How to preserve empty lines?

[Jinjinov]

Would it be possible to preserve empty lines?

Using UseSoftlineBreakAsHardlineBreak() preserves new lines, but not empty lines.

I tried using text.Replace("\n", "<br>") but then titles and lists don't work.

I tried using text.Replace("\n", "<br>\n") then titles and lists work, but there are too many empty lines.

I tried using text.Replace("\n\n", "<br><br>") but then all markdown after a list is wrong.

I tried using text.Replace("\n\n", "<br>\n") then titles and lists work, but not all empty lines are preserved.

I tried using text.Replace("\n\n", "<br><br>\n") then titles and lists work, but everything else is wrong.

Would it be possible to specify my own rule for this?

[xoofx]

Probably duplicate of #698.

Would it be possible to preserve empty lines?
Would it be possible to specify my own rule for this?

The CommonMark specs are treating empty lines in a specific way (e.g they are used to stop processing list..etc.) and they have many associated rules with them.

Changing this behavior (even with an opt-in switch) is not something I would like to maintain, and I'm not even sure it is practical, feasible without conflicting with existing rules. As you realized yourself, empty lines have a context dependent behavior.

So my main advice would be to not pursue this road 🙂

[Jinjinov]

I understand that this is not compliant with CommonMark and would make no sense in implementing it in Markdig.

I am writing a note editor with these specifications:

1. all url links must be converted from simple text to <a href>
2. all empty lines must be preserved
3. using Markdown for titles, lists, preformatted text is a bonus (optional)

I decided to use Markdig, because it covers 1. and 3. but the most important features are detecting links in simple text and preserving empty lines.

Can you give me a few starting points how could I write a custom Markdig extension that would preserve empty lines?

[Jinjinov]

This is what ChatGPT wrote, but it doesn't work:

public class PreserveEmptyLinesExtension : IMarkdownExtension
{
    public void Setup(MarkdownPipelineBuilder pipeline)
    {
        // Add a block parser that preserves empty lines
        pipeline.BlockParsers.Insert(0, new PreserveEmptyLinesParser());
    }

    public void Setup(MarkdownPipeline pipeline, IMarkdownRenderer renderer)
    {
        // No renderer modifications necessary
    }

    private class PreserveEmptyLinesParser : BlockParser
    {
        public PreserveEmptyLinesParser()
        {
            OpeningCharacters = new char[0];
        }

        public override BlockState TryOpen(BlockProcessor processor)
        {
            // Preserve the empty line as a new line block
            if (processor.IsBlankLine)
            {
                processor.NewBlocks.Push(new ParagraphBlock(this));
                return BlockState.Continue;
            }

            return BlockState.None;
        }

        public override BlockState TryContinue(BlockProcessor processor, Block block)
        {
            // Continue the block normally
            return BlockState.None;
        }
    }
}

[xoofx]

Can you give me a few starting points how could I write a custom Markdig extension that would preserve empty lines?

This more likely not trivial and unlikely possible by extending Markdig. You would have to fork it and modify its internals.

[Jinjinov]

Thank you for your explanations.