require 'digest/md5'
def gfm(text)
# Extract pre blocks
extractions = {}
text.gsub!(%r{<pre>.*?</pre>}m) do |match|
md5 = Digest::MD5.hexdigest(match)
extractions[md5] = match
"{gfm-extraction-#{md5}}"
end
# prevent foo_bar_baz from ending up with an italic word in the middle
text.gsub!(/(^(?! {4}|\t)\w+_\w+_\w[\w_]*)/) do |x|
x.gsub('_', '\_') if x.split('').sort.to_s[0..1] == '__'
end
# in very clear cases, let newlines become <br /> tags
text.gsub!(/^[\w\<][^\n]*\n+/) do |x|
x =~ /\n{2}/ ? x : (x.strip!; x << " \n")
end
# Insert pre block extractions
text.gsub!(/\{gfm-extraction-([0-9a-f]{32})\}/) do
"\n\n" + extractions[$1]
end
text
end
if $0 == __FILE__
require 'test/unit'
require 'shoulda'
class GFMTest < Test::Unit::TestCase
context "GFM" do
should "not touch single underscores inside words" do
assert_equal "foo_bar", gfm("foo_bar")
end
should "not touch underscores in code blocks" do
assert_equal " foo_bar_baz", gfm(" foo_bar_baz")
end
should "not touch underscores in pre blocks" do
assert_equal "\n\n<pre>\nfoo_bar_baz\n</pre>", gfm("<pre>\nfoo_bar_baz\n</pre>")
end
should "not treat pre blocks with pre-text differently" do
a = "\n\n<pre>\nthis is `a\\_test` and this\\_too\n</pre>"
b = "hmm<pre>\nthis is `a\\_test` and this\\_too\n</pre>"
assert_equal gfm(a)[2..-1], gfm(b)[3..-1]
end
should "escape two or more underscores inside words" do
assert_equal "foo\\_bar\\_baz", gfm("foo_bar_baz")
end
should "turn newlines into br tags in simple cases" do
assert_equal "foo \nbar", gfm("foo\nbar")
end
should "convert newlines in all groups" do
assert_equal "apple \npear \norange\n\nruby \npython \nerlang",
gfm("apple\npear\norange\n\nruby\npython\nerlang")
end
should "convert newlines in even long groups" do
assert_equal "apple \npear \norange \nbanana\n\nruby \npython \nerlang",
gfm("apple\npear\norange\nbanana\n\nruby\npython\nerlang")
end
should "not convert newlines in lists" do
assert_equal "# foo\n# bar", gfm("# foo\n# bar")
assert_equal "* foo\n* bar", gfm("* foo\n* bar")
end
end
end
end