reinit the tree, so we can have metadata

1 files changed, 212 insertions, 0 deletions

diff --git a/eclass/estack.eclass b/eclass/estack.eclass
new file mode 100644
index 000000000000..f548abf8c283
--- /dev/null
+++ b/eclass/estack.eclass
@@ -0,0 +1,212 @@
+# Copyright 1999-2017 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+# @ECLASS: estack.eclass
+# @MAINTAINER:
+# base-system@gentoo.org
+# @BLURB: stack-like value storage support
+# @DESCRIPTION:
+# Support for storing values on stack-like variables.
+
+if [[ -z ${_ESTACK_ECLASS} ]]; then
+
+# @FUNCTION: estack_push
+# @USAGE: <stack> [items to push]
+# @DESCRIPTION:
+# Push any number of items onto the specified stack.  Pick a name that
+# is a valid variable (i.e. stick to alphanumerics), and push as many
+# items as you like onto the stack at once.
+#
+# The following code snippet will echo 5, then 4, then 3, then ...
+# @CODE
+#		estack_push mystack 1 2 3 4 5
+#		while estack_pop mystack i ; do
+#			echo "${i}"
+#		done
+# @CODE
+estack_push() {
+	[[ $# -eq 0 ]] && die "estack_push: incorrect # of arguments"
+	local stack_name="_ESTACK_$1_" ; shift
+	eval ${stack_name}+=\( \"\$@\" \)
+}
+
+# @FUNCTION: estack_pop
+# @USAGE: <stack> [variable]
+# @DESCRIPTION:
+# Pop a single item off the specified stack.  If a variable is specified,
+# the popped item is stored there.  If no more items are available, return
+# 1, else return 0.  See estack_push for more info.
+estack_pop() {
+	[[ $# -eq 0 || $# -gt 2 ]] && die "estack_pop: incorrect # of arguments"
+
+	# We use the fugly _estack_xxx var names to avoid collision with
+	# passing back the return value.  If we used "local i" and the
+	# caller ran `estack_pop ... i`, we'd end up setting the local
+	# copy of "i" rather than the caller's copy.  The _estack_xxx
+	# garbage is preferable to using $1/$2 everywhere as that is a
+	# bit harder to read.
+	local _estack_name="_ESTACK_$1_" ; shift
+	local _estack_retvar=$1 ; shift
+	eval local _estack_i=\${#${_estack_name}\[@\]}
+	# Don't warn -- let the caller interpret this as a failure
+	# or as normal behavior (akin to `shift`)
+	[[ $(( --_estack_i )) -eq -1 ]] && return 1
+
+	if [[ -n ${_estack_retvar} ]] ; then
+		eval ${_estack_retvar}=\"\${${_estack_name}\[${_estack_i}\]}\"
+	fi
+	eval unset \"${_estack_name}\[${_estack_i}\]\"
+}
+
+# @FUNCTION: evar_push
+# @USAGE: <variable to save> [more vars to save]
+# @DESCRIPTION:
+# This let's you temporarily modify a variable and then restore it (including
+# set vs unset semantics).  Arrays are not supported at this time.
+#
+# This is meant for variables where using `local` does not work (such as
+# exported variables, or only temporarily changing things in a func).
+#
+# For example:
+# @CODE
+#		evar_push LC_ALL
+#		export LC_ALL=C
+#		... do some stuff that needs LC_ALL=C set ...
+#		evar_pop
+#
+#		# You can also save/restore more than one var at a time
+#		evar_push BUTTERFLY IN THE SKY
+#		... do stuff with the vars ...
+#		evar_pop     # This restores just one var, SKY
+#		... do more stuff ...
+#		evar_pop 3   # This pops the remaining 3 vars
+# @CODE
+evar_push() {
+	local var val
+	for var ; do
+		[[ ${!var+set} == "set" ]] \
+			&& val=${!var} \
+			|| val="unset_76fc3c462065bb4ca959f939e6793f94"
+		estack_push evar "${var}" "${val}"
+	done
+}
+
+# @FUNCTION: evar_push_set
+# @USAGE: <variable to save> [new value to store]
+# @DESCRIPTION:
+# This is a handy shortcut to save and temporarily set a variable.  If a value
+# is not specified, the var will be unset.
+evar_push_set() {
+	local var=$1
+	evar_push ${var}
+	case $# in
+	1) unset ${var} ;;
+	2) printf -v "${var}" '%s' "$2" ;;
+	*) die "${FUNCNAME}: incorrect # of args: $*" ;;
+	esac
+}
+
+# @FUNCTION: evar_pop
+# @USAGE: [number of vars to restore]
+# @DESCRIPTION:
+# Restore the variables to the state saved with the corresponding
+# evar_push call.  See that function for more details.
+evar_pop() {
+	local cnt=${1:-bad}
+	case $# in
+	0) cnt=1 ;;
+	1) isdigit "${cnt}" || die "${FUNCNAME}: first arg must be a number: $*" ;;
+	*) die "${FUNCNAME}: only accepts one arg: $*" ;;
+	esac
+
+	local var val
+	while (( cnt-- )) ; do
+		estack_pop evar val || die "${FUNCNAME}: unbalanced push"
+		estack_pop evar var || die "${FUNCNAME}: unbalanced push"
+		[[ ${val} == "unset_76fc3c462065bb4ca959f939e6793f94" ]] \
+			&& unset ${var} \
+			|| printf -v "${var}" '%s' "${val}"
+	done
+}
+
+# @FUNCTION: eshopts_push
+# @USAGE: [options to `set` or `shopt`]
+# @DESCRIPTION:
+# Often times code will want to enable a shell option to change code behavior.
+# Since changing shell options can easily break other pieces of code (which
+# assume the default state), eshopts_push is used to (1) push the current shell
+# options onto a stack and (2) pass the specified arguments to set.
+#
+# If the first argument is '-s' or '-u', we assume you want to call `shopt`
+# rather than `set` as there are some options only available via that.
+#
+# A common example is to disable shell globbing so that special meaning/care
+# may be used with variables/arguments to custom functions.  That would be:
+# @CODE
+#		eshopts_push -o noglob
+#		for x in ${foo} ; do
+#			if ...some check... ; then
+#				eshopts_pop
+#				return 0
+#			fi
+#		done
+#		eshopts_pop
+# @CODE
+eshopts_push() {
+	if [[ $1 == -[su] ]] ; then
+		estack_push eshopts "$(shopt -p)"
+		[[ $# -eq 0 ]] && return 0
+		shopt "$@" || die "${FUNCNAME}: bad options to shopt: $*"
+	else
+		estack_push eshopts "$(shopt -p -o)"
+		[[ $# -eq 0 ]] && return 0
+		set "$@" || die "${FUNCNAME}: bad options to set: $*"
+	fi
+}
+
+# @FUNCTION: eshopts_pop
+# @USAGE:
+# @DESCRIPTION:
+# Restore the shell options to the state saved with the corresponding
+# eshopts_push call.  See that function for more details.
+eshopts_pop() {
+	local s
+	estack_pop eshopts s || die "${FUNCNAME}: unbalanced push"
+	eval "${s}" || die "${FUNCNAME}: sanity: invalid shopt options: ${s}"
+}
+
+# @FUNCTION: eumask_push
+# @USAGE: <new umask>
+# @DESCRIPTION:
+# Set the umask to the new value specified while saving the previous
+# value onto a stack.  Useful for temporarily changing the umask.
+eumask_push() {
+	estack_push eumask "$(umask)"
+	umask "$@" || die "${FUNCNAME}: bad options to umask: $*"
+}
+
+# @FUNCTION: eumask_pop
+# @USAGE:
+# @DESCRIPTION:
+# Restore the previous umask state.
+eumask_pop() {
+	[[ $# -eq 0 ]] || die "${FUNCNAME}: we take no options"
+	local s
+	estack_pop eumask s || die "${FUNCNAME}: unbalanced push"
+	umask ${s} || die "${FUNCNAME}: sanity: could not restore umask: ${s}"
+}
+
+# @FUNCTION: isdigit
+# @USAGE: <number> [more numbers]
+# @DESCRIPTION:
+# Return true if all arguments are numbers.
+isdigit() {
+	local d
+	for d ; do
+		[[ ${d:-bad} == *[!0-9]* ]] && return 1
+	done
+	return 0
+}
+
+_ESTACK_ECLASS=1
+fi #_ESTACK_ECLASS