模块 RDoc::Encoding - rdoc：Ruby 标准库文档

change_encoding(text, encoding) 点击切换源

根据 encoding 更改编码，无需转换并返回新字符串

# File rdoc/encoding.rb, line 112
def self.change_encoding text, encoding
  if text.kind_of? RDoc::Comment
    text.encode! encoding
  else
    String.new text, encoding: encoding
  end
end

detect_encoding(string) 点击切换源

根据魔术注释检测 string 的编码

# File rdoc/encoding.rb, line 92
def self.detect_encoding string
  result = HEADER_REGEXP.match string
  name = result && result[:name]

  name ? Encoding.find(name) : nil
end

read_file(filename, encoding, force_transcode = false) 点击切换源

读取 filename 的内容并处理文件中的任何编码指令。

内容将被转换为 encoding。如果文件无法转换，将打印警告并返回 nil。

如果 force_transcode 为 true，则文档将被转码，并且目标编码中的任何未知字符都将被替换为“？”

# File rdoc/encoding.rb, line 32
def self.read_file filename, encoding, force_transcode = false
  content = File.open filename, "rb" do |f| f.read end
  content.gsub!("\r\n", "\n") if RUBY_PLATFORM =~ /mswin|mingw/

  utf8 = content.sub!(/\A\xef\xbb\xbf/, '')

  enc = RDoc::Encoding.detect_encoding content
  content = RDoc::Encoding.change_encoding content, enc if enc

  begin
    encoding ||= Encoding.default_external
    orig_encoding = content.encoding

    if not orig_encoding.ascii_compatible? then
      content = content.encode encoding
    elsif utf8 then
      content = RDoc::Encoding.change_encoding content, Encoding::UTF_8
      content = content.encode encoding
    else
      # assume the content is in our output encoding
      content = RDoc::Encoding.change_encoding content, encoding
    end

    unless content.valid_encoding? then
      # revert and try to transcode
      content = RDoc::Encoding.change_encoding content, orig_encoding
      content = content.encode encoding
    end

    unless content.valid_encoding? then
      warn "unable to convert #{filename} to #{encoding}, skipping"
      content = nil
    end
  rescue Encoding::InvalidByteSequenceError,
         Encoding::UndefinedConversionError => e
    if force_transcode then
      content = RDoc::Encoding.change_encoding content, orig_encoding
      content = content.encode(encoding,
                               :invalid => :replace,
                               :undef => :replace,
                               :replace => '?')
      return content
    else
      warn "unable to convert #{e.message} for #{filename}, skipping"
      return nil
    end
  end

  content
rescue ArgumentError => e
  raise unless e.message =~ /unknown encoding name - (.*)/
  warn "unknown encoding name \"#{$1}\" for #{filename}, skipping"
  nil
rescue Errno::EISDIR, Errno::ENOENT
  nil
end

remove_magic_comment(string) 点击切换源

删除魔术注释和 shebang

# File rdoc/encoding.rb, line 102
def self.remove_magic_comment string
  string.sub HEADER_REGEXP do |s|
    s.gsub(/[^\n]/, '')
  end
end