jsmin.rb

#!/usr/bin/ruby
# jsmin.rb 2007-07-20
# Author: Uladzislau Latynski
#
# This work is a translation from C to Ruby of jsmin.c published by
# Douglas Crockford. Permission is hereby granted to use the Ruby
# version under the same conditions as the jsmin.c on which it is
# based.
#
# jsmin.c
# 2003-04-21
#
# Copyright (c) 2002 Douglas Crockford  (www.crockford.com)
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of
# this software and associated documentation files (the "Software"), to deal in
# the Software without restriction, including without limitation the rights to
# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
# of the Software, and to permit persons to whom the Software is furnished to do
# so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# The Software shall be used for Good, not Evil.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

EOF = -1
$the_a = ""
$the_b = ""

# is_alphanum? -- return true if the character is a letter, digit, underscore,
# dollar sign, or non-ASCII character
def is_alphanum?(c)
  !(!c || c == EOF) && (c =~ /\w|\$|\\/ || c[0] > 126)
end

# get -- return the next character from stdin. Watch out for lookahead. If
# the character is a control character, translate it to a space or linefeed.
def get
  c = $stdin.getc
  return EOF if !c
  c = c.chr
  return c if c >= " " || c == "\n" || c.unpack("c") == EOF
  return "\n" if c == "\r"
  return " "
end

# Get the next character without getting it.
def peek
  look_ahead_char = $stdin.getc
  $stdin.ungetc(look_ahead_char)
  look_ahead_char.chr
end

# mynext -- get the next character, excluding comments.
# peek() is used to see if a '/' is followed by a '/' or '*'.
def mynext
  c = get
  if c == "/"
    if peek == "/" 
      while true
        c = get
        return c if c <= "\n"
      end
    end
    if peek == "*"
      get
      while true
        case get
        when "*"
          if peek == "/"
            get
            return " "
          end
        when EOF
          raise "Unterminated comment"
        end
      end
    end
  end
  return c
end

# action -- do something! What you do is determined by the argument: 1
# Output A. Copy B to A. Get the next B. 2 Copy B to A. Get the next B.
# (Delete A). 3 Get the next B. (Delete B). action treats a string as a
# single character. Wow! action recognizes a regular expression if it is
# preceded by ( or , or =.
def action(a)
  if a == 1
    $stdout.write $the_a
  end
  if [1, 2].include?(a)
    $the_a = $the_b
    if ["\'", "\""].include?($the_a)
      while (true)
        $stdout.write $the_a
        $the_a = get
        break if $the_a == $the_b
        raise "Unterminated string literal" if $the_a <= "\n"
        if $the_a == "\\"
          $stdout.write $the_a
          $the_a = get
        end
      end
    end
  end
  if (1..3).include?(a)
    $the_b = mynext
    if $the_b == "/" && %w[( , = : \[ ! & | ? { } ; \n].include?($the_a)
      $stdout.write $the_a
      $stdout.write $the_b
      while true
        $the_a = get
        if $the_a == "/"
          break
        elsif $the_a == "\\"
          $stdout.write $the_a
          $the_a = get
        elsif $the_a <= "\n"
          raise "Unterminated RegExp Literal"
        end
        $stdout.write $the_a
      end
      $the_b = mynext
    end
  end
end

# jsmin -- Copy the input to the output, deleting the characters which are
# insignificant to JavaScript. Comments will be removed. Tabs will be
# replaced with spaces. Carriage returns will be replaced with linefeeds.
# Most spaces and linefeeds will be removed.
def jsmin
  $the_a = "\n"
  action(3)
  while $the_a != EOF
    case $the_a
    when " "
      is_alphanum?($the_b) ? action(1) : action(2)
    when "\n"
      case $the_b
      when "{", "[", "(", "+", "-"
        action(1)
      when " "
        action(3)
      else
        is_alphanum?($the_b) ? action(1) : action(2)
      end
    else
      case ($the_b)
      when " "
        is_alphanum?($the_a) ?  action(1) : action(3)
      when "\n"
        case $the_a
        when "}", "]", ")", "+", "-", "\"", "\\", "'", '"'
          action(1)
        else
          is_alphanum?($the_a) ?  action(1) : action(3)
        end
      else
        action(1)
      end
    end
  end
end

ARGV.each { |arg| $stdout.write "// #{arg}\n" }

jsmin