oliverbooth.dev/OliverBooth/Markdown/Timestamp/TimestampInlineParser.cs

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C#
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2023-08-11 14:51:20 +00:00
using Markdig.Helpers;
using Markdig.Parsers;
namespace OliverBooth.Markdown.Timestamp;
/// <summary>
/// Represents a Markdown inline parser that matches Discord-style timestamps.
/// </summary>
public sealed class TimestampInlineParser : InlineParser
{
/// <summary>
/// Initializes a new instance of the <see cref="TimestampInlineParser" /> class.
/// </summary>
public TimestampInlineParser()
{
OpeningCharacters = new[] { '<' };
}
/// <inheritdoc />
public override bool Match(InlineProcessor processor, ref StringSlice slice)
{
// Previous char must be a space
if (!slice.PeekCharExtra(-1).IsWhiteSpaceOrZero())
{
return false;
}
ReadOnlySpan<char> span = slice.Text.AsSpan(slice.Start, slice.Length);
if (!TryConsumeTimestamp(span, out ReadOnlySpan<char> rawTimestamp, out char format))
{
return false;
}
if (!long.TryParse(rawTimestamp, out long timestamp))
{
return false;
}
bool hasFormat = format != '\0';
processor.Inline = new TimestampInline
{
Format = (TimestampFormat)format,
Timestamp = DateTimeOffset.FromUnixTimeSeconds(timestamp)
};
int paddingCount = hasFormat ? 6 : 4; // <t:*> or optionally <t:*:*>
slice.Start += rawTimestamp.Length + paddingCount;
return true;
}
private bool TryConsumeTimestamp(ReadOnlySpan<char> source,
out ReadOnlySpan<char> timestamp,
out char format)
{
timestamp = default;
format = default;
if (!source.StartsWith("<t:")) return false;
timestamp = source[3..];
if (timestamp.IndexOf('>') == -1)
{
timestamp = default;
return false;
}
int delimiterIndex = timestamp.IndexOf(':');
if (delimiterIndex == 0)
{
// invalid format <t::*>
timestamp = default;
return false;
}
if (delimiterIndex == -1)
{
// no format, default to relative
format = 'R';
timestamp = timestamp[..^1]; // trim >
}
else
{
// use specified format
format = timestamp[^2];
timestamp = timestamp[..^3];
}
return true;
}
}