Merge branch 'array-flatten-function' of https://github.com/kzon/ClickHouse into kzon-array-flatten-function

dbms/src/Functions/flatten.cpp

@@ -0,0 +1,82 @@
+#include <Functions/IFunction.h>
+#include <Functions/FunctionFactory.h>
+#include <Functions/FunctionHelpers.h>
+#include <DataTypes/DataTypeArray.h>
+#include <Columns/ColumnArray.h>
+
+namespace DB
+{
+
+/// flatten([[1, 2, 3], [4, 5]]) = [1, 2, 3, 4, 5] - flatten array.
+class FunctionFlatten : public IFunction
+{
+public:
+    static constexpr auto name = "flatten";
+
+    static FunctionPtr create(const Context & context) { return std::make_shared<FunctionFlatten>(context); }
+
+    size_t getNumberOfArguments() const override { return 1; }
+
+    DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
+    {
+        if (!isArray(arguments[0]))
+            throw Exception("Illegal type " + arguments[0]->getName() +
+                            " of argument of function " + getName() +
+                            ", expected Array", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
+
+        DataTypePtr nested_type = arguments[0];
+        while (isArray(nested_type))
+            nested_type = checkAndGetDataType<DataTypeArray>(nested_type.get())->getNestedType();
+
+        return std::make_shared<DataTypeArray>(nested_type);
+    }
+
+    void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t input_rows_count) override
+    {
+        const auto * arg_col = checkAndGetColumn<ColumnArray>(block.getByPosition(arguments[0]).column.get());
+        const IColumn & arg_data = arg_col->getData();
+        const IColumn::Offsets & arg_offsets = arg_col->getOffsets();
+
+        const DataTypePtr & result_type = block.getByPosition(result).type;
+        const DataTypePtr & result_nested_type = dynamic_cast<const DataTypeArray &>(*result_type).getNestedType();
+        auto result_col = ColumnArray::create(result_nested_type->createColumn());
+        IColumn & result_data = result_col->getData();
+        IColumn::Offsets & result_offsets = result_col->getOffsets();
+
+        // todo
+        // result_data.reserve();
+        // result_offsets.resize();
+
+        IColumn::Offset current_offset = 0;
+        for (size_t i = 0; i < input_rows_count; ++i)
+        {
+            const auto & flatten_data = flatten(arg_data, current_offset, arg_offsets[i]);
+            result_data.insertRangeFrom(flatten_data, 0, flatten_data.size());
+            current_offset += flatten_data.size();
+            result_offsets[i] = current_offset;
+        }
+
+        block.getByPosition(result).column = std::move(result_col);
+    }
+
+private:
+    String getName() const override
+    {
+        return name;
+    }
+
+    bool addField(DataTypePtr type_res, const Field & f, Array & arr) const;
+
+    const ColumnArray & flatten(const IColumn & /*data*/, size_t /*from*/, size_t /*to*/) const
+    {
+        // todo
+    }
+};
+
+
+void registerFunctionFlatten(FunctionFactory & factory)
+{
+    factory.registerFunction<FunctionFlatten>();
+}
+
+}

dbms/src/Functions/registerFunctionsArray.cpp

@@ -30,6 +30,7 @@ void registerFunctionArrayEnumerateUniqRanked(FunctionFactory &);
 void registerFunctionArrayEnumerateDenseRanked(FunctionFactory &);
 void registerFunctionArrayUniq(FunctionFactory &);
 void registerFunctionArrayDistinct(FunctionFactory &);
+void registerFunctionFlatten(FunctionFactory &);
 void registerFunctionArrayWithConstant(FunctionFactory &);
 
 void registerFunctionsArray(FunctionFactory & factory)
@@ -61,6 +62,7 @@ void registerFunctionsArray(FunctionFactory & factory)
     registerFunctionArrayEnumerateDenseRanked(factory);
     registerFunctionArrayUniq(factory);
     registerFunctionArrayDistinct(factory);
+    registerFunctionFlatten(factory);
     registerFunctionArrayWithConstant(factory);
 }