jellyfin-server/MediaBrowser.Controller/Sorting/AlphanumComparator.cs

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#nullable enable
using System;
using System.Collections.Generic;
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namespace MediaBrowser.Controller.Sorting
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{
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public class AlphanumComparator : IComparer<string?>
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{
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public static int CompareValues(string? s1, string? s2)
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{
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if (s1 == null && s2 == null)
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{
return 0;
}
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else if (s1 == null)
{
return -1;
}
else if (s2 == null)
{
return 1;
}
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int len1 = s1.Length;
int len2 = s2.Length;
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// Early return for empty strings
if (len1 == 0 && len2 == 0)
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{
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return 0;
}
else if (len1 == 0)
{
return -1;
}
else if (len2 == 0)
{
return 1;
}
int pos1 = 0;
int pos2 = 0;
do
{
int start1 = pos1;
int start2 = pos2;
bool isNum1 = char.IsDigit(s1[pos1++]);
bool isNum2 = char.IsDigit(s2[pos2++]);
while (pos1 < len1 && char.IsDigit(s1[pos1]) == isNum1)
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{
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pos1++;
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}
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while (pos2 < len2 && char.IsDigit(s2[pos2]) == isNum2)
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{
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pos2++;
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}
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var span1 = s1.AsSpan(start1, pos1 - start1);
var span2 = s2.AsSpan(start2, pos2 - start2);
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if (isNum1 && isNum2)
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{
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// Trim leading zeros so we can compare the length
// of the strings to find the largest number
span1 = span1.TrimStart('0');
span2 = span2.TrimStart('0');
var span1Len = span1.Length;
var span2Len = span2.Length;
if (span1Len < span2Len)
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{
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return -1;
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}
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else if (span1Len > span2Len)
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{
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return 1;
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}
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else if (span1Len >= 20) // Number is probably too big for a ulong
{
// Trim all the first digits that are the same
int i = 0;
while (i < span1Len && span1[i] == span2[i])
{
i++;
}
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// If there are no more digits it's the same number
if (i == span1Len)
{
continue;
}
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// Only need to compare the most significant digit
span1 = span1.Slice(i, 1);
span2 = span2.Slice(i, 1);
}
if (!ulong.TryParse(span1, out var num1)
|| !ulong.TryParse(span2, out var num2))
{
return 0;
}
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else if (num1 < num2)
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{
return -1;
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}
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else if (num1 > num2)
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{
return 1;
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}
}
else
{
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int result = span1.CompareTo(span2, StringComparison.InvariantCulture);
if (result != 0)
{
return result;
}
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}
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} while (pos1 < len1 && pos2 < len2);
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return len1 - len2;
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}
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/// <inheritdoc />
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public int Compare(string x, string y)
{
return CompareValues(x, y);
}
}
}