3.6 KiB
This is an implementation of John Gruber's markdown in Go. It is a translation of peg-markdown, written by John MacFarlane in C, into Go. It is using a modified version of Andrew J Snodgrass' PEG parser peg -- now supporting LEG grammars --, which is itself based on the parser used by peg-markdown.
Support for HTML output is implemented, but Groff and LaTeX output have not been ported. The output should be identical to that of peg-markdown.
The Go version is around 5x slower than the original C
version. A marked speed improvement has been achieved by
converting function preformat from concatenating strings
to using bytes.Buffer. At other places, where this kind of
modification had been tried, performance did not improve. Also,
pre-allocating a large buffer for elements didn't show a
significant difference from allocating elements one at a time.
Installation
Provided you have a recent copy of Go, and git is available,
goinstall github.com/knieriem/markdown
should install the package into
$GOROOT/src/pkg/github.com/knieriem/markdown, and build
it. During the build, a copy of knieriem/peg will be
downloaded from github and compiled (make peg if done
manually).
NOTE: At the moment, goinstall most likely will fail, as it does not use the package's Makefile, but generates its own, which is not sufficient as it does not know how to build parser.leg.go from parser.leg. As a workaround, after the failed goinstall, please do the following steps to finish the installation:
cd $GOROOT/src/pkg/github.com/knieriem/markdown
gomake install
See doc.go for an example how to use the package.
To update knieriem/peg run gomake update-peg. This
will fetch available revisions from github, and remove the
old leg binary.
To create the command line program markdown, run
cd $GOROOT/src/pkg/github.com/knieriem/markdown
gomake cmd
the binary should then be available in subdirectory cmd.
To run the Markdown 1.0.3 test suite, type
make mdtest
This will download peg-markdown, in case you have git
available, build cmd/markdown, and run the test suite.
The test suite will fail on one test, for the same reason which applies to peg-markdown, because the grammar is the same. See the original README for details.
Extensions
In addition to the extensions already present in peg-markdown,
this package also supports definition lists (option -dlists)
similar to the way they are described in the documentation of
PHP Markdown Extra.
Definitions (<dd>...</dd>) are implemented using ListTight
and ListLoose, on which bullet lists and ordered lists are based
already. If there is an empty line between the definition title and
the first definition, a loose list is expected, a tight list otherwise.
As definition item markers both : and ~ can be used.
Todo
-
Implement definition lists (work in progress), and perhaps tables
-
Rename element key identifiers, so that they are not public
-
Where appropriate, use more idiomatic Go code
Subdirectory Index
-
peg – PEG parser generator (modified) from Andrew J Snodgrass
-
peg/leg – LEG parser generator, based on PEG
-
cmd – command line program
markdown