module Haml::Util

A module containing various useful functions.

Public Instance Methods

balance(scanner, start, finish, count = 0) click to toggle source

Moves a scanner through a balanced pair of characters. For example:

Foo (Bar (Baz bang) bop) (Bang (bop bip))
^                       ^
from                    to

@param scanner [StringScanner] The string scanner to move @param start [String] The character opening the balanced pair. @param finish [String] The character closing the balanced pair. @param count [Fixnum] The number of opening characters matched

before calling this method

@return [(String, String)] The string matched within the balanced pair

and the rest of the string.
`["Foo (Bar (Baz bang) bop)", " (Bang (bop bip))"]` in the example above.
# File lib/haml/util.rb, line 168
def balance(scanner, start, finish, count = 0)
  str = ''.dup
  scanner = StringScanner.new(scanner) unless scanner.is_a? StringScanner
  regexp = Regexp.new("(.*?)[\\#{start.chr}\\#{finish.chr}]", Regexp::MULTILINE)
  while scanner.scan(regexp)
    str << scanner.matched
    count += 1 if scanner.matched[-1] == start
    count -= 1 if scanner.matched[-1] == finish
    return [str.strip, scanner.rest] if count == 0
  end
end
check_encoding(str) { |<<rstrip, i + 1| ... } click to toggle source

Checks that the encoding of a string is valid and cleans up potential encoding gotchas like the UTF-8 BOM. If it’s not, yields an error string describing the invalid character and the line on which it occurs.

@param str [String] The string of which to check the encoding @yield [msg] A block in which an encoding error can be raised.

Only yields if there is an encoding error

@yieldparam msg [String] The error message to be raised @return [String] ‘str`, potentially with encoding gotchas like BOMs removed

# File lib/haml/util.rb, line 62
    def check_encoding(str)
      if str.valid_encoding?
        # Get rid of the Unicode BOM if possible
        # Shortcut for UTF-8 which might be the majority case
        if str.encoding == Encoding::UTF_8
          return str.gsub(/\A\uFEFF/, '')
        elsif str.encoding.name =~ /^UTF-(16|32)(BE|LE)?$/
          return str.gsub(Regexp.new("\\A\uFEFF".encode(str.encoding)), '')
        else
          return str
        end
      end

      encoding = str.encoding
      newlines = Regexp.new("\r\n|\r|\n".encode(encoding).force_encoding(Encoding::ASCII_8BIT))
      str.force_encoding(Encoding::ASCII_8BIT).split(newlines).each_with_index do |line, i|
        begin
          line.encode(encoding)
        rescue Encoding::UndefinedConversionError => e
          yield <<MSG.rstrip, i + 1
Invalid #{encoding.name} character #{e.error_char.dump}
MSG
        end
      end
      return str
    end
check_haml_encoding(str, &block) click to toggle source

Like {#check_encoding}, but also checks for a Ruby-style ‘-# coding:` comment at the beginning of the template and uses that encoding if it exists.

The Haml encoding rules are simple. If a ‘-# coding:` comment exists, we assume that that’s the original encoding of the document. Otherwise, we use whatever encoding Ruby has.

Haml uses the same rules for parsing coding comments as Ruby. This means that it can understand Emacs-style comments (e.g. ‘-*- encoding: “utf-8” -*-`), and also that it cannot understand non-ASCII-compatible encodings such as `UTF-16` and `UTF-32`.

@param str [String] The Haml template of which to check the encoding @yield [msg] A block in which an encoding error can be raised.

Only yields if there is an encoding error

@yieldparam msg [String] The error message to be raised @return [String] The original string encoded properly @raise [ArgumentError] if the document declares an unknown encoding

# File lib/haml/util.rb, line 109
def check_haml_encoding(str, &block)
  str = str.dup if str.frozen?

  bom, encoding = parse_haml_magic_comment(str)
  if encoding; str.force_encoding(encoding)
  elsif bom; str.force_encoding(Encoding::UTF_8)
  end

  return check_encoding(str, &block)
end
contains_interpolation?(str) click to toggle source
# File lib/haml/util.rb, line 197
def contains_interpolation?(str)
  /#[\{$@]/ === str
end
handle_interpolation(str) { |scan while scan(/(.*?)(\\*)#([\{@$])/)| ... } click to toggle source

Scans through a string looking for the interoplation-opening ‘#{` and, when it’s found, yields the scanner to the calling code so it can handle it properly.

The scanner will have any backslashes immediately in front of the ‘#{` as the second capture group (`scan`), and the text prior to that as the first (`scan`).

@yieldparam scan [StringScanner] The scanner scanning through the string @return [String] The text remaining in the scanner after all ‘#{`s have been processed

# File lib/haml/util.rb, line 147
def handle_interpolation(str)
  scan = StringScanner.new(str)
  yield scan while scan.scan(/(.*?)(\\*)#([\{@$])/)
  scan.rest
end
html_safe(text) click to toggle source

Returns the given text, marked as being HTML-safe. With older versions of the Rails XSS-safety mechanism, this destructively modifies the HTML-safety of ‘text`.

It only works if you are using ActiveSupport or the parameter ‘text` implements the html_safe method.

@param text [String, nil] @return [String, nil] ‘text`, marked as HTML-safe

# File lib/haml/util.rb, line 47
def html_safe(text)
  return unless text
  text.html_safe
end
human_indentation(indentation) click to toggle source

Formats a string for use in error messages about indentation.

@param indentation [String] The string used for indentation @return [String] The name of the indentation (e.g. ‘“12 spaces”`, `“1 tab”`)

# File lib/haml/util.rb, line 184
def human_indentation(indentation)
  if !indentation.include?(?\t)
    noun = 'space'
  elsif !indentation.include?(?\s)
    noun = 'tab'
  else
    return indentation.inspect
  end

  singular = indentation.length == 1
  "#{indentation.length} #{noun}#{'s' unless singular}"
end
inspect_obj(obj) click to toggle source

Like ‘Object#inspect`, but preserves non-ASCII characters rather than escaping them. This is necessary so that the precompiled Haml template can be `#encode`d into `@options` before being evaluated.

@param obj {Object} @return {String}

# File lib/haml/util.rb, line 126
def inspect_obj(obj)
  case obj
  when String
    %Q!"#{obj.gsub(/[\x00-\x7F]+/) {|s| s.dump[1...-1]}}"!
  when Symbol
    ":#{inspect_obj(obj.to_s)}"
  else
    obj.inspect
  end
end
rails_xss_safe?() click to toggle source
# File lib/haml/template.rb, line 31
def rails_xss_safe?; true; end
silence_warnings() { || ... } click to toggle source

Silence all output to STDERR within a block.

@yield A block in which no output will be printed to STDERR

# File lib/haml/util.rb, line 20
def silence_warnings
  the_real_stderr, $stderr = $stderr, StringIO.new
  yield
ensure
  $stderr = the_real_stderr
end
unescape_interpolation(str, escape_html = nil) click to toggle source
# File lib/haml/util.rb, line 201
def unescape_interpolation(str, escape_html = nil)
  res = ''.dup
  rest = Haml::Util.handle_interpolation str.dump do |scan|
    escapes = (scan[2].size - 1) / 2
    char = scan[3] # '{', '@' or '$'
    res << scan.matched[0...-3 - escapes]
    if escapes % 2 == 1
      res << "\##{char}"
    else
      interpolated = if char == '{'
        balance(scan, ?{, ?}, 1)[0][0...-1]
      else
        scan.scan(/\w+/)
      end
      content = eval("\"#{interpolated}\"")
      content = "#{char}#{content}" if char == '@' || char == '$'
      content = "Haml::Helpers.html_escape((#{content}))" if escape_html

      res << "\#{#{content}}"
    end
  end
  res + rest
end

Private Instance Methods

parse_haml_magic_comment(str) click to toggle source

Parses a magic comment at the beginning of a Haml file. The parsing rules are basically the same as Ruby’s.

@return [(Boolean, String or nil)]

Whether the document begins with a UTF-8 BOM,
and the declared encoding of the document (or nil if none is declared)
# File lib/haml/util.rb, line 233
def parse_haml_magic_comment(str)
  scanner = StringScanner.new(str.dup.force_encoding(Encoding::ASCII_8BIT))
  bom = scanner.scan(/\xEF\xBB\xBF/n)
  return bom unless scanner.scan(/-\s*#\s*/n)
  if (coding = try_parse_haml_emacs_magic_comment(scanner))
    return bom, coding
  end

  return bom unless scanner.scan(/.*?coding[=:]\s*([\w-]+)/in)
  return bom, scanner[1]
end
try_parse_haml_emacs_magic_comment(scanner) click to toggle source
# File lib/haml/util.rb, line 245
def try_parse_haml_emacs_magic_comment(scanner)
  pos = scanner.pos
  return unless scanner.scan(/.*?-\*-\s*/n)
  # From Ruby's parse.y
  return unless scanner.scan(/([^\s'":;]+)\s*:\s*("(?:\\.|[^"])*"|[^"\s;]+?)[\s;]*-\*-/n)
  name, val = scanner[1], scanner[2]
  return unless name =~ /(en)?coding/in
  val = $1 if val =~ /^"(.*)"$/n
  return val
ensure
  scanner.pos = pos
end