NamedMember.cs

using System;
using System.Reflection;
using System.Collections.Generic;
using System.Runtime.ExceptionServices;
using System.Threading.Tasks;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Exceptions;
using Waher.Script.Functions.Runtime;
using Waher.Script.Model;
using Waher.Script.Objects;
using Waher.Script.Operators.Vectors;
using System.Threading;
 
namespace Waher.Script.Operators.Membership
{
    public class NamedMember : NullCheckUnaryOperator
    {
        private readonly string name;
 
        public NamedMember(ScriptNode Operand, string Name, bool NullCheck, int Start, int Length, Expression Expression)
            : base(Operand, NullCheck, Start, Length, Expression)
        {
            this.name = Name;
            this.isAsync = true;
        }
 
        public string Name => this.name;
 
        public override bool IsAsynchronous => true;
 
        public override IElement Evaluate(IElement Operand, Variables Variables)
        {
            return this.EvaluateAsync(Operand, Variables).Result;
        }
 
        public override async Task<IElement> EvaluateAsync(IElement Operand, Variables Variables)
        {
            object Value = Operand.AssociatedObjectValue;
            object Instance;
 
            if (Value is null && this.nullCheck)
                return ObjectValue.Null;
 
            Type T;
 
            T = Value as Type;
            if (T is null)
            {
                Instance = Value;
                T = Value?.GetType() ?? typeof(object);
            }
            else
                Instance = null;
 
            await this.synchObject.WaitAsync();
            try
            {
                if (T != this.type)
                {
                    this.type = T;
                    this.field = null;
                    this._event = null;
                    this.methods = null;
                    this.nameIndex = null;
                    this.property = T.GetRuntimeProperty(this.name);
 
                    if (this.property is null)
                    {
                        this.field = T.GetRuntimeField(this.name);
                        if (this.field is null)
                        {
                            this._event = T.GetRuntimeEvent(this.name);
                            if (this._event is null)
                            {
                                List<MethodLambda> Methods = null;
 
                                foreach (MethodInfo MI in T.GetRuntimeMethods())
                                {
                                    if (!MI.IsAbstract && MI.IsPublic && MI.Name == this.name)
                                    {
                                        if (Methods is null)
                                            Methods = new List<MethodLambda>();
 
                                        Methods.Add(new MethodLambda(Instance, MI));
                                    }
                                }
 
                                this.methods = Methods?.ToArray();
                                if (this.methods is null)
                                {
                                    if (VectorIndex.TryGetIndexProperty(T, true, false, out this.property, out _))
                                        this.nameIndex = new string[] { this.name };
                                }
                            }
                            else
                            {
                                if (!this._event.AddMethod.IsPublic)
                                    throw new ScriptRuntimeException("Event not accessible: " + this.name, this);
                            }
                        }
                        else
                        {
                            if (!this.field.IsPublic)
                                throw new ScriptRuntimeException("Field not accessible: " + this.name, this);
                        }
                    }
                    else
                    {
                        if (!this.property.CanRead)
                            throw new ScriptRuntimeException("Property cannot be read: " + this.name, this);
                        else if (!this.property.GetMethod.IsPublic)
                            throw new ScriptRuntimeException("Property not accessible: " + this.name, this);
                    }
                }
 
                object Result = null;
 
                if (!(this.property is null))
                {
                    try
                    {
                        if (!(this.nameIndex is null))
                            Result = await WaitPossibleTask(this.property.GetValue(Instance, this.nameIndex));
                        else
                            Result = await WaitPossibleTask(this.property.GetValue(Instance, null));
                    }
                    catch (Exception ex)
                    {
                        if (Instance is null)
                            Result = this.property;
                        else
                            ExceptionDispatchInfo.Capture(ex).Throw();
                    }
 
                    return Expression.Encapsulate(Result);
                }
                else if (!(this.field is null))
                {
                    try
                    {
                        Result = await WaitPossibleTask(this.field.GetValue(Instance));
                    }
                    catch (Exception ex)
                    {
                        if (Instance is null)
                            Result = this.field;
                        else
                            ExceptionDispatchInfo.Capture(ex).Throw();
                    }
 
                    return Expression.Encapsulate(Result);
                }
                else if (!(this._event is null))
                    return Expression.Encapsulate(this._event);
                else if (!(this.methods is null))
                {
                    if (this.methods.Length == 1)
                        return Expression.Encapsulate(this.methods[0]);
                    else
                        return Expression.Encapsulate(this.methods);
                }
                else if (Operand.IsScalar)
                    throw new ScriptRuntimeException("Member '" + this.name + "' not found on type '" + T.FullName + "'.", this);
            }
            finally
            {
                this.synchObject.Release();
            }
 
            LinkedList<IElement> Elements = new LinkedList<IElement>();
 
            foreach (IElement E in Operand.ChildElements)
                Elements.AddLast(await EvaluateDynamic(E, this.name, this.nullCheck, this));
 
            return Operand.Encapsulate(Elements, this);
        }
 
        private Type type = null;
        private PropertyInfo property = null;
        private FieldInfo field = null;
        private EventInfo _event = null;
        private MethodLambda[] methods = null;
        private string[] nameIndex = null;
        private readonly SemaphoreSlim synchObject = new SemaphoreSlim(1);
 
        internal static readonly Type[] stringType = new Type[] { typeof(string) };
 
        public static async Task<IElement> EvaluateDynamic(IElement Operand, string Name, bool NullCheck, ScriptNode Node)
        {
            object Value = Operand.AssociatedObjectValue;
            object Instance;
            Type T;
 
            if (Value is null && NullCheck)
                return ObjectValue.Null;
 
            T = Value as Type;
            if (T is null)
            {
                Instance = Value;
                T = Value.GetType();
            }
            else
                Instance = null;
 
            PropertyInfo Property = T.GetRuntimeProperty(Name);
            if (!(Property is null))
            {
                if (!Property.CanRead)
                    throw new ScriptRuntimeException("Property cannot be read: " + Name, Node);
                else if (!Property.GetMethod.IsPublic)
                    throw new ScriptRuntimeException("Property not accessible: " + Name, Node);
                else
                    return Expression.Encapsulate(await WaitPossibleTask(Property.GetValue(Instance, null)));
            }
 
            FieldInfo Field = T.GetRuntimeField(Name);
            if (!(Field is null))
            {
                if (!Field.IsPublic)
                    throw new ScriptRuntimeException("Field not accessible: " + Name, Node);
                else
                    return Expression.Encapsulate(await WaitPossibleTask(Field.GetValue(Instance)));
            }
 
            EventInfo Event = T.GetRuntimeEvent(Name);
            if (!(Event is null))
                return Expression.Encapsulate(Event);
 
            List<MethodLambda> Methods = null;
 
            foreach (MethodInfo MI in T.GetRuntimeMethods())
            {
                if (!MI.IsAbstract && MI.IsPublic && MI.Name == Name)
                {
                    if (Methods is null)
                        Methods = new List<MethodLambda>();
 
                    Methods.Add(new MethodLambda(Instance, MI));
                }
            }
 
            if (!(Methods is null))
            {
                if (Methods.Count == 1)
                    return Expression.Encapsulate(Methods[0]);
                else
                    return Expression.Encapsulate(Methods.ToArray());
            }
 
            if (VectorIndex.TryGetIndexProperty(T, true, false, out Property, out _))
                return Expression.Encapsulate(await WaitPossibleTask(Property.GetValue(Instance, new string[] { Name })));
 
            if (Operand.IsScalar)
                throw new ScriptRuntimeException("Member '" + Name + "' not found on type '" + T.FullName + "'.", Node);
 
            LinkedList<IElement> Elements = new LinkedList<IElement>();
 
            foreach (IElement E in Operand.ChildElements)
                Elements.AddLast(await EvaluateDynamic(E, Name, NullCheck, Node));
 
            return Operand.Encapsulate(Elements, Node);
        }
    }
}