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We have the `# frozen_string_literal: true` comment on all our files. This means all string literals are frozen. There is no need to call #freeze on any literals. For files with `# frozen_string_literal: true` ``` puts %w{a b}[0].frozen? => true puts "hi".frozen? => true puts "a #{1} b".frozen? => true puts ("a " + "b").frozen? => false puts (-("a " + "b")).frozen? => true ``` For more details see: https://samsaffron.com/archive/2018/02/16/reducing-string-duplication-in-ruby
195 lines
4.7 KiB
Ruby
195 lines
4.7 KiB
Ruby
# frozen_string_literal: true
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class PlainTextToMarkdown
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SIGNATURE_SEPARATOR ||= "-- "
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def initialize(plaintext, opts = {})
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@plaintext = plaintext
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@lines = []
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@format_flowed = opts[:format_flowed] || false
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@delete_flowed_space = opts[:delete_flowed_space] || false
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end
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def to_markdown
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prepare_lines
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classify_lines
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markdown = +""
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last_quote_level = 0
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last_line_blank = false
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@lines.each do |line|
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current_line_blank = line.text.blank?
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unless last_line_blank && current_line_blank
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if line.quote_level > 0
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quote_identifiers = ">" * line.quote_level
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markdown << quote_identifiers << "\n" unless line.quote_level >= last_quote_level || current_line_blank
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markdown << quote_identifiers
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markdown << " " unless current_line_blank
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else
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markdown << "\n" unless last_quote_level == 0 || current_line_blank
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end
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markdown << convert_text(line)
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markdown << "\n"
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end
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last_line_blank = current_line_blank
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last_quote_level = line.quote_level
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end
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markdown.rstrip!
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markdown
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end
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private
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class CodeBlock < Struct.new(:start_line, :end_line)
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def initialize(start_line, end_line = nil)
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super
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end
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def valid?
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start_line.present? && end_line.present?
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end
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end
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class Line < Struct.new(:text, :quote_level, :code_block)
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def initialize(text, quote_level = 0, code_block = nil)
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super
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end
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def valid_code_block?
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code_block&.valid?
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end
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end
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def prepare_lines
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previous_line = nil
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@plaintext.each_line do |text|
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text.chomp!
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line = Line.new(text)
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remove_quote_level_indicators!(line)
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if @format_flowed
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line = merge_lines(line, previous_line)
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@lines << line unless line == previous_line
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else
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@lines << line
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end
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previous_line = line
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end
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end
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def classify_lines
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previous_line = nil
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@lines.each do |line|
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classify_line_as_code!(line, previous_line)
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previous_line = line
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end
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end
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# @param line [Line]
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def remove_quote_level_indicators!(line)
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match_data = line.text.match(/^(?<indicators>>+)\s?(?<text>.*)/)
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if match_data
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line.text = match_data[:text]
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line.quote_level = match_data[:indicators].length
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end
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end
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# @param line [Line]
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# @param previous_line [Line]
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# @return [Line]
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def merge_lines(line, previous_line)
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return line if previous_line.nil? || line.text.blank?
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return line if line.text == SIGNATURE_SEPARATOR || previous_line.text == SIGNATURE_SEPARATOR
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return line unless line.quote_level == previous_line.quote_level && previous_line.text.end_with?(" ")
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previous_line.text = previous_line.text[0...-1] if @delete_flowed_space
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previous_line.text += line.text
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previous_line
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end
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# @param line [Line]
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# @param previous_line [Line]
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def classify_line_as_code!(line, previous_line)
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line.code_block = previous_line.code_block unless previous_line.nil? || previous_line.valid_code_block?
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return unless line.text =~ /^\s{0,3}```/
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if line.code_block.present?
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line.code_block.end_line = line
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else
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line.code_block = CodeBlock.new(line)
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end
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end
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# @param line [Line]
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# @return [string]
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def convert_text(line)
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text = line.text
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if line.valid_code_block?
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code_block = line.code_block
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return code_block.start_line == line || code_block.end_line == line ? text.lstrip : text
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end
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converted_text = replace_duplicate_links(text)
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converted_text = escape_special_characters(converted_text)
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converted_text = indent_with_non_breaking_spaces(converted_text)
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converted_text
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end
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URL_REGEX ||= URI.regexp(%w{http https ftp mailto})
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BEFORE ||= Regexp.escape(%Q|([<«"“'‘|)
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AFTER ||= Regexp.escape(%Q|)]>»"”'’|)
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def replace_duplicate_links(text)
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urls = Set.new
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text.scan(URL_REGEX) { urls << $& }
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urls.each do |url|
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escaped = Regexp.escape(url)
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text.gsub!(Regexp.new(%Q|#{escaped}\s*[#{BEFORE}]?#{escaped}[#{AFTER}]?|, Regexp::IGNORECASE), url)
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end
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text
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end
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def indent_with_non_breaking_spaces(text)
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text.sub(/^\s+/) do |s|
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# replace tabs with 2 spaces
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s.gsub!("\t", " ")
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# replace indentation with non-breaking spaces
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s.length > 1 ? " " * s.length : s
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end
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end
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def escape_special_characters(text)
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urls = Set.new
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text.scan(URL_REGEX) { urls << $& }
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hoisted = urls
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.map { |url| [SecureRandom.hex, url] }
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.to_h
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hoisted.each { |h, url| text.gsub!(url, h) }
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text.gsub!(/[\\`*_{}\[\]()#+\-.!~]/) { |c| "\\#{c}" }
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text = CGI.escapeHTML(text)
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hoisted.each { |h, url| text.gsub!(h, url) }
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text
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end
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end
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