# 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.

require 'stringio'

module AssetsBooster
  module Compiler
    class JSMin
            
      # class variables
      @@EOF = -1
      @@theA = ""
      @@theB = ""
      @@input = ""
      @@output = ""

      # singleton methods
      class << self
                
        def name
          "Douglas Crockford's JSMin"
        end
        
        def compile(incoming)
          @@output = StringIO.new("","w")
          if incoming.is_a? String
            @@input = StringIO.new(incoming,"r")
          elsif incoming.kind_of? IO
            @@input = incoming
          else 
            raise CompileError.new("JSMin can only compress strings or files.")
          end
          jsmin
          @@output.string
        end
      
      
        protected
          # isAlphanum -- return true if the character is a letter, digit, underscore,
          # dollar sign, or non-ASCII character
          def isAlphanum(c)
             return false if !c || c == @@EOF
             return ((c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') ||
                     (c >= 'A' && c <= 'Z') || c == '_' || c == '$' ||
                     c == '\\' || c[0].ord > 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 = @@input.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()
              lookaheadChar = @@input.getc
              @@input.ungetc(lookaheadChar)
              return lookaheadChar.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
                          if (c <= "\n")
                          return c
                          end
                      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)
                  @@output.write $theA
              end
              if(a==1 || a==2)
                  $theA = $theB
                  if ($theA == "\'" || $theA == "\"")
                      while (true)
                          @@output.write $theA
                          $theA = get
                          break if ($theA == $theB)
                          raise "Unterminated string literal" if ($theA <= "\n")
                          if ($theA == "\\")
                              @@output.write $theA
                              $theA = get
                          end
                      end
                  end
              end
              if(a==1 || a==2 || a==3)
                  $theB = mynext
                  if ($theB == "/" && ($theA == "(" || $theA == "," || $theA == "=" ||
                                       $theA == ":" || $theA == "[" || $theA == "!" ||
                                       $theA == "&" || $theA == "|" || $theA == "?" ||
                                       $theA == "{" || $theA == "}" || $theA == ";" ||
                                       $theA == "\n"))
                      @@output.write $theA
                      @@output.write $theB
                      while (true)
                          $theA = get
                          if ($theA == "/")
                              break
                          elsif ($theA == "\\")
                              @@output.write $theA
                              $theA = get
                          elsif ($theA <= "\n")
                              raise "Unterminated RegExp Literal"
                          end
                          @@output.write $theA
                      end
                      $theB = 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
              $theA = "\n"
              action(3)
              while ($theA != @@EOF)
                  case $theA
                  when " "
                      if (isAlphanum($theB))
                          action(1)
                      else
                          action(2)
                      end
                  when "\n"
                      case ($theB)
                      when "{","[","(","+","-"
                          action(1)
                      when " "
                          action(3)
                      else
                          if (isAlphanum($theB))
                              action(1)
                          else
                              action(2)
                          end
                      end
                  else
                      case ($theB)
                      when " "
                          if (isAlphanum($theA))
                              action(1)
                          else
                              action(3)
                          end
                      when "\n"
                          case ($theA)
                          when "}","]",")","+","-","\"","\\", "'", '"'
                              action(1)
                          else
                              if (isAlphanum($theA))
                                  action(1)
                              else
                                  action(3)
                              end
                          end
                      else
                          action(1)
                      end
                  end
              end
          end
      end
    end
  end
end