[oneTBB] Improve oneTBB type & named requirements (#496)

Co-authored-by: Alexey Kukanov <[email protected]>

Co-authored-by: kboyarinov <[email protected]>

Author: aepanchi

source/elements/oneTBB/source/algorithms/functions/feeder.rst

@@ -33,10 +33,13 @@ Member functions
 
     Adds item to a collection of work items to be processed.
 
+    **Requirements**: The ``Item`` type must meet the `CopyConstructible` requirements from the [copyconstructible] section of the ISO C++ Standard.
+
 .. cpp:function:: void add( Item&& item )
 
     Same as the above but uses the move constructor of ``Item``, if available.
-
+ 
+    **Requirements**: The ``Item`` type must meet the `MoveConstructible` requirements from the [moveconstructible] section of the ISO C++ Standard.
 
 .. caution::
 

source/elements/oneTBB/source/algorithms/functions/parallel_for_each_func.rst

@@ -37,8 +37,11 @@ Function template that processes work items in parallel.
 Requirements:
 
 * The ``Body`` type must meet the :doc:`ParallelForEachBody requirements <../../named_requirements/algorithms/par_for_each_body>`.
-* The ``InputIterator`` type must meet the `Input Iterator` requirements from the [input.iterators] ISO C++ Standard section.
+* The ``InputIterator`` type must meet the `Input Iterator` requirements from the [input.iterators] section of the ISO C++ Standard.
+* If ``InputIterator`` type does not meet the `Forward Iterator` requirements from the [forward.iterators] section of the ISO C++ Standard,
+  the ``std::iterator_traits<InputIterator>::value_type`` type must be constructible from ``std::iterator_traits<InputIterator>::reference``.
 * The ``Container`` type must meet the :doc:`ContainerBasedSequence requirements <../../named_requirements/algorithms/container_based_sequence>`.
+* The type returned by ``Container::begin()`` must meet the same requirements as the ``InputIterator`` type above.
 
 The ``parallel_for_each`` template has two forms.
 

source/elements/oneTBB/source/algorithms/functions/parallel_reduce_func.rst

@@ -50,6 +50,8 @@ Requirements:
 
 * The ``Range`` type must meet the :doc:`Range requirements <../../named_requirements/algorithms/range>`.
 * The ``Body`` type must meet the :doc:`ParallelReduceBody requirements <../../named_requirements/algorithms/par_reduce_body>`.
+* The ``Value`` type must meet the `CopyConstructible` requirements from the [copyconstructible] section and
+  `CopyAssignable` requirements from the [copyassignable] section of the ISO C++ Standard.
 * The ``Func`` type must meet the :doc:`ParallelReduceFunc requirements <../../named_requirements/algorithms/par_reduce_func>`.
 * The ``Reduction`` types must meet :doc:`ParallelReduceReduction requirements <../../named_requirements/algorithms/par_reduce_reduction>`.
 

source/elements/oneTBB/source/algorithms/functions/parallel_scan_func.rst

@@ -32,6 +32,8 @@ Requirements:
 
 * The ``Range`` type must meet the :doc:`Range requirement <../../named_requirements/algorithms/range>`.
 * The ``Body`` type must meet the :doc:`ParallelScanBody requirements <../../named_requirements/algorithms/par_scan_body>`.
+* The ``Value`` type must meet the `CopyConstructible` requirements from the [copyconstructible] section and
+  `CopyAssignable` requirements from the [copyassignable] section of the ISO C++ Standard.
 * The ``Scan`` type must meet the :doc:`ParallelScanFunc requirements <../../named_requirements/algorithms/par_scan_func>`.
 * The ``Combine`` type must meet the :doc:`ParallelScanCombine requirements <../../named_requirements/algorithms/par_scan_combine>`.
 

source/elements/oneTBB/source/named_requirements/algorithms/filter_body.rst

@@ -25,7 +25,7 @@ A type `Body` should meet one of the following requirements depending on the fil
 
 .. namespace:: FirstFilterBody
 
-.. cpp:function:: OutputType Body::operator()( oneapi::tbb::flow_control fc ) const
+.. cpp:function:: OutputType Body::operator()( oneapi::tbb::flow_control& fc ) const
 
     Returns the next item from an input stream. Calls ``fc.stop()`` at the end of an input stream.
 
@@ -45,7 +45,7 @@ A type `Body` should meet one of the following requirements depending on the fil
 
 .. namespace:: SingleFilterBody
 
-.. cpp:function:: void Body::operator()( oneapi::tbb::flow_control fc ) const
+.. cpp:function:: void Body::operator()( oneapi::tbb::flow_control& fc ) const
 
     Processes an element from an input stream. Calls ``fc.stop()`` at the end of an input stream.
 

source/elements/oneTBB/source/named_requirements/algorithms/par_for_index.rst

@@ -25,31 +25,48 @@ A type `Index` satisfies `ParallelForIndex` if it meets the following requiremen
 
     Destructor.
 
-.. cpp:function:: void operator=( const Index& )
+.. cpp:function:: Index& operator=( const Index& )
 
     Assignment.
 
-    .. note::
+.. cpp:function:: Index& operator++()
 
-         The return type ``void`` in the pseudo-signature denotes that
-         ``operator=`` is not required to return a value. The actual ``operator=``
-         can return a value, which will be ignored.
+    Adjust ``*this`` to the next value.
 
 .. cpp:function:: bool operator<( const Index& i, const Index& j )
 
     Value of *i* precedes value of *j*.
 
+.. cpp:function:: bool operator<=( const Index& i, const Index& j )
+
+    Value of *i* precedes or equal to the value of *j*.
+
 .. cpp:function:: D operator-( const Index& i, const Index& j )
 
     Number of values in range ``[i,j)``.
 
+.. cpp:function:: Index operator+( const Index& i, const Index& j )
+
+    Sum of *i* and *j* values.
+
 .. cpp:function:: Index operator+( const Index& i, D k )
 
     *k*-th value after *i*.
 
+.. cpp:function:: Index operator*( const Index& i, const Index& j )
+
+    Multiplication of *i* and *j* values.
+
+.. cpp:function:: Index operator/( const Index& i, const Index& j )
+
+    Quotient of *i* and *j* values.
+
 ``D`` is the type of the expression ``j-i``. It can be any integral type that is convertible to ``size_t``.
 Examples that model the Index requirements are integral types and pointers.
 
+**_NOTE:_** It is recommended to use integral types as ``ParallelForIndex``. See the ``[basic.fundamental]``
+section of the ISO C++ Standard for information about integral types.
+
 See also:
 
 * :doc:`parallel_for algorithm <../../algorithms/functions/parallel_for_func>`