Parsing issue with multiple links

[matt-oakes]

I'm using your library and I came across some markdown that crashed the parser:

Markdown with a [link](http://google.com) and [phone number](tel:+441234567890).\n\nNew paragraph!

What was happening was the first link was being matched but the regex was too greedy and also matched all the text in between the start of the first link and the end of the last link. When the URL was parsed it was obviously invalid and hance url was nil. Once we attempted to add the attribute with the nil url value it crashed the application.

The regex I came up with to fix this was:

static NSString *CNMarkdownLinkRegex = @"(?<!\\!)\\[.*?\\]\\(\\S*\\)";

The change is the addition of the ? inside the \\[.*?\\] part. This means it will lazily match, rather than greedily consuming as much as it can. I also changed the link part to use \S because URL's should not contain whitespace. Ideally we'd only match for valid URL characters.

[laptobbe]

Great work! We should also add some tests to cover this. Could you create a pull request with the tests and this fix? Otherwise I can have a look at it.

[matt-oakes]

Sure I'll submit a pull request soon. I'm not using your library directly as a Pod because I need to customise the attributes I'm applying for each element, so it's a little more work. I'll do it soon though!

[laptobbe]

Thanks!

Maybe we could add a formatting block to each method that adds a specific parsing rule? That way you could use the regexes defined in the project but set your own formatting if needed.