Ruby Regex matching string before and after certain characters

Question

Hi,

I've got a string like this:

<block trace="true" name="AssignResources: Append Resources">

I need to get the word (or the characters to next whitespace) after < (in this case block) and the words before = (here trace and name).

I tried several regex patterns, but all my attempts return the word with the "delimiters" characters included... like ;block.

I'm sure it's not that hard, but I've not found the solution yet.

Anybody's got a hint?
Thanks.

Btw: I want to replace the pattern matches with gsub.

EDIT:

Solved it with following regexes:

1) /\s(\w+)="(.*?)"/ matches all attr and their values in $1 and $2.

2) /<!--.*-->/ matches comments

3) /<([\/|!|\?]?)([A-Za-z0-9]+)[^\s|>|\/]*/ matches all tag names, wheter they're in a closing tag, self closing tag, <?xml>-tag or DTD-tag. $1 includes optional prefixed / ! or ? or nothing and $2 contains the tagname

Answer 1

You can try:

<([^ ]*)\s([^=]*)=

Answer 2

'<block trace="true" name="AssignResources: Append Resources">'[/<(\w+)/, 1]
#=> "block"

If you pass a regex and an index i to String#[], it'll return the value of the ith capturing group.

Edit:

In 1.9 you can use /(?<=&lt;)\w+/ to require the presence of the < without matching it. In 1.8 there is no way to do that. The best you can do is to put the part, you don't want to replace, in a capturing group and and access that group in the replacement like this:

"lo<la li".gsub(/(<)(\w+)/, '\1 --\2--')
 #=> "lo< --la-- li"

Answer 3

<block trace="true" name="AssignResources: Append Resources">

<([^\s]+)\s+([^=]+)="([^"]*)"\s+([^=]+)="([^"]*)"\s*>

#result:

$1 block
$2 trace
$3 true
$4 name
$5 AssignResources: Append Resources

Update: I don't know ruby, but based on the description of gsub here, I believe that something like the following should do the trick.

str = '<block trace="true" name="AssignResources: Append Resources">'
repl = str.gsub(/<([^\s]+)\s+([^=]+)="([^"]*)"\s+([^=]+)="([^"]*)"\s*>/, 
    "tag name: \\1\n\\2 is \\3 and \\4 is \\5\n")
print repl

Answer 4

Its looks so much like parsing HTML with regex to me

Ruby has very good html parser called Nokogiri

And Here is howto for that

require 'nokogiri'

html=Nokogiri::HTML('<block trace="true" name="AssignResources: Append Resources">')

html.xpath("//*").each do |s|
    puts s.node_name #block
    puts s.keys #trace, name
    puts s.values #true, AssignResources: Append Resources
end

Answer 5

Most probably you should go with Nokigiri or something similar. I couldn't fit it in one gsub but in two:

>> m,r=0,["<blockie ", " tracie=", " namie="]
>> s.gsub(/<.*?([^\s]+)\s/, r[0]).gsub(/\s([^=]+)=/) {|ma| m+=1; r[m]}
=> "<blockie tracie="true" namie="AssignResources: Append Resources">"