3.2 KiB
Black Friday
This is an implementation of John Gruber's markdown in Go. It is a translation of the upskirt library written in C with a few minor changes. It retains the paranoia of the original (it is careful not to trust its input, and as such it should be safe to feed it arbitrary user-supplied inputs). It also retains the emphasis on high performance, and the source is almost as ugly as the original.
HTML output is currently supported, along with Smartypants extensions. An experimental LaTeX output engine is also included.
Installation
Assuming you have recent version of Go installed, along with git:
goinstall github.com/russross/blackfriday
will download, compile, and install the package into
$GOROOT/src/pkg/github.com/russross/blackfriday.
Check out example/main.go for an example of how to use it. Run
gomake in that directory to build a simple command-line markdown
tool:
cd $GOROOT/src/pkg/github.com/russross/blackfriday/example
gomake
will build the binary markdown in the example directory.
Features
All features of upskirt are supported, including:
-
The Markdown v1.0.3 test suite passes with the
--tidyoption. Without--tidy, the differences appear to be bugs/dubious features in the original. -
Common extensions, including table support, fenced code blocks, autolinks, strikethroughs, non-strict emphasis, etc.
-
Paranoid parsing, making it safe to feed untrusted used input without fear of bad things happening. There are still some corner cases that are untested, but it is already more strict than upskirt (Go's bounds-checking uncovered a few off-by-one errors that were present in the C code).
-
Good performance. I have not done rigorous benchmarking, but informal testing suggests it is around 3.5x slower than upskirt.
-
Minimal dependencies. blackfriday only depends on standard library packages in Go. The source code is pretty self-contained, so it is easy to add to any project.
-
Output successfully validates using the W3C validation tool for HTML 4.01 and XHTML 1.0 Transitional.
Extensions
In addition to the extensions offered by upskirt, this package implements two additional Smartypants options:
- LaTeX-style dash parsing, where
--is translated into–, and---is translated into— - Generic fractions, where anything that looks like a fraction is
translated into suitable HTML (instead of just a few special
cases). For example,
4/5becomes<sup>4</sup>⁄<sub>5</sub>, which renders as 4⁄5.
LaTeX Output
A rudimentary LaTeX rendering backend is also included. To see an
example of its usage, see main.go:
It renders some basic documents, but is only experimental at this point. In particular, it does not do any inline escaping, so input that happens to look like LaTeX code will be passed through without modification.
Todo
- More unit testing
- Code cleanup
- Better code documentation
- Markdown pretty-printer output engine