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support proxying return values in API proxies

This commit is contained in:
Shockah 2022-02-09 20:07:01 +01:00
parent 5a92b0cd35
commit 43ad219b75
3 changed files with 186 additions and 45 deletions
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183
src/SMAPI/Framework/Reflection/InterfaceProxyBuilder.cs
View File

@ -1,13 +1,22 @@
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Reflection.Emit;
using HarmonyLib;
namespace StardewModdingAPI.Framework.Reflection
{
/// <summary>Generates a proxy class to access a mod API through an arbitrary interface.</summary>
internal class InterfaceProxyBuilder
{
/*********
** Consts
*********/
private static readonly string TargetFieldName = "__Target";
private static readonly string GlueFieldName = "__Glue";
private static readonly MethodInfo CreateInstanceForProxyTypeNameMethod = typeof(InterfaceProxyGlue).GetMethod(nameof(InterfaceProxyGlue.CreateInstanceForProxyTypeName), new Type[] { typeof(string), typeof(object) });
/*********
** Fields
*********/
@ -22,11 +31,14 @@ namespace StardewModdingAPI.Framework.Reflection
** Public methods
*********/
/// <summary>Construct an instance.</summary>
/// <param name="factory">The <see cref="InterfaceProxyFactory"/> that requested to build a proxy.</param>
/// <param name="name">The type name to generate.</param>
/// <param name="moduleBuilder">The CLR module in which to create proxy classes.</param>
/// <param name="interfaceType">The interface type to implement.</param>
/// <param name="targetType">The target type.</param>
public InterfaceProxyBuilder(string name, ModuleBuilder moduleBuilder, Type interfaceType, Type targetType)
/// <param name="sourceModID">The unique ID of the mod consuming the API.</param>
/// <param name="targetModID">The unique ID of the mod providing the API.</param>
public InterfaceProxyBuilder(InterfaceProxyFactory factory, string name, ModuleBuilder moduleBuilder, Type interfaceType, Type targetType, string sourceModID, string targetModID)
{
// validate
if (name == null)
@ -38,12 +50,13 @@ namespace StardewModdingAPI.Framework.Reflection
TypeBuilder proxyBuilder = moduleBuilder.DefineType(name, TypeAttributes.Public | TypeAttributes.Class);
proxyBuilder.AddInterfaceImplementation(interfaceType);
// create field to store target instance
FieldBuilder targetField = proxyBuilder.DefineField("__Target", targetType, FieldAttributes.Private);
// create fields to store target instance and proxy factory
FieldBuilder targetField = proxyBuilder.DefineField(TargetFieldName, targetType, FieldAttributes.Private);
FieldBuilder glueField = proxyBuilder.DefineField(GlueFieldName, typeof(InterfaceProxyGlue), FieldAttributes.Private);
// create constructor which accepts target instance and sets field
// create constructor which accepts target instance + factory, and sets fields
{
ConstructorBuilder constructor = proxyBuilder.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard | CallingConventions.HasThis, new[] { targetType });
ConstructorBuilder constructor = proxyBuilder.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard | CallingConventions.HasThis, new[] { targetType, typeof(InterfaceProxyGlue) });
ILGenerator il = constructor.GetILGenerator();
il.Emit(OpCodes.Ldarg_0); // this
@ -52,6 +65,9 @@ namespace StardewModdingAPI.Framework.Reflection
il.Emit(OpCodes.Ldarg_0); // this
il.Emit(OpCodes.Ldarg_1); // load argument
il.Emit(OpCodes.Stfld, targetField); // set field to loaded argument
il.Emit(OpCodes.Ldarg_0); // this
il.Emit(OpCodes.Ldarg_2); // load argument
il.Emit(OpCodes.Stfld, glueField); // set field to loaded argument
il.Emit(OpCodes.Ret);
}
@ -65,15 +81,20 @@ namespace StardewModdingAPI.Framework.Reflection
}
}
bool AreTypesMatching(Type targetType, Type proxyType, MethodTypeMatchingPart part)
MatchingTypesResult AreTypesMatching(Type targetType, Type proxyType, MethodTypeMatchingPart part)
{
var typeA = part == MethodTypeMatchingPart.Parameter ? targetType : proxyType;
var typeB = part == MethodTypeMatchingPart.Parameter ? proxyType : targetType;
if (typeA.IsGenericMethodParameter != typeB.IsGenericMethodParameter)
return false;
return MatchingTypesResult.False;
// TODO: decide if "assignable" checking is desired (instead of just 1:1 type equality)
return typeA.IsGenericMethodParameter ? typeA.GenericParameterPosition == typeB.GenericParameterPosition : typeA.IsAssignableFrom(typeB);
if (typeA.IsGenericMethodParameter ? typeA.GenericParameterPosition == typeB.GenericParameterPosition : typeA.IsAssignableFrom(typeB))
return MatchingTypesResult.True;
if (!proxyType.IsGenericMethodParameter && proxyType.IsInterface && proxyType.Assembly == interfaceType.Assembly)
return MatchingTypesResult.IfProxied;
return MatchingTypesResult.False;
}
// proxy methods
@ -81,30 +102,61 @@ namespace StardewModdingAPI.Framework.Reflection
{
var proxyMethodParameters = proxyMethod.GetParameters();
var proxyMethodGenericArguments = proxyMethod.GetGenericArguments();
var targetMethod = allTargetMethods.Where(m =>
foreach (MethodInfo targetMethod in allTargetMethods)
{
if (m.Name != proxyMethod.Name)
return false;
// checking if `targetMethod` matches `proxyMethod`
if (m.GetGenericArguments().Length != proxyMethodGenericArguments.Length)
return false;
if (!AreTypesMatching(m.ReturnType, proxyMethod.ReturnType, MethodTypeMatchingPart.ReturnType))
return false;
if (targetMethod.Name != proxyMethod.Name)
continue;
if (targetMethod.GetGenericArguments().Length != proxyMethodGenericArguments.Length)
continue;
var positionsToProxy = new HashSet<int?>(); // null = return type; anything else = parameter position
var mParameters = m.GetParameters();
if (m.GetParameters().Length != proxyMethodParameters.Length)
return false;
switch (AreTypesMatching(targetMethod.ReturnType, proxyMethod.ReturnType, MethodTypeMatchingPart.ReturnType))
{
case MatchingTypesResult.False:
continue;
case MatchingTypesResult.True:
break;
case MatchingTypesResult.IfProxied:
positionsToProxy.Add(null);
break;
}
var mParameters = targetMethod.GetParameters();
if (mParameters.Length != proxyMethodParameters.Length)
continue;
for (int i = 0; i < mParameters.Length; i++)
{
if (!AreTypesMatching(mParameters[i].ParameterType, proxyMethodParameters[i].ParameterType, MethodTypeMatchingPart.Parameter))
return false;
switch (AreTypesMatching(mParameters[i].ParameterType, proxyMethodParameters[i].ParameterType, MethodTypeMatchingPart.Parameter))
{
case MatchingTypesResult.False:
goto targetMethodLoopContinue;
case MatchingTypesResult.True:
break;
case MatchingTypesResult.IfProxied:
if (proxyMethodParameters[i].IsOut)
{
positionsToProxy.Add(i);
break;
}
else
{
goto targetMethodLoopContinue;
}
}
}
return true;
}).FirstOrDefault();
if (targetMethod == null)
throw new InvalidOperationException($"The {interfaceType.FullName} interface defines method {proxyMethod.Name} which doesn't exist in the API.");
this.ProxyMethod(proxyBuilder, proxyMethod, targetMethod, targetField);
// method matched; proxying
this.ProxyMethod(factory, proxyBuilder, proxyMethod, targetMethod, targetField, glueField, positionsToProxy, sourceModID, targetModID);
goto proxyMethodLoopContinue;
targetMethodLoopContinue:;
}
throw new InvalidOperationException($"The {interfaceType.FullName} interface defines method {proxyMethod.Name} which doesn't exist in the API.");
proxyMethodLoopContinue:;
}
// save info
@ -114,12 +166,13 @@ namespace StardewModdingAPI.Framework.Reflection
/// <summary>Create an instance of the proxy for a target instance.</summary>
/// <param name="targetInstance">The target instance.</param>
public object CreateInstance(object targetInstance)
/// <param name="factory">The <see cref="InterfaceProxyFactory"/> that requested to build a proxy.</param>
public object CreateInstance(object targetInstance, InterfaceProxyFactory factory)
{
ConstructorInfo constructor = this.ProxyType.GetConstructor(new[] { this.TargetType });
ConstructorInfo constructor = this.ProxyType.GetConstructor(new[] { this.TargetType, typeof(InterfaceProxyGlue) });
if (constructor == null)
throw new InvalidOperationException($"Couldn't find the constructor for generated proxy type '{this.ProxyType.Name}'."); // should never happen
return constructor.Invoke(new[] { targetInstance });
return constructor.Invoke(new[] { targetInstance, new InterfaceProxyGlue(factory) });
}
@ -127,11 +180,16 @@ namespace StardewModdingAPI.Framework.Reflection
** Private methods
*********/
/// <summary>Define a method which proxies access to a method on the target.</summary>
/// <param name="factory">The <see cref="InterfaceProxyFactory"/> that requested to build a proxy.</param>
/// <param name="proxyBuilder">The proxy type being generated.</param>
/// <param name="proxy">The proxy method.</param>
/// <param name="target">The target method.</param>
/// <param name="instanceField">The proxy field containing the API instance.</param>
private void ProxyMethod(TypeBuilder proxyBuilder, MethodInfo proxy, MethodInfo target, FieldBuilder instanceField)
/// <param name="glueField">The proxy field containing an <see cref="InterfaceProxyGlue"/>.</param>
/// <param name="positionsToProxy">Parameter type positions (or null for the return type) for which types should also be proxied.</param>
/// <param name="sourceModID">The unique ID of the mod consuming the API.</param>
/// <param name="targetModID">The unique ID of the mod providing the API.</param>
private void ProxyMethod(InterfaceProxyFactory factory, TypeBuilder proxyBuilder, MethodInfo proxy, MethodInfo target, FieldBuilder instanceField, FieldBuilder glueField, ISet<int?> positionsToProxy, string sourceModID, string targetModID)
{
MethodBuilder methodBuilder = proxyBuilder.DefineMethod(proxy.Name, MethodAttributes.Public | MethodAttributes.Final | MethodAttributes.Virtual);
@ -143,7 +201,8 @@ namespace StardewModdingAPI.Framework.Reflection
genericTypeParameterBuilders[i].SetGenericParameterAttributes(proxyGenericArguments[i].GenericParameterAttributes);
// set up return type
methodBuilder.SetReturnType(proxy.ReturnType.IsGenericMethodParameter ? genericTypeParameterBuilders[proxy.ReturnType.GenericParameterPosition] : proxy.ReturnType);
Type returnType = proxy.ReturnType.IsGenericMethodParameter ? genericTypeParameterBuilders[proxy.ReturnType.GenericParameterPosition] : proxy.ReturnType;
methodBuilder.SetReturnType(returnType);
// set up parameters
Type[] argTypes = proxy.GetParameters()
@ -152,18 +211,62 @@ namespace StardewModdingAPI.Framework.Reflection
.ToArray();
methodBuilder.SetParameters(argTypes);
// proxy additional types
string returnValueProxyTypeName = null;
string[] parameterProxyTypeNames = new string[argTypes.Length];
if (positionsToProxy.Count > 0)
{
var targetParameters = target.GetParameters();
foreach (int? position in positionsToProxy)
{
// we don't check for generics here, because earlier code does and generic positions won't end up here
if (position == null) // it's the return type
{
var builder = factory.ObtainBuilder(target.ReturnType, proxy.ReturnType, sourceModID, targetModID);
returnType = proxy.ReturnType;
returnValueProxyTypeName = builder.ProxyType.FullName;
}
else // it's one of the parameters
{
var builder = factory.ObtainBuilder(targetParameters[position.Value].ParameterType, argTypes[position.Value], sourceModID, targetModID);
argTypes[position.Value] = proxy.ReturnType;
parameterProxyTypeNames[position.Value] = builder.ProxyType.FullName;
}
}
methodBuilder.SetReturnType(returnType);
methodBuilder.SetParameters(argTypes);
}
// create method body
{
ILGenerator il = methodBuilder.GetILGenerator();
// load target instance
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Ldfld, instanceField);
void EmitCallInstance()
{
// load target instance
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Ldfld, instanceField);
// invoke target method on instance
for (int i = 0; i < argTypes.Length; i++)
il.Emit(OpCodes.Ldarg, i + 1);
il.Emit(OpCodes.Call, target);
// invoke target method on instance
for (int i = 0; i < argTypes.Length; i++)
il.Emit(OpCodes.Ldarg, i + 1);
il.Emit(OpCodes.Callvirt, target);
}
if (returnValueProxyTypeName == null)
{
EmitCallInstance();
}
else
{
// this.Glue.CreateInstanceForProxyTypeName(proxyTypeName, this.Instance.Call(args))
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Ldfld, glueField);
il.Emit(OpCodes.Ldstr, returnValueProxyTypeName);
EmitCallInstance();
il.Emit(OpCodes.Call, CreateInstanceForProxyTypeNameMethod);
}
// return result
il.Emit(OpCodes.Ret);
@ -175,5 +278,11 @@ namespace StardewModdingAPI.Framework.Reflection
{
ReturnType, Parameter
}
/// <summary>The result of matching a target and a proxy type.</summary>
private enum MatchingTypesResult
{
False, IfProxied, True
}
}
}

30
src/SMAPI/Framework/Reflection/InterfaceProxyFactory.cs
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@ -35,26 +35,40 @@ namespace StardewModdingAPI.Framework.Reflection
/// <param name="targetModID">The unique ID of the mod providing the API.</param>
public TInterface CreateProxy<TInterface>(object instance, string sourceModID, string targetModID)
where TInterface : class
{
// validate
if (instance == null)
throw new InvalidOperationException("Can't proxy access to a null API.");
// create instance
InterfaceProxyBuilder builder = this.ObtainBuilder(instance.GetType(), typeof(TInterface), sourceModID, targetModID);
return (TInterface)builder.CreateInstance(instance, this);
}
internal InterfaceProxyBuilder ObtainBuilder(Type targetType, Type interfaceType, string sourceModID, string targetModID)
{
lock (this.Builders)
{
// validate
if (instance == null)
throw new InvalidOperationException("Can't proxy access to a null API.");
if (!typeof(TInterface).IsInterface)
if (!interfaceType.IsInterface)
throw new InvalidOperationException("The proxy type must be an interface, not a class.");
// get proxy type
Type targetType = instance.GetType();
string proxyTypeName = $"StardewModdingAPI.Proxies.From<{sourceModID}_{typeof(TInterface).FullName}>_To<{targetModID}_{targetType.FullName}>";
string proxyTypeName = $"StardewModdingAPI.Proxies.From<{sourceModID}_{interfaceType.FullName}>_To<{targetModID}_{targetType.FullName}>";
if (!this.Builders.TryGetValue(proxyTypeName, out InterfaceProxyBuilder builder))
{
builder = new InterfaceProxyBuilder(proxyTypeName, this.ModuleBuilder, typeof(TInterface), targetType);
builder = new InterfaceProxyBuilder(this, proxyTypeName, this.ModuleBuilder, interfaceType, targetType, sourceModID, targetModID);
this.Builders[proxyTypeName] = builder;
}
return builder;
}
}
// create instance
return (TInterface)builder.CreateInstance(instance);
internal InterfaceProxyBuilder GetBuilderByProxyTypeName(string proxyTypeName)
{
lock (this.Builders)
{
return this.Builders.TryGetValue(proxyTypeName, out InterfaceProxyBuilder builder) ? builder : null;
}
}
}

18
src/SMAPI/Framework/Reflection/InterfaceProxyGlue.cs Normal file
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@ -0,0 +1,18 @@
namespace StardewModdingAPI.Framework.Reflection
{
public sealed class InterfaceProxyGlue
{
private readonly InterfaceProxyFactory Factory;
internal InterfaceProxyGlue(InterfaceProxyFactory factory)
{
this.Factory = factory;
}
public object CreateInstanceForProxyTypeName(string proxyTypeName, object toProxy)
{
var builder = this.Factory.GetBuilderByProxyTypeName(proxyTypeName);
return builder.CreateInstance(toProxy, this.Factory);
}
}
}