eclass/app-alternatives: Import from Gentoo and allow EAPI 7
Upstream added this eclass to handle alternatives. Since we don't
support EAPI=8 yet, patch this to allow EAPI 7.
BUG=b:268247620
TEST=emerge-${BOARD} app-alternatives/yacc
Cq-Depend: chromium:4233878
Change-Id: I544f4516481477e854a147838f7862e2e3017700
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/eclass-overlay/+/4234219
Tested-by: Allen Webb <allenwebb@google.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Allen Webb <allenwebb@google.com>
diff --git a/eclass/app-alternatives.eclass b/eclass/app-alternatives.eclass
new file mode 100644
index 0000000..aa33d2d
--- /dev/null
+++ b/eclass/app-alternatives.eclass
@@ -0,0 +1,84 @@
+# Copyright 2022 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+# @ECLASS: app-alternatives.eclass
+# @MAINTAINER:
+# Michał Górny <mgorny@gentoo.org>
+# @AUTHOR:
+# Michał Górny <mgorny@gentoo.org>
+# @SUPPORTED_EAPIS: 7 8
+# @BLURB: Common logic for app-alternatives/*
+# @DESCRIPTION:
+# This eclass provides common logic shared by app-alternatives/*
+# ebuilds. A global ALTERNATIVES variable needs to be declared
+# that lists available options and their respective dependencies.
+# HOMEPAGE, S, LICENSE, SLOT, IUSE, REQUIRED_USE and RDEPEND are set.
+# A get_alternative() function is provided that determines the selected
+# alternative and prints its respective flag name.
+
+case ${EAPI} in
+ 7|8) ;;
+ *) die "${ECLASS}: EAPI ${EAPI:-0} unsupported."
+esac
+
+if [[ ! ${_APP_ALTERNATIVES_ECLASS} ]]; then
+_APP_ALTERNATIVES_ECLASS=1
+
+# @ECLASS_VARIABLE: ALTERNATIVES
+# @PRE_INHERIT
+# @REQUIRED
+# @DESCRIPTION:
+# Array of "flag:dependency" pairs specifying the available
+# alternatives. The default provider must be listed first.
+
+# @FUNCTION: _app-alternatives_set_globals
+# @INTERNAL
+# @DESCRIPTION:
+# Set ebuild metadata variables.
+_app-alternatives_set_globals() {
+ debug-print-function ${FUNCNAME} "${@}"
+
+ if [[ ${ALTERNATIVES@a} != *a* ]]; then
+ die 'ALTERNATIVES must be an array.'
+ elif [[ ${#ALTERNATIVES[@]} -eq 0 ]]; then
+ die 'ALTERNATIVES must not be empty.'
+ fi
+
+ HOMEPAGE="https://wiki.gentoo.org/wiki/Project:Base/Alternatives"
+ S=${WORKDIR}
+
+ LICENSE="CC0-1.0"
+ SLOT="0"
+
+ # yep, that's a cheap hack adding '+' to the first flag
+ IUSE="+${ALTERNATIVES[*]%%:*}"
+ REQUIRED_USE="^^ ( ${ALTERNATIVES[*]%%:*} )"
+ RDEPEND=""
+
+ local flag dep
+ for flag in "${ALTERNATIVES[@]}"; do
+ [[ ${flag} != *:* ]] && die "Invalid ALTERNATIVES item: ${flag}"
+ dep=${flag#*:}
+ flag=${flag%%:*}
+ RDEPEND+="
+ ${flag}? ( ${dep} )
+ "
+ done
+}
+_app-alternatives_set_globals
+
+# @FUNCTION: get_alternative
+# @DESCRIPTION:
+# Get the flag name for the selected alternative (i.e. the USE flag set).
+get_alternative() {
+ debug-print-function ${FUNCNAME} "${@}"
+
+ local flag
+ for flag in "${ALTERNATIVES[@]%%:*}"; do
+ usev "${flag}" && return
+ done
+
+ die "No selected alternative found (REQUIRED_USE ignored?!)"
+}
+
+fi
