class Gem::Platform

def initialize(arch)
  case arch
  when Array then
    @cpu, @os, @version = arch
  when String then
    arch = arch.split '-'
    if arch.length > 2 and arch.last !~ /\d/ then # reassemble x86-linux-gnu
      extra = arch.pop
      arch.last << "-#{extra}"
    end
    cpu = arch.shift
    @cpu = case cpu
           when /i\d86/ then 'x86'
           else cpu
           end
    if arch.length == 2 and arch.last =~ /^\d+(\.\d+)?$/ then # for command-line
      @os, @version = arch
      return
    end
    os, = arch
    @cpu, os = nil, cpu if os.nil? # legacy jruby
    @os, @version = case os
                    when /aix(\d+)?/ then             [ 'aix',       $1  ]
                    when /cygwin/ then                [ 'cygwin',    nil ]
                    when /darwin(\d+)?/ then          [ 'darwin',    $1  ]
                    when /^macruby$/ then             [ 'macruby',   nil ]
                    when /freebsd(\d+)?/ then         [ 'freebsd',   $1  ]
                    when /hpux(\d+)?/ then            [ 'hpux',      $1  ]
                    when /^java$/, /^jruby$/ then     [ 'java',      nil ]
                    when /^java([\d.]*)/ then         [ 'java',      $1  ]
                    when /^dalvik(\d+)?$/ then        [ 'dalvik',    $1  ]
                    when /^dotnet$/ then              [ 'dotnet',    nil ]
                    when /^dotnet([\d.]*)/ then       [ 'dotnet',    $1  ]
                    when /linux/ then                 [ 'linux',     $1  ]
                    when /mingw32/ then               [ 'mingw32',   nil ]
                    when /(mswin\d+)(\_(\d+))?/ then
                      os, version = $1, $3
                      @cpu = 'x86' if @cpu.nil? and os =~ /32$/
                      [os, version]
                    when /netbsdelf/ then             [ 'netbsdelf', nil ]
                    when /openbsd(\d+\.\d+)?/ then    [ 'openbsd',   $1  ]
                    when /bitrig(\d+\.\d+)?/ then     [ 'bitrig',    $1  ]
                    when /solaris(\d+\.\d+)?/ then    [ 'solaris',   $1  ]
                    # test
                    when /^(\w+_platform)(\d+)?/ then [ $1,          $2  ]
                    else                              [ 'unknown',   nil ]
                    end
  when Gem::Platform then
    @cpu = arch.cpu
    @os = arch.os
    @version = arch.version
  else
    raise ArgumentError, "invalid argument #{arch.inspect}"
  end
end