initial importshlib

1 files changed, 166 insertions, 0 deletions

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+#!/bin/bash
+# a schemaless argument parser
+
+# this file is licensed under any of the following SPDX licenses
+# to be chosen by the user:
+# * 0BSD (https://spdx.org/licenses/0BSD.html)
+# * BlueOak-1.0.0 (https://blueoakcouncil.org/license/1.0.0)
+# * CC0-1.0 (https://creativecommons.org/publicdomain/zero/1.0/)
+# * Unlicense (https://unlicense.org/)
+
+# things you can do with it:
+# -fval | -f=val | -f val: set "f" to "val"
+# --foo=val | --foo val: set "foo" to "val"
+# @oval | @o=val | @o val: add "val" to the "o" array
+# @@opt=val | @@opt val: add "val" to the "opt" array
+# --: stop parsing options, put the rest into $@
+
+# you may have noticed:
+# * there are no booleans, long or short. you can emulate them by =yes|no, or have a dedicated options|o array.
+# * you cannot reset arrays: you actually can, by using -oval and --opt=val, but you can never make them empty
+
+# something you may not notice without reading the code:
+# * values may contain spaces, but may *not* contain literal 's, arg names may not contain spaces, which will break horribly
+# * this leaks __die(), __verify(), and $__options. Technically also parse().
+# * this is not compatible with numerical args, like -9
+
+# reading notes:
+# let NUM is true if num > 0
+# this is the same as (( NUM ))
+
+# usage:
+# 1. save this to some file (let's say ./args.bash)
+# 2. optionally, define default values for any of your arguments
+# 3. optionally, define any namerefs to have long/short variants (e.g declare -n r=repo, which will make @r and @@repo the same)
+# 4. . ./args.bash "$@"
+
+__die() {
+	echo "$@" >&2
+	exit
+}
+
+# $1 is arg, $2 is val
+__verify() {
+	[[ ${1% *} != $1 ]] && __die "args may not contain spaces, but `$1` does"
+	[[ "${2%\'*}" != $2 ]] && __die "values may not contain 's, but `$2` does"
+	true
+}
+
+parse() {
+	declare one two val arg
+	declare -g __options
+
+	while let $#; do
+		arg="$1"
+		one="${arg::1}"
+		two="${arg::2}"
+		# needed because we check -v
+		unset val; declare val
+		shift
+
+		case "$arg" in
+		# literal --, stop processing options
+		--) __options+=("$@"); return ;;
+		# long option
+		--*)
+			# the arg without the --
+			arg=${arg:2}
+
+			# if there's a = in there, we know the value
+			if [[ ${arg%%=*} != $arg ]]; then
+				val=${arg#*=}
+				arg=${arg%%=*}
+			fi
+
+			# else, use the next arg
+			if [[ ! -v val ]]; then
+				let $# || __die "--$arg needs a value, found none"
+				val=$1
+				shift
+			fi
+
+			__verify "$arg" "$val"
+			eval $arg="'$val'"
+		;;
+		# short option
+		-*)
+			# the arg without the -
+			arg=${arg:1}
+
+			# we're dealing with -f=val
+			if [[ ${arg:1:1} = '=' ]]; then
+				val=${arg:2}
+				arg=${arg::1}
+			fi
+
+			# we haven't found an =, and there's space left - that must be the value
+			if [[ ! -v val ]] && (( ${#arg} > 1 )); then
+				val=${arg:1}
+				arg=${arg::1}
+			fi
+
+			# we still haven't found the value, use the next arg
+			if [[ ! -v val ]]; then
+				let $# || __die "-$arg needs a value, found none"
+				val=$1
+				shift
+			fi
+
+			__verify "$arg" "$val"
+			eval $arg="'$val'"
+		;;
+		# long array
+		@@*)
+			# the arg without the @@
+			arg=${arg:2}
+
+			# if there's a = in there, we know the value
+			if [[ ${arg%%=*} != $arg ]]; then
+				val=${arg#*=}
+				arg=${arg%%=*}
+			fi
+
+			# else, use the next arg
+			if [[ ! -v val ]]; then
+				let $# || __die "@@$arg needs a value, found none"
+				val=$1
+				shift
+			fi
+
+			__verify "$arg" "$val"
+			eval $arg+="('$val')"
+		;;
+		# short array
+		@*)
+			# the arg without the @
+			arg=${arg:1}
+
+			# we're dealing with @f=val
+			if [[ ${arg:1:1} = '=' ]]; then
+				val=${arg:2}
+				arg=${arg::1}
+			fi
+
+			# we haven't found an =, and there's space left - that must be the value
+			if [[ ! -v val ]] && (( ${#arg} > 1 )); then
+				val=${arg:1}
+				arg=${arg::1}
+			fi
+
+			# we still haven't found the value, use the next arg
+			if [[ ! -v val ]]; then
+				let $# || __die "@$arg needs a value, found none"
+				val=$1
+				shift
+			fi
+
+			__verify "$arg" "$val"
+			eval $arg+="('$val')"
+		;;
+		*) __options+=("$arg") ;;
+		esac
+	done
+}
+
+parse "$@"
+set -- "${__options[@]}"