Class: Contrast::Agent::Assess::Policy::Propagator::Remove

Inherits:
Base
  • Object
show all
Defined in:
lib/contrast/agent/assess/policy/propagator/remove.rb

Overview

Propagation that results in all the tags of the source being applied to the totality of the target and then those sections which have been removed from the target are removed from the tags. The target’s preexisting tags are also updated by this removal.

Class Method Summary collapse

Methods inherited from Base

find_source, tracked_value?

Class Method Details

.handle_removal(source_chars, target) ⇒ Object 



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# File 'lib/contrast/agent/assess/policy/propagator/remove.rb', line 29

def handle_removal source_chars, target
  properties = Contrast::Agent::Assess::Tracker.properties(target)
  return unless properties

  source_idx = 0

  target_chars = target.chars
  target_idx = 0

  remove_ranges = []
  start = nil

  # loop over the target, the result of the delete
  # every range of characters that it differs from the source
  # represents a section that was deleted. these sections
  # need to have their tags updated
  target_len = target_chars.length
  while target_idx < target_len
    target_char = target_chars[target_idx]
    source_char = source_chars[source_idx]
    if target_char == source_char
      target_idx += 1
      if start
        remove_ranges << (start...source_idx)
        start = nil
      end
    else
      start ||= source_idx
    end
    source_idx += 1
  end

  # once we're done looping over the target, anything left
  # over is extra from the source that was deleted. tags
  # applying to it need to be removed.
  remove_ranges << (source_idx...source_chars.length) if source_idx != source_chars.length

  # handle deleting the removed ranges
  properties.delete_tags_at_ranges(remove_ranges)
end

.propagate(propagation_node, preshift, target) ⇒ Object

For the source, append its tags to the target. Once the tag is applied, remove the section that was removed by the delete. Unlike additive propagation, this currently only supports one source



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# File 'lib/contrast/agent/assess/policy/propagator/remove.rb', line 19

def propagate propagation_node, preshift, target
  properties = Contrast::Agent::Assess::Tracker.properties(target)
  return unless properties

  source = find_source(propagation_node.sources[0], preshift)
  properties.copy_from(source, target, 0, propagation_node.untags)
  source_chars = source.is_a?(String) ? source.chars : source.string.chars
  handle_removal(source_chars, target)
end