Introducing the PxIndex gem

require 'pxindex'

s =<<EOF
<?ph schema="entries[title, tags]/entry[title, desc, target, private]"?>
title: fun

# a

apple
antelope
asterisk
  configuring
  creating a new dialplan


# b

button
EOF

pxi = PxIndex.new(s)
a = pxi.q?('apple').map(&:title)
#=> ["apple"]