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Syntax ↑

A syntax highlighting a library for Ruby.

The official mtainained fork of this library is here. However, there’s currently none or not much new development going on and the original author, @jamis, recommends using CodeRay, over this library.

About ↑

This is a simple syntax highlighting library for Ruby. It is a naive syntax analysis tool, meaning that it does not “understand” the syntaxes of the languages it processes, but merely does some semi-intelligent pattern matching.

Usage ↑

There are primarily two uses for the Syntax library:

# Convert text from a supported syntax to a supported highlight format (like HTML). # Tokenize text in a supported syntax and process the tokens directly.

Highlighting a supported syntax ↑

require 'syntax/convertors/html'

convertor = Syntax::Convertors::HTML.for_syntax "ruby"
puts convertor.convert( File.read( "file.rb" ) )

The above snippet will emit HTML, using spans and CSS to indicate the different highlight “groups”. (Sample CSS files are included in the “data” directory.)

Tokenize text ↑

require 'syntax'

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

Tokenizing is straightforward process. Each time a new token is discovered by the tokenizer, it is yielded to the given block.

  • token.group is the lexical group to which the token belongs. Each supported syntax may have it’s own set of lexical groups.

  • token.instruction is an instruction used to determine how this token should be treated. It will be :none for normal tokens, :region_open if the token starts a nested region, and :region_close if it closes the last opened region.

  • token is itself a subclass of String, so you can use it just as you would a string. It represents the lexeme that was actually parsed.