// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System.Diagnostics.CodeAnalysis;
 
namespace Analyzer.Utilities.Lightup
{
    /// <summary>
    /// Represents the nullability of values that can be assigned
    /// to an expression used as an lvalue.
    /// </summary>
    [SuppressMessage("Design", "CA1028:Enum Storage should be Int32", Justification = "Underlying type must match the original underlying type.")]
    internal enum NullableAnnotation : byte
    {
        /// <summary>
        /// The expression has not been analyzed, or the syntax is
        /// not an expression (such as a statement).
        /// </summary>
        /// <remarks>
        /// There are a few different reasons the expression could
        /// have not been analyzed:
        ///     1) The symbol producing the expression comes from
        ///        a method that has not been annotated, such as
        ///        invoking a C# 7.3 or earlier method, or a
        ///        method in this compilation that is in a disabled
        ///        context.
        ///     2) Nullable is completely disabled in this
        ///        compilation.
        /// </remarks>
        None = 0,
 
        /// <summary>
        /// The expression is not annotated (does not have a ?).
        /// </summary>
        NotAnnotated,
 
        /// <summary>
        /// The expression is annotated (does have a ?).
        /// </summary>
        Annotated,
    }
}