Question

I’m trying to complete an assignment where I am supposed to write a Ruby regular expression to capture items between html tags but I’m really stuck. I’ve searched everywhere but I can only find advice about using html parsers and other programs that I don’t think we are allowed to use because we have only learned regular expressions so far.

The example text is:

<span id="animal_display">
    <a href="/b/bird">Bird</a>     
    <a href="/c/cat">Cat</a>
    <a href="/c/dog">Dog</a>
</span>

I’m trying to capture Bird Cat Dog

Using this regular expression, I am able to get the first occurrence:

 /<span id="animal_display">.*?<[^>]+>(.*?)<\/[^>]+>.*<\/span>/m

I can get all three with this, but I want to be able to use the regular expression on lists that might have more than three items:

 /<span id="animal_display">\s*<[^>]+>\s*(.*?)<\/a>.\s*<[^>]+>\s*(.*?)<\/a>.\s*<[^>]+>\s*(.*?)<\/a>.<\/span>/

Is there a more generalized regular expression that could work on an unspecified number of items? Any advice would be greatly appreciated.

Answer 1

This isn’t a complete answer, but sometimes a hairy capturing regex can be simplified by tackling the problem from the other direction — using split:

html  = '...'
r     = / <a[^>]*>\s* | <\/a>[^<]+ /mx
parts = html.split(r)

parts.each { |p| puts p.inspect }

# Output
"<span id=\"animal_display\">                "
"Bird"
""
"Cat"
""
"Dog"
"</span>"