gistfile1.txt

2.0.0p0 :012 > binding.pry

Frame number: 0/12
[2] pry(main)> show-source d.find

From: enum.c (C Method):
Owner: Enumerable
Visibility: public
Number of lines: 18

static VALUE
enum_find(int argc, VALUE *argv, VALUE obj)
{
    NODE *memo;
    VALUE if_none;

    rb_scan_args(argc, argv, "01", &if_none);
    RETURN_ENUMERATOR(obj, argc, argv);
    memo = NEW_MEMO(Qundef, 0, 0);
    rb_block_call(obj, id_each, 0, 0, find_i, (VALUE)memo);
    if (memo->u3.cnt) {
        return memo->u1.value;
    }
    if (!NIL_P(if_none)) {
        return rb_funcall(if_none, id_call, 0, 0);
    }
    return Qnil;
}
[3] pry(main)> d
=> #(Document:0x1dd33fc {
  name = "document",
  children = [
    #(DTD:0x1dd30b4 { name = "html" }),
    #(Element:0x1dd2e48 {
      name = "html",
      children = [
        #(Element:0x1dd2c68 {
          name = "body",
          children = [ #(Element:0x1dd2a88 { name = "blockquote" })]
          })]
      })]
  })
[4] pry(main)> show-source d.xpath

From: /usr/local/rvm/gems/ruby-2.0.0-p0/gems/nokogiri-1.6.0/lib/nokogiri/xml/node.rb @ line 145:
Owner: Nokogiri::XML::Node
Visibility: public
Number of lines: 26

def xpath *paths
  return NodeSet.new(document) unless document

  paths, handler, ns, binds = extract_params(paths)

  sets = paths.map { |path|
    ctx = XPathContext.new(self)
    ctx.register_namespaces(ns)
    path = path.gsub(/xmlns:/, ' :') unless Nokogiri.uses_libxml?

    binds.each do |key,value|
      ctx.register_variable key.to_s, value
    end if binds

    ctx.evaluate(path, handler)
  }
  return sets.first if sets.length == 1

  NodeSet.new(document) do |combined|
    sets.each do |set|
      set.each do |node|
        combined << node
      end
    end
  end
end