XmlParsingExampleExplained.rb

# This script can be run using any of the following:
#
# ruby XmlParsingExampleExplained < file1.xml 
# cat file1.xml | ruby XmlParsingExampleExplained
# ruby XmlParsingExampleExplained file1.xml 
#
# Note that multiple XML files should NOT be specified at the same time, as was possible in the regex matching example.

# Require the Nokogiri library -- this library must be installed with 'gem install nokogiri'
require 'nokogiri'

# Read everything from standard input or from files specified as command line arguments
content = ARGF.read

# Parse the content as an XML document
doc = Nokogiri::XML(content)

# Run an XPath query to find all <article-title> tags
matches = doc.xpath('//article-title')

# Extract the content from the tags and replace any runs of multiple spaces in the titles with a single space
matches = matches.map { |t| t.content.gsub(/\s+/, ' ') }

# Print out the matches
puts matches