#!/bin/bash
  
  # Copyright 2012  Johns Hopkins University (Author: Daniel Povey);
  #                 Arnab Ghoshal, Karel Vesely
  
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #  http://www.apache.org/licenses/LICENSE-2.0
  #
  # THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  # KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
  # WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
  # MERCHANTABLITY OR NON-INFRINGEMENT.
  # See the Apache 2 License for the specific language governing permissions and
  # limitations under the License.
  
  
  # Parse command-line options.
  # To be sourced by another script (as in ". parse_options.sh").
  # Option format is: --option-name arg
  # and shell variable "option_name" gets set to value "arg."
  # The exception is --help, which takes no arguments, but prints the
  # $help_message variable (if defined).
  
  
  ###
  ### The --config file options have lower priority to command line
  ### options, so we need to import them first...
  ###
  
  # Now import all the configs specified by command-line, in left-to-right order
  for ((argpos=1; argpos<$#; argpos++)); do
    if [ "${!argpos}" == "--config" ]; then
      argpos_plus1=$((argpos+1))
      config=${!argpos_plus1}
      [ ! -r $config ] && echo "$0: missing config '$config'" && exit 1
      . $config  # source the config file.
    fi
  done
  
  
  ###
  ### Now we process the command line options
  ###
  while true; do
    [ -z "${1:-}" ] && break;  # break if there are no arguments
    case "$1" in
      # If the enclosing script is called with --help option, print the help
      # message and exit.  Scripts should put help messages in $help_message
      --help|-h) if [ -z "$help_message" ]; then echo "No help found." 1>&2;
        else printf "$help_message
  " 1>&2 ; fi;
        exit 0 ;;
      --*=*) echo "$0: options to scripts must be of the form --name value, got '$1'"
        exit 1 ;;
      # If the first command-line argument begins with "--" (e.g. --foo-bar),
      # then work out the variable name as $name, which will equal "foo_bar".
      --*) name=`echo "$1" | sed s/^--// | sed s/-/_/g`;
        # Next we test whether the variable in question is undefned-- if so it's
        # an invalid option and we die.  Note: $0 evaluates to the name of the
        # enclosing script.
        # The test [ -z ${foo_bar+xxx} ] will return true if the variable foo_bar
        # is undefined.  We then have to wrap this test inside "eval" because
        # foo_bar is itself inside a variable ($name).
        eval '[ -z "${'$name'+xxx}" ]' && echo "$0: invalid option $1" 1>&2 && exit 1;
  
        oldval="`eval echo \\$$name`";
        # Work out whether we seem to be expecting a Boolean argument.
        if [ "$oldval" == "true" ] || [ "$oldval" == "false" ]; then
          was_bool=true;
        else
          was_bool=false;
        fi
  
        # Set the variable to the right value-- the escaped quotes make it work if
        # the option had spaces, like --cmd "queue.pl -sync y"
        eval $name=\"$2\";
  
        # Check that Boolean-valued arguments are really Boolean.
        if $was_bool && [[ "$2" != "true" && "$2" != "false" ]]; then
          echo "$0: expected \"true\" or \"false\": $1 $2" 1>&2
          exit 1;
        fi
        shift 2;
        ;;
    *) break;
    esac
  done
  
  
  # Check for an empty argument to the --cmd option, which can easily occur as a
  # result of scripting errors.
  [ ! -z "${cmd+xxx}" ] && [ -z "$cmd" ] && echo "$0: empty argument to --cmd option" 1>&2 && exit 1;
  
  
  true; # so this script returns exit code 0.