ruby - How to find a word NOT inside <a> tag? -

i need regular expressions. task simular twitter's hashtags: have string words staring #. example:

foo #bar hello 

i'm replacing hashtags links before saved database , strings this:

foo <a href="bar">#bar</a> 

after need re-parse string , don't want replace #bar inside <a> tag twice. need regexp should find word beginning # , placed not inside >, <, > , </a>.

to input:

foo #bar hello 

to output:

foo <a href="bar">#bar</a> hello 

idempotently, can pass output through function , not change, use this:

str1 = "foo #bar hello" str2 = 'foo <a href="bar">#bar</a> hello' replace_func = -> str { str.sub(/#(\w+)(?=[^<]*?(?:<[^\/]|$))/, '<a href="\1">#\1</a>')} replace_func[str1] replace_func[str2] # both return: "foo <a href=\"bar\">#bar</a> hello" 

live demo

additionally nokogiri can used simply:

require 'nokogiri' doc = nokogiri::xml('<p>' + you_string + '</p>') doc.search('//p').each |node|   node.content = node.content.sub(/#\w+/) end