I'd like to figure out a way to get to the HTML result (mentioned further below) by using the following Ruby code and Nokogiri:
require 'rubygems'
require 'nokogiri'
value = Nokogiri::HTML.parse(<<-HTML_END)
"<html>
<body>
<p id='1'>A</p>
<p id='2'>B</p>
<h1>Bla</h1>
<p id='3'>C</p>
<p id='4'>D</p>
<p id='5'>E</p>
</body>
</html>"
HTML_END
# The selected-array is given by the application.
# It consists of a sorted array with all ids of
# <p> that need to be enclosed by the <div>
selected = ["2","3","4"]
first_p = selected.first
last_p = selected.last
#
# WHAT RUBY CODE DO I NEED TO INSERT HERE TO GET
# THE RESULTING HTML AS SEEN BELOW?
#
The resulting HTML should look like this (please note the inserted <div id='XYZ'>):
<html>
<body>
<p id='1'>A</p>
<div id='XYZ'>
<p id='2'>B</p>
<h1>Bla</h1>
<p id='3'>C</p>
<p id='4'>D</p>
</div>
<p id='5'>E</p>
</body>
</html>
In these kinds of situations you typically want to use whatever SAX interface the underlying library offers you, to traverse and rewrite the input XML (or XHTML) statefully and serially:
require 'nokogiri'
require 'CGI'
Nokogiri::XML::SAX::Parser.new(
Class.new(Nokogiri::XML::SAX::Document) {
def initialize first_p, last_p
@first_p, @last_p = first_p, last_p
end
def start_document
puts '<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">'
end
def start_element name, attrs = []
attrs = Hash[*attrs]
@depth += 1 unless @depth.nil?
print '<div>' if name=='p' && attrs['id'] == @first_p
@depth = 1 if name=='p' && attrs['id'] == @last_p && @depth.nil?
print "<#{ [ name, attrs.collect { |k,v| "#{k}=\"#{CGI::escapeHTML(v)}\"" } ].flatten.join(' ') }>"
end
def end_element name
@depth -= 1 unless @depth.nil?
print "</#{name}>"
if @depth == 0
print '</div>'
@depth = nil
end
end
def cdata_block string
print "<![CDATA[#{CGI::escapeHTML(string)}]]>"
end
def characters string
print CGI::escapeHTML(string)
end
def comment string
print "<!--#{string}-->"
end
}.new('2', '4')
).parse(<<-HTML_END)
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
<html>
<body>
<!-- comment -->
<![CDATA[
cdata goes here
]]>
"special" entities
<p id="1">A</p>
<p id="2">B</p>
<p id="3">C</p>
<p id="4">D</p>
<p id="5">E</p>
<emptytag/>
</body>
</html>
HTML_END
Alternatively, you can also use the DOM model interface (instead of the SAX interface) to load the entire document into memory (in the same way that you started doing in your original question), and then perform node manipulation (insertion and removal) as follows:
require 'rubygems'
require 'nokogiri'
doc = Nokogiri::HTML.parse(<<-HTML_END)
<html>
<body>
<p id='1'>A</p>
<p id='2'>B</p>
<p id='3'>C</p>
<p id='4'>D</p>
<p id='5'>E</p>
</body>
</html>
HTML_END
first_p = "2"
last_p = "4"
doc.css("p[id=\"#{first_p}\"] ~ p[id=\"#{last_p}\"]").each { |node|
div_node = nil
node.parent.children.each { |sibling_node|
if sibling_node.name == 'p' && sibling_node['id'] == first_p
div_node = Nokogiri::XML::Node.new('div', doc)
sibling_node.add_previous_sibling(div_node)
end
unless div_node.nil?
sibling_node.remove
div_node << sibling_node
end
if sibling_node.name == 'p' && sibling_node['id'] == last_p
div_node = nil
end
}
}
puts doc
This is the working solution I've implemented into my project (Vlad@SO & Whitelist@irc#rubyonrails: Thanks for your help and inspiration.):
require 'rubygems'
require 'nokogiri'
value = Nokogiri::HTML.parse(<<-HTML_END)
"<html>
<body>
<p id='1'>A</p>
<p id='2'>B</p>
<h1>Bla</h1>
<p id='3'>C</p>
<p id='4'>D</p>
<p id='5'>E</p>
</body>
</html>"
HTML_END
# The selected-array is given by the application.
# It consists of a sorted array with all ids of
# <p> that need to be enclosed by the <div>
selected = ["2","3","4"]
# We want an elements, not nodesets!
# .first returns Nokogiri::XML::Element instead of Nokogiri::XML::nodeset
first_p = value.css("p##{selected.first}").first
last_p = value.css("p##{selected.last}").first
parent = value.css('body').first
# build and set new div_node
div_node = Nokogiri::XML::Node.new('div', value)
div_node['class'] = 'XYZ'
# add div_node before first_p
first_p.add_previous_sibling(div_node)
selected_node = false
parent.children.each do |tag|
# if it's the first_p
selected_node = true if selected.include? tag['id']
# if it's anything between the first_p and the last_p
div_node.add_child(tag) if selected_node
# if it's the last_p
selected_node = false if selected.last == tag['id']
end
puts value.to_html
