const_reverse_iterator operator-
+            (
+                const label n
+            ) const noexcept;
+
+            //- Difference operator
+            inline constexpr label operator-
+            (
+                const const_reverse_iterator& iter
+            ) const noexcept;
+
+
+        // Comparison
+
+            //- Test for equality of values (ignore stride)
+            inline constexpr bool operator==(const const_reverse_iterator& iter)
+            const noexcept;
+
+            //- Reverse compare less-than values (ignore stride)
+            inline constexpr bool operator<(const const_reverse_iterator& iter)
+            const noexcept;
+
+
+        // Derived comparisons
 
-            //- Test for inequality of values (not stride)
             constexpr bool operator!=(const const_reverse_iterator& iter)
             const noexcept
             {
-                return !equals(iter);
+                return !(*this == iter);
+            }
+
+            constexpr bool operator<=(const const_reverse_iterator& iter)
+            const noexcept
+            {
+                return !(iter < *this);
+            }
+
+            constexpr bool operator>(const const_reverse_iterator& iter)
+            const noexcept
+            {
+                return (iter < *this);
+            }
+
+            constexpr bool operator>=(const const_reverse_iterator& iter)
+            const noexcept
+            {
+                return !(*this < iter);
             }
         };
 };

src/OpenFOAM/primitives/ranges/sliceRange/sliceRangeI.H

@@ -72,7 +72,7 @@ inline constexpr Foam::sliceRange::indexer::indexer
 
 inline Foam::label
 Foam::sliceRange::indexer::
-operator()()
+operator()() noexcept
 {
     const label old(value_);
     next();
@@ -80,6 +80,16 @@ operator()()
 }
 
 
+// * * * * * * * * * * * * * * Forward Iterators * * * * * * * * * * * * * * //
+
+inline constexpr Foam::label
+Foam::sliceRange::const_iterator::
+operator[](const label n) const noexcept
+{
+    return value(n);
+}
+
+
 inline Foam::sliceRange::const_iterator&
 Foam::sliceRange::const_iterator::
 operator++() noexcept
@@ -89,6 +99,35 @@ operator++() noexcept
 }
 
 
+inline Foam::sliceRange::const_iterator
+Foam::sliceRange::const_iterator::
+operator++(int) noexcept
+{
+    const_iterator old(*this);
+    next();
+    return old;
+}
+
+
+inline Foam::sliceRange::const_iterator&
+Foam::sliceRange::const_iterator::
+operator--() noexcept
+{
+    prev();
+    return *this;
+}
+
+
+inline Foam::sliceRange::const_iterator
+Foam::sliceRange::const_iterator::
+operator--(int) noexcept
+{
+    const_iterator old(*this);
+    prev();
+    return old;
+}
+
+
 inline Foam::sliceRange::const_iterator&
 Foam::sliceRange::const_iterator::
 operator+=(const label n) noexcept
@@ -98,15 +137,6 @@ operator+=(const label n) noexcept
 }
 
 
-inline Foam::sliceRange::const_iterator&
-Foam::sliceRange::const_iterator::
-operator--() noexcept
-{
-    prev();
-    return *this;
-}
-
-
 inline Foam::sliceRange::const_iterator&
 Foam::sliceRange::const_iterator::
 operator-=(const label n) noexcept
@@ -116,6 +146,56 @@ operator-=(const label n) noexcept
 }
 
 
+inline constexpr Foam::sliceRange::const_iterator
+Foam::sliceRange::const_iterator::
+operator+(const label n) const noexcept
+{
+    return const_iterator(value(n), stride());
+}
+
+
+inline constexpr Foam::sliceRange::const_iterator
+Foam::sliceRange::const_iterator::
+operator-(const label n) const noexcept
+{
+    return const_iterator(value(-n), stride());
+}
+
+
+inline constexpr Foam::label
+Foam::sliceRange::const_iterator::
+operator-(const const_iterator& iter) const noexcept
+{
+    return (stride() ? (value() - iter.value()) / stride() : label{0});
+}
+
+
+inline constexpr bool
+Foam::sliceRange::const_iterator::
+operator==(const const_iterator& iter) const noexcept
+{
+    return (value() == iter.value());
+}
+
+
+inline constexpr bool
+Foam::sliceRange::const_iterator::
+operator<(const const_iterator& iter) const noexcept
+{
+    return (value() < iter.value());
+}
+
+
+// * * * * * * * * * * * * * * Reverse Iterators * * * * * * * * * * * * * * //
+
+inline constexpr Foam::label
+Foam::sliceRange::const_reverse_iterator::
+operator[](const label n) const noexcept
+{
+    return value(-n);
+}
+
+
 inline Foam::sliceRange::const_reverse_iterator&
 Foam::sliceRange::const_reverse_iterator::
 operator++() noexcept
@@ -125,6 +205,35 @@ operator++() noexcept
 }
 
 
+inline Foam::sliceRange::const_reverse_iterator
+Foam::sliceRange::const_reverse_iterator::
+operator++(int) noexcept
+{
+    const_reverse_iterator old(*this);
+    prev();
+    return old;
+}
+
+
+inline Foam::sliceRange::const_reverse_iterator&
+Foam::sliceRange::const_reverse_iterator::
+operator--() noexcept
+{
+    next();
+    return *this;
+}
+
+
+inline Foam::sliceRange::const_reverse_iterator
+Foam::sliceRange::const_reverse_iterator::
+operator--(int) noexcept
+{
+    const_reverse_iterator old(*this);
+    next();
+    return old;
+}
+
+
 inline Foam::sliceRange::const_reverse_iterator&
 Foam::sliceRange::const_reverse_iterator::
 operator+=(const label n) noexcept
@@ -134,15 +243,6 @@ operator+=(const label n) noexcept
 }
 
 
-inline Foam::sliceRange::const_reverse_iterator&
-Foam::sliceRange::const_reverse_iterator::
-operator--() noexcept
-{
-    next();
-    return *this;
-}
-
-
 inline Foam::sliceRange::const_reverse_iterator&
 Foam::sliceRange::const_reverse_iterator::
 operator-=(const label n) noexcept
@@ -152,6 +252,46 @@ operator-=(const label n) noexcept
 }
 
 
+inline constexpr Foam::sliceRange::const_reverse_iterator
+Foam::sliceRange::const_reverse_iterator::
+operator+(const label n) const noexcept
+{
+    return const_reverse_iterator(value(-n), stride());
+}
+
+
+inline constexpr Foam::sliceRange::const_reverse_iterator
+Foam::sliceRange::const_reverse_iterator::
+operator-(const label n) const noexcept
+{
+    return const_reverse_iterator(value(n), stride());
+}
+
+
+inline constexpr Foam::label
+Foam::sliceRange::const_reverse_iterator::
+operator-(const const_reverse_iterator& iter) const noexcept
+{
+    return (stride() ? (iter.value() - value()) / stride() : label{0});
+}
+
+
+inline constexpr bool
+Foam::sliceRange::const_reverse_iterator::
+operator==(const const_reverse_iterator& iter) const noexcept
+{
+    return (value() == iter.value());
+}
+
+
+inline constexpr bool
+Foam::sliceRange::const_reverse_iterator::
+operator<(const const_reverse_iterator& iter) const noexcept
+{
+    return (iter.value() < value());
+}
+
+
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
 inline Foam::sliceRange::indexer