Support escaped quotes in generic attribute values

[jnraine]

Hi! I've been using Markdig and it's been great. Wanted to contribute back with this small feature.

This is my first PR here so happy to make any revisions or tweaks as necessary. And also, if this isn't something wanted by the maintainers, feel free to close.

Summary

• Add backslash escape handling for quoted attribute values following kramdown's approach
• This allows including quote characters within attribute values using backslash escapes (e.g. data-value="hello \"world\"")
• It also works with single-quotes

Motivation

This was discovered when using markdown to generate Word documents from the Markdig AST. Word field codes use quoted strings:

[January 15, 2026](){field="DATE @ \"MMMM d, yyyy\""}

This can work if the outer quotes are changed to single-quotes but escape sequences are useful for our context (and we preprocess the markdown so it works with Markdig today).

Implementation

Follows the same hasEscape pattern used in LinkHelper.TryParseTitle, using IsAsciiPunctuation() for escaping.

This matches kramdown's behavior for inline attribute lists:

"If you need to use the value delimiter (a single or a double quote) inside the value, you need to escape it with a backslash."

See: https://kramdown.gettalong.org/syntax.html

Test plan

• Added 6 test cases covering escaped double/single quotes, escaped backslashes, and complex escape sequences

[MihaZupan]

Suggested change

	line.SkipChar(); // Skip closing quote
	c = line.CurrentChar;
	c = line.NextChar(); // Skip closing quote

[MihaZupan]

Since you can't stackalloc in a loop, this'll have to either be new ValueStringBuilder([]), or move the search logic into a separate helper method.

[MihaZupan]

Suggested change

valueBuilder.Dispose();

(the ToString already disposes)

[MihaZupan]

IMO it might be a bit easier to read if you change the structure to something like

string value;

if (c == '\'' || c == '"')
{
    // ...
    value = valueBuilder.ToString();
}
else
{
    int start = line.Start;
    // ...
    value = slice.Text.Substring(...);
}

properties ??= new();
properties.Add(new KeyValuePair<string, string?>(name, value));

[Copilot]

Pull request overview

Adds support for backslash-escaped quotes (and related escape sequences) inside quoted generic attribute values, enabling attribute strings that contain quote characters (e.g., Word field codes).

Changes:

• Update GenericAttributesParser to parse quoted attribute values with backslash-escape handling.
• Add spec cases covering escaped double/single quotes, escaped backslashes, non-escapable sequences, and a Word field-code example.
• Regenerate the corresponding spec-based NUnit test file.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/Markdig/Extensions/GenericAttributes/GenericAttributesParser.cs	Implements escape-aware parsing for quoted generic attribute values.
src/Markdig.Tests/Specs/GenericAttributesSpecs.md	Adds 6 spec examples documenting and validating escape behavior.
src/Markdig.Tests/Specs/GenericAttributesSpecs.generated.cs	Regenerated NUnit tests for the added spec examples.

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[Copilot]

ValueStringBuilder.ToString() already calls Dispose() (see Markdig.Helpers.ValueStringBuilder.ToString). The explicit valueBuilder.Dispose() right after valueBuilder.ToString() is redundant and can be removed to match existing usage patterns (e.g., HtmlHelper.TryParseHtmlTag).

[Copilot]

In this prose section, \" will be interpreted by Markdown and likely render without the backslash, which makes the documentation misleading. Consider using an inline code span (e.g., `\"`) or escaping the backslash (\\") so the rendered spec text shows the intended sequence.

Suggested change

	Escaped quotes (\") allow including quote characters within quoted values.
	Escaped quotes (`\"`) allow including quote characters within quoted values.