[QUIZ] Syntax Highlighting (#218)

[Daniel Moore]

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

The three rules of Ruby Quiz:

1. Please do not post any solutions or spoiler discussion for this
quiz until 48 hours have elapsed from the time this message was
sent.

2. Support Ruby Quiz by submitting ideas and responses
as often as you can!
Visit: http://rubyquiz.strd6.com/suggestions

3. Enjoy!

Suggestion: A [QUIZ] in the subject of emails about the problem
helps everyone on Ruby Talk follow the discussion. Please reply to
the original quiz message, if you can.

RSS Feed: http://rubyquiz.strd6.com/quizzes.rss

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

## Syntax Highlighting (# 218)

Namo namah Rubyists,

This week's quiz is to write a syntax highlighter. Your program or
method will take as input unadorned Ruby code and return marked-up
code. Different syntactical elements of the code should have different
styles. As an additional challenge you may wish to indicate syntax
errors at the point in which they occur in the code. You may choose
any output style that you like. If you are unsure of what to use to
colorize output, then check out Term::ANSIColor[1].

Have Fun!

[1]: http://flori.github.com/term-ansicolor/

 

[Daniel Moore]

This week's quiz was solved by Caleb Clausen.

Caleb used the `RubyLexer` gem to parse a Ruby file given as a command
line argument. `Term::ANSIColor` is used to color the tokens.

def coloruby file,fd=open(file)
lexer=RubyLexer.new(file,fd)
begin
token=lexer.get1token
print token.colorize
end until RubyLexer::EoiToken===token
ensure
print Term::ANSIColor.reset
end

The `coloruby` method uses `RubyLexer` to generate a stream of tokens.
Each token is then colorized and printed out. After all the tokens are
printed the color is reset with `Term::ANSIColor.reset` so that any
following text won't receive collateral colorization.

So how are these tokens colorized anyway? Caleb's solution opens up
the `RubyLexer` class and adds a `colorize` method to all tokens.
`Term::ANSIColor` is also included in the `Token` class so that all
the color methods are available as well.

class Token
include Term::ANSIColor

def colorize
color+ident.to_s
end
end

Each individual token class may define its own different color or
colorize method.

class MethNameToken
alias color green
end

class KeywordToken
def colorize
if /[^a-z]/i===ident
yellow+ident
else
red+ident
end
end
end

The end result is nice colorful Ruby code.[1]

Thank you Caleb for your solution to this week's quiz!

[Syntax Highlighting (#218) - Solutions][2]

[1]: http://rubyquiz.strd6.com/quizzes/218/colorized.png
[2]: http://rubyquiz.strd6.com/quizzes/218.tar.gz