Add replace_entities to the XML PushParser

[spraints]

795cc5a resolved #76 for Nokogiri::XML::SAX::Parser. This branch adds the same option to Nokogiri::XML::SAX::PushParser.

For example:

require 'nokogiri'
include Nokogiri::XML

def main
  before
  after
end

def before
  puts '-'*40, 'before:'
  parser = SAX::PushParser.new(Dest.new)
  parser << doc
  parser.finish
end

def after
  puts '-'*40, 'after:'
  parser = SAX::PushParser.new(Dest.new)
  parser.replace_entities = true
  parser << doc
  parser.finish
end

def doc
  '<e a="x &amp; y">p &amp; q</e>'
end

class Dest < SAX::Document
  def start_element(name, attrs)
    p attrs
  end
  def characters(text)
    p text
  end
end

main

Output:

----------------------------------------
before:
[["a", "x & y"]]
"p "
"&"
" q"
----------------------------------------
after:
[["a", "x & y"]]
"p "
"&"
" q"

[flavorjones]

Tentatively targetting this change for 1.7.0.

[rosenfeld]

I don't understand. With replace_entities set to false, which I believe is the default, no substitutions should be made, right? So, I'd expect before to print & rather than &. Isn't this a bug? I'm particularly interested on being able to get the raw value without any substitutions, which I think should be libxml2 default behavior, right?

[spraints]

With replace_entities set to false, which I believe is the default, no substitutions should be made, right? So, I'd expect before to print & rather than &. Isn't this a bug?

It might be, but that's not the goal of this PR. This branch lets me tell libxml2 to replace & (or &) with &.

[flavorjones]

ZOMG, I've merged this in. Thank you for your patience, and apologies this took so long to get any attention.

[spraints]

💖 thanks!