1 files changed, 176 insertions, 0 deletions
diff --git a/gbpm.sh b/gbpm.sh
new file mode 100755
index 0000000..50ff7a2
--- /dev/null
+++ b/gbpm.sh
@@ -0,0 +1,176 @@
+#!/usr/bin/env bash
+#
+# Copyright 2014 David Vazgenovich Shakaryan
+# Distributed under the terms of the MIT License.
+#
+# gbpm
+# https://git.potato.am/gbpm.git/
+# Manage multiple Python/Ruby/etc. installations with no black magic.
+#
+# Output must be executed: gbpm() { . <(/path/to/gbpm.sh "${@}"); }
+
+GBPM_VERSION='0.4'
+
+: ${GBPM_OPTS_PATH:="${HOME}/.pythons"}
+
+_echo() {
+	echo "echo '${@//\'/\'\\\'\'}'"
+}
+
+_export() {
+	echo "export PATH='${PATH//\'/\'\\\'\'}'"
+	echo 'hash -r'
+}
+
+_warn() {
+	echo "echo 'gbpm: ${@//\'/\'\\\'\'}' >&2"
+}
+
+_die() {
+	[[ -n "${@}" ]] && _warn "${@}"
+
+	echo 'false'
+	exit 1
+}
+
+_populate_dirs() {
+	[[ -d "${GBPM_OPTS_PATH}" ]] \
+		|| _die "directory ${GBPM_OPTS_PATH} does not exist"
+
+	mapfile -td $'\0' dirs < <(shopt -s nullglob;
+		printf '%s\0' "${GBPM_OPTS_PATH}"/* | sort -zV)
+
+	[[ -n "${dirs}" ]] || _die "directory ${GBPM_OPTS_PATH} is empty"
+}
+
+_populate_selected() {
+	local dir dirs
+
+	mapfile -td : dirs < <(printf %s "${PATH}")
+
+	selected=()
+	for dir in "${dirs[@]}"; do
+		if [[ "${dir}" == "${GBPM_OPTS_PATH}/"* ]]; then
+			dir="${dir%/bin}"
+			selected+=("${dir##*/}")
+		fi
+	done
+
+	[[ "${#selected[@]}" -ne 0 ]] || return 1
+	[[ "${#selected[@]}" -eq 1 ]] \
+		|| _warn 'warning: multiple managed paths found in PATH'
+}
+
+_clear() {
+	local dir dirs cdirs
+
+	mapfile -td : dirs < <(printf %s "${PATH}")
+
+	for dir in "${dirs[@]}"; do
+		if [[ "${dir}" == "${GBPM_OPTS_PATH}/"* ]]; then
+			_echo "removing ${dir} from PATH"
+		else
+			cdirs+=("${dir}")
+		fi
+	done
+
+	[[ "${#cdirs[@]}" -ne "${#dirs[@]}" ]] || return 1
+
+	PATH="$(IFS=':'; echo "${cdirs[*]}")"
+}
+
+_add() {
+	_echo "adding ${1}/bin to PATH"
+
+	PATH="${1}/bin:${PATH}"
+}
+
+cmd_ls() {
+	local dir dirs selected str
+
+	_populate_dirs
+	_populate_selected
+
+	for dir in "${dirs[@]}"; do
+		str="  ${dir##*/}"
+
+		[[ "${dir##*/}" == "${selected}" ]] && str="${str/ /*}"
+
+		_echo "${str}"
+	done
+}
+
+cmd_get() {
+	local dir selected
+
+	_populate_selected || _die 'no managed path found in PATH'
+
+	for dir in "${selected[@]}"; do
+		_echo "${dir}"
+	done
+}
+
+cmd_set() {
+	[[ -n "${1}" ]] || _die 'set command requires an argument'
+
+	local dir dirs match match_start
+
+	_populate_dirs
+
+	for dir in "${dirs[@]}"; do
+		[[ "${dir##*/}" == *"${1}"* ]] || continue
+
+		match="${dir}"
+
+		# match from start of version is preferred. we assume the
+		# version is at the beginning of the directory name or
+		# immediately following a hyphen. this avoids unintuitive
+		# behaviour like `2.1' matching `3.2.1' over `2.1.0'.
+		if [[ "${dir##*/}" == "${1}"* ||
+			"${dir##*/}" == *-"${1}"* ]]; then
+			match_start="${dir}"
+		fi
+	done
+
+	[[ -n "${match}" ]] || _die 'no matching version found'
+	[[ -n "${match_start}" ]] && match="${match_start}"
+
+	_clear
+	_add "${match}"
+	_export
+}
+
+cmd_clear() {
+	_clear || _die 'no managed path found in PATH'
+	_export
+}
+
+cmd_version() {
+	_echo "gbpm ${GBPM_VERSION}"
+}
+
+cmd_help() {
+	_echo 'Usage: gbpm <command> [args]'
+	_echo
+	_echo 'Commands:'
+	_echo '  ls       List all available versions'
+	_echo '  get      Display currently selected version'
+	_echo '  set      Select specified version'
+	_echo '  clear    Unselect any selected versions'
+	_echo '  version  Display gbpm version'
+}
+
+case "${1}" in
+	'ls')
+		cmd_ls ;;
+	'get')
+		cmd_get ;;
+	'set')
+		cmd_set "${2}" ;;
+	'clear')
+		cmd_clear ;;
+	'version')
+		cmd_version ;;
+	*)
+		cmd_help ;;
+esac