Markdown Discuss - Aug 2007 - Backtick Hickup

I'm using Michel Fortin's MDTest cases to rewrite my html2text.php
script.
Just now I stumbled upon this bug (in PHP Markdown at least):

# Input:

    Backtick: ``\```

# Output:

<p>Backtick: ``&#96;``</p>

# Should-Be Output:

<p>Backtick: <code>`</code></p>

If you (Michel) are already aware of this, just ignore me ;-)

-- 
Milian Wolff
http://milianw.de

Le 2007-08-08 ? 18:29, Milian Wolff a ?crit :
> I'm using Michel Fortin's MDTest cases to rewrite my html2text.php
> script.
> Just now I stumbled upon this bug (in PHP Markdown at least):
>
> # Input:
>
>     Backtick: ``\```
>
> # Output:
>
> <p>Backtick: ``&#96;``</p>
>
> # Should-Be Output:
>
> <p>Backtick: <code>`</code></p>
I understand that this is some test case of your own, is it?

This was the expected output for Markdown 1.0, and it is the actual  
output for the corresponding PHP Markdown version 1.0:

     <p>Backtick: <code>`</code></p>

There has been a change in version 1.0.1 so that character escapes  
inside code spans are ignored. That way, you don't have to double- 
escape backslashes in code (that's quite handy). The output generated  
by PHP Markdown 1.0.1 looks like this:

     <p>Backtick: `````</p>

To come to this result, Markdown first see two blocks of backticks,  
one of two backticks `` and one of tree ``` with a backslash \  
inbetween. Since the number of backticks do not match, it does not  
become a code span and the usual rules for text apply: the backslash  
disappear while escaping the first backtick and you get a five- 
backtick block.

Since PHP Markdown 1.0.1g, escaped characters are encoded as numeric  
entities in the output so they don't have to be double-escaped if you  
use PHP SmartyPants. This produce the result you get:

     <p>Backtick: ``&#96;``</p>

You can test all versions of PHP Markdown on the "all-versions"  
dingus here:
<http://www.michelf.com/projects/php-markdown/dingus/?all-versions>

Also, if you want a single backtick inside a code block, just write:

     Backtick: `` ` ``

This is explained in the [syntax description page][1] on Daring  
Fireball.

  [1]: http://daringfireball.net/projects/markdown/syntax#code


Michel Fortin
michel.fortin at michelf.com
http://www.michelf.com/

On Aug 9, 2007, at 10:01 AM, Michel Fortin wrote:
> Le 2007-08-08 ? 18:29, Milian Wolff a ?crit :
>
>> [...]
>> # Input:
>>
>>     Backtick: ``\```
>>
> [...] To come to this result, Markdown first see two blocks of  
> backticks, one of two backticks `` and one of tree ``` with a  
> backslash \ inbetween. [...]
I would have expected it to see first two back-ticks, then scan  
forward until another two back-ticks are seen (since the open-token  
defines the close-token) and thus give this output:

     <p>Backtick: <code>\</code>`</p>

I know most Markdown parsers do not follow conventional parser  
wisdom, but IMO this is also the interpretation that suits an  
incremental tokenizer/parser best compared to your interpretation,  
which requires a look-ahead to potentially the end of the document,  
each time one or more back-ticks are seen.