Blackfriday is a Markdown processor implemented in Go. It
is paranoid about its input (so you can safely feed it user-supplied
data), it is fast, it supports common extensions (tables, smart
punctuation substitutions, etc.), and it is safe for all utf-8
(unicode) input.
HTML output is currently supported, along with Smartypants
extensions. An experimental LaTeX output engine is also included.
It started as a translation from C of upskirt.
Blackfriday is compatible with Go 1. If you are using an older
release of Go, consider using v1.1 of blackfriday, which was based
on the last stable release of Go prior to Go 1. You can find it as a
tagged commit on github.
With Go 1 and git installed:
go get github.com/russross/blackfriday
will download, compile, and install the package into your $GOPATH
directory hierarchy. Alternatively, you can import it into a
project:
import "github.com/russross/blackfriday"
and when you build that project with go build, blackfriday will be
downloaded and installed automatically.
For basic usage, it is as simple as getting your input into a byte
slice and calling:
output := blackfriday.MarkdownBasic(input)
This renders it with no extensions enabled. To get a more useful
feature set, use this instead:
output := blackfriday.MarkdownCommon(input)
If you want to customize the set of options, first get a renderer
(currently either the HTML or LaTeX output engines), then use it to
call the more general Markdown function. For examples, see the
implementations of MarkdownBasic and MarkdownCommon in
markdown.go.
You can also check out blackfriday-tool for a more complete example
of how to use it. Download and install it using:
go get github.com/russross/blackfriday-tool
This is a simple command-line tool that allows you to process a
markdown file using a standalone program. You can also browse the
source directly on github if you are just looking for some example
code:
Note that if you have not already done so, installing
blackfriday-tool will be sufficient to download and install
blackfriday in addition to the tool itself. The tool binary will be
installed in $GOPATH/bin. This is a statically-linked binary that
can be copied to wherever you need it without worrying about
dependencies and library versions.
All features of upskirt are supported, including:
Compatibility. The Markdown v1.0.3 test suite passes with
the --tidy option. Without --tidy, the differences are
mostly in whitespace and entity escaping, where blackfriday is
more consistent and cleaner.
Common extensions, including table support, fenced code
blocks, autolinks, strikethroughs, non-strict emphasis, etc.
Safety. Blackfriday is paranoid when parsing, making it safe
to feed untrusted user input without fear of bad things
happening. The test suite stress tests this and there are no
known inputs that make it crash. If you find one, please let me
know and send me the input that does it.
Fast processing. It is fast enough to render on-demand in
most web applications without having to cache the output.
Thread safety. You can run multiple parsers in different
goroutines without ill effect. There is no dependence on global
shared state.
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, including
Google App Engine projects.
Standards compliant. Output successfully validates using the
W3C validation tool for HTML 4.01 and XHTML 1.0 Transitional.
In addition to the standard markdown syntax, this package
implements the following extensions:
Intra-word emphasis supression. The _ character is
commonly used inside words when discussing code, so having
markdown interpret it as an emphasis command is usually the
wrong thing. Blackfriday lets you treat all emphasis markers as
normal characters when they occur inside a word.
Tables. Tables can be created by drawing them in the input
using a simple syntax:
Name | Age
--------|------
Bob | 27
Alice | 23
Fenced code blocks. In addition to the normal 4-space
indentation to mark code blocks, you can explicitly mark them
and supply a language (to make syntax highlighting simple). Just
mark it like this:
``` go
func getTrue() bool {
return true
}
```
You can use 3 or more backticks to mark the beginning of the
block, and the same number to mark the end of the block.
Autolinking. Blackfriday can find URLs that have not been
explicitly marked as links and turn them into links.
Strikethrough. Use two tildes (~~) to mark text that
should be crossed out.
Hard line breaks. With this extension enabled (it is off by
default in the MarkdownBasic and MarkdownCommon convenience
functions), newlines in the input translate into line breaks in
the output.
Smart quotes. Smartypants-style punctuation substitution is
supported, turning normal double- and single-quote marks into
curly quotes, etc.
LaTeX-style dash parsing is an additional option, where --
is translated into –, and --- is translated into
—. This differs from most smartypants processors, which
turn a single hyphen into an ndash and a double hyphen into an
mdash.
Smart fractions, where anything that looks like a fraction
is translated into suitable HTML (instead of just a few special
cases like most smartypant processors). For example, 4/5
becomes <sup>4</sup>⁄<sub>5</sub>, which renders as
4⁄5.
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.
Blackfriday is distributed under the Simplified BSD License:
Copyright © 2011 Russ Ross
All rights reserved.Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials provided with
the distribution.THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
“AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.