umark

umark is a Rust Markdown parser workspace with:

• umark-lib: the parsing library
• umark: a small CLI wrapper

The default parsing mode is GitHub Flavored Markdown (GFM).

Features

• CommonMark-style core parsing
• GFM extensions: tables, task lists, strikethrough, literal autolinks (https://..., www..., emails), footnotes, Mermaid fenced chart blocks (```mermaid), reference links ([label]: https://...), and ordered list start values (3. item)
• Raw HTML passthrough in regular mode
• Safe parsing mode that rejects script tags and raw HTML

Project Layout

• umark-lib/src/lib.rs: parser implementation and public API
• umark/src/main.rs: CLI entrypoint

Build

cargo build

CLI Usage

umark <input.md> <output.html> [--flavor gfm|commonmark] [--safe]

Examples:

# Default GFM parsing
umark README.md README.html

# CommonMark mode
umark README.md README-commonmark.html --flavor commonmark

# Safe mode (rejects raw HTML and script tags)
umark -- README.md README-safe.html --safe

Library Usage

Parse a Markdown string

use umark_lib::parse;

let html = parse("# Hello");
assert!(html.contains("<h1>Hello</h1>"));

Choose parsing flavor

use umark_lib::{parse_with_flavor, MarkdownFlavor};

let gfm = parse_with_flavor("~~done~~", MarkdownFlavor::Gfm);
let commonmark = parse_with_flavor("~~done~~", MarkdownFlavor::CommonMark);

assert!(gfm.contains("<del>done</del>"));
assert!(!commonmark.contains("<del>done</del>"));

Safe parsing

use umark_lib::safe_parse;

assert!(safe_parse("normal text").is_ok());
assert!(safe_parse("<script>alert(1)</script>").is_err());
assert!(safe_parse("x <span>raw html</span>").is_err());

Parse from file

use umark_lib::parse_from_file;

parse_from_file("input.md", "output.html")?;
# Ok::<(), Box<dyn std::error::Error>>(())

Parse from file in safe mode

use umark_lib::safe_parse_from_file;

safe_parse_from_file("input.md", "output.html")?;
# Ok::<(), Box<dyn std::error::Error>>(())

Mermaid Chart Support

In GFM mode:

```mermaid
flowchart TD
  A --> B
```

is rendered as:

<pre class="mermaid">flowchart TD
  A --&gt; B</pre>

When using parse_from_file* in GFM mode and Mermaid blocks are present, a Mermaid runtime script is automatically appended to the output HTML so charts render in a browser.

Safety Notes

• safe_parse* rejects any raw HTML and script tags.
• parse* allows raw HTML passthrough.
• Safe mode is stricter by design and may reject content that regular parsing accepts.