SwitchExpression.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(SwitchExpressionProxy))]
public sealed class SwitchExpression : Expression
{
    public sealed override Type Type { get; }
 
    public sealed override ExpressionType NodeType => ExpressionType.Switch;
 
    public Expression SwitchValue { get; }
 
    public ReadOnlyCollection<SwitchCase> Cases { get; }
 
    public Expression? DefaultBody { get; }
 
    public MethodInfo? Comparison { get; }
 
    internal bool IsLifted
    {
        get
        {
            if (SwitchValue.Type.IsNullableType())
            {
                if (!(Comparison == null))
                {
                    return !TypeUtils.AreEquivalent(SwitchValue.Type, Comparison.GetParametersCached()[0].ParameterType.GetNonRefType());
                }
                return true;
            }
            return false;
        }
    }
 
    internal SwitchExpression(Type type, Expression switchValue, Expression defaultBody, MethodInfo comparison, ReadOnlyCollection<SwitchCase> cases)
    {
        Type = type;
        SwitchValue = switchValue;
        DefaultBody = defaultBody;
        Comparison = comparison;
        Cases = cases;
    }
 
    protected internal override Expression Accept(ExpressionVisitor visitor)
    {
        return visitor.VisitSwitch(this);
    }
 
    public SwitchExpression Update(Expression switchValue, IEnumerable<SwitchCase>? cases, Expression? defaultBody)
    {
        if (switchValue == SwitchValue && defaultBody == DefaultBody && cases != null && ExpressionUtils.SameElements(ref cases, Cases))
        {
            return this;
        }
        return Expression.Switch(Type, switchValue, defaultBody, Comparison, cases);
    }
}