oliverbooth.dev/OliverBooth.Extensions.Markdig/Markdown/Callout/CalloutInlineParser.cs

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C#
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using System.Reflection;
using Cysharp.Text;
using Markdig.Helpers;
using Markdig.Parsers;
using Markdig.Renderers.Html;
using Markdig.Syntax;
namespace OliverBooth.Extensions.Markdig.Markdown.Callout;
/// <summary>
/// An inline parser for Obsidian-style callouts (<c>[!NOTE]</c> etc.)
/// </summary>
internal sealed class CalloutInlineParser : InlineParser
{
// ugly hack to access internal method
private static readonly MethodInfo ReplaceParentContainerMethod =
typeof(InlineProcessor).GetMethod("ReplaceParentContainer", BindingFlags.Instance | BindingFlags.NonPublic)!;
/// <summary>
/// Initializes a new instance of the <see cref="CalloutInlineParser" /> class.
/// </summary>
public CalloutInlineParser()
{
OpeningCharacters = ['['];
}
/// <inheritdoc />
public override bool Match(InlineProcessor processor, ref StringSlice slice)
{
// We expect the alert to be the first child of a quote block. Example:
// > [!NOTE]
// > This is a note
if (processor.Block is not ParagraphBlock { Parent: QuoteBlock quoteBlock } paragraphBlock ||
paragraphBlock.Inline?.FirstChild != null)
{
return false;
}
StringSlice cache = slice;
char current = slice.NextChar();
if (current != '!')
{
slice = cache;
return false;
}
current = slice.NextChar(); // skip !
int start = slice.Start;
int end = start;
while (current.IsAlphaUpper())
{
end = slice.Start;
current = slice.NextChar();
}
if (current != ']' || start == end)
{
slice = cache;
return false;
}
var type = new StringSlice(slice.Text, start, end);
current = slice.NextChar(); // skip ]
start = slice.Start;
bool fold = false;
if (current == '-')
{
fold = true;
current = slice.NextChar(); // skip -
start = slice.Start;
}
ReadTitle(current, ref slice, out StringSlice title, out end);
var callout = new CalloutBlock(type)
{
Foldable = fold,
Span = quoteBlock.Span,
TrailingWhitespaceTrivia = new StringSlice(slice.Text, start, end),
Line = quoteBlock.Line,
Column = quoteBlock.Column,
Title = title
};
AddAttributes(callout, type);
ReplaceQuoteBlock(processor, quoteBlock, callout);
return true;
}
private static void ReadTitle(char startChar, ref StringSlice slice, out StringSlice title, out int end)
{
using Utf16ValueStringBuilder builder = ZString.CreateStringBuilder();
char current = startChar;
while (true)
{
if (current is not ('\0' or '\r' or '\n'))
{
builder.Append(current);
current = slice.NextChar();
continue;
}
end = slice.Start;
if (HandleCharacter(ref slice, ref end, ref current))
{
continue;
}
break;
}
title = new StringSlice(builder.ToString(), 0, builder.Length);
}
private static bool HandleCharacter(ref StringSlice slice, ref int end, ref char current)
{
switch (current)
{
case '\r':
current = slice.NextChar(); // skip \r
if (current is not ('\0' or '\n'))
{
return true;
}
end = slice.Start;
if (current == '\n')
{
slice.NextChar(); // skip \n
}
break;
case '\n':
slice.NextChar(); // skip \n
break;
}
return false;
}
private static void AddAttributes(IMarkdownObject callout, StringSlice type)
{
HtmlAttributes attributes = callout.GetAttributes();
attributes.AddClass("callout");
attributes.AddProperty("data-callout", type.AsSpan().ToString().ToLowerInvariant());
}
private static void ReplaceQuoteBlock(InlineProcessor processor, QuoteBlock quoteBlock, CalloutBlock callout)
{
ContainerBlock? parentQuoteBlock = quoteBlock.Parent;
if (parentQuoteBlock is null)
{
return;
}
int indexOfQuoteBlock = parentQuoteBlock.IndexOf(quoteBlock);
parentQuoteBlock[indexOfQuoteBlock] = callout;
while (quoteBlock.Count > 0)
{
var block = quoteBlock[0];
quoteBlock.RemoveAt(0);
callout.Add(block);
}
ReplaceParentContainerMethod.Invoke(processor, [quoteBlock, callout]);
// ReplaceParentContainer(processor, quoteBlock, callout);
}
}