[GitHub] [incubator-doris] adonis0147 commented on a diff in pull request #9056: [feature-wip](array-type) Add array aggregation functions

[GitBox <gi...@apache.org>]

adonis0147 commented on code in PR #9056:
URL: https://github.com/apache/incubator-doris/pull/9056#discussion_r892647180


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be/src/vec/functions/array/function_array_mapped.h:
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@@ -0,0 +1,77 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+// This file is copied from
+// https://github.com/ClickHouse/ClickHouse/blob/master/src/Functions/array/FunctionArrayMapped.h
+// and modified by Doris
+
+#include "vec/columns/column.h"
+#include "vec/columns/column_nullable.h"
+#include "vec/data_types/data_type_array.h"
+#include "vec/data_types/data_type_nullable.h"
+#include "vec/functions/function.h"
+
+namespace doris {
+namespace vectorized {
+
+/** Higher-order functions for arrays.
+  * These functions optionally apply a map (transform) to array (or multiple arrays of identical size) by lambda function,
+  *  and return some result based on that transformation.
+  *
+  * Examples:
+  * arrayMap(x1,...,xn -> expression, array1,...,arrayn) - apply the expression to each element of the array (or set of parallel arrays).
+  * arrayFilter(x -> predicate, array) - leave in the array only the elements for which the expression is true.
+  *
+  * For some functions arrayCount, arrayExists, arrayAll, an overload of the form f(array) is available,
+  *  which works in the same way as f(x -> x, array).
+  *
+  * See the example of Impl template parameter in arrayMap.cpp
+  */
+template <typename Impl, typename Name>
+class FunctionArrayMapped : public IFunction {
+public:
+    static constexpr auto name = Name::name;
+    static FunctionPtr create() { return std::make_shared<FunctionArrayMapped>(); }
+
+    String get_name() const override { return name; }
+    Status execute_impl(FunctionContext* context, Block& block, const ColumnNumbers& arguments,
+                        size_t result, size_t input_rows_count) override {
+        const auto& typed_column = block.get_by_position(arguments[0]);
+        const typename Impl::column_type* column_array;
+        if (typed_column.column->is_nullable()) {

Review Comment:
   `NULL` values will be skipped.



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