jvanstraten commented on a change in pull request #12279: URL: https://github.com/apache/arrow/pull/12279#discussion_r797650229
########## File path: cpp/src/arrow/engine/substrait/expression_internal.cc ########## @@ -0,0 +1,902 @@ +// 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 API is EXPERIMENTAL. + +#include "arrow/engine/substrait/expression_internal.h" + +#include <utility> + +#include "arrow/builder.h" +#include "arrow/compute/cast.h" +#include "arrow/compute/exec/expression.h" +#include "arrow/compute/exec/expression_internal.h" +#include "arrow/engine/substrait/extension_types.h" +#include "arrow/engine/substrait/type_internal.h" +#include "arrow/engine/visibility.h" +#include "arrow/result.h" +#include "arrow/status.h" +#include "arrow/util/make_unique.h" +#include "arrow/visit_scalar_inline.h" + +namespace arrow { + +using internal::checked_cast; + +namespace engine { + +namespace internal { +using ::arrow::internal::make_unique; +} // namespace internal + +namespace { + +std::shared_ptr<FixedSizeBinaryScalar> FixedSizeBinaryScalarFromBytes( + const std::string& bytes) { + auto buf = Buffer::FromString(bytes); + auto type = fixed_size_binary(static_cast<int>(buf->size())); + return std::make_shared<FixedSizeBinaryScalar>(std::move(buf), std::move(type)); +} + +} // namespace + +Result<compute::Expression> FromProto(const substrait::Expression& expr, + const ExtensionSet& ext_set) { + switch (expr.rex_type_case()) { + case substrait::Expression::kLiteral: { + ARROW_ASSIGN_OR_RAISE(auto datum, FromProto(expr.literal(), ext_set)); + return compute::literal(std::move(datum)); + } + + case substrait::Expression::kSelection: { + if (!expr.selection().has_direct_reference()) break; + + util::optional<compute::Expression> out; + if (expr.selection().has_expression()) { + ARROW_ASSIGN_OR_RAISE(out, FromProto(expr.selection().expression(), ext_set)); + } + + const auto* ref = &expr.selection().direct_reference(); + while (ref != nullptr) { + switch (ref->reference_type_case()) { + case substrait::Expression::ReferenceSegment::kStructField: { + auto index = ref->struct_field().field(); + if (!out) { + // Root StructField (column selection) + out = compute::field_ref(FieldRef(index)); + } else if (auto out_ref = out->field_ref()) { + // Nested StructFields on the root (selection of struct-typed column + // combined with selecting struct fields) + out = compute::field_ref(FieldRef(*out_ref, index)); + } else if (out->call() && out->call()->function_name == "struct_field") { + // Nested StructFields on top of an arbitrary expression + std::static_pointer_cast<arrow::compute::StructFieldOptions>( + out->call()->options) + ->indices.push_back(index); + } else { + // First StructField on top of an arbitrary expression + out = compute::call("struct_field", {std::move(*out)}, + arrow::compute::StructFieldOptions({index})); + } + + // Segment handled, continue with child segment (if any) + if (ref->struct_field().has_child()) { + ref = &ref->struct_field().child(); + } else { + ref = nullptr; + } + break; + } + case substrait::Expression::ReferenceSegment::kListElement: { + if (!out) { + // Root ListField (illegal) + return Status::Invalid( + "substrait::ListElement cannot take a Relation as an argument"); + } + + // ListField on top of an arbitrary expression + out = compute::call( + "list_element", + {std::move(*out), compute::literal(ref->list_element().offset())}); + + // Segment handled, continue with child segment (if any) + if (ref->list_element().has_child()) { + ref = &ref->list_element().child(); + } else { + ref = nullptr; + } + break; + } + default: + // Unimplemented construct, break out of loop + out.reset(); + ref = nullptr; + } + } + if (out) { + return *std::move(out); + } + break; + } + + case substrait::Expression::kIfThen: { + const auto& if_then = expr.if_then(); + if (!if_then.has_else_()) break; + if (if_then.ifs_size() == 0) break; + + if (if_then.ifs_size() == 1) { + ARROW_ASSIGN_OR_RAISE(auto if_, FromProto(if_then.ifs(0).if_(), ext_set)); + ARROW_ASSIGN_OR_RAISE(auto then, FromProto(if_then.ifs(0).then(), ext_set)); + ARROW_ASSIGN_OR_RAISE(auto else_, FromProto(if_then.else_(), ext_set)); + return compute::call("if_else", + {std::move(if_), std::move(then), std::move(else_)}); + } + + std::vector<compute::Expression> conditions, args; + std::vector<std::string> condition_names; + conditions.reserve(if_then.ifs_size()); + condition_names.reserve(if_then.ifs_size()); + size_t name_counter = 0; + args.reserve(if_then.ifs_size() + 2); + args.emplace_back(); + for (auto if_ : if_then.ifs()) { + ARROW_ASSIGN_OR_RAISE(auto compute_if, FromProto(if_.if_(), ext_set)); + ARROW_ASSIGN_OR_RAISE(auto compute_then, FromProto(if_.then(), ext_set)); + conditions.emplace_back(std::move(compute_if)); + args.emplace_back(std::move(compute_then)); + condition_names.emplace_back("cond" + std::to_string(++name_counter)); + } + ARROW_ASSIGN_OR_RAISE(auto compute_else, FromProto(if_then.else_(), ext_set)); + args.emplace_back(std::move(compute_else)); + args[0] = compute::call("make_struct", std::move(conditions), + compute::MakeStructOptions(condition_names)); + return compute::call("case_when", std::move(args)); + } + + case substrait::Expression::kScalarFunction: { + const auto& scalar_fn = expr.scalar_function(); + + auto id = ext_set.function_ids()[scalar_fn.function_reference()]; + + std::vector<compute::Expression> arguments(scalar_fn.args_size()); + for (int i = 0; i < scalar_fn.args_size(); ++i) { + ARROW_ASSIGN_OR_RAISE(arguments[i], FromProto(scalar_fn.args(i), ext_set)); + } + + return compute::call(id.name.to_string(), std::move(arguments)); + } + + default: + break; + } + + return Status::NotImplemented("conversion to arrow::compute::Expression from ", + expr.DebugString()); +} + +Result<Datum> FromProto(const substrait::Expression::Literal& lit, + const ExtensionSet& ext_set) { + if (lit.nullable()) { + // FIXME not sure how this field should be interpreted and there's no way to round + // trip it through arrow + return Status::Invalid( + "Nullable Literals - Literal.nullable must be left at the default"); + } + + switch (lit.literal_type_case()) { + case substrait::Expression::Literal::kBoolean: + return Datum(lit.boolean()); + + case substrait::Expression::Literal::kI8: + return Datum(static_cast<int8_t>(lit.i8())); + case substrait::Expression::Literal::kI16: + return Datum(static_cast<int16_t>(lit.i16())); + case substrait::Expression::Literal::kI32: + return Datum(static_cast<int32_t>(lit.i32())); + case substrait::Expression::Literal::kI64: + return Datum(static_cast<int64_t>(lit.i64())); + + case substrait::Expression::Literal::kFp32: + return Datum(lit.fp32()); + case substrait::Expression::Literal::kFp64: + return Datum(lit.fp64()); + + case substrait::Expression::Literal::kString: + return Datum(lit.string()); + case substrait::Expression::Literal::kBinary: + return Datum(BinaryScalar(Buffer::FromString(lit.binary()))); + + case substrait::Expression::Literal::kTimestamp: + return Datum( + TimestampScalar(static_cast<int64_t>(lit.timestamp()), TimeUnit::MICRO)); + + case substrait::Expression::Literal::kTimestampTz: + return Datum(TimestampScalar(static_cast<int64_t>(lit.timestamp_tz()), + TimeUnit::MICRO, TimestampTzTimezoneString())); + + case substrait::Expression::Literal::kDate: + return Datum(Date64Scalar(static_cast<int64_t>(lit.date()))); Review comment: You're right. a284e18 -- This is an automated message from the Apache Git Service. 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