Spurious <li> generated when list followed by 3

[dubstep]

RedCloth master generates a spurios

element when a numbered or
undumbered list is followed by three or more newlines.

RedCloth.new("* one\n* two\n* three \n\n\n").to_html
#=>
“

\n\t
• one
\n\t
• two
\n\t
• three
\n

\n

”

note extra trailing

outside

A colleague generated a pull request with a new rspec test that exposes
this bug:

spec exposes trailing <li> bug

I checked and the bug is present on master.

I just took a look at the ragel code but it’s been quite a while since
I’ve used ragel and it’s not quite as easy to parse as
Ruby

Seems like li_open in lib/redcloth/formatters/html.rb is being called
incorrectly when the thrid newline is parsed.

Here are the locations in the code where li_open is referenced:

$ ack --all-types li_open

ext/redcloth_scan/redcloth.h
202: ASET(“type”, “li_open”);

ext/redcloth_scan/RedclothScanService.java
95: ASET(“type”, “li_open”);

lib/redcloth/formatters/html.rb
50: def li_open(opts)

lib/redcloth/formatters/latex.rb
103: def li_open(opts)

ragel/redcloth_scan.java.rl
94: ASET(“type”, “li_open”);

ragel/redcloth_scan.rb.rl
309: ASET(“type”, “li_open”)

[stepheneb]

found the bug in a lighthouse ticket from last February:

http://jgarber.lighthouseapp.com/projects/13054/tickets/183-three-newlines-after-a-list-at-end-of-file-make-dangling-li

[stepheneb]

I checked and the bug is present on master.
202: ASET(“type”, “li_open”);
ragel/redcloth_scan.java.rl
94: ASET(“type”, “li_open”);

ragel/redcloth_scan.rb.rl
309: ASET(“type”, “li_open”)

Here’s the new spec test:

it “should not add spurious li tags to the end of markup” do
input = “* one\n* two\n* three \n\n”
failing_input = “* one\n* two\n* three \n\n\n”
RedCloth.new(input).to_html.should_not match /

$/
RedCloth.new(failing_input).to_html.should_not match /

$/
end

When I run the spec test in the debugger:

$ rspec -d spec/parser_spec.rb

RedCloth::Formatters::HTML.li_open(opts) is called once for each of the
three list items in the first test:

RedCloth.new(input).to_html.should_not match /<li>$/

and then called again once for each list item in the second test:

RedCloth.new(failing_input).to_html.should_not match /<li>$/

and then it is called a seventh time with this argument:
{:type=>“li_open”, :nest=>0, :text=>""}

50 def li_open(opts)
51 debugger
=> 52 “#{”\t" * opts[:nest]}<li#{pba(opts)}>#{opts[:text]}"
53 end

values of argument opts:

1: {:type=>“li_open”, :nest=>1, :text=>“one”}
2: {:type=>“li_open”, :nest=>1, :text=>“two”}
3: {:type=>“li_open”, :nest=>1, :text=>“three”}
4: {:type=>“li_open”, :nest=>1, :text=>“one”}
5: {:type=>“li_open”, :nest=>1, :text=>“two”}
6: {:type=>“li_open”, :nest=>1, :text=>“three”}
7: {:type=>“li_open”, :nest=>0, :text=>""}

The nesting level is 0 and the text is an empty string …

Is there a way to tell more about what the ragel machine has been doing
and why li_open was called this last time?

[stepheneb]

Yep, it’s an ugly one. I’ve tried to figure it out last year, but have
never
been able to. Ragel is just too much of a black boxat least to me it is.
I’ve printed state machine diagrams that take up the whole floor trying
to
figure out this stuff. It’s impossible!

I don’t think crazy edge cases like this one will get resolved until I
switch RedCloth to a different architecture that has a little more
transparency.

Jason

On Fri, Jan 14, 2011 at 1:21 AM, Stephen B. <

[stepheneb]

Thanks so much for the patch! Applied.

On Fri, Jan 14, 2011 at 11:54 AM, Stephen B. <

[stepheneb]

Yep, it’s an ugly one. I’ve tried to figure it out last year, but have never been
able to. Ragel isjust too much of a black box-at least to me it is. I’ve printed
state machine diagrams that take up the whole floor trying to figure out this
stuff. It’s impossible!

I don’t think crazy edge cases like this one will get resolved until I switch
RedCloth to a different architecture that has a little more transparency.

Fixed in new pull request: https://github.com/jgarber/redcloth/pull/2

Ticket updated also.

[stepheneb]

At 6:41 PM -0600 1/23/11, Jason G. wrote:

Thanks so much for the patch! Applied.

Your welcome!

I was surprised that I was able to find the place to fix the bug as
quickly as I did – I didn’t want to spend much time and wasn’t sure
ragel would come back to me fast enough.

I was very glad there are a bunch of tests – because I sure couldn’t
easily tell that my change wouldn’t break something else important.

What’s your plan for releasing 4.2.4?

In terms of changes in operation since 4.2.3 it looks like just:

Fix double-push attempt.
https://github.com/jgarber/redcloth/commit/25360cdc922bea6f5f956ec3ddfbfc6c1ec54018

and

fix dangling

https://github.com/jgarber/redcloth/commit/ade0bfd1a44dedc2498112a069d0c77505ceb5e4

Some other changes to the build process.

[stepheneb]

I was waiting to release until multi-byte characters in Java were
fixed, but seems like that’s not likely to happen anytime soon. I’ll
go ahead and release. Thanks for the nudge.

Jason

On Sun, Jan 23, 2011 at 10:00 PM, Stephen B.

[stepheneb]

At 7:01 AM -0600 1/24/11, Jason G. wrote:

I was waiting to release until multi-byte characters in Java were
fixed, but seems like that’s not likely to happen anytime soon. I’ll
go ahead and release. Thanks for the nudge.

$ gem search RedCloth -r

*** REMOTE GEMS ***

RedCloth (4.2.3 ruby universal-java x86-mswin32-60)

4.2.4 nudge

[stepheneb]

Ta da! https://rubygems.org/gems/RedCloth/versions/4.2.4

Thanks for the nudges,
Jason

On Sun, Feb 6, 2011 at 4:05 PM, Stephen B. <