// 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.Threading;
using Microsoft.CodeAnalysis.CSharp.Extensions.ContextQuery;
 
namespace Microsoft.CodeAnalysis.CSharp.Completion.KeywordRecommenders
{
    internal class StackAllocKeywordRecommender : AbstractSyntacticSingleKeywordRecommender
    {
        public StackAllocKeywordRecommender()
            : base(SyntaxKind.StackAllocKeyword)
        {
        }
 
        protected override bool IsValidContext(int position, CSharpSyntaxContext context, CancellationToken cancellationToken)
        {
            // Beginning with C# 8.0, stackalloc expression can be used inside other expressions
            // whenever a Span<T> or ReadOnlySpan<T> variable is allowed.
            return (context.IsAnyExpressionContext && !context.IsConstantExpressionContext) ||
                       context.IsStatementContext ||
                       context.IsGlobalStatementContext;
        }
    }
}