Zigdown: Markdown parser in Zig

Zigdown, inspired by Glow and mdcat, is a tool to parse and render Markdown-like content to the terminal or to HTML.

This will likely forever be a WIP, but it currently supports the the most common features of simple Markdown files.

This is not a CommonMark-compliant Markdown parser, nor will it ever be one!

Features & Future Work

• Headers
• Basic text formatting (Bold, italic, underline)
• (Clickable) Links
• Quote blocks
• Unordered lists
• Ordered lists
• Code blocks, including syntax highlighting using TreeSitter
• Images (rendered to the console using the
• Kitty graphics protocol
• Neovim integration
  • Optional: If you have Lua 5.1 system libraries, can build as a Lua plugin module
• Task lists
• Complete NeoVim integration (w/ image rendering)
• Tables
• Web-based images (fetch & display in-terminal)
• Autolinks, references

Caveats

Note that I am not planning to implement complete CommonMark specification support, or even full Markdown support by any definition. Rather, the goal is to support "nicely formatted" Markdown, making some simplifying assumptions about what constitutes a paragraph vs. a code block, for example. The "nicely formatted" caveat simplifies the parser somewhat, enabling easier extension for new features like special warnings, note boxes, and other custom directives.

Usage

The current version of Zig this code compiles with is 0.13.0.

zig build run -- -c test/sample.md
zig build -l # List build options
zig build -Dtarget=x86_64-linux-musl # Compile for x86-64 Linux using
                                     # statically-linked MUSL libC

zig build will create a zigdown binary at zig-out/bin/zigdown. Add -Doptimize=ReleaseSafe to enable optimizations while keeping safety checks and backtraces upon errors. The shorthand options -Dsafe and -Dfast also enable ReleaseSafe and ReleaseFast, respectively.

Enabling Syntax Highlighting

To enable syntax highlighting within code blocks, you must install the necessary TreeSitter language parsers and highlight queries for the languages you'd like to highlight. This can be done by building and installing each language into a location in your $LD_LIBRARY_PATH environment variable.

Using Zigdown

The Zigdown cli tool can do this for you; for example, to download, build, and install the C and C++ parsers and their highlight queries:

zigdown -p c,cpp # Assumes both exist at github.com/tree-sitter on the 'master' branch
zigdown -p maxxnino:zig  # Specify the Github user; still assumes the 'master' branch
zigdown -p tree-sitter:master:rust # Specify Github user, branch, and language

TODO: Load a color scheme and a capture name -> color mapping at runtime (from file) instead of a short hard-coded mapping.

Installing Manually

You can also install manually if Zigdown doesn't properly fetch the repo for you (or if the repo is not setup in a standard manner and requires custom setup). For example, to install the C++ parser from the default tree-sitter project on Github:

#!/usr/bin/env bash

# Ensure the TS_CONFIG_DIR is available
export TS_CONFIG_DIR=$HOME/.config/tree-sitter/
mkdir -p ${TS_CONFIG_DIR}/parsers
cd ${TS_CONFIG_DIR}/parsers

# Clone and build a TreeSitter parser library
git clone https://github.com/tree-sitter/tree-sitter-cpp
cd tree-sitter-cpp
make install PREFIX=$HOME/.local/

# Add the install directory to LD_LIBRARY_PATH (if not done so already)
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$HOME/.local/lib/

In addition to having the parser libraries available for dlopen, you will also need the highlight queries. For this, use the provided bash script ./tools/fetch_queries.sh. This will install the queries to $TS_CONFIG_DIR/queries, which defaults to $HOME/.config/tree-sitter/queries.

Sample Render