64 lines
1.4 KiB
C#
64 lines
1.4 KiB
C#
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using System.Buffers;
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using System.Globalization;
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using DotNext.Buffers;
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using CommunityToolkit.HighPerformance.Buffers;
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namespace DotNetDDI.Integrations.Kea;
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public static class KeaDhcpLease
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{
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private static ReadOnlySpan<char> EscapeTag => ['&', '#', 'x'];
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// ref: https://github.com/isc-projects/kea/blob/Kea-2.5.3/src/lib/util/csv_file.cc#L479
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public static string Unescape(in ReadOnlySpan<char> text)
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{
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return text.IndexOf(EscapeTag) switch
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{
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-1 => text.ToString(),
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int i => SlowPath(i, text)
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};
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static string SlowPath(int esc_pos, in ReadOnlySpan<char> text)
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{
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SpanReader<char> reader = new(text);
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using ArrayPoolBufferWriter<char> writer = new(text.Length);
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while (reader.RemainingCount > 0)
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{
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writer.Write(reader.Read(esc_pos));
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reader.Advance(EscapeTag.Length);
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bool converted = false;
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char escapedChar = default;
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if (reader.RemainingCount >= 2)
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{
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if (byte.TryParse(reader.RemainingSpan[..2], NumberStyles.AllowHexSpecifier, null, out var b))
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{
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converted = true;
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escapedChar = (char)b;
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reader.Advance(2);
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}
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}
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if (converted)
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{
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writer.Write([escapedChar]);
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}
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else
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{
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writer.Write(EscapeTag);
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}
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esc_pos = reader.RemainingSpan.IndexOf(EscapeTag);
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if (esc_pos == -1)
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{
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writer.Write(reader.ReadToEnd());
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}
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}
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return writer.WrittenSpan.ToString();
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}
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}
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}
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