#!/usr/bin/ruby

class List
  def initialize( list )
    @list = list
  end

  def print_list
    @list.each {|elm| print elm, " "}
    print "\n"
  end

  def delete( element )
    @list.delete( element )
  end

  def add_elm( element )
    @list.push( element )
  end

  def move( src, dest )
    @list.delete( src )
    if ((i = @list.index( dest )) != nil)
      @list = @list[0...i].push( src ) + @list[i..@list.size]
    end
  end

  def insert( src, dest )
    if ((i = @list.index( dest )) != nil)
      @list = @list[0...i].push( src ) + @list[i..@list.size]
    end
  end
end

a = List.new( ["apple", "orange", "banana", "grape"] ) 	# original list
print "original list:\n"
a.print_list

a.delete("banana")					# delete element
print "remove \"banana\":\n"
a.print_list

a.move("grape", "apple")				# move element
print "move \"grape\", before \"apple\":\n"
a.print_list

a.insert("plum", "orange")				# insert element
print "insert \"plum\" before \"orange\":\n"
a.print_list