// 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.
 
#nullable disable
 
using System.Collections.Generic;
 
namespace Microsoft.CodeAnalysis.Differencing;
 
/// <summary>
/// Calculates longest common substring using Wagner algorithm.
/// </summary>
internal sealed class LongestCommonSubstring : LongestCommonSubsequence<string>
{
    private static readonly LongestCommonSubstring s_instance = new();
 
    private LongestCommonSubstring()
    {
    }
 
    protected override bool ItemsEqual(string oldSequence, int oldIndex, string newSequence, int newIndex)
        => oldSequence[oldIndex] == newSequence[newIndex];
 
    public static double ComputePrefixDistance(string oldValue, int oldLength, string newValue, int newLength)
        => s_instance.ComputeDistance(oldValue, oldLength, newValue, newLength);
 
    public static IEnumerable<SequenceEdit> GetEdits(string oldValue, string newValue)
        => s_instance.GetEdits(oldValue, oldValue.Length, newValue, newValue.Length);
}