Powershell-flavored command line argument parser

ps_getopt.sh

#!/bin/bash
#
# Powershell-flavored command line argument parser.
#
# See ps_getopt_sample.sh for usage.
# <https://gist.github.com/gocha/8c74f9724bfb9c1e3a98b28bd5cceddc>
#
# License: Unlicensed

declare -A params

#######################################
# Output error message to STDERR
# Globals:
#   None
# Arguments:
#   Message
# Returns:
#   None
#######################################
ps_getopt::error() {
  echo "$(basename $0): $@" >&2
}

#######################################
# Return whether the elements contain the specified value
# Globals:
#   None
# Arguments:
#   $1  value to compare the elements to
#   ... the elements to examine
# Returns:
#   0   element is found
#   1   no such element is found
#######################################
ps_getopt::elementIn() {
  local e match="$1"
  shift

  for e; do
    [[ "$e" == "$match" ]] && return 0
  done
  return 1
}

#######################################
# Parse command line arguments
# Globals:
#   params                [out] the hash table to store the parameters
# Arguments:
#   $1  [in] the global array symbol for the name of all acceptable parameters (ALL_PARAMS[@])
#   $2  [in] the global array symbol for the name of positional parameters (ORDINAL_PARAMS[@])
#   $3  [in] the global array symbol for the name of mandatory parameters (MANDATORY_PARAMS[@])
#   $4  [in] the global array symbol for the name of parameters which allows an empty string (EMPTY_ALLOWED_PARAMS[@])
#   $5  [in] the global array symbol for the name of switch (boolean) parameters (SWITCH_TYPE_PARAMS[@])
#   ... the command line arguments
# Returns:
#   0   upon success
#   1   on error
#######################################
ps_getopt() {
  if [ $# -lt 5 ]; then
    # 引数が少なすぎます。
    error "ps_getopt: Too few arguments."
    return 1
  fi

  local all_params=$1
  local ordinal_params=$2
  local mandatory_params=$3
  local empty_allowed_params=$4
  local switch_type_params=$5
  shift 5

  params=()
  while [[ $# -ne 0 ]]; do
    local arg=$1

    local param_name=""
    if [[ "${arg:0:1}" = "-" ]]; then
      param_name=${arg:1}
      shift
    else
      # Find the first parameter that is not binded yet.
      for name in ${!ordinal_params}; do
        if [[ -z "${params[${name}]}" ]]; then
          param_name=${name}
          break
        fi
      done

      if [[ -z "${param_name}" ]]; then
        # 引数 '${arg}' を受け入れる位置指定パラメーターが見つかりません。
        ps_getopt::error "A positional parameter cannot be found that accepts argument '${arg}'."
        return 1
      fi
    fi

    if ! ps_getopt::elementIn "${param_name}" "${!all_params}"; then
      # パラメーター名 '${param_name}' に一致するパラメーターが見つかりません。
      ps_getopt::error "A parameter cannot be found that matches parameter name '${param_name}'."
      return 1
    fi

    if [[ ! -z "${params[${param_name}]}" ]]; then
      # パラメーター '${param_name}' が複数回指定されているため、パラメーターをバインドできません。
      ps_getopt::error "Cannot bind parameter because parameter '${param_name}' is specified more than once."
      return 1
    fi

    if ps_getopt::elementIn "${param_name}" "${!switch_type_params}"; then
      params[${param_name}]="true"
    else
      if ! ps_getopt::elementIn "${param_name}" "${!empty_allowed_params}"; then
        if [[ -z "$1" ]]; then
          # 引数が空の文字列であるため、パラメーター '${param_name}' にバインドできません。
          ps_getopt::error "Cannot bind argument to parameter '${param_name}' because it is null."
          return 1
        fi
      fi

      params[${param_name}]=$1
      shift
    fi
  done

  local first_prompt="true"
  for name in "${!mandatory_params}"; do
    if ! ps_getopt::elementIn "${name}" "${!params[@]}"; then
      if [[ ! -z "${first_prompt}" ]]; then
        # 次のパラメーターに値を指定してください:
        echo "Supply values for the following parameters:" >&2
        unset first_prompt
      fi

      read -p "${name}: " 'params[${name}]'
      if ! ps_getopt::elementIn "${name}" "${!empty_allowed_params}"; then
        if [[ -z "${params[${name}]}" ]]; then
          # 引数が空の文字列であるため、パラメーター '${name}' にバインドできません。
          ps_getopt::error "Cannot bind argument to parameter '${name}' because it is null."
          return 1
        fi
      fi
    fi
  done
  [[ -z "${first_prompt}" ]] && echo

  return 0
}