Add explode_outer and explode_outer_position

cpp/include/cudf/reshape.hpp

@@ -150,8 +150,8 @@ std::unique_ptr<table> explode(
  * [[20,25],   200],
  * [[30],      300],
  * returns
- * [0,   5,    100],
- * [1,   10,   100],
+ * [0,   5,     100],
+ * [1,   10,    100],
  * [2,   15,    100],
  * [0,   20,    200],
  * [1,   25,    200],
@@ -164,8 +164,8 @@ std::unique_ptr<table> explode(
  * [null,        200],
  * [[],          300],
  * returns
- * [0,    5,     100],
- * [1,    null,  100],
+ * [0,     5,    100],
+ * [1,  null,    100],
  * [2,    15,    100],
  * ```
  * Note that null lists are not included in the resulting table, but nulls inside
@@ -183,6 +183,92 @@ std::unique_ptr<table> explode_position(
   size_type explode_column_idx,
   rmm::mr::device_memory_resource* mr = rmm::mr::get_current_device_resource());
 
+/**
+ * @brief Explodes a list column's elements retaining any null entries or empty lists inside.
+ *
+ * Any list is exploded, which means the elements of the list in each row are expanded into new rows
+ * in the output. The corresponding rows for other columns in the input are duplicated. Example:
+ * ```
+ * [[5,10,15], 100],
+ * [[20,25],   200],
+ * [[30],      300],
+ * returns
+ * [5,         100],
+ * [10,        100],
+ * [15,        100],
+ * [20,        200],
+ * [25,        200],
+ * [30,        300],
+ * ```
+ *
+ * Nulls and empty lists propagate as null entries in the result.
+ *```
+ * [[5,null,15], 100],
+ * [null,        200],
+ * [[],          300],
+ * returns
+ * [5,           100],
+ * [null,        100],
+ * [15,          100],
+ * [null,        200],
+ * [null,        300],
+ * ```
+ *
+ * @param input_table Table to explode.
+ * @param explode_column_idx Column index to explode inside the table.
+ * @param mr Device memory resource used to allocate the returned column's device memory.
+ *
+ * @return A new table with explode_col exploded.
+ */
+std::unique_ptr<table> explode_outer(
+  table_view const& input_table,
+  size_type explode_column_idx,
+  rmm::mr::device_memory_resource* mr = rmm::mr::get_current_device_resource());
+
+/**
+ * @brief Explodes a list column's elements retaining any null entries or empty lists and includes a
+ *position column.
+ *
+ * Any list is exploded, which means the elements of the list in each row are expanded into new rows
+ * in the output. The corresponding rows for other columns in the input are duplicated. A position
+ * column is added that has the index inside the original list for each row. Example:
+ * ```
+ * [[5,10,15], 100],
+ * [[20,25],   200],
+ * [[30],      300],
+ * returns
+ * [0,   5,    100],
+ * [1,  10,    100],
+ * [2,  15,    100],
+ * [0,  20,    200],
+ * [1,  25,    200],
+ * [0,  30,    300],
+ * ```
+ *
+ * Nulls and empty lists propagate as null entries in the result.
+ *```
+ * [[5,null,15], 100],
+ * [null,        200],
+ * [[],          300],
+ * returns
+ * [0,     5,    100],
+ * [1,  null,    100],
+ * [2,    15,    100],
+ * [0,  null,    200],
+ * [0,  null,    300],
+ * ```
+ *
+ * @param input_table Table to explode.
+ * @param explode_column_idx Column index to explode inside the table.
+ * @param mr Device memory resource used to allocate the returned column's device memory.
+ *
+ * @return A new table with explode_col exploded.
+ */
+std::unique_ptr<table> explode_outer_position(
+  table_view const& input_table,
+  size_type explode_column_idx,
+  rmm::mr::device_memory_resource* mr = rmm::mr::get_current_device_resource());
+
 /** @} */  // end of group
 
 }  // namespace cudf