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.
A simple benchmark has been done by comparing the execution time of the Go binary (cmd/main.go) and the original C implementation's binary needed for processing a Markdown document, which had been created by concatenating ten Markdown syntax descriptions.
In December 2010, the 8g compiled Go version still was
around 3.5 times slower than the original C version.
In the meantime Go compilers and runtime have been improved,
which reduced the factor down to around 2.5 for both 8g and 6g
for the unmodified sources.
After some current changes to the peg/leg parser generator
the Markdown parser can take advantage of the switch optimization
now. This further reduced the execution time difference
to 1.9x for 6/8g.
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.
See doc.go for an example how to use the package.
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.
Goinstall is creating its own Makefiles to build
packages, based on the .go files found in the directory.
It would not know about parser.leg.go, which had to be built
by leg from the parser.leg grammar source file first.
Because of this, to make markdown installable using
goinstall, parser.leg.go has been added to the VCS.
Make will update parser.leg.go using leg, which is part of
knieriem/peg at github, if parser.leg has been changed. If
a copy of this package has not yet been downloaded -- i.e. no
directory ./peg is present --, make will perform the
necessary steps automatically (run make peg to manually
download knieriem/peg).
To update knieriem/peg run gomake update-peg. This will
fetch available revisions from github, and remove the old
leg binary.
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.
-
Implement tables
-
Rename element key identifiers, so that they are not public
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Where appropriate, use more idiomatic Go code
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peg – PEG parser generator (modified) from Andrew J Snodgrass
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peg/leg – LEG parser generator, based on PEG
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cmd – command line program
markdown