RubyQuiz #148: Postfix to Infix

Posted by Alpha Tue, 04 Dec 2007 00:49:00 GMT

My extremely lazy whack at the latest Ruby Quiz. Turns a postfix expression into an infix expression via regular expressions.

#!/usr/bin/env ruby

str = ARGV[0].split(/\s+/).join('_')

while str.include?('_')
  str.sub!(/([^_]+)_([^_]+)_([+\-*\/])/, '(\1 \3 \2)')
end

puts str

A few test cases I used in developing the solution before turning it into an actual script:

require 'test/unit'

def postfix_to_infix(str)
  str = str.split(/[^.\d+\-*\/]/).join(' ')
  while str !~ /^\(.*\)$/
    str.sub!(/([^ ]+) ([^ ]+) ([+\-*\/])/, '(\1\3\2)')
  end
  str.gsub(/([+\-*\/])/, ' \1 ').sub(/^\((.*)\)$/, '\1')
end

class PostfixToInfixTest < Test::Unit::TestCase
  def test_postfix_to_infix
    assert_equal '2 + 3', postfix_to_infix('2 3 +')
    assert_equal '12 + 34', postfix_to_infix('12 34 +')
    assert_equal '1.2 + 3.4', postfix_to_infix('1.2 3.4 +')
    assert_equal '(1 - 2) - (3 + 4)', postfix_to_infix('1 2 - 3 4 + -')
    assert_equal '(56 * (34 + 213.7)) - 678', postfix_to_infix('56 34 213.7 + * 678 -')
  end
end

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AWStats with lighttpd on Ubuntu

Posted by Alpha Mon, 03 Dec 2007 01:23:00 GMT

Throughout this post, I’ll use foobar as a fake domain. You should replace this with the appropriate domain(s) for your own use.

First, install AWStats.

$ sudo apt-get install awstats

/etc/lighttpd.conf will need to be modified; this will be slightly different if you want to use a directory instead of a subdomain to check your stats.

/etc/lighttpd/lighttpd.conf

server.modules += ( "mod_cgi" )

$HTTP["host"] =~ "stats.foobar" {
  alias.url = ( "/icon/" => "/usr/share/awstats/icon/",
                "/css/" => "/usr/share/doc/awstats/examples/css/",
                "/cgi-bin/" => "/usr/lib/cgi-bin/" )
  cgi.assign = ( ".pl" => "/usr/bin/perl", ".cgi" => "/usr/bin/perl" )
}

Make sure this works by visiting http://stats.foobar/cgi-bin/awstats.pl. You should get an error message from the AWStats CGI file.

In /etc/awstats, make a awstats.foobar.conf file, replacing foobar with whatever is appropriate for your purposes.

/etc/awstats/awstats.foobar.conf

LogFile="/var/log/lighttpd/access.log"
LogType=W
LogFormat=1
SiteDomain="foobar"
HostAliases="localhost 127.0.0.1 REGEX[foobar$]"
DNSLookup=1
DirData="/var/lib/awstats"
DirCgi="/cgi-bin"
DirIcons="/icon"
SkipHosts="127.0.0.1 localhost REGEX[^192\.168\.]"

Run awstats.pl to initialize the statistics database.

$ sudo -u www-data /usr/lib/cgi-bin/awstats.pl -config=foobar -update

Your stats should now be visible at http://stats.foobar/cgi-bin/awstats.pl?config=foobar.

Now all that’s left is editing the crontab and logrotate configuration files to automatically populate the stats.

/etc/cron.d/awstats

0,10,20,30,40,50 * * * * www-data [ -x /usr/lib/cgi-bin/awstats.pl -a -f /etc/awstats/awstats.foobar.conf -a -r /var/log/lighttpd/access.log ] && /usr/lib/cgi-bin/awstats.pl -config=foobar -update >/dev/null

/etc/logrotate.d/lighttpd

prerotate
  /usr/lib/cgi-bin/awstats.pl -config=foobar -update
endscript

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The code behind the Ultraviolet textfilter

Posted by Alpha Sun, 02 Dec 2007 05:55:00 GMT

To start, we need to install Ultraviolet. Since the library uses Oniguruma, we’ll have to install that as well.

$ sudo apt-get install libonig-dev
$ sudo gem install ultraviolet

Use irb to copy the CSS syntax files into Typo’s stylesheet directory. From the base directory of the Typo installation:

$ mkdir public/stylesheets/ultraviolet
$ irb -ruv
irb(main):001:0> Uv.copy_files 'xhtml', 'public/stylesheets/ultraviolet'

Copy one of the existing textfilters to use as a base.

$ cd vendor/plugins
$ cp -r typo_textfilter_code typo_textfilter_ultraviolet
$ cd typo_textfilter_ultraviolet
$ mv lib/typo_textfilter_code.rb lib/typo_textfilter_ultraviolet.rb

Modify init.rb to require the Ultraviolet textfilter instead of the code textfilter.

init.rb

# Include hook code here

require 'typo_textfilter_ultraviolet'

And last, edit lib/typo_textfilter_ultraviolet.rb to use Ultraviolet instead of the Syntax library.

lib/typo_textfilter_ultraviolet.rb

require 'uv'

class Typo
  class Textfilter
    class Ultraviolet < TextFilterPlugin::MacroPre
      plugin_display_name "Ultraviolet"
      plugin_description "Apply syntax highlighting to a code block using Ultraviolet"

      def self.help_text
        syntaxes, themes = [Uv.syntaxes, Uv.themes].map do |ary|
          ary.sort.map {|i| "* #{i.gsub('_', '\_')}" }.join("\n")
        end

        %{
This uses the [Ultraviolet](http://ultraviolet.rubyforge.org/) syntax highlighting engine. Options:

* **lang**. Sets the programming language. The default language is Ruby.
* **linenumber**. Turns on line numbering. Use `linenumber="true"` to enable.
* **theme**. Sets the theme. The default theme is Idle.

### Supported themes:
#{themes}

### Supported languages:
#{syntaxes}
}
      end

      def self.macrofilter(blog,content,attrib,params,text="")
        lang       = attrib['lang'] || 'ruby'
        theme      = attrib['theme'] || 'idle'
        linenumber = attrib['linenumber']

        text = text.to_s.gsub(/\r/,'').gsub(/\A\n/,'').chomp

        result = Uv.parse(text, 'xhtml', lang, linenumber, theme)

        set_whiteboard(blog, content, theme)

        "<notextile>#{result}</notextile>"
      end

      def self.set_whiteboard(blog, content, theme)
        content.whiteboard["page_header_ultraviolet_#{theme}"] = <<-HTML
          <link href="#{blog.base_url}/stylesheets/ultraviolet/#{theme}.css" media="all" rel="Stylesheet" type="text/css" />
        HTML
      end 
    end
  end
end

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Ultraviolet syntax highlighting test

Posted by Alpha Sun, 02 Dec 2007 01:53:00 GMT

Ruby:

class Foo
  def bar
    puts "hello world"
  end
end

C with linenumbers using the blackboard theme:

   1  void bar() {
   2    printf("hello world\n");
   3  }

Objective-C with the twilight theme:

#import <Foundation/NSObject.h>

@interface Fraction: NSObject {
    int numerator;
    int denominator;
}

-(void) print;
-(void) setNumerator: (int) d;
-(void) setDenominator: (int) d;
-(int) numerator;
-(int) denominator;
@end

Python with linenumbers and using the pastels_on_dark theme:

   1  class MyClass:
   2      "A simple example class"
   3      i = 12345
   4      def f(self):
   5          return 'hello world'

Done using Ultraviolet.

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