Scope1.cs

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using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Dynamic.Utils;
 
namespace System.Linq.Expressions;
 
internal sealed class Scope1 : ScopeExpression
{
    private object _body;
 
    internal override int ExpressionCount => 1;
 
    internal Scope1(IReadOnlyList<ParameterExpression> variables, Expression body)
        : this(variables, (object)body)
    {
    }
 
    private Scope1(IReadOnlyList<ParameterExpression> variables, object body)
        : base(variables)
    {
        _body = body;
    }
 
    internal override bool SameExpressions(ICollection<Expression> expressions)
    {
        if (expressions.Count == 1)
        {
            if (_body is ReadOnlyCollection<Expression> current)
            {
                return ExpressionUtils.SameElements(expressions, current);
            }
            using IEnumerator<Expression> enumerator = expressions.GetEnumerator();
            enumerator.MoveNext();
            return ExpressionUtils.ReturnObject<Expression>(_body) == enumerator.Current;
        }
        return false;
    }
 
    internal override Expression GetExpression(int index)
    {
        if (index == 0)
        {
            return ExpressionUtils.ReturnObject<Expression>(_body);
        }
        throw Error.ArgumentOutOfRange("index");
    }
 
    internal override ReadOnlyCollection<Expression> GetOrMakeExpressions()
    {
        return BlockExpression.ReturnReadOnlyExpressions(this, ref _body);
    }
 
    internal override BlockExpression Rewrite(ReadOnlyCollection<ParameterExpression> variables, Expression[] args)
    {
        if (args == null)
        {
            Expression.ValidateVariables(variables, "variables");
            return new Scope1(variables, _body);
        }
        return new Scope1(ReuseOrValidateVariables(variables), args[0]);
    }
}