Class: Banzai::Filter::TaskListFilter

Inherits:
HTML::Pipeline::Filter
  • Object
show all
Includes:
Concerns::PipelineTimingCheck
Defined in:
lib/banzai/filter/task_list_filter.rb

Overview

TaskListFilter annotates task list items with aria-labels, adds strikethroughs to the text body of inapplicable items (created with ‘[~]`).

This should be run on the HTML generated by the Markdown filter, which handles the actual parsing, after the SanitizationFilter.

Constant Summary collapse

CSS = 
'input.task-list-item-checkbox'
XPATH = 
Gitlab::Utils::Nokogiri.css_to_xpath(CSS).freeze

Constants included from Concerns::PipelineTimingCheck

Concerns::PipelineTimingCheck::MAX_PIPELINE_SECONDS

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Concerns::PipelineTimingCheck

#exceeded_pipeline_max?

Class Method Details

.text_for_task_item_from_input(input) ⇒ Object

Gets the text for the task list item, given the <input> checkbox that declares it.



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# File 'lib/banzai/filter/task_list_filter.rb', line 51

def text_for_task_item_from_input(input)
  text_content = +''
  yield_next_siblings_until(input, %w[ol ul]) do |el|
    text_content << el.text
  end
  text_content.strip
end

.text_html_for_task_item_from_input(input) ⇒ Object

Gets the HTML corresponding to the task list item text, given the <input> checkbox that declares it. This should be used for task list item matching only.



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# File 'lib/banzai/filter/task_list_filter.rb', line 61

def text_html_for_task_item_from_input(input)
  html_content = +''
  yield_next_siblings_until(input, %w[ol ul]) do |el|
    html_content << el.to_html
  end
  html_content
end

.yield_next_siblings_until(start, els) ⇒ Object

Yields the #next_sibling of start, and then the #next_sibling of that, until either there are no more next siblings or a matching element is encountered.

The following #next_sibling is evaluated before each element is yielded, so they can safely be reparented or removed without affecting iteration.



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# File 'lib/banzai/filter/task_list_filter.rb', line 74

def yield_next_siblings_until(start, els)
  it = start.next_sibling
  while it && els.exclude?(it.name)
    following = it.next_sibling
    yield it
    it = following
  end
end

.yield_text_nodes_without_descending_into(start, els) ⇒ Object

Starting from start, iteratively yield text nodes contained within its children, and its (repeated) #next_siblings and their children, not descending into any of the elements given by els.

The following #next_sibling is evaluated before yielding, as above.



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# File 'lib/banzai/filter/task_list_filter.rb', line 88

def yield_text_nodes_without_descending_into(start, els)
  stack = [start]
  while stack.any?
    it = stack.pop

    stack << it.next_sibling if it.next_sibling

    if it.text?
      yield it unless it.content.blank?
    elsif els.exclude?(it.name)
      stack.concat(it.children.reverse)
    end
  end
end

Instance Method Details

#call ⇒ Object 



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# File 'lib/banzai/filter/task_list_filter.rb', line 16

def call
  doc.xpath(XPATH).each do |node|
    text_content = self.class.text_for_task_item_from_input(node)
    truncated_text_content = text_content.truncate(100, separator: ' ', omission: '…')
    node['aria-label'] = format(_('Check option: %{option}'), option: truncated_text_content)

    next unless node.has_attribute?('data-inapplicable')

    # We manually apply a <s> to strikethrough text in inapplicable task items,
    # specifically in tight lists where text within the list items isn't contained in a paragraph.
    # (Those are handled entirely by styles.)
    #
    # To handle tight lists, we wrap every text node after the checkbox in <s>, not descending
    # into <p> or <div> (as they're indicative of non-tight lists) or <ul> or <ol> (as we
    # explicitly want to avoid strikethrough styles on sublists, which may have applicable
    # task items!).

    # This is awkward, but we need to include a text node with a space after the input.
    # Otherwise, the strikethrough will start *immediately* next to the <input>, because
    # the first next sibling of the input is always a text node that starts with a space!
    space = node.add_next_sibling(node.document.create_text_node(' '))

    inapplicable_s = node.document.create_element('s')
    inapplicable_s['class'] = 'inapplicable'

    self.class.yield_text_nodes_without_descending_into(space.next_sibling, %w[p div ul ol]) do |el|
      el.wrap(inapplicable_s)
    end
  end

  doc
end