From e4817a48f568c0000a925d19e4885c87129908e8 Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Sun, 06 Dec 2015 18:21:35 -0500
Subject: tools/shpp.sh: New file

---
diff --git a/tools/shpp.sh b/tools/shpp.sh
new file mode 100755
index 0000000..c54c7b7
--- /dev/null
+++ b/tools/shpp.sh
@@ -0,0 +1,165 @@
+#!/bin/sh
+#
+# Shell command language preprocessor
+#
+# Copyright (C) 2015  Patrick "P. J." McDermott
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+set -u
+
+VERSION='0.1.0'
+FS="$(printf '\034')"
+
+die()
+{
+	local fmt="${1}"
+	shift 1
+
+	printf "shpp: ${fmt}\n" "${@}"
+	exit 2
+}
+
+preprocess()
+{
+	local vars="${1}"
+	local input="${2}"
+	local output="${3}"
+	local def=
+	local var=
+	local val=
+
+	# Open output file.
+	if [ "x${output}" = 'x-' ]; then
+		if ! exec 3>&1; then
+			die 'Cannot duplicate output file descriptor'
+		fi
+	else
+		if ! exec 3>"${outfile}~"; then
+			die 'Cannot open file "%s"' "${output}~"
+		fi
+	fi
+
+	IFS="${FS}"
+	for def in ${vars}; do
+		case "${def}" in
+			*=*)
+				var="${def%%=*}"
+				val="${def#*=}"
+				;;
+			*)
+				var="${def%%=*}"
+				val='true'
+				;;
+		esac
+		case "${var}" in
+			*[!A-Za-z0-9_]*)
+				error 'Invalid variable name "%s"' "${var}"
+				continue
+				;;
+			[0-9]*)
+				error 'Invalid variable name "%s"' "${var}"
+				continue
+				;;
+		esac
+		printf "%s='" "${var}" >&3
+		printf '%s' "${val}" | sed "s/'/'\\\\''/g" >&3
+		printf "'\n" >&3
+	done
+	unset IFS
+
+	# Read input file.
+	if ! cat "${input}" >&3; then
+		die 'Cannot read file "%s"' "${input}"
+	fi
+
+	# Close output file, make it executable, and set its name.
+	if ! [ "x${output}" = 'x-' ]; then
+		exec 3>&-
+		if ! mv "${output}~" "${output}"; then
+			die 'Cannot rename file to "%s"' "${output}"
+		fi
+	fi
+}
+
+usage()
+{
+	printf 'Usage: %s [option ...] <infile> [<outfile>]\n' "${0}"
+}
+
+help()
+{
+	usage
+	cat <<EOF
+Options:
+  -h                Display this information
+  -V                Display preprocessor version information
+  -D <var>[=<val>]  Predefine <var> as a variable with value <val> (default
+                    "true")
+EOF
+}
+
+version()
+{
+	cat <<EOF
+shpp ${VERSION}
+Copyright (C) 2015  Patrick "P. J." McDermott
+License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+EOF
+}
+
+main()
+{
+	local opt=
+	local vars=
+	local infile=
+	local outfile=
+
+	while getopts 'hVD:' opt; do
+		case "${opt}" in
+			'h')
+				help
+				exit
+				;;
+			'V')
+				version
+				exit
+				;;
+			'D')
+				vars="${vars}${OPTARG}${FS}"
+				;;
+		esac
+	done
+	shift $(($OPTIND - 1))
+
+	case ${#} in
+		1)
+			infile="${1}"
+			outfile='-'
+			;;
+		2)
+			infile="${1}"
+			outfile="${2}"
+			;;
+		*)
+			usage >&2
+			exit 1
+	esac
+
+	preprocess "${vars}" "${infile}" "${outfile}"
+}
+
+main "${@}"
--
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