masto-fe/app/models/keyword_mute.rb
David Yip 4a64181461 Allow keywords to match either substrings or whole words.
Word-boundary matching only works as intended in English and languages
that use similar word-breaking characters; it doesn't work so well in
(say) Japanese, Chinese, or Thai.  It's unacceptable to have a feature
that doesn't work as intended for some languages.  (Moreso especially
considering that it's likely that the largest contingent on the Mastodon
bit of the fediverse speaks Japanese.)

There are rules specified in Unicode TR29[1] for word-breaking across
all languages supported by Unicode, but the rules deliberately do not
cover all cases.  In fact, TR29 states

    For example, reliable detection of word boundaries in languages such
    as Thai, Lao, Chinese, or Japanese requires the use of dictionary
    lookup, analogous to English hyphenation.

So we aren't going to be able to make word detection work with regexes
within Mastodon (or glitchsoc).  However, for a first pass (even if it's
kind of punting) we can allow the user to choose whether they want word
or substring detection and warn about the limitations of this
implementation in, say, docs.

[1]: https://unicode.org/reports/tr29/
     https://web.archive.org/web/20171001005125/https://unicode.org/reports/tr29/
2017-10-21 14:54:36 -05:00

49 lines
1.2 KiB
Ruby

# frozen_string_literal: true
# == Schema Information
#
# Table name: keyword_mutes
#
# id :integer not null, primary key
# account_id :integer not null
# keyword :string not null
# whole_word :boolean default(TRUE), not null
# created_at :datetime not null
# updated_at :datetime not null
#
class KeywordMute < ApplicationRecord
belongs_to :account, required: true
validates_presence_of :keyword
after_commit :invalidate_cached_matcher
def self.matcher_for(account_id)
Rails.cache.fetch("keyword_mutes:matcher:#{account_id}") { Matcher.new(account_id) }
end
private
def invalidate_cached_matcher
Rails.cache.delete("keyword_mutes:matcher:#{account_id}")
end
class Matcher
attr_reader :regex
def initialize(account_id)
re = [].tap do |arr|
KeywordMute.where(account_id: account_id).select(:keyword, :id, :whole_word).find_each do |m|
boundary = m.whole_word ? '\b' : ''
arr << "#{boundary}#{Regexp.escape(m.keyword.strip)}#{boundary}"
end
end.join('|')
@regex = /#{re}/i unless re.empty?
end
def =~(str)
regex ? regex =~ str : false
end
end
end