Introduction
Avalanche.Emit is a class library for building Types and emitting opcodes by utilizing Avalanche.Service architecture. This library is a helper to the System.Reflection.Emit namespace.
The following example creates a type with method "int MyFunction(int x) => x < 5 ? 0 : 1;"
// Service that handles assembly builder, module builder and type builder
IService service = Services.Create((ServiceHandlers.Instance, EmitHandlers.Instance), CachePolicies.Default);
// Request to create type builder
IRequestFor<TypeBuilder> typeBuilder = new TypeBuilderRequest("MyClass_", TypeAttributes.Public | TypeAttributes.Class | TypeAttributes.AutoClass);
// Request to create method builder for "MyFunction"
IRequestFor<MethodBuilder> myFunc = new MethodBuilderRequest("MyFunction", MethodAttributes.Public | MethodAttributes.Virtual, typeof(int), typeof(int));
// Request to create il generator
IRequestFor<ILGenerator> il = ILGeneratorRequest.Default;
// Define labels
IRequestFor<Label> trueLabel = new LabelRequest(), falseLabel = new LabelRequest();
// "return x < 5 ? 0 : 1"
il = il.Append(OpCodes.Ldarg_1).Append(OpCodes.Ldc_I4_5).Append(OpCodes.Clt).Append(OpCodes.Brtrue_S, falseLabel);
// true: return 1;
il = il.Append(new MarkLabelRequest(trueLabel)).Append(OpCodes.Ldc_I4_1).Append(OpCodes.Ret);
// false: return 0;
il = il.Append(new MarkLabelRequest(falseLabel)).Append(OpCodes.Ldc_I4_0).Append(OpCodes.Ret);
// Add il to "MyFunction"
myFunc = myFunc.Append(il);
// Add "MyFunction"
typeBuilder = typeBuilder.Append(myFunc);
// Request to build type
IRequestFor<Type> type = new TypeRequest(typeBuilder);
// Request to create new instance
IRequestFor<Object> newRequest = type.NewRequest();
// Print request
newRequest.PrintTreeTo(Console.Out);
// Get instance
object instance = service.GetRequired<IRequestFor<object>, object>(newRequest);
// Evaluate: value = 4 < 5 ? 0 : 1;
int value = (int)instance.GetType().GetMethod("MyFunction", new Type[] { typeof(int) })!.Invoke(instance, new object[] { 4 })!;
// Print
Console.WriteLine(value);
View complete request
NewRequest
└── Type = TypeRequest
└── Key = ContextRequest<TypeBuilder>
├── Key = "System.Reflection.Emit.TypeBuilder"
├── Value = TypeBuilderRequest
│ ├── Name = "MyClass_"
│ └── Attributes = AutoLayout, AnsiClass, Class, Public, AutoClass
└── Requests[0] = ContextRequest<MethodBuilder>
├── Key = "System.Reflection.Emit.Builder"
├── Value = MethodBuilderRequest
│ ├── Name = "MyFunction"
│ ├── Attributes = PrivateScope, Public, Virtual
│ ├── ReturnType = System.Int32
│ └── ParameterTypes[0] = System.Int32
└── Requests[0] = ContextRequest<ILGenerator>
├── Key = "System.Reflection.Emit.ILGenerator"
├── Value = ILGeneratorRequest
├── Requests[0] = Emit
│ └── Opcode = ldarg.1
├── Requests[1] = Emit
│ └── Opcode = ldc.i4.5
├── Requests[2] = Emit
│ └── Opcode = clt
├── Requests[3] = Emit
│ ├── Opcode = brtrue.s
│ └── Parameters[0] = LabelRequest
│ └── Id = 49972132
├── Requests[4] = MarkLabelRequest
│ └── Label = LabelRequest
│ └── Id = 65204782
├── Requests[5] = Emit
│ └── Opcode = ldc.i4.1
├── Requests[6] = Emit
│ └── Opcode = ret
├── Requests[7] = MarkLabelRequest
│ └── Label = LabelRequest
├── Requests[8] = Emit
│ └── Opcode = ldc.i4.0
└── Requests[9] = Emit
└── Opcode = ret
Emit Handlers
EmitHandlers is a collection of handlers that participate in building a type. EmitHandlers requires cache and ServiceHandlers as helper handlers.
// Service that handles assembly builder, module builder and type builder
IService service = Services.Create((ServiceHandlers.Instance, EmitHandlers.Instance), CachePolicies.Default);
EmitHandlers ├── TypeBuilderFactory ├── TypeFactory ├── TypeBuiltHandler ├── ConstructorBuilderFactory ├── MethodBuilderFactory ├── FieldBuilderFactory ├── PropertyBuilderFactory ├── DefineMethodOverrideHandler ├── ILGeneratorFactory ├── PropertyBuilderSetSetterHandler ├── PropertyBuilderSetGetterHandler ├── EmitHandler ├── EmitLdIndHandler ├── EmitStIndHandler ├── EmitCastHandler ├── LocalBuilderFactory ├── LabelFactory └── MarkLabelRequestHandler
Full Example
Full example
using System;
using System.Reflection;
using System.Reflection.Emit;
using Avalanche.Emit;
using Avalanche.Service;
public class index
{
public static void Run()
{
{
// <1>
// Service that handles assembly builder, module builder and type builder
IService service = Services.Create((ServiceHandlers.Instance, EmitHandlers.Instance), CachePolicies.Default);
// Request to create type builder
IRequestFor<TypeBuilder> typeBuilder = new TypeBuilderRequest("MyClass_", TypeAttributes.Public | TypeAttributes.Class | TypeAttributes.AutoClass);
// Request to create method builder for "MyFunction"
IRequestFor<MethodBuilder> myFunc = new MethodBuilderRequest("MyFunction", MethodAttributes.Public | MethodAttributes.Virtual, typeof(int), typeof(int));
// Request to create il generator
IRequestFor<ILGenerator> il = ILGeneratorRequest.Default;
// Define labels
IRequestFor<Label> trueLabel = new LabelRequest(), falseLabel = new LabelRequest();
// "return x < 5 ? 0 : 1"
il = il.Append(OpCodes.Ldarg_1).Append(OpCodes.Ldc_I4_5).Append(OpCodes.Clt).Append(OpCodes.Brtrue_S, falseLabel);
// true: return 1;
il = il.Append(new MarkLabelRequest(trueLabel)).Append(OpCodes.Ldc_I4_1).Append(OpCodes.Ret);
// false: return 0;
il = il.Append(new MarkLabelRequest(falseLabel)).Append(OpCodes.Ldc_I4_0).Append(OpCodes.Ret);
// Add il to "MyFunction"
myFunc = myFunc.Append(il);
// Add "MyFunction"
typeBuilder = typeBuilder.Append(myFunc);
// Request to build type
IRequestFor<Type> type = new TypeRequest(typeBuilder);
// Request to create new instance
IRequestFor<Object> newRequest = type.NewRequest();
// Print request
newRequest.PrintTreeTo(Console.Out);
// Get instance
object instance = service.GetRequired<IRequestFor<object>, object>(newRequest);
// Evaluate: value = 4 < 5 ? 0 : 1;
int value = (int)instance.GetType().GetMethod("MyFunction", new Type[] { typeof(int) })!.Invoke(instance, new object[] { 4 })!;
// Print
Console.WriteLine(value);
// </1>
}
{
// <2>
// Service that handles assembly builder, module builder and type builder
IService service = Services.Create((ServiceHandlers.Instance, EmitHandlers.Instance), CachePolicies.Default);
// </2>
Console.WriteLine( HandlerInfoPrintTreeExtensions.PrintTree(EmitHandlers.Instance) );
}
}
}