HoistedLocals.cs

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using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Dynamic.Utils;
using System.Runtime.CompilerServices;
 
namespace System.Linq.Expressions.Compiler;
 
internal sealed class HoistedLocals
{
    internal readonly HoistedLocals Parent;
 
    internal readonly ReadOnlyDictionary<Expression, int> Indexes;
 
    internal readonly ReadOnlyCollection<ParameterExpression> Variables;
 
    internal readonly ParameterExpression SelfVariable;
 
    internal ParameterExpression ParentVariable => Parent?.SelfVariable;
 
    internal HoistedLocals(HoistedLocals parent, ReadOnlyCollection<ParameterExpression> vars)
    {
        if (parent != null)
        {
            vars = vars.AddFirst(parent.SelfVariable);
        }
        Dictionary<Expression, int> dictionary = new Dictionary<Expression, int>(vars.Count);
        for (int i = 0; i < vars.Count; i++)
        {
            dictionary.Add(vars[i], i);
        }
        SelfVariable = Expression.Variable(typeof(object[]), null);
        Parent = parent;
        Variables = vars;
        Indexes = new ReadOnlyDictionary<Expression, int>(dictionary);
    }
 
    internal static object[] GetParent(object[] locals)
    {
        return ((StrongBox<object[]>)locals[0]).Value;
    }
}