ninja-utils.eclass: Add a new eclass to handle calling ninja

eclass/ninja-utils.eclass

@@ -0,0 +1,57 @@
+# Copyright 1999-2017 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+# @ECLASS: ninja-utils.eclass
+# @MAINTAINER:
+# Michał Górny <mgorny@gentoo.org>
+# Mike Gilbert <floppym@gentoo.org>
+# @AUTHOR:
+# Michał Górny <mgorny@gentoo.org>
+# Mike Gilbert <floppym@gentoo.org>
+# @BLURB: common bits to run dev-util/ninja builder
+# @DESCRIPTION:
+# This eclass provides a single function -- eninja -- that can be used
+# to run the ninja builder alike emake. It does not define any
+# dependencies, you need to depend on dev-util/ninja yourself. Since
+# ninja is rarely used stand-alone, most of the time this eclass will
+# be used indirectly by the eclasses for other build systems (CMake,
+# Meson).
+
+if [[ -z ${_NINJA_UTILS_ECLASS} ]]; then
+
+case ${EAPI:-0} in
+	0|1|3) die "EAPI=${EAPI:-0} is not supported (too old)";;
+	# copied from cmake-utils
+	2|4|5|6) ;;
+	*) die "EAPI=${EAPI} is not yet supported" ;;
+esac
+
+# @ECLASS-VARIABLE: NINJAOPTS
+# @DEFAULT_UNSET
+# @DESCRIPTION:
+# The default set of options to pass to Ninja. Similar to MAKEOPTS,
+# supposed to be set in make.conf. If unset, eninja() will convert
+# MAKEOPTS instead.
+
+inherit multiprocessing
+
+# @FUNCTION: eninja
+# @USAGE: [<args>...]
+# @DESCRIPTION:
+# Call Ninja, passing the NINJAOPTS (or converted MAKEOPTS), followed
+# by the supplied arguments. This function dies if ninja fails. Starting
+# with EAPI 6, it also supports being called via 'nonfatal'.
+eninja() {
+	local nonfatal_args=()
+	[[ ${EAPI:-0} != [245] ]] && nonfatal_args+=( -n )
+
+	if [[ -z ${NINJAOPTS+set} ]]; then
+		NINJAOPTS="-j$(makeopts_jobs) -l$(makeopts_loadavg "${MAKEOPTS}" 0)"
+	fi
+	set -- ninja -v ${NINJAOPTS} "$@"
+	echo "$@" >&2
+	"$@" || die "${nonfatal_args[@]}" "${*} failed"
+}
+
+_NINJA_UTILS_ECLASS=1
+fi