MethodBuilder

MethodBuilderRequest is used to acquire a MethodBuilder.

// Request to create method builder for "MyFunction"
IRequestFor<MethodBuilder> myFunc = new MethodBuilderRequest(
    Name: "MyFunction",
    Attributes: MethodAttributes.Public | MethodAttributes.Virtual,
    ReturnType: typeof(int),
    ParameterTypes: typeof(int));

Opcodes are added to method request.

// 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);

Method request is added to type request.

// Request to create type builder
IRequestFor<TypeBuilder> typeBuilder = new TypeBuilderRequest(
    nameRequest: "MyClass6x", 
    attributes: TypeAttributes.Public | TypeAttributes.Class | TypeAttributes.AutoClass);
// Add "MyFunction" to type request
typeBuilder = typeBuilder.Append(myFunc);

MethodRequest is gets built as part of type request.

// 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);

Opcodes can also be added to List<IRequestFor<ILGenerator>> to conserve object[] array allocations.

// Request to create il generator
List<IRequest> il = new();
// Define labels
IRequestFor<Label> trueLabel = new LabelRequest(), falseLabel = new LabelRequest();
// "return x < 5 ? 0 : 1"
il.Add(OpCodes.Ldarg_1).Add(OpCodes.Ldc_I4_5).Add(OpCodes.Clt).Add(OpCodes.Brtrue_S, falseLabel);
// true: return 1;
il.Add(new MarkLabelRequest(trueLabel));
il.Add(OpCodes.Ldc_I4_1);
il.Add(OpCodes.Ret);
// false: return 0;
il.Add(new MarkLabelRequest(falseLabel));
il.Add(OpCodes.Ldc_I4_0);
il.Add(OpCodes.Ret);
// Add il to "MyFunction"
myFunc = myFunc.Append(ILGeneratorRequest.Default.Append(il));

Full Example

Full example

using System;
using System.Collections.Generic;
using System.Reflection;
using System.Reflection.Emit;
using Avalanche.Emit;
using Avalanche.Service;

public class methodbuilder
{
    public static void Run()
    {
        {
            // Service that handles assembly builder, module builder and types
            IService service = Services.Create((ServiceHandlers.Instance, EmitHandlers.Instance), CachePolicies.Default);
            // <1>
            // Request to create method builder for "MyFunction"
            IRequestFor<MethodBuilder> myFunc = new MethodBuilderRequest(
                Name: "MyFunction",
                Attributes: MethodAttributes.Public | MethodAttributes.Virtual,
                ReturnType: typeof(int),
                ParameterTypes: typeof(int));
            // </1>
            // <2>
            // 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);
            // </2>
            // <3>
            // Request to create type builder
            IRequestFor<TypeBuilder> typeBuilder = new TypeBuilderRequest(
                nameRequest: "MyClass6x", 
                attributes: TypeAttributes.Public | TypeAttributes.Class | TypeAttributes.AutoClass);
            // Add "MyFunction" to type request
            typeBuilder = typeBuilder.Append(myFunc);
            // </3>
            // <4>
            // 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);
            // </4>
        }
        {
            // Service that handles assembly builder, module builder and types
            IService service = Services.Create((ServiceHandlers.Instance, EmitHandlers.Instance), CachePolicies.Default);
            // Request to create method builder for "MyFunction"
            IRequestFor<MethodBuilder> myFunc = new MethodBuilderRequest(
                Name: "MyFunction",
                Attributes: MethodAttributes.Public | MethodAttributes.Virtual,
                ReturnType: typeof(int),
                ParameterTypes: typeof(int));
            // <11>
            // Request to create il generator
            List<IRequest> il = new();
            // Define labels
            IRequestFor<Label> trueLabel = new LabelRequest(), falseLabel = new LabelRequest();
            // "return x < 5 ? 0 : 1"
            il.Add(OpCodes.Ldarg_1).Add(OpCodes.Ldc_I4_5).Add(OpCodes.Clt).Add(OpCodes.Brtrue_S, falseLabel);
            // true: return 1;
            il.Add(new MarkLabelRequest(trueLabel));
            il.Add(OpCodes.Ldc_I4_1);
            il.Add(OpCodes.Ret);
            // false: return 0;
            il.Add(new MarkLabelRequest(falseLabel));
            il.Add(OpCodes.Ldc_I4_0);
            il.Add(OpCodes.Ret);
            // Add il to "MyFunction"
            myFunc = myFunc.Append(ILGeneratorRequest.Default.Append(il));
            // </11>
            // Request to create type builder
            IRequestFor<TypeBuilder> typeBuilder = new TypeBuilderRequest(
                nameRequest: "MyClass6z",
                attributes: TypeAttributes.Public | TypeAttributes.Class | TypeAttributes.AutoClass);
            // Add "MyFunction" to type request
            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);
        }
    }
}