westonpace commented on code in PR #34133: URL: https://github.com/apache/arrow/pull/34133#discussion_r1138629019
########## csharp/src/Apache.Arrow/C/CArrowSchema.cs: ########## @@ -0,0 +1,124 @@ +// 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. + +using System; +using System.Runtime.InteropServices; +using Apache.Arrow.Types; + +namespace Apache.Arrow.C +{ + /// <summary> + /// An Arrow C Data Interface Schema, which represents a type, field, or schema. + /// </summary> + /// <remarks> + /// This is used to export <see cref="ArrowType"/>, <see cref="Field"/>, or + /// <see cref="Schema"/> to other languages. It matches the layout of the + /// ArrowSchema struct described in https://github.com/apache/arrow/blob/main/cpp/src/arrow/c/abi.h. + /// </remarks> + [StructLayout(LayoutKind.Sequential)] + public unsafe struct CArrowSchema + { + public byte* format; + public byte* name; + public byte* metadata; + public long flags; + public long n_children; + public CArrowSchema** children; + public CArrowSchema* dictionary; + public delegate* unmanaged[Stdcall]<CArrowSchema*, void> release; + public void* private_data; + + /// <summary> + /// Allocate and zero-initialize an unmanaged pointer of this type. + /// </summary> + /// <remarks> + /// This pointer must later be freed by <see cref="Free"/>. + /// </remarks> + public static CArrowSchema* Create() + { + var ptr = (CArrowSchema*)Marshal.AllocHGlobal(sizeof(CArrowSchema)); + + ptr->format = null; + ptr->name = null; + ptr->metadata = null; + ptr->flags = 0; + ptr->n_children = 0; + ptr->children = null; + ptr->dictionary = null; + ptr->release = null; + ptr->private_data = null; + + return ptr; + } + + /// <summary> + /// Free a pointer that was allocated in <see cref="Create"/>. + /// </summary> + /// <remarks> + /// Do not call this on a pointer that was allocated elsewhere. + /// </remarks> + public static void Free(CArrowSchema* schema) + { + if (schema->release != null) + { + // Call release if not already called. + schema->release(schema); + } + Marshal.FreeHGlobal((IntPtr)schema); + } + + + /// <summary> + /// Whether this field is semantically nullable (regardless of whether it actually has null values) + /// </summary> + public const long ArrowFlagDictionaryOrdered = 1; + /// <summary> + /// For dictionary-encoded types, whether the ordering of dictionary indices is semantically meaningful. + /// </summary> + public const long ArrowFlagNullable = 2; Review Comment: ```suggestion /// <summary> /// For dictionary-encoded types, whether the ordering of dictionary indices is semantically meaningful. /// </summary> public const long ArrowFlagDictionaryOrdered = 1; /// <summary> /// Whether this field is semantically nullable (regardless of whether it actually has null values) /// </summary> public const long ArrowFlagNullable = 2; ``` Looks like these comments got swapped ########## csharp/src/Apache.Arrow/C/CArrowSchemaImporter.cs: ########## @@ -0,0 +1,301 @@ +// 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. + + +using System; +using System.Collections.Generic; +using System.IO; +using System.Linq; +using Apache.Arrow.Types; + +namespace Apache.Arrow.C +{ + public static class CArrowSchemaImporter + { + /// <summary> + /// Import C pointer as an <see cref="ArrowType"/>. + /// </summary> + /// <remarks> + /// This will call the release callback on the passed struct, even if + /// this function fails. + /// </remarks> + /// <examples> + /// Typically, you will allocate a uninitialized CArrowSchema pointer, Review Comment: ```suggestion /// Typically, you will allocate an uninitialized CArrowSchema pointer, ``` ########## csharp/src/Apache.Arrow/C/CArrowSchemaExporter.cs: ########## @@ -0,0 +1,265 @@ +// 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. + + +using System; +using System.Collections.Generic; +using System.IO; +using System.Linq; +using System.Runtime.InteropServices; +using Apache.Arrow.Types; + +namespace Apache.Arrow.C +{ + public static class CArrowSchemaExporter + { + /// <summary> + /// Export a type to a <see cref="CArrowSchema"/>. + /// </summary> + /// <param name="datatype">The datatype to export</param> + /// <param name="schema">An allocated but uninitialized CArrowSchema pointer.</param> + /// <example> + /// <code> + /// CArrowSchema* exportPtr = CArrowSchema.Create(); + /// CArrowSchemaExporter.ExportType(dataType, exportPtr); + /// foreign_import_function(exportPtr); + /// CArrowSchema.Free(exportPtr); Review Comment: Won't this trigger a call to `exportPtr->release`? Is that safe given that you've already passed ownership during the `foreign_import_function`. ########## csharp/src/Apache.Arrow/C/CArrowSchemaExporter.cs: ########## @@ -0,0 +1,265 @@ +// 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. + + +using System; +using System.Collections.Generic; +using System.IO; +using System.Linq; +using System.Runtime.InteropServices; +using Apache.Arrow.Types; + +namespace Apache.Arrow.C +{ + public static class CArrowSchemaExporter + { + /// <summary> + /// Export a type to a <see cref="CArrowSchema"/>. + /// </summary> + /// <param name="datatype">The datatype to export</param> + /// <param name="schema">An allocated but uninitialized CArrowSchema pointer.</param> + /// <example> + /// <code> + /// CArrowSchema* exportPtr = CArrowSchema.Create(); + /// CArrowSchemaExporter.ExportType(dataType, exportPtr); + /// foreign_import_function(exportPtr); + /// CArrowSchema.Free(exportPtr); + /// </code> + /// </example> + public static unsafe void ExportType(IArrowType datatype, CArrowSchema* schema) + { + if (schema == null) + { + throw new ArgumentNullException("Cannot export schema to a null pointer."); + } + if (schema->release != null) + { + throw new ArgumentException("Cannot export schema to a struct that is already initialized."); + } + + schema->format = StringUtil.ToCStringUtf8(GetFormat(datatype)); + schema->name = null; + schema->metadata = null; + schema->flags = GetFlags(datatype); + + schema->children = ConstructChildren(datatype, out var numChildren); + schema->n_children = numChildren; + + schema->dictionary = ConstructDictionary(datatype); + + schema->release = (delegate* unmanaged[Stdcall]<CArrowSchema*, void>)Marshal.GetFunctionPointerForDelegate( + ReleaseCArrowSchema); + + schema->private_data = null; + } + + /// <summary> + /// Export a field to a <see cref="CArrowSchema"/>. + /// </summary> + /// <param name="field">The field to export</param> + /// <param name="schema">An allocated but uninitialized CArrowSchema pointer.</param> + /// <example> + /// <code> + /// CArrowSchema* exportPtr = CArrowSchema.Create(); + /// CArrowSchemaExporter.ExportType(field, exportPtr); + /// foreign_import_function(exportPtr); + /// CArrowSchema.Free(exportPtr); + /// </code> + /// </example> + public static unsafe void ExportField(Field field, CArrowSchema* schema) + { + ExportType(field.DataType, schema); + schema->name = StringUtil.ToCStringUtf8(field.Name); + // TODO: field metadata + schema->metadata = null; + schema->flags = GetFlags(field.DataType, field.IsNullable); + } + + /// <summary> + /// Export a schema to a <see cref="CArrowSchema"/>. + /// </summary> + /// <param name="schema">The schema to export</param> + /// <param name="out_schema">An allocated but uninitialized CArrowSchema pointer.</param> + /// <example> + /// <code> + /// CArrowSchema* exportPtr = CArrowSchema.Create(); + /// CArrowSchemaExporter.ExportType(schema, exportPtr); + /// foreign_import_function(exportPtr); + /// CArrowSchema.Free(exportPtr); + /// </code> + /// </example> + public static unsafe void ExportSchema(Schema schema, CArrowSchema* out_schema) + { + var structType = new StructType(schema.FieldsList); + // TODO: top-level metadata + ExportType(structType, out_schema); + } + + private static char FormatTimeUnit(TimeUnit unit) => unit switch + { + TimeUnit.Second => 's', + TimeUnit.Millisecond => 'm', + TimeUnit.Microsecond => 'u', + TimeUnit.Nanosecond => 'n', + _ => throw new InvalidDataException($"Unsupported time unit for export: {unit}"), + }; + + private static string GetFormat(IArrowType datatype) + { + switch (datatype) + { + case NullType _: return "n"; + case BooleanType _: return "b"; + // Integers + case Int8Type _: return "c"; + case UInt8Type _: return "C"; + case Int16Type _: return "s"; + case UInt16Type _: return "S"; + case Int32Type _: return "i"; + case UInt32Type _: return "I"; + case Int64Type _: return "l"; + case UInt64Type _: return "L"; + // Floats + case HalfFloatType _: return "e"; + case FloatType _: return "f"; + case DoubleType _: return "g"; + // Decimal + case Decimal128Type decimalType: + return $"d:{decimalType.Precision},{decimalType.Scale}"; + case Decimal256Type decimalType: + return $"d:{decimalType.Precision},{decimalType.Scale},256"; + // Binary + case BinaryType _: return "z"; + case StringType _: return "u"; + case FixedSizeBinaryType binaryType: + return $"w:{binaryType.ByteWidth}"; + // Date + case Date32Type _: return "tdD"; + case Date64Type _: return "tdm"; + // Time + case Time32Type timeType: + return String.Format("tt{0}", FormatTimeUnit(timeType.Unit)); + case Time64Type timeType: + // Same prefix as Time32, but allowed time units are different. + return String.Format("tt{0}", FormatTimeUnit(timeType.Unit)); + // Timestamp + case TimestampType timestampType: + return String.Format("ts{0}:{1}", FormatTimeUnit(timestampType.Unit), timestampType.Timezone); + // Nested + case ListType _: return "+l"; + case StructType _: return "+s"; + // Dictionary + case DictionaryType dictionaryType: + return GetFormat(dictionaryType.IndexType); + default: throw new NotImplementedException($"Exporting {datatype.Name} not implemented"); + }; + } + + private static long GetFlags(IArrowType datatype, bool nullable = true) + { + long flags = 0; + + if (nullable) + { + flags |= CArrowSchema.ArrowFlagNullable; + } + + if (datatype is DictionaryType dictionaryType) + { + if (dictionaryType.Ordered) + { + flags |= CArrowSchema.ArrowFlagDictionaryOrdered; + } + } + + // TODO: when we implement MapType, make sure to set the KEYS_SORTED flag. Review Comment: Could you check if the type id is a map type and throw a "not supported" exception? This way, when map type is eventually added, it won't silently do the wrong thing if we miss this spot. ########## csharp/src/Apache.Arrow/C/CArrowSchemaImporter.cs: ########## @@ -0,0 +1,301 @@ +// 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. + + +using System; +using System.Collections.Generic; +using System.IO; +using System.Linq; +using Apache.Arrow.Types; + +namespace Apache.Arrow.C +{ + public static class CArrowSchemaImporter + { + /// <summary> + /// Import C pointer as an <see cref="ArrowType"/>. + /// </summary> + /// <remarks> + /// This will call the release callback on the passed struct, even if + /// this function fails. + /// </remarks> + /// <examples> + /// Typically, you will allocate a uninitialized CArrowSchema pointer, + /// pass that to external function, and then use this method to import + /// the result. + /// + /// <code> + /// CArrowSchema* importedPtr = CArrowSchema.Create(); + /// foreign_export_function(importedPtr); + /// ArrowType importedType = CArrowSchemaImporter.ImportType(importedPtr); + /// CArrowSchema.Free(importedPtr); + /// </code> + /// </examples> + public static unsafe ArrowType ImportType(CArrowSchema* ptr) + { + using var importedType = new ImportedArrowSchema(ptr); + return importedType.GetAsType(); + } + + /// <summary> + /// Import C pointer as an <see cref="Field"/>. Review Comment: ```suggestion /// Import C pointer as a <see cref="Field"/>. ``` ########## csharp/src/Apache.Arrow/C/CArrowSchemaExporter.cs: ########## @@ -0,0 +1,265 @@ +// 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. + + +using System; +using System.Collections.Generic; +using System.IO; +using System.Linq; +using System.Runtime.InteropServices; +using Apache.Arrow.Types; + +namespace Apache.Arrow.C +{ + public static class CArrowSchemaExporter + { + /// <summary> + /// Export a type to a <see cref="CArrowSchema"/>. + /// </summary> + /// <param name="datatype">The datatype to export</param> + /// <param name="schema">An allocated but uninitialized CArrowSchema pointer.</param> + /// <example> + /// <code> + /// CArrowSchema* exportPtr = CArrowSchema.Create(); + /// CArrowSchemaExporter.ExportType(dataType, exportPtr); + /// foreign_import_function(exportPtr); + /// CArrowSchema.Free(exportPtr); + /// </code> + /// </example> + public static unsafe void ExportType(IArrowType datatype, CArrowSchema* schema) + { + if (schema == null) + { + throw new ArgumentNullException("Cannot export schema to a null pointer."); + } + if (schema->release != null) + { + throw new ArgumentException("Cannot export schema to a struct that is already initialized."); + } + + schema->format = StringUtil.ToCStringUtf8(GetFormat(datatype)); + schema->name = null; + schema->metadata = null; + schema->flags = GetFlags(datatype); + + schema->children = ConstructChildren(datatype, out var numChildren); + schema->n_children = numChildren; + + schema->dictionary = ConstructDictionary(datatype); + + schema->release = (delegate* unmanaged[Stdcall]<CArrowSchema*, void>)Marshal.GetFunctionPointerForDelegate( + ReleaseCArrowSchema); + + schema->private_data = null; + } + + /// <summary> + /// Export a field to a <see cref="CArrowSchema"/>. + /// </summary> + /// <param name="field">The field to export</param> + /// <param name="schema">An allocated but uninitialized CArrowSchema pointer.</param> + /// <example> + /// <code> + /// CArrowSchema* exportPtr = CArrowSchema.Create(); + /// CArrowSchemaExporter.ExportType(field, exportPtr); + /// foreign_import_function(exportPtr); + /// CArrowSchema.Free(exportPtr); + /// </code> + /// </example> + public static unsafe void ExportField(Field field, CArrowSchema* schema) + { + ExportType(field.DataType, schema); + schema->name = StringUtil.ToCStringUtf8(field.Name); + // TODO: field metadata + schema->metadata = null; + schema->flags = GetFlags(field.DataType, field.IsNullable); + } + + /// <summary> + /// Export a schema to a <see cref="CArrowSchema"/>. + /// </summary> + /// <param name="schema">The schema to export</param> + /// <param name="out_schema">An allocated but uninitialized CArrowSchema pointer.</param> + /// <example> + /// <code> + /// CArrowSchema* exportPtr = CArrowSchema.Create(); + /// CArrowSchemaExporter.ExportType(schema, exportPtr); + /// foreign_import_function(exportPtr); + /// CArrowSchema.Free(exportPtr); + /// </code> + /// </example> + public static unsafe void ExportSchema(Schema schema, CArrowSchema* out_schema) + { + var structType = new StructType(schema.FieldsList); + // TODO: top-level metadata + ExportType(structType, out_schema); + } + + private static char FormatTimeUnit(TimeUnit unit) => unit switch + { + TimeUnit.Second => 's', + TimeUnit.Millisecond => 'm', + TimeUnit.Microsecond => 'u', + TimeUnit.Nanosecond => 'n', + _ => throw new InvalidDataException($"Unsupported time unit for export: {unit}"), + }; + + private static string GetFormat(IArrowType datatype) + { + switch (datatype) + { + case NullType _: return "n"; + case BooleanType _: return "b"; + // Integers + case Int8Type _: return "c"; + case UInt8Type _: return "C"; + case Int16Type _: return "s"; + case UInt16Type _: return "S"; + case Int32Type _: return "i"; + case UInt32Type _: return "I"; + case Int64Type _: return "l"; + case UInt64Type _: return "L"; + // Floats + case HalfFloatType _: return "e"; + case FloatType _: return "f"; + case DoubleType _: return "g"; + // Decimal + case Decimal128Type decimalType: + return $"d:{decimalType.Precision},{decimalType.Scale}"; + case Decimal256Type decimalType: + return $"d:{decimalType.Precision},{decimalType.Scale},256"; + // Binary + case BinaryType _: return "z"; + case StringType _: return "u"; + case FixedSizeBinaryType binaryType: + return $"w:{binaryType.ByteWidth}"; + // Date + case Date32Type _: return "tdD"; + case Date64Type _: return "tdm"; + // Time + case Time32Type timeType: + return String.Format("tt{0}", FormatTimeUnit(timeType.Unit)); + case Time64Type timeType: + // Same prefix as Time32, but allowed time units are different. + return String.Format("tt{0}", FormatTimeUnit(timeType.Unit)); + // Timestamp + case TimestampType timestampType: + return String.Format("ts{0}:{1}", FormatTimeUnit(timestampType.Unit), timestampType.Timezone); + // Nested + case ListType _: return "+l"; + case StructType _: return "+s"; + // Dictionary + case DictionaryType dictionaryType: + return GetFormat(dictionaryType.IndexType); + default: throw new NotImplementedException($"Exporting {datatype.Name} not implemented"); + }; + } + + private static long GetFlags(IArrowType datatype, bool nullable = true) + { + long flags = 0; + + if (nullable) + { + flags |= CArrowSchema.ArrowFlagNullable; + } + + if (datatype is DictionaryType dictionaryType) + { + if (dictionaryType.Ordered) + { + flags |= CArrowSchema.ArrowFlagDictionaryOrdered; + } + } + + // TODO: when we implement MapType, make sure to set the KEYS_SORTED flag. + return flags; + } + + private static unsafe CArrowSchema** ConstructChildren(IArrowType datatype, out long numChildren) + { + if (datatype is NestedType nestedType) + { + IReadOnlyList<Field> fields = nestedType.Fields; + int numFields = fields.Count; + numChildren = numFields; Review Comment: Is there a chance that `numChildren` could be 0? Does `AllocHGlobal` return `IntPtr.Zero` in that case? Maybe more of a concern on import but I seem to recall a zero-field union being a useless, but technically possible, data type. ########## csharp/src/Apache.Arrow/C/CArrowSchemaImporter.cs: ########## @@ -0,0 +1,301 @@ +// 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. + + +using System; +using System.Collections.Generic; +using System.IO; +using System.Linq; +using Apache.Arrow.Types; + +namespace Apache.Arrow.C +{ + public static class CArrowSchemaImporter + { + /// <summary> + /// Import C pointer as an <see cref="ArrowType"/>. + /// </summary> + /// <remarks> + /// This will call the release callback on the passed struct, even if + /// this function fails. + /// </remarks> + /// <examples> + /// Typically, you will allocate a uninitialized CArrowSchema pointer, + /// pass that to external function, and then use this method to import + /// the result. + /// + /// <code> + /// CArrowSchema* importedPtr = CArrowSchema.Create(); + /// foreign_export_function(importedPtr); + /// ArrowType importedType = CArrowSchemaImporter.ImportType(importedPtr); + /// CArrowSchema.Free(importedPtr); + /// </code> + /// </examples> + public static unsafe ArrowType ImportType(CArrowSchema* ptr) + { + using var importedType = new ImportedArrowSchema(ptr); + return importedType.GetAsType(); + } + + /// <summary> + /// Import C pointer as an <see cref="Field"/>. + /// </summary> + /// <remarks> + /// This will call the release callback on the passed struct, even if + /// this function fails. + /// </remarks> + /// <examples> + /// Typically, you will allocate a uninitialized CArrowSchema pointer, Review Comment: ```suggestion /// Typically, you will allocate an uninitialized CArrowSchema pointer, ``` ########## csharp/src/Apache.Arrow/C/CArrowSchemaImporter.cs: ########## @@ -0,0 +1,301 @@ +// 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. + + +using System; +using System.Collections.Generic; +using System.IO; +using System.Linq; +using Apache.Arrow.Types; + +namespace Apache.Arrow.C +{ + public static class CArrowSchemaImporter + { + /// <summary> + /// Import C pointer as an <see cref="ArrowType"/>. + /// </summary> + /// <remarks> + /// This will call the release callback on the passed struct, even if + /// this function fails. + /// </remarks> + /// <examples> + /// Typically, you will allocate a uninitialized CArrowSchema pointer, + /// pass that to external function, and then use this method to import + /// the result. + /// + /// <code> + /// CArrowSchema* importedPtr = CArrowSchema.Create(); + /// foreign_export_function(importedPtr); + /// ArrowType importedType = CArrowSchemaImporter.ImportType(importedPtr); + /// CArrowSchema.Free(importedPtr); + /// </code> + /// </examples> + public static unsafe ArrowType ImportType(CArrowSchema* ptr) + { + using var importedType = new ImportedArrowSchema(ptr); + return importedType.GetAsType(); + } + + /// <summary> + /// Import C pointer as an <see cref="Field"/>. + /// </summary> + /// <remarks> + /// This will call the release callback on the passed struct, even if + /// this function fails. + /// </remarks> + /// <examples> + /// Typically, you will allocate a uninitialized CArrowSchema pointer, + /// pass that to external function, and then use this method to import + /// the result. + /// + /// <code> + /// CArrowSchema* importedPtr = CArrowSchema.Create(); + /// foreign_export_function(importedPtr); + /// Field importedField = CArrowSchemaImporter.ImportField(importedPtr); + /// CArrowSchema.Free(importedPtr); + /// </code> + /// </examples> + public static unsafe Field ImportField(CArrowSchema* ptr) + { + using var importedField = new ImportedArrowSchema(ptr); + return importedField.GetAsField(); + } + + /// <summary> + /// Import C pointer as an <see cref="Schema"/>. Review Comment: ```suggestion /// Import C pointer as a <see cref="Schema"/>. ``` ########## csharp/src/Apache.Arrow/C/CArrowSchemaImporter.cs: ########## @@ -0,0 +1,301 @@ +// 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. + + +using System; +using System.Collections.Generic; +using System.IO; +using System.Linq; +using Apache.Arrow.Types; + +namespace Apache.Arrow.C +{ + public static class CArrowSchemaImporter + { + /// <summary> + /// Import C pointer as an <see cref="ArrowType"/>. + /// </summary> + /// <remarks> + /// This will call the release callback on the passed struct, even if + /// this function fails. + /// </remarks> + /// <examples> + /// Typically, you will allocate a uninitialized CArrowSchema pointer, + /// pass that to external function, and then use this method to import + /// the result. + /// + /// <code> + /// CArrowSchema* importedPtr = CArrowSchema.Create(); + /// foreign_export_function(importedPtr); + /// ArrowType importedType = CArrowSchemaImporter.ImportType(importedPtr); + /// CArrowSchema.Free(importedPtr); + /// </code> + /// </examples> + public static unsafe ArrowType ImportType(CArrowSchema* ptr) + { + using var importedType = new ImportedArrowSchema(ptr); + return importedType.GetAsType(); + } + + /// <summary> + /// Import C pointer as an <see cref="Field"/>. + /// </summary> + /// <remarks> + /// This will call the release callback on the passed struct, even if + /// this function fails. + /// </remarks> + /// <examples> + /// Typically, you will allocate a uninitialized CArrowSchema pointer, + /// pass that to external function, and then use this method to import + /// the result. + /// + /// <code> + /// CArrowSchema* importedPtr = CArrowSchema.Create(); + /// foreign_export_function(importedPtr); + /// Field importedField = CArrowSchemaImporter.ImportField(importedPtr); + /// CArrowSchema.Free(importedPtr); + /// </code> + /// </examples> + public static unsafe Field ImportField(CArrowSchema* ptr) + { + using var importedField = new ImportedArrowSchema(ptr); + return importedField.GetAsField(); + } + + /// <summary> + /// Import C pointer as an <see cref="Schema"/>. + /// </summary> + /// <remarks> + /// This will call the release callback on the passed struct, even if + /// this function fails. + /// </remarks> + /// <examples> + /// Typically, you will allocate a uninitialized CArrowSchema pointer, Review Comment: ```suggestion /// Typically, you will allocate an uninitialized CArrowSchema pointer, ``` -- This is an automated message from the Apache Git Service. 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