Class: XmlTruncator

Inherits:
Object
  • Object
show all
Defined in:
lib/end_point_blank/xml_truncator.rb

Constant Summary collapse

MAX_BYTES = 
10000
MAX_DEPTH = 
6
MAX_CHILDREN = 
20
MAX_ATTRIBUTES = 
20
MAX_TEXT = 
200
TEXT_SUFFIX = 
"..."

Class Method Summary collapse

Class Method Details

.compact_fallback(root_name) ⇒ Object 



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# File 'lib/end_point_blank/xml_truncator.rb', line 79

def self.compact_fallback(root_name)
  "<#{root_name}><truncated/></#{root_name}>"
end

.parse_xml(input) ⇒ Object 



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# File 'lib/end_point_blank/xml_truncator.rb', line 30

def self.parse_xml(input)
  REXML::Document.new(input)
rescue REXML::ParseException
  nil
end

.prune_element(element, depth:) ⇒ Object 



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# File 'lib/end_point_blank/xml_truncator.rb', line 36

def self.prune_element(element, depth:)
  pruned = REXML::Element.new(element.expanded_name)

  element.attributes.each_with_index do |(name, value), idx|
    break if idx >= MAX_ATTRIBUTES
    pruned.add_attribute(name, truncate_text(value, max: 100))
  end

  if depth >= MAX_DEPTH
    pruned.add_element("truncated")
    return pruned
  end

  element_count = 0

  element.children.each do |child|
    case child
    when REXML::Element
      if element_count >= MAX_CHILDREN
        pruned.add_element("truncated")
        break
      end

      pruned.add_element(prune_element(child, depth: depth + 1))
      element_count += 1
    when REXML::CData
      pruned.add(REXML::CData.new(truncate_text(child.value)))
    when REXML::Text
      text = truncate_text(child.value)
      pruned.add_text(text) unless text.empty?
    end
  end

  pruned
end

.render_element(element) ⇒ Object 



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# File 'lib/end_point_blank/xml_truncator.rb', line 72

def self.render_element(element)
  formatter = REXML::Formatters::Default.new
  output = +""
  formatter.write(element, output)
  output
end

.truncate(xml, limit: MAX_BYTES) ⇒ Object 



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# File 'lib/end_point_blank/xml_truncator.rb', line 12

def self.truncate(xml, limit: MAX_BYTES)
  input = xml.to_s
  return "" if input.empty?
  return input if input.bytesize <= limit

  document = parse_xml(input)
  return StringTruncator.truncate(input, limit:, suffix: "<truncated/>") unless document&.root

  pruned_root = prune_element(document.root, depth: 0)
  output = render_element(pruned_root)
  return output if output.bytesize <= limit

  compact = compact_fallback(document.root.expanded_name)
  return compact if compact.bytesize <= limit

  "<truncated/>"
end

.truncate_text(text, max: MAX_TEXT) ⇒ Object 



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# File 'lib/end_point_blank/xml_truncator.rb', line 83

def self.truncate_text(text, max: MAX_TEXT)
  value = text.to_s
  return value if value.bytesize <= max

  value.byteslice(0, max - TEXT_SUFFIX.bytesize) + TEXT_SUFFIX
end