// 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.Shared.Extensions;

namespace Microsoft.CodeAnalysis.Shared.Utilities;

internal sealed partial class SemanticMap
{
    private sealed class Walker(SemanticModel semanticModel, SemanticMap map, CancellationToken cancellationToken)
    {
        public void Visit(SyntaxNode node)
        {
            foreach (var child in node.DescendantNodesAndTokensAndSelf())
            {
                if (child.AsNode(out var childNode))
                {
                    var info = semanticModel.GetSymbolInfo(childNode);
                    if (!IsNone(info))
                    {
                        map._expressionToInfoMap.Add(childNode, info);
                    }
                }
                else if (child.IsToken)
                {
                    var childToken = child.AsToken();
                    var info = semanticModel.GetSymbolInfo(childToken, cancellationToken);
                    if (!IsNone(info))
                    {
                        map._tokenToInfoMap.Add(childToken, info);
                    }
                }
                else
                {
                    throw ExceptionUtilities.Unreachable();
                }
            }
        }

        private static bool IsNone(SymbolInfo info)
            => info.Symbol == null && info.CandidateSymbols.Length == 0;
    }
}