pitrou commented on code in PR #39091: URL: https://github.com/apache/arrow/pull/39091#discussion_r1481461703
########## swift/Arrow/Sources/Arrow/ArrowCImporter.swift: ########## @@ -0,0 +1,143 @@ +// 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. + +import Foundation +import ArrowC + +public class ArrowCImporter { + private func appendToBuffer( + _ cBuffer: UnsafeRawPointer?, + arrowBuffers: inout [ArrowBuffer], + byteCount: Int, + length: UInt, + nullCount: UInt? = nil) { + if cBuffer == nil { + arrowBuffers.append(ArrowBuffer.createEmptyBuffer()) + return + } + + let allocator = MemoryAllocator(64) + let pointer = allocator.allocateArray(byteCount) + pointer.copyMemory(from: cBuffer!, byteCount: byteCount) + arrowBuffers.append(ArrowBuffer(length: length, capacity: UInt(byteCount), rawPointer: pointer)) + } + + public init() {} + + public func importType(_ cArrow: String, name: String = "") -> + Result<ArrowField, ArrowError> { + do { + let type = try ArrowType.fromCDataFormatId(cArrow) + return .success(ArrowField(name, type: ArrowType(type.info), isNullable: true)) + } catch { + return .failure(.invalid("\(error)")) + } + } + + public func importField(_ cSchema: ArrowC.ArrowSchema) -> + Result<ArrowField, ArrowError> { + if cSchema.n_children > 0 { + return .failure(.invalid("Children currently not supported")) + } else if cSchema.dictionary != nil { + return .failure(.invalid("Dictinoary types currently not supported")) + } + + switch importType( + String(cString: cSchema.format), name: String(cString: cSchema.name)) { + case .success(let field): + release(cSchema) + return .success(field) + case .failure(let err): + return .failure(err) + } + } + + public func importArray( + _ cArray: ArrowC.ArrowArray, + arrowType: ArrowType, + isNullable: Bool = false) -> Result<ArrowArrayHolder, ArrowError> { + let arrowField = ArrowField("", type: arrowType, isNullable: isNullable) + return importArray(cArray, arrowField: arrowField) + } + + public func importArray( + _ cArray: ArrowC.ArrowArray, + arrowField: ArrowField) -> Result<ArrowArrayHolder, ArrowError> { + if cArray.null_count < 0 { + return .failure(.invalid("Uncomputed null count is not supported")) + } else if cArray.n_children > 0 { + return .failure(.invalid("Children currently not supported")) + } else if cArray.dictionary != nil { + return .failure(.invalid("Dictinoary types currently not supported")) + } + + let arrowType = arrowField.type + let length = UInt(cArray.length) + let nullCount = UInt(cArray.null_count) + let nullBytes = Int(ceil(Double(length) / 8)) + var arrowBuffers = [ArrowBuffer]() + + if cArray.n_buffers > 0 { + if cArray.buffers == nil { + return .failure(.invalid("C array buffers is nil")) + } + + switch arrowType.info { + case .variableInfo: + if cArray.n_buffers != 3 { + return .failure( + .invalid("Variable buffer count expected 3 but found \(cArray.n_buffers)")) + } + + appendToBuffer(cArray.buffers[0], arrowBuffers: &arrowBuffers, byteCount: nullBytes, length: length, + nullCount: nullCount) + let byteCount = MemoryLayout<Int32>.stride * Int(length) Review Comment: I don't know how far you are in implementing Arrow datatypes, but note that large types such as LargeString have 64-bit offsets. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
