Use a tree‐based approach for advanced text formatting (#1907)

* Use a tree‐based approach for adv. text formatting

Sanitizing HTML/Markdown means parsing the content into an HTML tree
under‐the‐hood anyway, and it is more accurate to do mention/hashtag
replacement on the text nodes in that tree than it is to try to hack it
in with regexes et cetera.

This undoes the overrides of `#entities` and `#rewrite` on
`AdvancedTextFormatter` but also stops using them, instead keeping
track of the parsed Nokogiri tree itself and using that in the `#to_s`
method.

Internally, this tree uses `<mastodon-entity>` nodes to keep track of
hashtags, links, and mentions. Sanitization is moved to the beginning,
so it should be known that these do not appear in the input.

* Also disallow entities inside of `<code>`

I think this is generally expected behaviour, and people are annoyed
when their code gets turned into links/hashtags/mentions.

* Minor cleanup to AdvancedTextFormatter

* Change AdvancedTextFormatter to rewrite entities in one pass and sanitize at the end

Also, minor refactoring to better match how other formatters are organized.

* Add some tests

Co-authored-by: Claire <claire.github-309c@sitedethib.com>
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kibigo! 2022-12-02 01:29:42 -08:00 committed by GitHub
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2 changed files with 49 additions and 43 deletions

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@ -19,6 +19,8 @@ class AdvancedTextFormatter < TextFormatter
end end
end end
attr_reader :content_type
# @param [String] text # @param [String] text
# @param [Hash] options # @param [Hash] options
# @option options [Boolean] :multiline # @option options [Boolean] :multiline
@ -27,7 +29,7 @@ class AdvancedTextFormatter < TextFormatter
# @option options [Array<Account>] :preloaded_accounts # @option options [Array<Account>] :preloaded_accounts
# @option options [String] :content_type # @option options [String] :content_type
def initialize(text, options = {}) def initialize(text, options = {})
content_type = options.delete(:content_type) @content_type = options.delete(:content_type)
super(text, options) super(text, options)
@text = format_markdown(text) if content_type == 'text/markdown' @text = format_markdown(text) if content_type == 'text/markdown'
@ -50,50 +52,50 @@ class AdvancedTextFormatter < TextFormatter
html.html_safe # rubocop:disable Rails/OutputSafety html.html_safe # rubocop:disable Rails/OutputSafety
end end
# Differs from `TextFormatter` by skipping HTML tags and entities # Differs from TextFormatter by operating on the parsed HTML tree
def entities def rewrite
@entities ||= begin if @tree.nil?
gaps = [] src = text.gsub(Sanitize::REGEX_UNSUITABLE_CHARS, '')
total_offset = 0 @tree = Nokogiri::HTML5.fragment(src)
document = @tree.document
escaped = text.gsub(/<[^>]*>|&#[0-9]+;/) do |match| @tree.xpath('.//text()[not(ancestor::a | ancestor::code)]').each do |text_node|
total_offset += match.length - 1 # Iterate over text elements and build up their replacements.
end_offset = Regexp.last_match.end(0) content = text_node.content
gaps << [end_offset - total_offset, total_offset] replacement = Nokogiri::XML::NodeSet.new(document)
' ' processed_index = 0
end Extractor.extract_entities_with_indices(
content,
Extractor.extract_entities_with_indices(escaped, extract_url_without_protocol: false).map do |entity| extract_url_without_protocol: false
start_pos, end_pos = entity[:indices] ) do |entity|
offset_idx = gaps.rindex { |gap| gap.first <= start_pos } # Iterate over entities in this text node.
offset = offset_idx.nil? ? 0 : gaps[offset_idx].last advance = entity[:indices].first - processed_index
entity.merge(indices: [start_pos + offset, end_pos + offset]) if advance.positive?
# Text node for content which precedes entity.
replacement << Nokogiri::XML::Text.new(
content[processed_index, advance],
document
)
end
replacement << Nokogiri::HTML5.fragment(yield(entity))
processed_index = entity[:indices].last
end
if processed_index < content.size
# Text node for remaining content.
replacement << Nokogiri::XML::Text.new(
content[processed_index, content.size - processed_index],
document
)
end
text_node.replace(replacement)
end end
end end
Sanitize.node!(@tree, Sanitize::Config::MASTODON_OUTGOING).to_html
end end
private private
# Differs from `TextFormatter` in that it keeps HTML; but it sanitizes at the end to remain safe
def rewrite
entities.sort_by! do |entity|
entity[:indices].first
end
result = ''.dup
last_index = entities.reduce(0) do |index, entity|
indices = entity[:indices]
result << text[index...indices.first]
result << yield(entity)
indices.last
end
result << text[last_index..-1]
Sanitize.fragment(result, Sanitize::Config::MASTODON_OUTGOING)
end
def format_markdown(html) def format_markdown(html)
html = markdown_formatter.render(html) html = markdown_formatter.render(html)
html.delete("\r").delete("\n") html.delete("\r").delete("\n")

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@ -35,7 +35,7 @@ RSpec.describe AdvancedTextFormatter do
end end
context 'given a block code' do context 'given a block code' do
let(:text) { "test\n\n```\nint main(void) {\n return 0;\n}\n```\n" } let(:text) { "test\n\n```\nint main(void) {\n return 0; // https://joinmastodon.org/foo\n}\n```\n" }
it 'formats code using <pre> and <code>' do it 'formats code using <pre> and <code>' do
is_expected.to include '<pre><code>int main' is_expected.to include '<pre><code>int main'
@ -44,13 +44,17 @@ RSpec.describe AdvancedTextFormatter do
it 'does not strip leading spaces' do it 'does not strip leading spaces' do
is_expected.to include '> return 0' is_expected.to include '> return 0'
end end
it 'does not format links' do
is_expected.to include 'return 0; // https://joinmastodon.org/foo'
end
end end
context 'given some quote' do context 'given a link in inline code using backticks' do
let(:text) { "> foo\n\nbar" } let(:text) { 'test `https://foo.bar/bar` bar' }
it 'formats code using <code>' do it 'does not rewrite the link' do
is_expected.to include '<blockquote><p>foo</p></blockquote>' is_expected.to include 'test <code>https://foo.bar/bar</code> bar'
end end
end end