dmarcotte / github-markdown-preview

Local previews for Github Flavored Markdown files

Local Github Markdown Preview

Use your favorite editor plus the usual edit/refresh cycle to quickly write and polish your markdown for Github.

This program marries html-pipeline with the Listen file watcher to provide a high-fidelity preview (in your local browser, automatically updating on edit) of how Github will render your markdown.

Installation

gem install github-markdown-preview

Usage

Generate a preview of how Github renders markdown files in a repository:

$ github-markdown-preview <path/to/markdown/file.md> # writes <path/to/markdown/file.md.html>

• The .html preview is written beside your .md file so that you can validate relative links locally
• The .html preview is deleted when the script exits

Comment mode

Use the -c switch to generate a preview of how Github renders comments/issues, which differs from repository markdown files in a few ways:

• newlines are rendered as hard breaks
• @mentions are linked to the user's home page
• Note: auto-linked references are not rendered as links. See #17

$ github-markdown-preview -c <path/to/comment/draft.md> # writes <path/to/comment/draft.md.html>

Enable syntax highlighting for code blocks

To enable syntax highlighting for code blocks, you will need to install github-linguist:

gem install github-linguist -v 3.3.1 # 3.3.1 is required
gem install rugged -v 0.23.0 # undeclared dependency of linguist

Note that this install will fail unless your system meets the requirements needed to build its native extensions:

• You will to either brew install icu4c or apt-get install libicu-dev
• On Mac, you will need to have XCode installed (seems like a full install is required, not just the Command Line Tools)

Code

Here's a sample file demonstrating how to call github-markdown-preview from your own code:

require 'github-markdown-preview'

# create a preview, which writes the source_file.md.html file to disk
preview = GithubMarkdownPreview::HtmlPreview.new('source_file.md')

# you can also configure your preview with a couple of options
preview = GithubMarkdownPreview::HtmlPreview.new('source_file.md', {
    :delete_on_exit => true, # delete the preview when the program exits
    :comment_mode => true, # render using the rules for Github comments/issues
    :preview_file => 'custom_preview_file.html' # write preview to the given filename,
                                                # rather than the default 'source_file.md.html'
})

# access the preview information
preview.source_file # returns 'source_file.md'
preview.preview_file # returns 'source_file.md.html'

# explicitly update the preview file from the source
preview.update

# watch the source file and update the preview on change
preview.watch # non-blocking watch
preview.watch! # blocking watch

# add a callback to be fired on update; add multiple listeners by calling again
preview.update { puts 'Preview updated!' }

# stop watching the file (only applies to non-blocking watch method)
preview.end_watch

# delete the preview file from disk
preview.delete

Development

$ bundle install
$ rake test

Alternatively, to test with optional dependencies

$ BUNDLE_GEMFILE=Gemfile.optional bundle install
$ BUNDLE_GEMFILE=Gemfile.optional rake test

To run your development copy of the main script without installing it

$ bundle exec bin/github-markdown-preview

To install the your development copy to your system

$ rake install

Contributing

Contributions welcome!

github-markdown-preview's Issues

Ubuntu installation error

I keep getting the following error:
Error installing github-markdown-preview: activesupport requires Ruby version >= 2.2.2

My ruby version is:
ruby 2.2.4p230 (2015-12-16 revision 53155) [x86_64-linux-gnu]

What seems to be the problem then?

Reference links in comment mode

Comment mode current does not properly render reference links.

A interesting complication: the links are only identified if the reference is valid (the commit/issue/pull exists). It will only be possible to get the correct preview by making calls out to Github to validate references.

So: should we try and implement this with the external dependency? Or keep the preview fully local and leave ignoring reference links as a known issue?

Serve whole directory instead of file

Thanks for the awesome gem ( the only one that worked fine with me )
the only thing is that it doesn't work with directories...
Is it possible to run github-markdow-preview path/to/dir and it works like a simple webserver (maybe on localhost:4000 ) to serve the whole directory ?
something similar to gollum but actually work ( gollum require you to commit the file in order to view it 👎 )

Unable to install gem

From the terminal:

Zoltans-MacBook-Air:~ zol$ gem install github-markdown-preview
ERROR:  While executing gem ... (Gem::RemoteFetcher::UnknownHostError)
    no such name (https://api.rubygems.org/quick/Marshal.4.8/multi_json-1.3.2.gemspec.rz)
Zoltans-MacBook-Air:~ zol$ rbenv versions
  system
* 2.1.0 (set by /Users/zol/.rbenv/version)
Zoltans-MacBook-Air:~ zol$ gem --version
2.2.0

I'm on a fresh install of rbenv and ruby 2.1.0

Inconsistency vs. Github for header rendering

Looks like Github takes #title, but we're only rendering as a title if there's a space: # test

Integrate shotgun?

Is it worthwhile for github-markdown-preview (standalone usage) to identify file-save events and regenerate the preview? I can contribute it if there is interest.

github-linguist complaint when using github-markdown-preview

Hey dmarcotte, thanks for the awesome tool. Lately I started getting this error and I'm not sure what I've done wrong.
Thanks!

$ gem install github-linguist
Fetching: pygments.rb-0.5.4.gem (100%)
Successfully installed pygments.rb-0.5.4
Fetching: github-linguist-2.10.0.gem (100%)
Successfully installed github-linguist-2.10.0
Parsing documentation for pygments.rb-0.5.4
Installing ri documentation for pygments.rb-0.5.4
Parsing documentation for github-linguist-2.10.0
Installing ri documentation for github-linguist-2.10.0
2 gems installed

$ github-markdown-preview Esquire.md
WARNING: Nokogiri was built against LibXML version 2.9.0, but has dynamically loaded 2.9.1
/Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/html-pipeline-0.3.1/lib/html/pipeline/syntax_highlight_filter.rb:4:in `rescue in <top (required)>': You need to install 'github-linguist' before using the SyntaxHighlightFilter. See README.md for details (LoadError)
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/html-pipeline-0.3.1/lib/html/pipeline/syntax_highlight_filter.rb:1:in `<top (required)>'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/github-markdown-preview-1.6.1/lib/github-markdown-preview/html_preview.rb:38:in `initialize'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/github-markdown-preview-1.6.1/bin/github-markdown-preview:26:in `new'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/github-markdown-preview-1.6.1/bin/github-markdown-preview:26:in `<top (required)>'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/bin/github-markdown-preview:23:in `load'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/bin/github-markdown-preview:23:in `<main>'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/bin/ruby_noexec_wrapper:14:in `eval'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/bin/ruby_noexec_wrapper:14:in `<main>'

$ gem install github-linguist
Successfully installed github-linguist-2.10.0
Parsing documentation for github-linguist-2.10.0
1 gem installed

$ github-markdown-preview Esquire.md
WARNING: Nokogiri was built against LibXML version 2.9.0, but has dynamically loaded 2.9.1
/Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/html-pipeline-0.3.1/lib/html/pipeline/syntax_highlight_filter.rb:4:in `rescue in <top (required)>': You need to install 'github-linguist' before using the SyntaxHighlightFilter. See README.md for details (LoadError)
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/html-pipeline-0.3.1/lib/html/pipeline/syntax_highlight_filter.rb:1:in `<top (required)>'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/github-markdown-preview-1.6.1/lib/github-markdown-preview/html_preview.rb:38:in `initialize'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/github-markdown-preview-1.6.1/bin/github-markdown-preview:26:in `new'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/github-markdown-preview-1.6.1/bin/github-markdown-preview:26:in `<top (required)>'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/bin/github-markdown-preview:23:in `load'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/bin/github-markdown-preview:23:in `<main>'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/bin/ruby_noexec_wrapper:14:in `eval'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/bin/ruby_noexec_wrapper:14:in `<main>'

$ gem install github-markdown-preview
Successfully installed github-markdown-preview-1.6.1
Parsing documentation for github-markdown-preview-1.6.1
1 gem installed

$ github-markdown-preview Esquire.md
WARNING: Nokogiri was built against LibXML version 2.9.0, but has dynamically loaded 2.9.1
/Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/html-pipeline-0.3.1/lib/html/pipeline/syntax_highlight_filter.rb:4:in `rescue in <top (required)>': You need to install 'github-linguist' before using the SyntaxHighlightFilter. See README.md for details (LoadError)
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/html-pipeline-0.3.1/lib/html/pipeline/syntax_highlight_filter.rb:1:in `<top (required)>'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/github-markdown-preview-1.6.1/lib/github-markdown-preview/html_preview.rb:38:in `initialize'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/github-markdown-preview-1.6.1/bin/github-markdown-preview:26:in `new'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/gems/github-markdown-preview-1.6.1/bin/github-markdown-preview:26:in `<top (required)>'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/bin/github-markdown-preview:23:in `load'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/bin/github-markdown-preview:23:in `<main>'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/bin/ruby_noexec_wrapper:14:in `eval'
    from /Users/my.user/.rvm/gems/ruby-2.0.0-p0/bin/ruby_noexec_wrapper:14:in `<main>'

Preview breaks with recent versions of html-pipeline

When running with v0.0.5 or v0.0.6 of html-pipeline, both throw similar errors. Here's the error with 0.0.6

~/work/github-markdown-preview (master) > ./github-markdown-preview.rb ~/work/something/README.md 
/Library/Ruby/Gems/1.8/gems/html-pipeline-0.0.6/lib/html/pipeline/filter.rb:172:in `needs': Missing context keys for HTML::Pipeline::CamoFilter: :asset_proxy, :asset_proxy_secret_key (ArgumentError)
    from /Library/Ruby/Gems/1.8/gems/html-pipeline-0.0.6/lib/html/pipeline/camo_filter.rb:40:in `validate'
    from /Library/Ruby/Gems/1.8/gems/html-pipeline-0.0.6/lib/html/pipeline/filter.rb:42:in `initialize'
    from /Library/Ruby/Gems/1.8/gems/html-pipeline-0.0.6/lib/html/pipeline/filter.rb:142:in `new'
    from /Library/Ruby/Gems/1.8/gems/html-pipeline-0.0.6/lib/html/pipeline/filter.rb:142:in `call'
    from /Library/Ruby/Gems/1.8/gems/html-pipeline-0.0.6/lib/html/pipeline.rb:86:in `call'
    from ./github-markdown-preview.rb:31:in `inject'
    from /Library/Ruby/Gems/1.8/gems/html-pipeline-0.0.6/lib/html/pipeline.rb:86:in `each'
    from /Library/Ruby/Gems/1.8/gems/html-pipeline-0.0.6/lib/html/pipeline.rb:86:in `inject'
    from /Library/Ruby/Gems/1.8/gems/html-pipeline-0.0.6/lib/html/pipeline.rb:86:in `call'
    from ./github-markdown-preview.rb:34:in `update_preview'
    from ./github-markdown-preview.rb:58

The latest working version seems to be v0.0.4.

Create an issues/pull requests/comments mode

Github's rendering of markdown differs between markdown files (which this program currently targets) and issues/pull requests/comments. Not all the features of Github Flavored Markdown are enabled for markdown files in a project's source (i.e markdown files don't get real line breaks or task lists).

It would be useful to have a mode where github-markdown-preview rendered full Github Flavored Markdown. I'm thinking something like:

github-markdown-preview -f myFile.md

(f for "flavored"... unless that's too confusing with the usual "force" meaning of that switch?)

Basic support for this should be pretty easy to add (define a new switch, then toggle :gfm=true in html_preview.rb based on it), though some stuff is almost certainly missing. For instance, there doesn't seem to be a filter for task lists built in to html-pipeline. Perhaps we just need to ask @jch real nicely to open source one 😄

Exit cleanly if file deleted?

Right now if a file under preview is moved or deleted, GHMP throws an uncaught exception but keeps running:

$ github-markdown-preview /tmp/foo.md &
[2] 64025
FVFYK0RTHV2H:Work la-dmoles$ Preview available at file:///private/tmp/foo.md.html
rm /tmp/foo.md
FVFYK0RTHV2H:Work la-dmoles$ E, [2019-07-11T09:26:39.413391 #64025] ERROR -- : exception while processing events: Source file deleted Backtrace:
 -- /Users/la-dmoles/.rvm/gems/ruby-2.6.3/gems/github-markdown-preview-5.0.0/lib/github-markdown-preview/html_preview.rb:95:in `update'
 -- /Users/la-dmoles/.rvm/gems/ruby-2.6.3/gems/github-markdown-preview-5.0.0/lib/github-markdown-preview/html_preview.rb:137:in `block in start_watch'
 -- /Users/la-dmoles/.rvm/gems/ruby-2.6.3/gems/listen-3.1.5/lib/listen/event/config.rb:23:in `call'
 -- /Users/la-dmoles/.rvm/gems/ruby-2.6.3/gems/listen-3.1.5/lib/listen/event/processor.rb:115:in `_process_changes'
 -- /Users/la-dmoles/.rvm/gems/ruby-2.6.3/gems/listen-3.1.5/lib/listen/event/processor.rb:19:in `block in loop_for'
 -- /Users/la-dmoles/.rvm/gems/ruby-2.6.3/gems/listen-3.1.5/lib/listen/event/processor.rb:15:in `loop'
 -- /Users/la-dmoles/.rvm/gems/ruby-2.6.3/gems/listen-3.1.5/lib/listen/event/processor.rb:15:in `loop_for'
 -- /Users/la-dmoles/.rvm/gems/ruby-2.6.3/gems/listen-3.1.5/lib/listen/event/loop.rb:84:in `_wait_for_changes'
 -- /Users/la-dmoles/.rvm/gems/ruby-2.6.3/gems/listen-3.1.5/lib/listen/event/loop.rb:42:in `block in setup'
 -- /Users/la-dmoles/.rvm/gems/ruby-2.6.3/gems/listen-3.1.5/lib/listen/internals/thread_pool.rb:6:in `block in add'
ps
  PID TTY           TIME CMD
58571 ttys000    0:00.09 -bash
40405 ttys001    0:00.08 -bash
64025 ttys003    0:00.54 ruby /Users/la-dmoles/.rvm/gems/ruby-2.6.3/bin/github-markdown-preview /tmp/foo.md   
64026 ttys003    0:00.01 /Users/la-dmoles/.rvm/gems/ruby-2.6.3/gems/rb-fsevent-0.10.3/bin/fsevent_watch --format=otnetstring --la

If it's been backgrounded (my usual workflow, I don't know how common it is), it then has to be explicitly foregrounded and Ctrl-C'd, or killed manually.

Would it make sense to exit more cleanly? It looks like something like this (if cleaned up a little bit) in HtmlPreview.start_watch might do it:

@listener = Listen.to(source_file_dir) do
  begin
    update
  rescue FileNotFoundError
    Listen::Logger.error("Source file deleted")
    end_watch
  end
end

But that might also complicate the sleep if blocking at the end -- might have to be a loop that checks @listener.processing?.

MacOS: An error occurred while installing json (1.8.3), and Bundler cannot continue

$ uname -a
Darwin warbookpro 16.6.0 Darwin Kernel Version 16.6.0: Fri Apr 14 16:21:16 PDT 2017; root:xnu-3789.60.24~6/RELEASE_X86_64 x86_64

I'm on MacOS:

$ sw_vers -productVersion
10.12.5

How to reproduce

$ rbenv install 2.4.0
$ rbenv local 2.4.0
$ rbenv local
2.4.0
$ ruby --version
ruby 2.4.0p0 (2016-12-24 revision 57164) [x86_64-darwin16]
$ gem --version  
2.6.8
$ bundle install

$ bundle install
Fetching gem metadata from https://rubygems.org/..........
Fetching version metadata from https://rubygems.org/...
Fetching dependency metadata from https://rubygems.org/..
Using rake 10.5.0
Using i18n 0.7.0
Installing json 1.8.3 with native extensions
Using minitest 5.10.1
Using thread_safe 0.3.5
Using crass 1.0.2
Using ffi 1.9.14
Using gemoji 2.1.0
Using github-markdown 0.6.8
Using mini_portile 0.6.2
Using rb-fsevent 0.9.8
Using bundler 1.14.6
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: /Users/gableroux/.gem/gems/json-1.8.3/ext/json/ext/generator
/Users/gableroux/.rbenv/versions/2.4.0/bin/ruby -r ./siteconf20170621-47299-7kcylr.rb extconf.rb
creating Makefile

current directory: /Users/gableroux/.gem/gems/json-1.8.3/ext/json/ext/generator
make "DESTDIR=" clean

current directory: /Users/gableroux/.gem/gems/json-1.8.3/ext/json/ext/generator
make "DESTDIR="
compiling generator.c
generator.c:861:25: error: use of undeclared identifier 'rb_cFixnum'
    } else if (klass == rb_cFixnum) {
                        ^
generator.c:863:25: error: use of undeclared identifier 'rb_cBignum'
    } else if (klass == rb_cBignum) {
                        ^
generator.c:975:5: warning: division by zero is undefined [-Wdivision-by-zero]
    rb_scan_args(argc, argv, "01", &opts);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2143:9: note: expanded from macro 'rb_scan_args'
        rb_scan_args0(argc,argvp,fmt,\
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2329:8: note: expanded from macro 'rb_scan_args0'
                     rb_scan_args_verify(fmt, varc), vars)
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2201:11: note: expanded from macro 'rb_scan_args_verify'
        verify = rb_scan_args_verify_count(fmt, varc); \
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: (skipping 4 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2167:6: note: expanded from macro 'rb_scan_args_count_hash'
     rb_scan_args_count_block(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2162:6: note: expanded from macro 'rb_scan_args_count_block'
     rb_scan_args_count_end(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2158:12: note: expanded from macro 'rb_scan_args_count_end'
    ((vari)/(!fmt[ofs] || rb_scan_args_bad_format(fmt)))
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
generator.c:975:5: warning: division by zero is undefined [-Wdivision-by-zero]
    rb_scan_args(argc, argv, "01", &opts);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2143:9: note: expanded from macro 'rb_scan_args'
        rb_scan_args0(argc,argvp,fmt,\
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2329:8: note: expanded from macro 'rb_scan_args0'
                     rb_scan_args_verify(fmt, varc), vars)
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2201:11: note: expanded from macro 'rb_scan_args_verify'
        verify = rb_scan_args_verify_count(fmt, varc); \
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: (skipping 4 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2167:6: note: expanded from macro 'rb_scan_args_count_hash'
     rb_scan_args_count_block(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2163:6: note: expanded from macro 'rb_scan_args_count_block'
     rb_scan_args_count_end(fmt, ofs+1, varc, vari+1))
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2158:12: note: expanded from macro 'rb_scan_args_count_end'
    ((vari)/(!fmt[ofs] || rb_scan_args_bad_format(fmt)))
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
generator.c:975:5: warning: division by zero is undefined [-Wdivision-by-zero]
    rb_scan_args(argc, argv, "01", &opts);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2143:9: note: expanded from macro 'rb_scan_args'
        rb_scan_args0(argc,argvp,fmt,\
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2329:8: note: expanded from macro 'rb_scan_args0'
                     rb_scan_args_verify(fmt, varc), vars)
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2201:11: note: expanded from macro 'rb_scan_args_verify'
        verify = rb_scan_args_verify_count(fmt, varc); \
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: (skipping 4 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2168:6: note: expanded from macro 'rb_scan_args_count_hash'
     rb_scan_args_count_block(fmt, ofs+1, varc, vari+1))
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2162:6: note: expanded from macro 'rb_scan_args_count_block'
     rb_scan_args_count_end(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2158:12: note: expanded from macro 'rb_scan_args_count_end'
    ((vari)/(!fmt[ofs] || rb_scan_args_bad_format(fmt)))
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
generator.c:975:5: warning: division by zero is undefined [-Wdivision-by-zero]
    rb_scan_args(argc, argv, "01", &opts);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2143:9: note: expanded from macro 'rb_scan_args'
        rb_scan_args0(argc,argvp,fmt,\
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2329:8: note: expanded from macro 'rb_scan_args0'
                     rb_scan_args_verify(fmt, varc), vars)
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2201:11: note: expanded from macro 'rb_scan_args_verify'
        verify = rb_scan_args_verify_count(fmt, varc); \
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: (skipping 4 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2167:6: note: expanded from macro 'rb_scan_args_count_hash'
     rb_scan_args_count_block(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2162:6: note: expanded from macro 'rb_scan_args_count_block'
     rb_scan_args_count_end(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2158:12: note: expanded from macro 'rb_scan_args_count_end'
    ((vari)/(!fmt[ofs] || rb_scan_args_bad_format(fmt)))
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
generator.c:975:5: warning: division by zero is undefined [-Wdivision-by-zero]
    rb_scan_args(argc, argv, "01", &opts);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2143:9: note: expanded from macro 'rb_scan_args'
        rb_scan_args0(argc,argvp,fmt,\
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2329:8: note: expanded from macro 'rb_scan_args0'
                     rb_scan_args_verify(fmt, varc), vars)
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2201:11: note: expanded from macro 'rb_scan_args_verify'
        verify = rb_scan_args_verify_count(fmt, varc); \
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: (skipping 4 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2167:6: note: expanded from macro 'rb_scan_args_count_hash'
     rb_scan_args_count_block(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2162:6: note: expanded from macro 'rb_scan_args_count_block'
     rb_scan_args_count_end(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2158:12: note: expanded from macro 'rb_scan_args_count_end'
    ((vari)/(!fmt[ofs] || rb_scan_args_bad_format(fmt)))
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
generator.c:975:5: warning: division by zero is undefined [-Wdivision-by-zero]
    rb_scan_args(argc, argv, "01", &opts);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2143:9: note: expanded from macro 'rb_scan_args'
        rb_scan_args0(argc,argvp,fmt,\
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2329:8: note: expanded from macro 'rb_scan_args0'
                     rb_scan_args_verify(fmt, varc), vars)
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2201:11: note: expanded from macro 'rb_scan_args_verify'
        verify = rb_scan_args_verify_count(fmt, varc); \
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: (skipping 5 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2167:6: note: expanded from macro 'rb_scan_args_count_hash'
     rb_scan_args_count_block(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2162:6: note: expanded from macro 'rb_scan_args_count_block'
     rb_scan_args_count_end(fmt, ofs, varc, vari) : \
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/gableroux/.rbenv/versions/2.4.0/include/ruby-2.4.0/ruby/ruby.h:2158:12: note: expanded from macro 'rb_scan_args_count_end'
    ((vari)/(!fmt[ofs] || rb_scan_args_bad_format(fmt)))
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6 warnings and 2 errors generated.
make: *** [generator.o] Error 1

make failed, exit code 2

Gem files will remain installed in /Users/gableroux/.gem/gems/json-1.8.3 for inspection.
Results logged to /Users/gableroux/.gem/extensions/x86_64-darwin-16/2.4.0-static/json-1.8.3/gem_make.out

An error occurred while installing json (1.8.3), and Bundler cannot continue.
Make sure that `gem install json -v '1.8.3'` succeeds before bundling.

Note: As shown here: #45 (comment) I was previously able to run this on a linux machine ;)

Intra-page links don't seem to work

On GitHub, I can link to another section on a page by linking to the name of the corresponding h2 (or whatever) by its HTML id. However, it seems that github-markdown-preview does not generate these ids currently.

Or maybe I missed something in the docs?

Also, superb work on this gem! It is truly a pleasure to use. 🎉

.gem/ruby/2.3.0/gems/listen-3.0.3/lib/listen/adapter/linux.rb:30:in `require': cannot load such file -- rb-inotify (LoadError)

Just installed the gem and having the following error:

$ github-markdown-preview test.md 
Preview available at file:///home/gableroux/test.md.html
/home/gableroux/.gem/ruby/2.3.0/gems/listen-3.0.3/lib/listen/adapter/linux.rb:30:in `require': cannot load such file -- rb-inotify (LoadError)
        from /home/gableroux/.gem/ruby/2.3.0/gems/listen-3.0.3/lib/listen/adapter/linux.rb:30:in `_configure'
        from /home/gableroux/.gem/ruby/2.3.0/gems/listen-3.0.3/lib/listen/adapter/base.rb:45:in `block in configure'
        from /home/gableroux/.gem/ruby/2.3.0/gems/listen-3.0.3/lib/listen/adapter/base.rb:40:in `each'
        from /home/gableroux/.gem/ruby/2.3.0/gems/listen-3.0.3/lib/listen/adapter/base.rb:40:in `configure'
        from /home/gableroux/.gem/ruby/2.3.0/gems/listen-3.0.3/lib/listen/adapter/base.rb:63:in `start'
        from /home/gableroux/.gem/ruby/2.3.0/gems/listen-3.0.3/lib/listen/backend.rb:26:in `start'
        from /home/gableroux/.gem/ruby/2.3.0/gems/listen-3.0.3/lib/listen/listener.rb:67:in `block in <class:Listener>'
        from /home/gableroux/.gem/ruby/2.3.0/gems/listen-3.0.3/lib/listen/fsm.rb:120:in `instance_eval'
        from /home/gableroux/.gem/ruby/2.3.0/gems/listen-3.0.3/lib/listen/fsm.rb:120:in `call'
        from /home/gableroux/.gem/ruby/2.3.0/gems/listen-3.0.3/lib/listen/fsm.rb:91:in `transition_with_callbacks!'
        from /home/gableroux/.gem/ruby/2.3.0/gems/listen-3.0.3/lib/listen/fsm.rb:57:in `transition'
        from /home/gableroux/.gem/ruby/2.3.0/gems/listen-3.0.3/lib/listen/listener.rb:90:in `start'
        from /home/gableroux/.gem/ruby/2.3.0/gems/github-markdown-preview-4.0.2/lib/github-markdown-preview/html_preview.rb:144:in `start_watch'
        from /home/gableroux/.gem/ruby/2.3.0/gems/github-markdown-preview-4.0.2/lib/github-markdown-preview/html_preview.rb:129:in `watch!'
        from /home/gableroux/.gem/ruby/2.3.0/gems/github-markdown-preview-4.0.2/bin/github-markdown-preview:48:in `<top (required)>'
        from /home/gableroux/.gem/ruby/2.3.0/bin/github-markdown-preview:22:in `load'
        from /home/gableroux/.gem/ruby/2.3.0/bin/github-markdown-preview:22:in `<main>'

https://github.com/guard/listen/blob/v3.0.8/lib/listen/adapter/linux.rb#L30

Points to:
https://github.com/nex3/rb-inotify

$ ruby --version                            
ruby 2.3.3p222 (2016-11-21 revision 56859) [x86_64-linux]

$ uname -a
Linux zbookarch.local 4.8.13-1-ARCH #1 SMP PREEMPT Fri Dec 9 07:24:34 CET 2016 x86_64 GNU/Linux

$ gem --version                                           
2.5.2

$ github-markdown-preview --version                               
github-markdown-preview version 4.0.2
$ gem list | grep github-markdown-preview
github-markdown-preview (4.0.2)

$ gem list | grep rb-inotify 
rb-inotify (0.9.7, 0.9.5)

That's probably an issue with https://github.com/guard/listen though.

uninitialized constant GitHub (NameError)

ruby 2.2.2p95 (2015-04-13 revision 50295) [i686-linux]

command doesn't work

I tried installing it, doing the correct gem install github-markdown-preview, I had a couple problems with dependencies, but I got it all installed and I would still get github-markdown-preview: command not found, so what's up with that?

Serving up example via server breaks formatting

This is a bit of a convoluted issue, but a real use case.

Using the new Intellij 13, my workflow is to start up the github-markdown-preview in the terminal (or through an external tool) and then right-click on the README.md.html (e.g.) and choose "Open in Browser". In the new intellij, they helpfully create an internal server running on a random port, so the URL that gets opened in the browser is http://localhost:63342/project-name/README.md.html.

This causes a failure in rendering because the generated file is specifically referencing a local file.

<link rel="stylesheet" type="text/css" href="/Users/my.name/.rvm/gems/ruby-2.0.0-p0/gems/github-markdown-preview-2.0.0/lib/github-markdown-preview/../../data/css/github.css">
<link rel="stylesheet" type="text/css" href="/Users/my.name/.rvm/gems/ruby-2.0.0-p0/gems/github-markdown-preview-2.0.0/lib/github-markdown-preview/../../data/css/github2.css">

The browser interprets these links to be relative to the localhost:63342 from above, and 404s.

One idea would be to make it reference file:///Users/...., but that doesn't work because the browser understands that to be a vulnerability (makes sense).

Another option would be to reference the github raw CSS from this project (or elsewhere).

<link rel="stylesheet" type="text/css" href="https://raw.github.com/dmarcotte/github-markdown-preview/master/data/css/github.css">
<link rel="stylesheet" type="text/css" href="https://raw.github.com/dmarcotte/github-markdown-preview/master/data/css/github2.css">

A third option is to not support this use case, which seems acceptable given the situation :)

Issue with HTML entities

The '—' does not preview correctly.

unitialized constant GitHub (NameError)

Hiya,

I'm ruby 2.2.0 and I just installed github-markdown-preview using gem install. I got this stacktrace:

/home/wasd/.rubies/ruby-2.2.0/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:69:in `require': uninitialized constant GitHub (NameError)
        from /home/wasd/.rubies/ruby-2.2.0/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:69:in `require'
        from /home/wasd/.gem/ruby/2.2.0/gems/html-pipeline-1.11.0/lib/html/pipeline/markdown_filter.rb:2:in `<top (required)>'
        from /home/wasd/.gem/ruby/2.2.0/gems/github-markdown-preview-3.1.3/lib/github-markdown-preview/html_preview.rb:68:in `pipeline_filters'
        from /home/wasd/.gem/ruby/2.2.0/gems/github-markdown-preview-3.1.3/lib/github-markdown-preview/html_preview.rb:41:in `initialize'
        from /home/wasd/.gem/ruby/2.2.0/gems/github-markdown-preview-3.1.3/bin/github-markdown-preview:31:in `new'
        from /home/wasd/.gem/ruby/2.2.0/gems/github-markdown-preview-3.1.3/bin/github-markdown-preview:31:in `<top (required)>'
        from /home/wasd/.gem/ruby/2.2.0/bin/github-markdown-preview:23:in `load'
        from /home/wasd/.gem/ruby/2.2.0/bin/github-markdown-preview:23:in `<main>'

Haxe is missing lexer (ArgumentError)

I'm getting this error:
Installed with gem install github-markdown-preview

Tried with:

ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-linux]
gem 1.8.23

and

ruby 2.0.0p247 (2013-06-27 revision 41674) [x86_64-linux]
gem 2.1.8

Stack trace

/home/nisse/.rvm/gems/ruby-2.0.0-p247/gems/github-linguist-2.9.5/lib/linguist/language.rb:240:in `initialize': Haxe is missing lexer (ArgumentError)
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/gems/github-linguist-2.9.5/lib/linguist/language.rb:39:in `new'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/gems/github-linguist-2.9.5/lib/linguist/language.rb:39:in `create'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/gems/github-linguist-2.9.5/lib/linguist/language.rb:478:in `block in <module:Linguist>'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/gems/github-linguist-2.9.5/lib/linguist/language.rb:458:in `each'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/gems/github-linguist-2.9.5/lib/linguist/language.rb:458:in `<module:Linguist>'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/gems/github-linguist-2.9.5/lib/linguist/language.rb:8:in `<top (required)>'
from /home/nisse/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/nisse/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/gems/github-linguist-2.9.5/lib/linguist/blob_helper.rb:2:in `<top (required)>'
from /home/nisse/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/nisse/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/gems/github-linguist-2.9.5/lib/linguist.rb:1:in `<top (required)>'
from /home/nisse/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/nisse/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/gems/html-pipeline-0.3.1/lib/html/pipeline/syntax_highlight_filter.rb:2:in `<top (required)>'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/gems/github-markdown-preview-1.6.0/lib/github-markdown-preview/html_preview.rb:38:in `initialize'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/gems/github-markdown-preview-1.6.0/bin/github-markdown-preview:26:in `new'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/gems/github-markdown-preview-1.6.0/bin/github-markdown-preview:26:in `<top (required)>'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/bin/github-markdown-preview:23:in `load'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/bin/github-markdown-preview:23:in `<main>'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/bin/ruby_executable_hooks:15:in `eval'
from /home/nisse/.rvm/gems/ruby-2.0.0-p247/bin/ruby_executable_hooks:15:in `<main>'

Nil reference parsing empty list items

Steps to reproduce:

• Create Markdown document containing a list with an empty item, e.g.

-

• Preview the document

Expected:

• Document previews correctly

Actual:

• github-markdown-preview exits with the stack trace below:

$ /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/github-markdown-preview-4.0.0/lib/github-markdown-preview/filter/task_list_filter.rb:30:in `block in call': undefined method `text?' for nil:NilClass (NoMethodError)
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/nokogiri-1.6.5/lib/nokogiri/xml/node_set.rb:237:in `block in each'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/nokogiri-1.6.5/lib/nokogiri/xml/node_set.rb:236:in `upto'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/nokogiri-1.6.5/lib/nokogiri/xml/node_set.rb:236:in `each'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/github-markdown-preview-4.0.0/lib/github-markdown-preview/filter/task_list_filter.rb:38:in `call'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/html-pipeline-2.0/lib/html/pipeline/filter.rb:130:in `call'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/html-pipeline-2.0/lib/html/pipeline.rb:121:in `block in perform_filter'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/html-pipeline-2.0/lib/html/pipeline.rb:159:in `instrument'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/html-pipeline-2.0/lib/html/pipeline.rb:120:in `perform_filter'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/html-pipeline-2.0/lib/html/pipeline.rb:106:in `block (2 levels) in call'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/html-pipeline-2.0/lib/html/pipeline.rb:105:in `each'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/html-pipeline-2.0/lib/html/pipeline.rb:105:in `inject'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/html-pipeline-2.0/lib/html/pipeline.rb:105:in `block in call'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/html-pipeline-2.0/lib/html/pipeline.rb:159:in `instrument'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/html-pipeline-2.0/lib/html/pipeline.rb:103:in `call'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/github-markdown-preview-4.0.0/lib/github-markdown-preview/html_preview.rb:96:in `update'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/github-markdown-preview-4.0.0/lib/github-markdown-preview/html_preview.rb:44:in `initialize'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/github-markdown-preview-4.0.0/bin/github-markdown-preview:31:in `new'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/gems/github-markdown-preview-4.0.0/bin/github-markdown-preview:31:in `<top (required)>'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/bin/github-markdown-preview:23:in `load'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/bin/github-markdown-preview:23:in `<main>'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/bin/ruby_executable_hooks:15:in `eval'
    from /Users/dmoles/.rvm/gems/ruby-2.2.2/bin/ruby_executable_hooks:15:in `<main>'