pythonnet/src/runtime/converterextensions.cs at fix-enum-codec · Waitingtolearn/pythonnet · GitHub

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namespace Python.Runtime

{

using System;

using System.Collections.Concurrent;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

using System.Reflection;

using Python.Runtime.Codecs;

/// <summary>

/// Defines <see cref="PyObject"/> conversion to CLR types (unmarshalling)

/// </summary>

public interface IPyObjectDecoder

{

/// <summary>

/// Checks if this decoder can decode from <paramref name="objectType"/> to <paramref name="targetType"/>

/// </summary>

bool CanDecode(PyType objectType, Type targetType);

/// <summary>

/// Attempts do decode <paramref name="pyObj"/> into a variable of specified type

/// </summary>

/// <typeparam name="T">CLR type to decode into</typeparam>

/// <param name="pyObj">Object to decode</param>

/// <param name="value">The variable, that will receive decoding result</param>

/// <returns></returns>

bool TryDecode<T>(PyObject pyObj, out T? value);

}

/// <summary>

/// Defines conversion from CLR objects into Python objects (e.g. <see cref="PyObject"/>) (marshalling)

/// </summary>

public interface IPyObjectEncoder

{

/// <summary>

/// Checks if encoder can encode CLR objects of specified type

/// </summary>

bool CanEncode(Type type);

/// <summary>

/// Attempts to encode CLR object <paramref name="value"/> into Python object

/// </summary>

PyObject? TryEncode(object value);

}

/// <summary>

/// This class allows to register additional marshalling codecs.

/// <para>Python.NET will pick suitable encoder/decoder registered first</para>

/// </summary>

public static class PyObjectConversions

{

static readonly DecoderGroup decoders = new DecoderGroup();

static readonly EncoderGroup encoders = new EncoderGroup();

/// <summary>

/// Registers specified encoder (marshaller)

/// <para>Python.NET will pick suitable encoder/decoder registered first</para>

/// </summary>

public static void RegisterEncoder(IPyObjectEncoder encoder)

{

if (encoder == null) throw new ArgumentNullException(nameof(encoder));

lock (encoders)

{

encoders.Add(encoder);

}

/// <summary>

/// Registers specified decoder (unmarshaller)

/// <para>Python.NET will pick suitable encoder/decoder registered first</para>

/// </summary>

public static void RegisterDecoder(IPyObjectDecoder decoder)

{

if (decoder == null) throw new ArgumentNullException(nameof(decoder));

lock (decoders)

{

decoders.Add(decoder);

}

#region Encoding

internal static PyObject? TryEncode(object obj, Type type)

{

if (obj == null) throw new ArgumentNullException(nameof(obj));

if (type == null) throw new ArgumentNullException(nameof(type));

foreach (var encoder in clrToPython.GetOrAdd(type, GetEncoders))

{

var result = encoder.TryEncode(obj);

if (result != null) return result;

}

return null;

}

static readonly ConcurrentDictionary<Type, IPyObjectEncoder[]>

clrToPython = new ConcurrentDictionary<Type, IPyObjectEncoder[]>();

static IPyObjectEncoder[] GetEncoders(Type type)

{

lock (encoders)

{

return encoders.GetEncoders(type).ToArray();

}

#endregion

#region Decoding

static readonly ConcurrentDictionary<TypePair, (PyType, Converter.TryConvertFromPythonDelegate?)> pythonToClr = new();

internal static bool TryDecode(BorrowedReference pyHandle, BorrowedReference pyType, Type targetType, out object? result)

{

if (pyHandle == null) throw new ArgumentNullException(nameof(pyHandle));

if (pyType == null) throw new ArgumentNullException(nameof(pyType));

if (targetType == null) throw new ArgumentNullException(nameof(targetType));

var key = new TypePair(pyType.DangerousGetAddress(), targetType);

var (_, decoder) = pythonToClr.GetOrAdd(key, pair => GetDecoder(pair.PyType, pair.ClrType));

result = null;

if (decoder == null) return false;

return decoder.Invoke(pyHandle, out result);

}

static (PyType, Converter.TryConvertFromPythonDelegate?) GetDecoder(IntPtr sourceType, Type targetType)

{

var sourceTypeRef = new BorrowedReference(sourceType);

Debug.Assert(PyType.IsType(sourceTypeRef));

var pyType = new PyType(sourceTypeRef, prevalidated: true);

IPyObjectDecoder? decoder;

lock (decoders)

{

decoder = decoders.GetDecoder(pyType, targetType);

if (decoder == null) return default;

}

var decode = genericDecode.MakeGenericMethod(targetType)!;

bool TryDecode(BorrowedReference pyHandle, out object? result)

{

var pyObj = new PyObject(pyHandle);

var @params = new object?[] { pyObj, null };

bool success = (bool)decode.Invoke(decoder, @params);

if (!success)

{

pyObj.Dispose();

}

result = @params[1];

return success;

}

// returning PyType here establishes strong reference to the object,

// that ensures the PyType we use as the converter cache key is not deallocated

return (pyType, TryDecode);

}

static readonly MethodInfo genericDecode = typeof(IPyObjectDecoder).GetMethod(nameof(IPyObjectDecoder.TryDecode));

#endregion

internal static void Reset()

{

lock (encoders)

lock (decoders)

{

clrToPython.Clear();

pythonToClr.Clear();

encoders.Dispose();

decoders.Dispose();

}

struct TypePair : IEquatable<TypePair>

{

internal readonly IntPtr PyType;

internal readonly Type ClrType;

public TypePair(IntPtr pyType, Type clrType)

{

this.PyType = pyType;

this.ClrType = clrType;

}

public override int GetHashCode()

=> this.ClrType.GetHashCode() ^ this.PyType.GetHashCode();

public bool Equals(TypePair other)

=> this.PyType == other.PyType && this.ClrType == other.ClrType;

public override bool Equals(object obj) => obj is TypePair other && this.Equals(other);

}

pythonnet/src/runtime/converterextensions.cs at fix-enum-codec · Waitingtolearn/pythonnet · GitHub

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