HTML::Selector #select #match

match(element, first?) => array or nil

Matches an element against the selector.

For a simple selector this method returns an array with the element if the element matches, nil otherwise.

For a complex selector (sibling and descendant) this method returns an array with all matching elements, nil if no match is found.

Use +first_only=true+ if you are only interested in the first element.

For example:

  if selector.match(element)
    puts "Element is a login form"
  end

[ hide source ]

     # File vendor/rails/actionpack/lib/action_controller/vendor/html-scanner/html/selector.rb, line 363

363:     def match(element, first_only = false)
364:       # Match element if no element name or element name same as element name
365:       if matched = (!@tag_name || @tag_name == element.name)
366:         # No match if one of the attribute matches failed
367:         for attr in @attributes
368:           if element.attributes[attr[0]] !~ attr[1]
369:             matched = false
370:             break
371:           end
372:         end
373:       end
374: 
375:       # Pseudo class matches (nth-child, empty, etc).
376:       if matched
377:         for pseudo in @pseudo
378:           unless pseudo.call(element)
379:             matched = false
380:             break
381:           end
382:         end
383:       end
384: 
385:       # Negation. Same rules as above, but we fail if a match is made.
386:       if matched && @negation
387:         for negation in @negation
388:           if negation[:tag_name] == element.name
389:             matched = false
390:           else
391:             for attr in negation[:attributes]
392:               if element.attributes[attr[0]] =~ attr[1]
393:                 matched = false
394:                 break
395:               end
396:             end
397:           end
398:           if matched
399:             for pseudo in negation[:pseudo]
400:               if pseudo.call(element)
401:                 matched = false
402:                 break
403:               end
404:             end
405:           end
406:           break unless matched
407:         end
408:       end
409: 
410:       # If element matched but depends on another element (child,
411:       # sibling, etc), apply the dependent matches instead.
412:       if matched && @depends
413:         matches = @depends.call(element, first_only)
414:       else
415:         matches = matched ? [element] : nil
416:       end
417: 
418:       # If this selector is part of the group, try all the alternative
419:       # selectors (unless first_only).
420:       if !first_only || !matches
421:         @alternates.each do |alternate|
422:           break if matches && first_only
423:           if subset = alternate.match(element, first_only)
424:             if matches
425:               matches.concat subset
426:             else
427:               matches = subset
428:             end
429:           end
430:         end
431:       end
432: 
433:       matches
434:     end

select(root) => array

Selects and returns an array with all matching elements, beginning with one node and traversing through all children depth-first. Returns an empty array if no match is found.

The root node may be any element in the document, or the document itself.

For example:

  selector = HTML::Selector.new "input[type=text]"
  matches = selector.select(element)
  matches.each do |match|
    puts "Found text field with name #{match.attributes['name']}"
  end

[ hide source ]

     # File vendor/rails/actionpack/lib/action_controller/vendor/html-scanner/html/selector.rb, line 453

453:     def select(root)
454:       matches = []
455:       stack = [root]
456:       while node = stack.pop
457:         if node.tag? && subset = match(node, false)
458:           subset.each do |match|
459:             matches << match unless matches.any? { |item| item.equal?(match) }
460:           end
461:         elsif children = node.children
462:           stack.concat children.reverse
463:         end
464:       end
465:       matches
466:     end