Add Doxygen CI check (#11057)

closes #9373
Add doxygen CI check to check warnings for missing documentation
Depends on PR #11056

Authors:
  - Karthikeyan (https://github.com/karthikeyann)

Approvers:
  - Conor Hoekstra (https://github.com/codereport)
  - Nghia Truong (https://github.com/ttnghia)
  - Sevag Hanssian (https://github.com/sevagh)

URL: #11057

ci/checks/style.sh

@@ -54,8 +54,21 @@ HEADER_META=`ci/checks/headers_test.sh`
 HEADER_META_RETVAL=$?
 echo -e "$HEADER_META"
 
+# Run doxygen and check for missing documentation
+DOXYGEN=`cd cpp/doxygen && { cat Doxyfile ; echo QUIET = YES; echo GENERATE_HTML = NO; }  | doxygen - 2>&1 | tail -n +3`
+DOXYGEN_RETVAL=$?
+
+if [ "$DOXYGEN_RETVAL" != "0" ] || [ ! -z "$DOXYGEN" ]; then
+  echo -e "\n\n>>>> FAILED: doxygen check; begin output\n\n"
+  echo -e "$DOXYGEN"
+  DOXYGEN_RETVAL=1 #because return value is not generated by doxygen 1.8.20
+  echo -e "\n\n>>>> FAILED: doxygen check; end output\n\n"
+else
+  echo -e "\n\n>>>> PASSED: doxygen check\n\n"
+fi
+
 RETVALS=(
-  $CR_RETVAL $PRE_COMMIT_RETVAL $CLANG_FORMAT_RETVAL
+  $CR_RETVAL $PRE_COMMIT_RETVAL $CLANG_FORMAT_RETVAL $DOXYGEN_RETVAL
 )
 IFS=$'\n'
 RETVAL=`echo "${RETVALS[*]}" | sort -nr | head -n1`

cpp/include/cudf/table/experimental/row_operators.cuh

@@ -456,19 +456,36 @@ struct weak_ordering_comparator_impl {
  * @brief Wraps and interprets the result of device_row_comparator, true if the result is
  * weak_ordering::LESS meaning one row is lexicographically *less* than another row.
  *
- * @tparam Nullate A cudf::nullate type describing whether to check for nulls.
+ * @tparam Comparator generic comparator that returns a weak_ordering
  */
 template <typename Comparator>
 struct less_comparator : weak_ordering_comparator_impl<Comparator, weak_ordering::LESS> {
+  /**
+   * @brief Constructs a less_comparator
+   *
+   * @param comparator The comparator to wrap
+   */
   less_comparator(Comparator const& comparator)
     : weak_ordering_comparator_impl<Comparator, weak_ordering::LESS>{comparator}
   {
   }
 };
 
+/**
+ * @brief Wraps and interprets the result of device_row_comparator, true if the result is
+ * weak_ordering::LESS or weak_ordering::EQUIVALENT meaning one row is lexicographically *less* than
+ * or *equivalent* to another row.
+ *
+ * @tparam Comparator generic comparator that returns a weak_ordering
+ */
 template <typename Comparator>
 struct less_equivalent_comparator
   : weak_ordering_comparator_impl<Comparator, weak_ordering::LESS, weak_ordering::EQUIVALENT> {
+  /**
+   * @brief Constructs a less_equivalent_comparator
+   *
+   * @param comparator The comparator to wrap
+   */
   less_equivalent_comparator(Comparator const& comparator)
     : weak_ordering_comparator_impl<Comparator, weak_ordering::LESS, weak_ordering::EQUIVALENT>{
         comparator}
@@ -644,6 +661,7 @@ class self_comparator {
       nullate, *d_t, *d_t, d_t->depths(), d_t->column_order(), d_t->null_precedence(), comparator}};
   }
 
+  /// @copydoc less()
   template <typename Nullate,
             typename PhysicalElementComparator = sorting_physical_element_comparator>
   auto less_equivalent(Nullate nullate                      = {},
@@ -781,6 +799,7 @@ class two_table_comparator {
                                                             comparator}}};
   }
 
+  /// @copydoc less()
   template <typename Nullate,
             typename PhysicalElementComparator = sorting_physical_element_comparator>
   auto less_equivalent(Nullate nullate                      = {},