IndexExpression.cs

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using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.Dynamic.Utils;
using System.Reflection;
 
namespace System.Linq.Expressions;
 
[DebuggerTypeProxy(typeof(IndexExpressionProxy))]
public sealed class IndexExpression : Expression, IArgumentProvider
{
    private IReadOnlyList<Expression> _arguments;
 
    public sealed override ExpressionType NodeType => ExpressionType.Index;
 
    public sealed override Type Type
    {
        get
        {
            if (Indexer != null)
            {
                return Indexer.PropertyType;
            }
            return Object.Type.GetElementType();
        }
    }
 
    public Expression? Object { get; }
 
    public PropertyInfo? Indexer { get; }
 
    public ReadOnlyCollection<Expression> Arguments => ExpressionUtils.ReturnReadOnly(ref _arguments);
 
    public int ArgumentCount => _arguments.Count;
 
    internal IndexExpression(Expression instance, PropertyInfo indexer, IReadOnlyList<Expression> arguments)
    {
        _ = indexer == null;
        Object = instance;
        Indexer = indexer;
        _arguments = arguments;
    }
 
    public IndexExpression Update(Expression @object, IEnumerable<Expression>? arguments)
    {
        if (@object == Object && arguments != null && ExpressionUtils.SameElements(ref arguments, Arguments))
        {
            return this;
        }
        return Expression.MakeIndex(@object, Indexer, arguments);
    }
 
    public Expression GetArgument(int index)
    {
        return _arguments[index];
    }
 
    protected internal override Expression Accept(ExpressionVisitor visitor)
    {
        return visitor.VisitIndex(this);
    }
 
    internal Expression Rewrite(Expression instance, Expression[] arguments)
    {
        return Expression.MakeIndex(instance, Indexer, arguments ?? _arguments);
    }
}