Class: HTML::Tag

Inherits:
Node show all
Defined in:
actionview/lib/action_view/vendor/html-scanner/html/node.rb,
actionview/lib/action_view/vendor/html-scanner/html/selector.rb

Overview

A Tag is any node that represents markup. It may be an opening tag, a closing tag, or a self-closing tag. It has a name, and may have a hash of attributes.

Instance Attribute Summary collapse

Attributes inherited from Node

#children, #line, #parent, #position

Instance Method Summary collapse

Methods inherited from Node

#find_all, parse, #validate_conditions

Constructor Details

#initialize(parent, line, pos, name, attributes, closing) ⇒ Tag

Create a new node as a child of the given parent, using the given content to describe the node. It will be parsed and the node name, attributes and closing status extracted.



291
292
293
294
295
296
 
# File 'actionview/lib/action_view/vendor/html-scanner/html/node.rb', line 291

def initialize(parent, line, pos, name, attributes, closing)
  super(parent, line, pos)
  @name = name
  @attributes = attributes
  @closing = closing
end

Instance Attribute Details

#attributes ⇒ Object (readonly)

Either nil, or a hash of attributes for this node.



283
284
285
 
# File 'actionview/lib/action_view/vendor/html-scanner/html/node.rb', line 283

def attributes
  @attributes
end

#closing ⇒ Object (readonly)

Either nil, :close, or :self



280
281
282
 
# File 'actionview/lib/action_view/vendor/html-scanner/html/node.rb', line 280

def closing
  @closing
end

#name ⇒ Object (readonly)

The name of this tag.



286
287
288
 
# File 'actionview/lib/action_view/vendor/html-scanner/html/node.rb', line 286

def name
  @name
end

Instance Method Details

#==(node) ⇒ Object 



507
508
509
510
511
 
# File 'actionview/lib/action_view/vendor/html-scanner/html/node.rb', line 507

def ==(node)
  return false unless super
  return false unless closing == node.closing && self.name == node.name
  attributes == node.attributes
end

#[](attr) ⇒ Object

A convenience for obtaining an attribute of the node. Returns nil if the node has no attributes.



300
301
302
 
# File 'actionview/lib/action_view/vendor/html-scanner/html/node.rb', line 300

def [](attr)
  @attributes ? @attributes[attr] : nil
end

#childless?(xml = false) ⇒ Boolean

Returns non-nil if this tag can contain child nodes.

Returns:

  • (Boolean) 


305
306
307
308
309
310
 
# File 'actionview/lib/action_view/vendor/html-scanner/html/node.rb', line 305

def childless?(xml = false)
  return false if xml && @closing.nil?
  !@closing.nil? ||
    @name =~ /^(img|br|hr|link|meta|area|base|basefont|
                col|frame|input|isindex|param)$/ox
end

#find(conditions) ⇒ Object

If either the node or any of its children meet the given conditions, the matching node is returned. Otherwise, nil is returned. (See the description of the valid conditions in the match method.)



333
334
335
 
# File 'actionview/lib/action_view/vendor/html-scanner/html/node.rb', line 333

def find(conditions)
  match(conditions) && self || super
end

#match(conditions) ⇒ Object

Returns true if the node meets any of the given conditions. The conditions parameter must be a hash of any of the following keys (all are optional):

  • :tag: the node name must match the corresponding value

  • :attributes: a hash. The node’s values must match the corresponding values in the hash.

  • :parent: a hash. The node’s parent must match the corresponding hash.

  • :child: a hash. At least one of the node’s immediate children must meet the criteria described by the hash.

  • :ancestor: a hash. At least one of the node’s ancestors must meet the criteria described by the hash.

  • :descendant: a hash. At least one of the node’s descendants must meet the criteria described by the hash.

  • :sibling: a hash. At least one of the node’s siblings must meet the criteria described by the hash.

  • :after: a hash. The node must be after any sibling meeting the criteria described by the hash, and at least one sibling must match.

  • :before: a hash. The node must be before any sibling meeting the criteria described by the hash, and at least one sibling must match.

  • :children: a hash, for counting children of a node. Accepts the keys:

** :count: either a number or a range which must equal (or

include) the number of children that match.

** :less_than: the number of matching children must be less than

this number.

** :greater_than: the number of matching children must be

greater than this number.

** :only: another hash consisting of the keys to use

to match on the children, and only matching children will be
counted.

Conditions are matched using the following algorithm:

  • if the condition is a string, it must be a substring of the value.

  • if the condition is a regexp, it must match the value.

  • if the condition is a number, the value must match number.to_s.

  • if the condition is true, the value must not be nil.

  • if the condition is false or nil, the value must be nil.

Usage:

# test if the node is a "span" tag
node.match tag: "span"

# test if the node's parent is a "div"
node.match parent: { tag: "div" }

# test if any of the node's ancestors are "table" tags
node.match ancestor: { tag: "table" }

# test if any of the node's immediate children are "em" tags
node.match child: { tag: "em" }

# test if any of the node's descendants are "strong" tags
node.match descendant: { tag: "strong" }

# test if the node has between 2 and 4 span tags as immediate children
node.match children: { count: 2..4, only: { tag: "span" } }

# get funky: test to see if the node is a "div", has a "ul" ancestor
# and an "li" parent (with "class" = "enum"), and whether or not it has
# a "span" descendant that contains # text matching /hello world/:
node.match tag: "div",
           ancestor: { tag: "ul" },
           parent: { tag: "li",
                        attributes: { class: "enum" } },
           descendant: { tag: "span",
                            child: /hello world/ }



412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
 
# File 'actionview/lib/action_view/vendor/html-scanner/html/node.rb', line 412

def match(conditions)
  conditions = validate_conditions(conditions)
  # check content of child nodes
  if conditions[:content]
    if children.empty?
      return false unless match_condition("", conditions[:content])
    else
      return false unless children.find { |child| child.match(conditions[:content]) }
    end
  end

  # test the name
  return false unless match_condition(@name, conditions[:tag]) if conditions[:tag]

  # test attributes
  (conditions[:attributes] || {}).each do |key, value|
    return false unless match_condition(self[key], value)
  end

  # test parent
  return false unless parent.match(conditions[:parent]) if conditions[:parent]

  # test children
  return false unless children.find { |child| child.match(conditions[:child]) } if conditions[:child]

  # test ancestors
  if conditions[:ancestor]
    return false unless catch :found do
      p = self
      throw :found, true if p.match(conditions[:ancestor]) while p = p.parent
    end
  end

  # test descendants
  if conditions[:descendant]
    return false unless children.find do |child|
      # test the child
      child.match(conditions[:descendant]) ||
      # test the child's descendants
      child.match(:descendant => conditions[:descendant])
    end
  end

  # count children
  if opts = conditions[:children]
    matches = children.select do |c|
      (c.kind_of?(HTML::Tag) and (c.closing == :self or ! c.childless?))
    end

    matches = matches.select { |c| c.match(opts[:only]) } if opts[:only]
    opts.each do |key, value|
      next if key == :only
      case key
        when :count
          if Integer === value
            return false if matches.length != value
          else
            return false unless value.include?(matches.length)
          end
        when :less_than
          return false unless matches.length < value
        when :greater_than
          return false unless matches.length > value
        else raise "unknown count condition #{key}"
      end
    end
  end

  # test siblings
  if conditions[:sibling] || conditions[:before] || conditions[:after]
    siblings = parent ? parent.children : []
    self_index = siblings.index(self)

    if conditions[:sibling]
      return false unless siblings.detect do |s|
        s != self && s.match(conditions[:sibling])
      end
    end

    if conditions[:before]
      return false unless siblings[self_index+1..-1].detect do |s|
        s != self && s.match(conditions[:before])
      end
    end

    if conditions[:after]
      return false unless siblings[0,self_index].detect do |s|
        s != self && s.match(conditions[:after])
      end
    end
  end

  true
end

#select(selector, *values) ⇒ Object 



823
824
825
826
 
# File 'actionview/lib/action_view/vendor/html-scanner/html/selector.rb', line 823

def select(selector, *values)
  selector = HTML::Selector.new(selector, values)
  selector.select(self)
end

#tag? ⇒ Boolean

Returns true, indicating that this node represents an HTML tag.

Returns:

  • (Boolean) 


338
339
340
 
# File 'actionview/lib/action_view/vendor/html-scanner/html/node.rb', line 338

def tag?
  true
end

#to_s ⇒ Object

Returns a textual representation of the node



313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
 
# File 'actionview/lib/action_view/vendor/html-scanner/html/node.rb', line 313

def to_s
  if @closing == :close
    "</#{@name}>"
  else
    s = "<#{@name}"
    @attributes.each do |k,v|
      s << " #{k}"
      s << "=\"#{v}\"" if String === v
    end
    s << " /" if @closing == :self
    s << ">"
    @children.each { |child| s << child.to_s }
    s << "</#{@name}>" if @closing != :self && !@children.empty?
    s
  end
end