Class: Html2rss::HtmlNavigator

Inherits:
Object
  • Object
show all
Defined in:
lib/html2rss/html_navigator.rb

Overview

HtmlNavigator provides methods to navigate through HTML nodes.

Class Method Summary collapse

Class Method Details

.descendant_of?(child_node, parent_node) ⇒ Boolean

Returns true if child_node is a descendant of parent_node. Walks up using parent pointers to avoid NodeSet allocations.

Parameters:

  • child_node (Nokogiri::XML::Node) —

    potential descendant

  • parent_node (Nokogiri::XML::Node) —

    potential ancestor

Returns:

  • (Boolean) —

    true when child_node is a descendant of parent_node



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# File 'lib/html2rss/html_navigator.rb', line 60

def descendant_of?(child_node, parent_node)
  curr = child_node.respond_to?(:parent) ? child_node.parent : nil
  while curr
    return true if curr == parent_node

    curr = curr.respond_to?(:parent) ? curr.parent : nil
  end
  false
end

.find_closest_selector_upwards(current_tag, selector) ⇒ Nokogiri::XML::Node?

Think of it as css_upwards method. It searches for the closest parent that matches the given selector.

Parameters:

  • current_tag (Nokogiri::XML::Node, nil) —

    starting node

  • selector (String) —

    CSS selector to search upwards for

Returns:

  • (Nokogiri::XML::Node, nil) —

    first matching node in upward traversal



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# File 'lib/html2rss/html_navigator.rb', line 30

def find_closest_selector_upwards(current_tag, selector)
  while current_tag
    found = current_tag.at_css(selector)
    return found if found

    return nil unless current_tag.respond_to?(:parent)

    current_tag = current_tag.parent
  end
end

.find_tag_in_ancestors(current_tag, tag_name) ⇒ Nokogiri::XML::Node?

Searches for the closest parent that matches the given tag name.

Parameters:

  • current_tag (Nokogiri::XML::Node) —

    starting node

  • tag_name (String) —

    tag name to find in ancestors

Returns:

  • (Nokogiri::XML::Node, nil) —

    matching ancestor node



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# File 'lib/html2rss/html_navigator.rb', line 47

def find_tag_in_ancestors(current_tag, tag_name)
  return current_tag if current_tag.name == tag_name

  current_tag.ancestors(tag_name).first
end

.parent_until_condition(node, condition) ⇒ Nokogiri::XML::Node?

Returns the first parent that satisfies the condition. If the condition is met, it returns the node itself.

Parameters:

  • node (Nokogiri::XML::Node) —

    The node to start the search from.

  • condition (Proc) —

    The condition to be met.

Returns:

  • (Nokogiri::XML::Node, nil) —

    The first parent that satisfies the condition.



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# File 'lib/html2rss/html_navigator.rb', line 15

def parent_until_condition(node, condition)
  while node && !node.document? && node.name != 'html'
    return node if condition.call(node)

    node = node.parent
  end
end