FieldInfo

AccessorRequest<NetField> requests for a field accessor of FieldInfo or PropertyInfo. (Avalanche.Accessor.Net.dll)

// Create description
FieldInfo fi = typeof(MyClass).GetField("Id")!;
// Create request
AccessorRequest request = new AccessorRequest(new NetField(fi));
// Create accessor
IContentAccessor<MyClass, int> idAccessor = Services.Create(NetAccessorHandlers.Instance).GetRequired<IRequest, IContentAccessor<MyClass, int>>(request);

ContentAccessorRequest(IFieldDescription) also request for IContentAccessor<Container, Content>. FieldInfo, PropertyInfo, MethodInfo, ParameterInfo, and IEnumerable<EmitLine> can be used to describe .Reader, .Writer and .Referer.

// Create description
FieldInfo fi = typeof(MyClass).GetField("Id")!;
IFieldDescription fieldDescription =
    new FieldDescription()
    .SetName("Id")
    .SetType(typeof(int))
    .SetReader(fi)
    .SetWriter(fi)
    .SetReferer(fi)
    .SetReadOnly();

// Create request
ContentAccessorRequest request = new ContentAccessorRequest(new NetField(fieldDescription));
// Create accessor
IContentAccessor<MyClass, int> idAccessor =
    Services.Create(NetAccessorHandlers.Instance).GetRequired<ContentAccessorRequest, IContentAccessor<MyClass, int>>(request);

ContentAccessorRequest(target, contentType) requests for specific ContentType.

// Create container target
IContainerTarget target = new NetField(typeof(MyClass).GetField("Id")!, typeof(object));
// Create request
ContentAccessorRequest request = new ContentAccessorRequest(target);
// Create accessor
IContentAccessor<MyClass, object> idAccessor =
    Services.Create(NetAccessorHandlers.Instance).GetRequired<ContentAccessorRequest, IContentAccessor<MyClass, object>>(request);

FieldDescriptionRequest(Target) requests a field description for FieldInfo, PropertyInfo, MethodInfo, ParameterInfo, and IEnumerable<EmitLine>.

// Get target
FieldInfo fi = typeof(MyClass).GetField("Id")!;
// Create description request
IRequestFor<IFieldDescription> fieldDescriptionRequest = new FieldDescriptionRequest(fi);
// Create request
IRequestFor<IContentAccessor> fieldAccessorRequest = new ContentAccessorRequest(new NetField(fieldDescriptionRequest));
// Create accessor
IContentAccessor<MyClass, int> idAccessor = Services.Create(NetAccessorHandlers.Instance).GetRequired<IRequestFor<IContentAccessor>, IContentAccessor<MyClass, int>>(fieldAccessorRequest);

Usage

.Reader reads the value from the field.

MyClass myRecord = new MyClass(50, "ABC");
int id = idAccessor.Reader.Read(myRecord);

.Writer writes value to field.

MyClass myRecord = new MyClass(50, "ABC");
idAccessor.Writer.Write(10, myRecord);

.Referer gets a pointer to field.

IReferer<MyClass, int> referer1 = new MyClassIdReferer(); 
MyClass myRecord = new MyClass(50, "ABC");
ref int pointer = ref referer1.GetReference(myRecord);

IRefererFromRef<MyStruct, int> referer2 = new MyStructIdReferer();
MyStruct myStruct = new MyStruct(7, "");
ref int id2 = ref referer2.GetReference(ref myStruct);

Implementation

The default implementations work for most cases, however, more specific custom implementations can be crafted.

Reader

public class MyClass
{
    public int Id;
    public string Label;

    public MyClass(int id, string label)
    {
        Id = id;
        Label = label;
    }
}

public struct MyStruct
{
    public int Id;
    public string Label;

    public MyStruct(int id, string label)
    {
        Id = id;
        Label = label;
    }
}

Reader can be created with delegate.

var myClassIdReader = DelegateWriter.Reader((MyClass record) => record.Id);
var myStructIdReader = DelegateWriter.Reader((MyStruct record) => record.Id);

Reader can be created with base class.

/// <summary></summary>
public class MyClassIdReader : WriterToRef<MyClass, int>
{
    /// <summary></summary>
    public override bool TryWrite(MyClass from, ref int to, IServiceProvider? context = null)
    {
        if (from == null) return false;
        to = from.Id;
        return true;
    }
}

/// <summary></summary>
public class MyStructIdReader : WriterToRef<MyStruct, int>
{
    /// <summary></summary>
    public override bool TryWrite(MyStruct from, ref int to, IServiceProvider? context = null)
    {
        to = from.Id;
        return true;
    }
}

Handler processes ReaderRequest.

// Create service
IService service = Services.Create((NetAccessorHandlers.Instance, new MyClassIdReaderBuilder()), CachePolicies.Default);
// Create field description
IFieldDescription fieldDescription = new FieldDescription().Read(typeof(MyClass).GetField("Id")!).SetReadOnly();
// Reader request
ReaderRequest request = new ReaderRequest(new NetField(fieldDescription));
// Get reader
IWriterBase<MyClass, int> myClassIdReader = service.GetRequired<ReaderRequest, IWriterBase<MyClass, int>>(request);
// Create class
MyClass myClass = new MyClass(6, "");
// Read
int id = myClassIdReader.Read(myClass);

public class MyClassIdReaderBuilder : IHandler<ReaderRequest, IWriterBase>
{
    [Order(-100)]
    public void Handle(IQuery<ReaderRequest, IWriterBase> query)
    {
        // Already handled
        if (query.Handled()) return;
        // Place here field description
        IFieldDescription fieldDescription;
        // Get field description
        if (query.Request.Target is INetField netFieldType && netFieldType.ContainerType is IFieldDescription fieldDescription1) fieldDescription = fieldDescription1;
        else if (query.Request.Target is INetType netType && netType.ContainerType is IFieldDescription fieldDescription2) fieldDescription = fieldDescription2;
        else if (query.Request.Target is IFieldDescription fieldDescription3) fieldDescription = fieldDescription3;
        else return;
        // Get record type
        Type recordType = fieldDescription.Record?.Type ?? (fieldDescription.Reader as MemberInfo)?.DeclaringType!;
        // This handler only handles "MyClass"
        if (!typeof(MyClass).Equals(recordType)) return;
        //
        if (!"Id".Equals(fieldDescription.Name?.ToString())) return;
        // Create reader
        IWriterBase reader = new MyClassIdReader();
        // Decorate IWriterBase<object, object> support
        reader = WriterAdapter.Create(reader);
        // Assign reader
        query.Response.SetValue(reader);

    }
}

Writer

Writer can be created with delegate.

var myClassIdWriter = DelegateWriter.Writer((int value, MyClass record) => record.Id = value);
var myStructIdWriter = DelegateWriter.Writer((int value, ref MyStruct record) => record.Id = value);

Writer can be created with base class.

/// <summary></summary>
public class MyClassIdWriter : Writer<int, MyClass>
{
    /// <summary></summary>
    public override bool TryWrite(int value, MyClass to, IServiceProvider? context = null)
    {
        if (to == null) return false;
        to.Id = value;
        return true;
    }
}

/// <summary></summary>
public class MyStructIdWriter : WriterToRef<int, MyStruct>
{
    /// <summary></summary>
    public override bool TryWrite(int value, ref MyStruct to, IServiceProvider? context = null)
    {
        to.Id = value;
        return true;
    }
}

Handler processes WriterRequest.

// Create service
IService service = Services.Create((NetAccessorHandlers.Instance, new MyClassIdWriterBuilder()), CachePolicies.Default);
// Create field description
IFieldDescription fieldDescription = new FieldDescription().Read(typeof(MyClass).GetField("Id")!).SetReadOnly();
// Writer request
WriterRequest request = new WriterRequest(new NetField(fieldDescription));
// Get writer
IWriter<int, MyClass> myClassIdWriter = service.GetRequired<WriterRequest, IWriter<int, MyClass>>(request);
// Create class
MyClass myClass = new MyClass(6, "");
// Write
myClassIdWriter.Write(2023, myClass);

public class MyClassIdWriterBuilder : IHandler<WriterRequest, IWriterBase>
{
    [Order(-100)]
    public void Handle(IQuery<WriterRequest, IWriterBase> query)
    {
        // Already handled
        if (query.Handled()) return;

        // 
        if (query.Request.Target is not IFieldDescription fieldDescription) return;
        // Get record type
        Type recordType = fieldDescription.Record?.Type ?? (fieldDescription.Writer as MemberInfo)?.DeclaringType!;
        // This handler only handles "MyClass"
        if (!typeof(MyClass).Equals(recordType)) return;
        //
        if (!"Id".Equals(fieldDescription.Name?.ToString())) return;
        // Create writer
        IWriterBase writer = new MyClassIdWriter();
        // Decorate IWriterBase<object, object> support
        writer = WriterAdapter.Create(writer);
        // Assign writer
        query.Response.SetValue(writer);

    }
}

Referer

Referer can be created with base class.

/// <summary></summary>
public class MyClassIdReferer : IReferer<MyClass, int>
{
    public bool CanRefer => true;
    public Type FromType => typeof(MyClass);
    public Type ToType => typeof(int);
    public ref int GetReference(MyClass record, IServiceProvider? context = null) => ref record.Id;
    public bool Accept(IWriterBaseVisitor visitor) => visitor is not IRefererVisitor v ? true : v.Visit(refererT: this);
}

/// <summary></summary>
public class MyStructIdReferer : IRefererFromRef<MyStruct, int>
{
    public bool CanRefer => true;
    public Type FromType => typeof(MyStruct);
    public Type ToType => typeof(int);
    public ref int GetReference(ref MyStruct record, IServiceProvider? context = null) => ref record.Id;
    public bool Accept(IWriterBaseVisitor visitor) => visitor is not IRefererVisitor v ? true : v.Visit(refererTFR: this);
}

Handler processes RefererRequest.

// Create service
IService service = Services.Create((NetAccessorHandlers.Instance, new MyClassIdRefererBuilder()), CachePolicies.Default);
// Create field description
IFieldDescription fieldDescription = new FieldDescription().Read(typeof(MyClass).GetField("Id")!).SetReadOnly();
// Referer request
RefererRequest request = new RefererRequest(new NetField(fieldDescription));
// Get referer
IReferer<MyClass, int> myClassIdReferer = service.GetRequired<RefererRequest, IReferer<MyClass, int>>(request);
// Create class
MyClass myClass = new MyClass(6, "");
// Read
ref int id = ref myClassIdReferer.GetReference(myClass);

public class MyClassIdRefererBuilder : IHandler<RefererRequest, IWriterBase>
{
    [Order(-100)]
    public void Handle(IQuery<RefererRequest, IWriterBase> query)
    {
        // Already handled
        if (query.Handled()) return;

        // 
        if (query.Request.Target is not IFieldDescription fieldDescription) return;
        // Get record type
        Type recordType = fieldDescription.Record?.Type ?? (fieldDescription.Referer as MemberInfo)?.DeclaringType!;
        // This handler only handles "MyClass"
        if (!typeof(MyClass).Equals(recordType)) return;
        //
        if (!"Id".Equals(fieldDescription.Name?.ToString())) return;
        // Create referer
        IWriterBase referer = new MyClassIdReferer();
        // Assign referer
        query.Response.SetValue(referer);
    }
}

Full Example

Full example

using System;
using System.Reflection;
using System.Runtime.Serialization;
using Avalanche.Accessor;
using Avalanche.DataType;
using Avalanche.Service;
using Avalanche.Utilities;
using Avalanche.Utilities.Record;
using Avalanche.Writer;

public class field
{
    public static void Run()
    {
        {
            // <10>
            // Create description
            FieldInfo fi = typeof(MyClass).GetField("Id")!;
            // Create request
            AccessorRequest request = new AccessorRequest(new NetField(fi));
            // Create accessor
            IContentAccessor<MyClass, int> idAccessor = Services.Create(NetAccessorHandlers.Instance).GetRequired<IRequest, IContentAccessor<MyClass, int>>(request);
            // </10>
        }        
        {
            // <11>
            // Create description
            FieldInfo fi = typeof(MyClass).GetField("Id")!;
            IFieldDescription fieldDescription =
                new FieldDescription()
                .SetName("Id")
                .SetType(typeof(int))
                .SetReader(fi)
                .SetWriter(fi)
                .SetReferer(fi)
                .SetReadOnly();

            // Create request
            ContentAccessorRequest request = new ContentAccessorRequest(new NetField(fieldDescription));
            // Create accessor
            IContentAccessor<MyClass, int> idAccessor =
                Services.Create(NetAccessorHandlers.Instance).GetRequired<ContentAccessorRequest, IContentAccessor<MyClass, int>>(request);
            // </11>
        }
        {
            // <11B>
            // Create container target
            IContainerTarget target = new NetField(typeof(MyClass).GetField("Id")!, typeof(object));
            // Create request
            ContentAccessorRequest request = new ContentAccessorRequest(target);
            // Create accessor
            IContentAccessor<MyClass, object> idAccessor =
                Services.Create(NetAccessorHandlers.Instance).GetRequired<ContentAccessorRequest, IContentAccessor<MyClass, object>>(request);
            // </11B>
        }
        {
            // <12>
            // Get target
            FieldInfo fi = typeof(MyClass).GetField("Id")!;
            // Create description request
            IRequestFor<IFieldDescription> fieldDescriptionRequest = new FieldDescriptionRequest(fi);
            // Create request
            IRequestFor<IContentAccessor> fieldAccessorRequest = new ContentAccessorRequest(new NetField(fieldDescriptionRequest));
            // Create accessor
            IContentAccessor<MyClass, int> idAccessor = Services.Create(NetAccessorHandlers.Instance).GetRequired<IRequestFor<IContentAccessor>, IContentAccessor<MyClass, int>>(fieldAccessorRequest);
            // </12>

            {
                // <51>
                MyClass myRecord = new MyClass(50, "ABC");
                int id = idAccessor.Reader.Read(myRecord);
                // </51>
            }
            {
                // <51E>
                var myClassIdReader = DelegateWriter.Reader((MyClass record) => record.Id);
                var myStructIdReader = DelegateWriter.Reader((MyStruct record) => record.Id);
                // </51E>
            }
            {
                // <51H>
                // Create service
                IService service = Services.Create((NetAccessorHandlers.Instance, new MyClassIdReaderBuilder()), CachePolicies.Default);
                // Create field description
                IFieldDescription fieldDescription = new FieldDescription().Read(typeof(MyClass).GetField("Id")!).SetReadOnly();
                // Reader request
                ReaderRequest request = new ReaderRequest(new NetField(fieldDescription));
                // Get reader
                IWriterBase<MyClass, int> myClassIdReader = service.GetRequired<ReaderRequest, IWriterBase<MyClass, int>>(request);
                // Create class
                MyClass myClass = new MyClass(6, "");
                // Read
                int id = myClassIdReader.Read(myClass);
                // </51H>
            }

            {
                // <52>
                MyClass myRecord = new MyClass(50, "ABC");
                idAccessor.Writer.Write(10, myRecord);
                // </52>
            }
            {
                // <52E>
                var myClassIdWriter = DelegateWriter.Writer((int value, MyClass record) => record.Id = value);
                var myStructIdWriter = DelegateWriter.Writer((int value, ref MyStruct record) => record.Id = value);
                // </52E>
            }
            {
                // <52H>
                // Create service
                IService service = Services.Create((NetAccessorHandlers.Instance, new MyClassIdWriterBuilder()), CachePolicies.Default);
                // Create field description
                IFieldDescription fieldDescription = new FieldDescription().Read(typeof(MyClass).GetField("Id")!).SetReadOnly();
                // Writer request
                WriterRequest request = new WriterRequest(new NetField(fieldDescription));
                // Get writer
                IWriter<int, MyClass> myClassIdWriter = service.GetRequired<WriterRequest, IWriter<int, MyClass>>(request);
                // Create class
                MyClass myClass = new MyClass(6, "");
                // Write
                myClassIdWriter.Write(2023, myClass);
                // </52H>
            }


            {
                // <53>
                IReferer<MyClass, int> referer1 = new MyClassIdReferer(); 
                MyClass myRecord = new MyClass(50, "ABC");
                ref int pointer = ref referer1.GetReference(myRecord);

                IRefererFromRef<MyStruct, int> referer2 = new MyStructIdReferer();
                MyStruct myStruct = new MyStruct(7, "");
                ref int id2 = ref referer2.GetReference(ref myStruct);
                // </53>
            }
            {
                // <53H>
                // Create service
                IService service = Services.Create((NetAccessorHandlers.Instance, new MyClassIdRefererBuilder()), CachePolicies.Default);
                // Create field description
                IFieldDescription fieldDescription = new FieldDescription().Read(typeof(MyClass).GetField("Id")!).SetReadOnly();
                // Referer request
                RefererRequest request = new RefererRequest(new NetField(fieldDescription));
                // Get referer
                IReferer<MyClass, int> myClassIdReferer = service.GetRequired<RefererRequest, IReferer<MyClass, int>>(request);
                // Create class
                MyClass myClass = new MyClass(6, "");
                // Read
                ref int id = ref myClassIdReferer.GetReference(myClass);
                // </53H>
            }
        }
    }

    // <100>
    public class MyClass
    {
        public int Id;
        public string Label;

        public MyClass(int id, string label)
        {
            Id = id;
            Label = label;
        }
    }

    public struct MyStruct
    {
        public int Id;
        public string Label;

        public MyStruct(int id, string label)
        {
            Id = id;
            Label = label;
        }
    }
    // </100>

    // <51F>
    /// <summary></summary>
    public class MyClassIdReader : WriterToRef<MyClass, int>
    {
        /// <summary></summary>
        public override bool TryWrite(MyClass from, ref int to, IServiceProvider? context = null)
        {
            if (from == null) return false;
            to = from.Id;
            return true;
        }
    }

    /// <summary></summary>
    public class MyStructIdReader : WriterToRef<MyStruct, int>
    {
        /// <summary></summary>
        public override bool TryWrite(MyStruct from, ref int to, IServiceProvider? context = null)
        {
            to = from.Id;
            return true;
        }
    }
    // </51F>
    // <51G>
    public class MyClassIdReaderBuilder : IHandler<ReaderRequest, IWriterBase>
    {
        [Order(-100)]
        public void Handle(IQuery<ReaderRequest, IWriterBase> query)
        {
            // Already handled
            if (query.Handled()) return;
            // Place here field description
            IFieldDescription fieldDescription;
            // Get field description
            if (query.Request.Target is INetField netFieldType && netFieldType.ContainerType is IFieldDescription fieldDescription1) fieldDescription = fieldDescription1;
            else if (query.Request.Target is INetType netType && netType.ContainerType is IFieldDescription fieldDescription2) fieldDescription = fieldDescription2;
            else if (query.Request.Target is IFieldDescription fieldDescription3) fieldDescription = fieldDescription3;
            else return;
            // Get record type
            Type recordType = fieldDescription.Record?.Type ?? (fieldDescription.Reader as MemberInfo)?.DeclaringType!;
            // This handler only handles "MyClass"
            if (!typeof(MyClass).Equals(recordType)) return;
            //
            if (!"Id".Equals(fieldDescription.Name?.ToString())) return;
            // Create reader
            IWriterBase reader = new MyClassIdReader();
            // Decorate IWriterBase<object, object> support
            reader = WriterAdapter.Create(reader);
            // Assign reader
            query.Response.SetValue(reader);

        }
    }
    // </51G>


    // <52F>
    /// <summary></summary>
    public class MyClassIdWriter : Writer<int, MyClass>
    {
        /// <summary></summary>
        public override bool TryWrite(int value, MyClass to, IServiceProvider? context = null)
        {
            if (to == null) return false;
            to.Id = value;
            return true;
        }
    }

    /// <summary></summary>
    public class MyStructIdWriter : WriterToRef<int, MyStruct>
    {
        /// <summary></summary>
        public override bool TryWrite(int value, ref MyStruct to, IServiceProvider? context = null)
        {
            to.Id = value;
            return true;
        }
    }
    // </52F>
    // <52G>
    public class MyClassIdWriterBuilder : IHandler<WriterRequest, IWriterBase>
    {
        [Order(-100)]
        public void Handle(IQuery<WriterRequest, IWriterBase> query)
        {
            // Already handled
            if (query.Handled()) return;

            // 
            if (query.Request.Target is not IFieldDescription fieldDescription) return;
            // Get record type
            Type recordType = fieldDescription.Record?.Type ?? (fieldDescription.Writer as MemberInfo)?.DeclaringType!;
            // This handler only handles "MyClass"
            if (!typeof(MyClass).Equals(recordType)) return;
            //
            if (!"Id".Equals(fieldDescription.Name?.ToString())) return;
            // Create writer
            IWriterBase writer = new MyClassIdWriter();
            // Decorate IWriterBase<object, object> support
            writer = WriterAdapter.Create(writer);
            // Assign writer
            query.Response.SetValue(writer);

        }
    }
    // </52G>

    // <53F>
    /// <summary></summary>
    public class MyClassIdReferer : IReferer<MyClass, int>
    {
        public bool CanRefer => true;
        public Type FromType => typeof(MyClass);
        public Type ToType => typeof(int);
        public ref int GetReference(MyClass record, IServiceProvider? context = null) => ref record.Id;
        public bool Accept(IWriterBaseVisitor visitor) => visitor is not IRefererVisitor v ? true : v.Visit(refererT: this);
    }

    /// <summary></summary>
    public class MyStructIdReferer : IRefererFromRef<MyStruct, int>
    {
        public bool CanRefer => true;
        public Type FromType => typeof(MyStruct);
        public Type ToType => typeof(int);
        public ref int GetReference(ref MyStruct record, IServiceProvider? context = null) => ref record.Id;
        public bool Accept(IWriterBaseVisitor visitor) => visitor is not IRefererVisitor v ? true : v.Visit(refererTFR: this);
    }
    // </53F>
    // <53G>
    public class MyClassIdRefererBuilder : IHandler<RefererRequest, IWriterBase>
    {
        [Order(-100)]
        public void Handle(IQuery<RefererRequest, IWriterBase> query)
        {
            // Already handled
            if (query.Handled()) return;

            // 
            if (query.Request.Target is not IFieldDescription fieldDescription) return;
            // Get record type
            Type recordType = fieldDescription.Record?.Type ?? (fieldDescription.Referer as MemberInfo)?.DeclaringType!;
            // This handler only handles "MyClass"
            if (!typeof(MyClass).Equals(recordType)) return;
            //
            if (!"Id".Equals(fieldDescription.Name?.ToString())) return;
            // Create referer
            IWriterBase referer = new MyClassIdReferer();
            // Assign referer
            query.Response.SetValue(referer);
        }
    }
    // </53G>

}