dev-python/pycparser: Enforce regenerating tables

Remove the pregenerated tables provided in the distfile to force
regenerating them. Generate the tables for every Python implementation
separately to avoid incompatibility/underoptimization problems (tables
built by Python 3.5+ are incompatible with older Python versions that
have 100 group-in-regex limit).

dev-python/pycparser/pycparser-2.18-r1.ebuild

@@ -0,0 +1,48 @@
+# Copyright 1999-2017 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=6
+
+PYTHON_COMPAT=( python2_7 python3_{4,5,6} pypy pypy3 )
+
+inherit distutils-r1
+
+DESCRIPTION="C parser and AST generator written in Python"
+HOMEPAGE="https://github.com/eliben/pycparser"
+SRC_URI="mirror://pypi/${PN:0:1}/${PN}/${P}.tar.gz"
+
+LICENSE="BSD"
+SLOT="0"
+KEYWORDS="~alpha ~amd64 ~arm ~arm64 ~hppa ~ia64 ~m68k ~mips ~ppc ~ppc64 ~s390 ~sh ~sparc ~x86 ~x64-cygwin ~x86-fbsd ~amd64-linux ~x86-linux ~ppc-macos ~x64-macos ~x86-macos ~sparc-solaris ~x64-solaris"
+IUSE="test"
+
+RDEPEND="dev-python/ply[${PYTHON_USEDEP}]"
+DEPEND="${RDEPEND}
+	dev-python/setuptools[${PYTHON_USEDEP}]
+	test? ( dev-python/nose[${PYTHON_USEDEP}] )"
+
+python_prepare_all() {
+	# remove the original files to guarantee their regen
+	rm pycparser/{c_ast,lextab,yacctab}.py || die
+
+	# kill sys.path manipulations to force the tests to use built files
+	sed -i -e '/sys\.path/d' tests/*.py || die
+
+	distutils-r1_python_prepare_all
+}
+
+python_compile() {
+	distutils-r1_python_compile
+
+	# note: tables built by py3.5+ are incompatible with older versions
+	# because of 100 group limit of 're' module -- just generate them
+	# separately optimized for each target instead
+	pushd "${BUILD_DIR}"/lib/pycparser > /dev/null || die
+	"${PYTHON}" _build_tables.py || die
+	popd > /dev/null || die
+}
+
+python_test() {
+	# change workdir to avoid '.' import
+	nosetests -v -w tests || die
+}