jsminlib.rb

# jsminlib.rb 2007-12-29
# Author: David Troy <dave@popvox.com>
# Based directly on jsmin.rb by Uladzislau Latynski
# Converted to use the JSMin class and the minimize method rathert han
# stdin/stdout
#
# 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.

class JSMin
  EOF = -1

  # isAlphanum -- return true if the character is a letter, digit, underscore,
  # dollar sign, or non-ASCII character
  def self.isAlphanum(c)
     return false if !c || c == JSMin::EOF
     return ((c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') ||
             (c >= 'A' && c <= 'Z') || c == '_' || c == '$' ||
             c == '\\' || 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 self.get()
    return JSMin::EOF if @@current>(@@text.length-1)
    c = @@text[@@current]
    @@current += 1
    c = c.chr
    return c if (c >= " " || c == "\n" || c.unpack("c") == JSMin::EOF)
    return "\n" if (c == "\r")
    return " "
  end

  # Get the next character without getting it.
  def self.peek()
      lookaheadChar = @@text[@@current]
      return lookaheadChar.chr
  end

  # mynext -- get the next character, excluding comments.
  # peek() is used to see if a '/' is followed by a '/' or '*'.
  def self.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 JSMin::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 self.action(a)
      if(a==1)
          @@output << @@theA
      end
      if(a==1 || a==2)
          @@theA = @@theB
          if (@@theA == "\'" || @@theA == "\"")
              while (true)
                  @@output << @@theA
                  @@theA = get
                  break if (@@theA == @@theB)
                  raise "Unterminated string literal" if (@@theA <= "\n")
                  if (@@theA == "\\")
                      @@output << @@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 << @@theA
              @@output << @@theB
              while (true)
                  @@theA = get
                  if (@@theA == "/")
                      break
                  elsif (@@theA == "\\")
                      @@output << @@theA
                      @@theA = get
                  elsif (@@theA <= "\n")
                      raise "Unterminated RegExp Literal" + @@output
                  end
                  @@output << @@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 self.minimize(jstext)
      @@theA = ""
      @@theB = ""
      @@current = 0
      @@output = ""

      @@text = jstext
      @@theA = "\n"
      action(3)
      while (@@theA != JSMin::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
      @@output
  end

end