bkietz commented on code in PR #35787: URL: https://github.com/apache/arrow/pull/35787#discussion_r1245512682
########## cpp/src/arrow/compute/kernels/vector_pairwise.cc: ########## @@ -0,0 +1,182 @@ +// 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. + +// Vector kernels for pairwise computation + +#include <iostream> +#include <memory> +#include "arrow/builder.h" +#include "arrow/compute/api_vector.h" +#include "arrow/compute/exec.h" +#include "arrow/compute/function.h" +#include "arrow/compute/kernel.h" +#include "arrow/compute/kernels/base_arithmetic_internal.h" +#include "arrow/compute/kernels/codegen_internal.h" +#include "arrow/compute/registry.h" +#include "arrow/compute/util.h" +#include "arrow/status.h" +#include "arrow/type.h" +#include "arrow/type_fwd.h" +#include "arrow/type_traits.h" +#include "arrow/util/bit_util.h" +#include "arrow/util/checked_cast.h" +#include "arrow/util/logging.h" +#include "arrow/visit_type_inline.h" + +namespace arrow::compute::internal { + +// We reuse the kernel exec function of a scalar binary function to compute pairwise +// results. For example, for pairwise_diff, we reuse subtract's kernel exec. +struct PairwiseState : KernelState { + PairwiseState(const PairwiseOptions& options, const ArrayKernelExec& scalar_exec) + : periods(options.periods), scalar_exec(scalar_exec) {} + + int64_t periods; + const ArrayKernelExec& scalar_exec; +}; + +KernelInit GeneratePairwiseInit(const ArrayKernelExec& scalar_exec) { + return [&scalar_exec](KernelContext* ctx, const KernelInitArgs& args) { + return std::make_unique<PairwiseState>( + checked_cast<const PairwiseOptions&>(*args.options), scalar_exec); + }; +} + +/// A generic pairwise implementation that can be reused by different ops. +Status PairwiseExecImpl(KernelContext* ctx, const ArraySpan& input, + const ArrayKernelExec& scalar_exec, int64_t periods, + ArrayData* result) { + auto offset = abs(periods); + offset = std::min(offset, input.length); + auto exec_length = input.length - offset; + // prepare bitmap + auto null_start = periods > 0 ? 0 : exec_length; + auto non_null_start = periods > 0 ? offset : 0; Review Comment: Nit: could we call these two regions "computed" and "margin"? I think that'll be more obvious for the next maintainer, and it'd help if we move *all* the start/length calculation to this preamble too ```suggestion // We only compute values in the region where the input-with-offset overlaps // the original input. The margin where these do not overlap gets filled with null. auto margin_length = std::min(abs(periods), input.length); auto computed_length = input.length - margin_length; auto margin_start = periods > 0 ? 0 : computed_length; auto left_start = periods > 0 ? margin_length : 0; auto right_start = periods > 0 ? 0 : margin_length; // ... // prepare bitmap ``` ########## cpp/src/arrow/compute/kernels/vector_pairwise.cc: ########## @@ -0,0 +1,182 @@ +// 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. + +// Vector kernels for pairwise computation + +#include <iostream> +#include <memory> +#include "arrow/builder.h" +#include "arrow/compute/api_vector.h" +#include "arrow/compute/exec.h" +#include "arrow/compute/function.h" +#include "arrow/compute/kernel.h" +#include "arrow/compute/kernels/base_arithmetic_internal.h" +#include "arrow/compute/kernels/codegen_internal.h" +#include "arrow/compute/registry.h" +#include "arrow/compute/util.h" +#include "arrow/status.h" +#include "arrow/type.h" +#include "arrow/type_fwd.h" +#include "arrow/type_traits.h" +#include "arrow/util/bit_util.h" +#include "arrow/util/checked_cast.h" +#include "arrow/util/logging.h" +#include "arrow/visit_type_inline.h" + +namespace arrow::compute::internal { + +// We reuse the kernel exec function of a scalar binary function to compute pairwise +// results. For example, for pairwise_diff, we reuse subtract's kernel exec. +struct PairwiseState : KernelState { + PairwiseState(const PairwiseOptions& options, const ArrayKernelExec& scalar_exec) + : periods(options.periods), scalar_exec(scalar_exec) {} + + int64_t periods; + const ArrayKernelExec& scalar_exec; +}; + +KernelInit GeneratePairwiseInit(const ArrayKernelExec& scalar_exec) { + return [&scalar_exec](KernelContext* ctx, const KernelInitArgs& args) { + return std::make_unique<PairwiseState>( + checked_cast<const PairwiseOptions&>(*args.options), scalar_exec); + }; +} + +/// A generic pairwise implementation that can be reused by different ops. +Status PairwiseExecImpl(KernelContext* ctx, const ArraySpan& input, + const ArrayKernelExec& scalar_exec, int64_t periods, + ArrayData* result) { + auto offset = abs(periods); + offset = std::min(offset, input.length); + auto exec_length = input.length - offset; + // prepare bitmap + auto null_start = periods > 0 ? 0 : exec_length; + auto non_null_start = periods > 0 ? offset : 0; + bit_util::ClearBitmap(result->buffers[0]->mutable_data(), null_start, offset); + for (int64_t i = non_null_start; i < non_null_start + exec_length; i++) { + if (input.IsValid(i) && input.IsValid(i - periods)) { + bit_util::SetBit(result->buffers[0]->mutable_data(), i); + } else { + bit_util::ClearBit(result->buffers[0]->mutable_data(), i); + } + } + // prepare input span + ArraySpan left(input); + left.SetSlice(periods > 0 ? offset : 0, exec_length); + ArraySpan right(input); + right.SetSlice(periods > 0 ? 0 : offset, exec_length); + // prepare output span + ArraySpan output_span; + output_span.SetMembers(*result); + output_span.offset = periods > 0 ? offset : 0; + output_span.length = exec_length; + ExecResult output{output_span}; + // execute scalar function + RETURN_NOT_OK(scalar_exec(ctx, ExecSpan({left, right}, exec_length), &output)); + + return Status::OK(); +} + +Status PairwiseExec(KernelContext* ctx, const ExecSpan& batch, ExecResult* out) { + const auto& state = checked_cast<const PairwiseState&>(*ctx->state()); + auto input = batch[0].array; + RETURN_NOT_OK(PairwiseExecImpl(ctx, batch[0].array, state.scalar_exec, state.periods, + out->array_data_mutable())); + return Status::OK(); +} + +const FunctionDoc pairwise_diff_doc( + "Compute first order difference of an array", + ("Computes the first order difference of an array, It internally calls \n" + "the scalar function \"subtract\" to compute \n differences, so its \n" + "behavior and supported types are the same as \n" + "\"subtract\". The period can be specified in :struct:`PairwiseOptions`.\n" + "\n" + "Results will wrap around on integer overflow. Use function \n" + "\"pairwise_diff_checked\" if you want overflow to return an error."), + {"input"}, "PairwiseOptions"); + +const FunctionDoc pairwise_diff_checked_doc( + "Compute first order difference of an array", + ("Computes the first order difference of an array, It internally calls \n" + "the scalar function \"subtract_checked\" (or the checked variant) to compute \n" + "differences, so its behavior and supported types are the same as \n" + "\"subtract_checked\". The period can be specified in :struct:`PairwiseOptions`.\n" + "\n" + "This function returns an error on overflow. For a variant that doesn't \n" + "fail on overflow, use function \"pairwise_diff\"."), + {"input"}, "PairwiseOptions"); + +const PairwiseOptions* GetDefaultPairwiseOptions() { + static const auto kDefaultPairwiseOptions = PairwiseOptions::Defaults(); + return &kDefaultPairwiseOptions; +} + +struct PairwiseKernelData { + InputType input; + OutputType output; + ArrayKernelExec exec; +}; + +void RegisterPairwiseDiffKernels(std::string_view func_name, + std::string_view base_func_name, const FunctionDoc& doc, + FunctionRegistry* registry) { + VectorKernel base_kernel; + base_kernel.can_execute_chunkwise = false; + base_kernel.null_handling = NullHandling::COMPUTED_PREALLOCATE; + base_kernel.mem_allocation = MemAllocation::PREALLOCATE; + base_kernel.init = OptionsWrapper<PairwiseOptions>::Init; + auto func = std::make_shared<VectorFunction>(std::string(func_name), Arity::Unary(), + doc, GetDefaultPairwiseOptions()); + + auto base_func_result = registry->GetFunction(std::string(base_func_name)); + DCHECK_OK(base_func_result.status()); + const auto& base_func = checked_cast<const ScalarFunction&>(**base_func_result); + DCHECK_EQ(base_func.arity().num_args, 2); + + for (const auto& base_func_kernel : base_func.kernels()) { + const auto& base_func_kernel_sig = base_func_kernel->signature; + if (base_func_kernel_sig->in_types()[0].Equals(base_func_kernel_sig->in_types()[1])) { Review Comment: Nit: de-nest ```suggestion if (!base_func_kernel_sig->in_types()[0].Equals(base_func_kernel_sig->in_types()[1])) { continue; } ``` ########## cpp/src/arrow/compute/kernels/vector_pairwise.cc: ########## @@ -0,0 +1,182 @@ +// 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. + +// Vector kernels for pairwise computation + +#include <iostream> +#include <memory> +#include "arrow/builder.h" +#include "arrow/compute/api_vector.h" +#include "arrow/compute/exec.h" +#include "arrow/compute/function.h" +#include "arrow/compute/kernel.h" +#include "arrow/compute/kernels/base_arithmetic_internal.h" +#include "arrow/compute/kernels/codegen_internal.h" +#include "arrow/compute/registry.h" +#include "arrow/compute/util.h" +#include "arrow/status.h" +#include "arrow/type.h" +#include "arrow/type_fwd.h" +#include "arrow/type_traits.h" +#include "arrow/util/bit_util.h" +#include "arrow/util/checked_cast.h" +#include "arrow/util/logging.h" +#include "arrow/visit_type_inline.h" + +namespace arrow::compute::internal { + +// We reuse the kernel exec function of a scalar binary function to compute pairwise +// results. For example, for pairwise_diff, we reuse subtract's kernel exec. +struct PairwiseState : KernelState { + PairwiseState(const PairwiseOptions& options, const ArrayKernelExec& scalar_exec) + : periods(options.periods), scalar_exec(scalar_exec) {} + + int64_t periods; + const ArrayKernelExec& scalar_exec; +}; + +KernelInit GeneratePairwiseInit(const ArrayKernelExec& scalar_exec) { + return [&scalar_exec](KernelContext* ctx, const KernelInitArgs& args) { + return std::make_unique<PairwiseState>( + checked_cast<const PairwiseOptions&>(*args.options), scalar_exec); + }; +} + +/// A generic pairwise implementation that can be reused by different ops. +Status PairwiseExecImpl(KernelContext* ctx, const ArraySpan& input, + const ArrayKernelExec& scalar_exec, int64_t periods, + ArrayData* result) { + auto offset = abs(periods); + offset = std::min(offset, input.length); + auto exec_length = input.length - offset; + // prepare bitmap + auto null_start = periods > 0 ? 0 : exec_length; + auto non_null_start = periods > 0 ? offset : 0; + bit_util::ClearBitmap(result->buffers[0]->mutable_data(), null_start, offset); + for (int64_t i = non_null_start; i < non_null_start + exec_length; i++) { + if (input.IsValid(i) && input.IsValid(i - periods)) { + bit_util::SetBit(result->buffers[0]->mutable_data(), i); + } else { + bit_util::ClearBit(result->buffers[0]->mutable_data(), i); + } + } + // prepare input span + ArraySpan left(input); + left.SetSlice(periods > 0 ? offset : 0, exec_length); + ArraySpan right(input); + right.SetSlice(periods > 0 ? 0 : offset, exec_length); + // prepare output span + ArraySpan output_span; + output_span.SetMembers(*result); + output_span.offset = periods > 0 ? offset : 0; + output_span.length = exec_length; + ExecResult output{output_span}; + // execute scalar function + RETURN_NOT_OK(scalar_exec(ctx, ExecSpan({left, right}, exec_length), &output)); + + return Status::OK(); +} + +Status PairwiseExec(KernelContext* ctx, const ExecSpan& batch, ExecResult* out) { + const auto& state = checked_cast<const PairwiseState&>(*ctx->state()); + auto input = batch[0].array; + RETURN_NOT_OK(PairwiseExecImpl(ctx, batch[0].array, state.scalar_exec, state.periods, + out->array_data_mutable())); + return Status::OK(); +} + +const FunctionDoc pairwise_diff_doc( + "Compute first order difference of an array", + ("Computes the first order difference of an array, It internally calls \n" + "the scalar function \"subtract\" to compute \n differences, so its \n" + "behavior and supported types are the same as \n" + "\"subtract\". The period can be specified in :struct:`PairwiseOptions`.\n" + "\n" + "Results will wrap around on integer overflow. Use function \n" + "\"pairwise_diff_checked\" if you want overflow to return an error."), + {"input"}, "PairwiseOptions"); + +const FunctionDoc pairwise_diff_checked_doc( + "Compute first order difference of an array", + ("Computes the first order difference of an array, It internally calls \n" + "the scalar function \"subtract_checked\" (or the checked variant) to compute \n" + "differences, so its behavior and supported types are the same as \n" + "\"subtract_checked\". The period can be specified in :struct:`PairwiseOptions`.\n" + "\n" + "This function returns an error on overflow. For a variant that doesn't \n" + "fail on overflow, use function \"pairwise_diff\"."), + {"input"}, "PairwiseOptions"); + +const PairwiseOptions* GetDefaultPairwiseOptions() { + static const auto kDefaultPairwiseOptions = PairwiseOptions::Defaults(); + return &kDefaultPairwiseOptions; +} + +struct PairwiseKernelData { + InputType input; + OutputType output; + ArrayKernelExec exec; +}; + +void RegisterPairwiseDiffKernels(std::string_view func_name, + std::string_view base_func_name, const FunctionDoc& doc, + FunctionRegistry* registry) { + VectorKernel base_kernel; Review Comment: Nit: since the base function here is "subtract", this naming could cause readers to conclude that the kernel is one of "subtract"'s kernels. ```suggestion VectorKernel kernel; ``` ########## docs/source/cpp/compute.rst: ########## @@ -1847,3 +1847,25 @@ replaced, based on the remaining inputs. results in a corresponding null in the output. Also see: :ref:`if_else <cpp-compute-scalar-selections>`. + +Pairwise functions +~~~~~~~~~~~~~~~~~~~~ +Pairwise functions are unary vector functions that perform a binary operation on +a pair of elements in the input array, typically on adjacent elements. The n-th +output is computed by applying the binary operation on the n-th and (n-p)-th, +where p is the period. The default period is 1. The period can also be negative. Review Comment: ```suggestion output is computed by applying the binary operation to the n-th and (n-p)-th inputs, where p is the period. The default period is 1, in which case the binary operation is applied to adjacent pairs of inputs. The period can also be negative, in which case the n-th output is computed by applying the binary operation to the n-th and (n+abs(p))-th inputs. ``` ########## cpp/src/arrow/compute/kernels/vector_pairwise.cc: ########## @@ -0,0 +1,182 @@ +// 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. + +// Vector kernels for pairwise computation + +#include <iostream> +#include <memory> +#include "arrow/builder.h" +#include "arrow/compute/api_vector.h" +#include "arrow/compute/exec.h" +#include "arrow/compute/function.h" +#include "arrow/compute/kernel.h" +#include "arrow/compute/kernels/base_arithmetic_internal.h" +#include "arrow/compute/kernels/codegen_internal.h" +#include "arrow/compute/registry.h" +#include "arrow/compute/util.h" +#include "arrow/status.h" +#include "arrow/type.h" +#include "arrow/type_fwd.h" +#include "arrow/type_traits.h" +#include "arrow/util/bit_util.h" +#include "arrow/util/checked_cast.h" +#include "arrow/util/logging.h" +#include "arrow/visit_type_inline.h" + +namespace arrow::compute::internal { + +// We reuse the kernel exec function of a scalar binary function to compute pairwise +// results. For example, for pairwise_diff, we reuse subtract's kernel exec. +struct PairwiseState : KernelState { + PairwiseState(const PairwiseOptions& options, const ArrayKernelExec& scalar_exec) + : periods(options.periods), scalar_exec(scalar_exec) {} + + int64_t periods; + const ArrayKernelExec& scalar_exec; +}; + +KernelInit GeneratePairwiseInit(const ArrayKernelExec& scalar_exec) { + return [&scalar_exec](KernelContext* ctx, const KernelInitArgs& args) { Review Comment: `ArrayKernelExec` is just a pointer so I think it's better to capture by value to make the lifetime obviously okay ```suggestion return [scalar_exec](KernelContext* ctx, const KernelInitArgs& args) { ``` ... it may be worthwhile to remove `GeneratePairwiseInit` too; it's only used once and writing the lambda inline is quite clear ########## cpp/src/arrow/compute/kernels/vector_pairwise.cc: ########## @@ -0,0 +1,182 @@ +// 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. + +// Vector kernels for pairwise computation + +#include <iostream> +#include <memory> +#include "arrow/builder.h" +#include "arrow/compute/api_vector.h" +#include "arrow/compute/exec.h" +#include "arrow/compute/function.h" +#include "arrow/compute/kernel.h" +#include "arrow/compute/kernels/base_arithmetic_internal.h" +#include "arrow/compute/kernels/codegen_internal.h" +#include "arrow/compute/registry.h" +#include "arrow/compute/util.h" +#include "arrow/status.h" +#include "arrow/type.h" +#include "arrow/type_fwd.h" +#include "arrow/type_traits.h" +#include "arrow/util/bit_util.h" +#include "arrow/util/checked_cast.h" +#include "arrow/util/logging.h" +#include "arrow/visit_type_inline.h" + +namespace arrow::compute::internal { + +// We reuse the kernel exec function of a scalar binary function to compute pairwise +// results. For example, for pairwise_diff, we reuse subtract's kernel exec. +struct PairwiseState : KernelState { + PairwiseState(const PairwiseOptions& options, const ArrayKernelExec& scalar_exec) + : periods(options.periods), scalar_exec(scalar_exec) {} + + int64_t periods; + const ArrayKernelExec& scalar_exec; +}; + +KernelInit GeneratePairwiseInit(const ArrayKernelExec& scalar_exec) { + return [&scalar_exec](KernelContext* ctx, const KernelInitArgs& args) { + return std::make_unique<PairwiseState>( + checked_cast<const PairwiseOptions&>(*args.options), scalar_exec); + }; +} + +/// A generic pairwise implementation that can be reused by different ops. +Status PairwiseExecImpl(KernelContext* ctx, const ArraySpan& input, + const ArrayKernelExec& scalar_exec, int64_t periods, + ArrayData* result) { + auto offset = abs(periods); + offset = std::min(offset, input.length); + auto exec_length = input.length - offset; + // prepare bitmap + auto null_start = periods > 0 ? 0 : exec_length; + auto non_null_start = periods > 0 ? offset : 0; + bit_util::ClearBitmap(result->buffers[0]->mutable_data(), null_start, offset); + for (int64_t i = non_null_start; i < non_null_start + exec_length; i++) { + if (input.IsValid(i) && input.IsValid(i - periods)) { + bit_util::SetBit(result->buffers[0]->mutable_data(), i); + } else { + bit_util::ClearBit(result->buffers[0]->mutable_data(), i); + } + } + // prepare input span + ArraySpan left(input); + left.SetSlice(periods > 0 ? offset : 0, exec_length); + ArraySpan right(input); + right.SetSlice(periods > 0 ? 0 : offset, exec_length); + // prepare output span + ArraySpan output_span; + output_span.SetMembers(*result); + output_span.offset = periods > 0 ? offset : 0; + output_span.length = exec_length; + ExecResult output{output_span}; + // execute scalar function + RETURN_NOT_OK(scalar_exec(ctx, ExecSpan({left, right}, exec_length), &output)); + + return Status::OK(); +} + +Status PairwiseExec(KernelContext* ctx, const ExecSpan& batch, ExecResult* out) { + const auto& state = checked_cast<const PairwiseState&>(*ctx->state()); + auto input = batch[0].array; + RETURN_NOT_OK(PairwiseExecImpl(ctx, batch[0].array, state.scalar_exec, state.periods, + out->array_data_mutable())); + return Status::OK(); +} + +const FunctionDoc pairwise_diff_doc( + "Compute first order difference of an array", + ("Computes the first order difference of an array, It internally calls \n" + "the scalar function \"subtract\" to compute \n differences, so its \n" + "behavior and supported types are the same as \n" + "\"subtract\". The period can be specified in :struct:`PairwiseOptions`.\n" + "\n" + "Results will wrap around on integer overflow. Use function \n" + "\"pairwise_diff_checked\" if you want overflow to return an error."), + {"input"}, "PairwiseOptions"); + +const FunctionDoc pairwise_diff_checked_doc( + "Compute first order difference of an array", + ("Computes the first order difference of an array, It internally calls \n" + "the scalar function \"subtract_checked\" (or the checked variant) to compute \n" + "differences, so its behavior and supported types are the same as \n" + "\"subtract_checked\". The period can be specified in :struct:`PairwiseOptions`.\n" + "\n" + "This function returns an error on overflow. For a variant that doesn't \n" + "fail on overflow, use function \"pairwise_diff\"."), + {"input"}, "PairwiseOptions"); + +const PairwiseOptions* GetDefaultPairwiseOptions() { + static const auto kDefaultPairwiseOptions = PairwiseOptions::Defaults(); + return &kDefaultPairwiseOptions; +} + +struct PairwiseKernelData { + InputType input; + OutputType output; + ArrayKernelExec exec; +}; + +void RegisterPairwiseDiffKernels(std::string_view func_name, + std::string_view base_func_name, const FunctionDoc& doc, + FunctionRegistry* registry) { + VectorKernel base_kernel; + base_kernel.can_execute_chunkwise = false; + base_kernel.null_handling = NullHandling::COMPUTED_PREALLOCATE; + base_kernel.mem_allocation = MemAllocation::PREALLOCATE; + base_kernel.init = OptionsWrapper<PairwiseOptions>::Init; + auto func = std::make_shared<VectorFunction>(std::string(func_name), Arity::Unary(), + doc, GetDefaultPairwiseOptions()); + + auto base_func_result = registry->GetFunction(std::string(base_func_name)); + DCHECK_OK(base_func_result.status()); + const auto& base_func = checked_cast<const ScalarFunction&>(**base_func_result); + DCHECK_EQ(base_func.arity().num_args, 2); + + for (const auto& base_func_kernel : base_func.kernels()) { + const auto& base_func_kernel_sig = base_func_kernel->signature; + if (base_func_kernel_sig->in_types()[0].Equals(base_func_kernel_sig->in_types()[1])) { + OutputType out_type(base_func_kernel_sig->out_type()); + // Need to wrap base output resolver + if (out_type.kind() == OutputType::COMPUTED) { + const auto& base_resolver = base_func_kernel_sig->out_type().resolver(); + auto resolver = [&base_resolver](KernelContext* ctx, + const std::vector<TypeHolder>& input_types) { + return base_resolver(ctx, {input_types[0], input_types[0]}); + }; + out_type = OutputType(resolver); Review Comment: Again, I think it's better to err on the side of safety when we can and just copy: ```suggestion out_type = OutputType([base_resolver=base_func_kernel_sig->out_type().resolver() ](KernelContext* ctx, const std::vector<TypeHolder>& input_types) { return base_resolver(ctx, {input_types[0], input_types[0]}); }); ``` -- This is an automated message from the Apache Git Service. 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