Ruby gems for highlighting code

Syntax

Project page: http://syntax.rubyforge.org/
Supported languages: Ruby, XML, YAML
Advantages: Rails plugin and manual on using it in Radiant exists.
Drawbacks: There are too few supported languages and themes.

Installation:

gem install syntax

Usage example:

require 'rubygems'
require 'syntax/convertors/html'

convertor = Syntax::Convertors::HTML.for_syntax “ruby”

html = convertor.convert( File.read( “program.rb” ) )
puts html

Besides code highlighting, this gem may be used for lexical analysis of source code for some further processing:

require 'syntax'

tokenizer = Syntax.load "ruby"
tokenizer.tokenize( File.read( "file.rb" ) ) do |token|
  puts "group(#{token.group}, #{token.instruction}) lexeme(#{token})"
end

P.S: Before publication i found a theme for Syntax, which looks like GitHub code highlighting.

UltraViolet

Project page: http://ultraviolet.rubyforge.org/
Supported languages: C, C++, Ruby, Bibtex, Latex, Diff, HTML, CSS and many others
Advantages: It use TextMate syntax files and so supports a lot of different languages.
Drawbacks: Documentation is very poor. It has a lot of dependencies and works slower than others. When rendering line numbers and copying rendered code, line numbers copy with it.

Installation:

gem install ultraviolet

During installation i had one problem: Ultraviolet depends on gem Oniguruma, which requires library Oniguruma installed in your system with headers. In Ubuntu you can install it from package repositories:

sudo apt-get install libonig2 libonig-dev

For other systems there is a good manual here.

Usage example:

require 'rubygems'
require 'uv'

result = Uv.parse( text, "xhtml", "ruby", true, "amy")

Method arguments:

1. text – source code
2. “xhtml” – output syntax
3. “ruby” – input language
4. true – render or not line numbers
5. “amy” – theme, which to usse

CodeRay

Project page: http://coderay.rubychan.de/
Supported languages: Ruby, C, Delphi, HTML, RHTML (Rails), Nitro-XHTML, CSS, Diff, Java, JavaScript, JSON, YAML
Advantages: It’s fastest gem in my performance measurements. Also, it has a number of options, allowing to customize output.
Drawbacks: Built-in themes looks poor, especially for C and Java.

Installation:

gem install coderay

Usage example:

require 'rubygems'
require 'coderay'

tokens = CodeRay.scan( text, :ruby )

print tokens.div( :line_numbers => :table, :css => :class, :style => :cycnus )

Highlighting methods (div,html,..) take following options:

• :tab_width – tabulation width in spaces. Default: 8


• :css – how to include the styles (:class и :style). Default: :class)


• :wrap – wrap result in html tag :page, :div, :span or not to wrap (nil)


• :line_numbers – how render line numbers (:table, :inline, :list or nil)


• :line_number_start – first line number


• :bold_every – make every n-th line number bold. Default: 10

CodeRay, as Syntax may be used to analyze source code, because object Tokens is a list of tokens with specified types.

Performance comparison

I wrote simple benchmark for these libraries, which may be found at http://gist.github.com/85970.

Below you can see measurement results while processing code fragments in Ruby and Xml:

                          user     system      total        real
ruby ultraviolet:    10.270000   0.600000  10.870000 ( 11.584088)
ruby coderay:         0.710000   0.030000   0.740000 (  0.923616)
ruby syntax:          2.030000   0.130000   2.160000 (  2.830979)
xml ultraviolet:      3.280000   0.190000   3.470000 (  3.793856)
xml coderay:          0.540000   0.000000   0.540000 (  0.701140)
xml syntax:           0.660000   0.060000   0.720000 (  0.854120)

And graph:

You can see, what CodeRay is fastest, and UltraViolet is slowest. However, i think that poor performance of UltraViolet is repaired by huge amount of supported languages and themes.

Links

• Syntax (En)
• Ultraviolet (En)
• Coderay (En)
• Syntax Gem (En)
• Colorful Ruby code for your blog (En)