kun yu 77e1ddd81b branch-0.4.0
Former-commit-id: a4df63653202df32d0b983de27f5c969905d17ac
2019-07-30 10:23:34 +08:00

102 lines
3.6 KiB
C++

// 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.
#pragma once
#include <memory>
#include "arrow/compute/kernel.h"
#include "arrow/status.h"
#include "arrow/util/visibility.h"
namespace arrow {
class Array;
namespace compute {
class FunctionContext;
struct ARROW_EXPORT TakeOptions {};
/// \brief Take from an array of values at indices in another array
///
/// The output array will be of the same type as the input values
/// array, with elements taken from the values array at the given
/// indices. If an index is null then the taken element will be null.
///
/// For example given values = ["a", "b", "c", null, "e", "f"] and
/// indices = [2, 1, null, 3], the output will be
/// = [values[2], values[1], null, values[3]]
/// = ["c", "b", null, null]
///
/// \param[in] ctx the FunctionContext
/// \param[in] values array from which to take
/// \param[in] indices which values to take
/// \param[in] options options
/// \param[out] out resulting array
ARROW_EXPORT
Status Take(FunctionContext* ctx, const Array& values, const Array& indices,
const TakeOptions& options, std::shared_ptr<Array>* out);
/// \brief Take from an array of values at indices in another array
///
/// \param[in] ctx the FunctionContext
/// \param[in] values datum from which to take
/// \param[in] indices which values to take
/// \param[in] options options
/// \param[out] out resulting datum
ARROW_EXPORT
Status Take(FunctionContext* ctx, const Datum& values, const Datum& indices,
const TakeOptions& options, Datum* out);
/// \brief BinaryKernel implementing Take operation
class ARROW_EXPORT TakeKernel : public BinaryKernel {
public:
explicit TakeKernel(const std::shared_ptr<DataType>& type, TakeOptions options = {})
: type_(type) {}
/// \brief BinaryKernel interface
///
/// delegates to subclasses via Take()
Status Call(FunctionContext* ctx, const Datum& values, const Datum& indices,
Datum* out) override;
/// \brief output type of this kernel (identical to type of values taken)
std::shared_ptr<DataType> out_type() const override { return type_; }
/// \brief factory for TakeKernels
///
/// \param[in] value_type constructed TakeKernel will support taking
/// values of this type
/// \param[in] index_type constructed TakeKernel will support taking
/// with indices of this type
/// \param[out] out created kernel
static Status Make(const std::shared_ptr<DataType>& value_type,
const std::shared_ptr<DataType>& index_type,
std::unique_ptr<TakeKernel>* out);
/// \brief single-array implementation
virtual Status Take(FunctionContext* ctx, const Array& values, const Array& indices,
std::shared_ptr<Array>* out) = 0;
protected:
std::shared_ptr<DataType> type_;
};
} // namespace compute
} // namespace arrow