llvm.eselect

# Copyright 2020-2022 Fabian Dreer
# Distributed under the terms of the GNU General Public License v2
# $Id: $

DESCRIPTION="Manage multiple installed llvm versions"
MAINTAINER="Fabian Dreer <infrasonics@gmx.de>"
VERSION=20220206

inherit config

# env.d file with higher priority to get the the selected version earlier into
# PATH
#
# sys-devel/llvm:9 installs the file /etc/env.d/10llvm-9990
ENVDLLVMFILE="${EROOT}/etc/env.d/09llvm"

# convert from an id (e.g. llvm-10) to its path set in its env.d file
id2path() {
	local id="${1/-//}"
	local paths=( $(find_paths) )
	for p in "${paths[@]}"; do
		if [[ "${p}" == *"${id}"* ]];then
			echo "${p}"
			break
		else continue
		fi
	done
}

# convert an llvm path to an identifier for display
path2id() {
	# Use a greedy match to only keep the last one in case EROOT contains "llvm/X"
	# Use `-E` for POSIX portability
	echo $(echo "${1}" | sed -Ee 's/^.*(llvm\/[[:digit:]]+)\/.*/\1/' | tr '/' '-')
}

# List all available llvm directories
find_paths() {
	local llvms=( $(for p in "${EROOT}"/etc/env.d/?0llvm*; do
		load_config "${p}" "PATH"
	done) )

	echo "${llvms[*]}"
}

# Find the file containing the given PATH value
find_file_by_path() {
	local wanted="${1}"
	for file in "${EROOT}"/etc/env.d/?0llvm*; do
		path=$(load_config "${file}" "PATH")
		if [[ "${1}" = "${path}" ]];then
			echo "${file}"
			break
		else continue
		fi
	done
}

find_targets() {
	# There should be no need to canonicalise links from env.d entries.
	# But make a nicer target name.
	for t in $(find_paths); do
		echo $(path2id "${t}")
	done
}

check_target() {
	local target=${1} targets
	targets=( $(find_targets) )

	# number from the list
	if is_number ${target} && [[ ${target} -ge 1 ]] ; then
		if [[ ${target} -gt ${#targets[@]} ]] ; then
			target="invalid"
		elif [[ -d $( id2path "${targets[$(( ${target} - 1 ))]}") ]] ; then
			target="$(id2path ${targets[$((${target} - 1 ))]} )"
		else
			write_warning_msg "${targets[$((${target} - 1 ))]}"
			target="invalid"
		fi
	elif [[ -d "$(id2path ${target})" ]]; then
			target="$(id2path ${target})"
	else
			target="invalid"
	fi

	echo "${target}"
}

# Takes a full target path, finds the corresponding llvm file in env.d and
# creates a link to it in order to overwrite the usage order in PATH
update_env() {
	local target="${1}"
	local file="$(find_file_by_path ${target})"

	# In case it's not a symlink, save the file and overwrite
	if [[ ! -L ${ENVDLLVMFILE} ]];then
		cp "${ENVDLLVMFILE}" "${ENVDLLVMFILE}.bak"
		write_warning_msg "Unexpected file \"${ENVDLLVMFILE}\""\
			"has been moved to \"${ENVDLLVMFILE}.bak\""
	fi
	ln -sf "${file}" "${ENVDLLVMFILE}"
}


### list action
describe_list() {
	echo "List all installed versions of llvm"
}

do_list() {
	local targets=( $(find_targets) )
	local paths=( $(find_paths) )
	local cur=$(load_config ${ENVDLLVMFILE} "PATH")

	# This should not happen
	if [[ ${#targets[@]} -ne ${#paths[@]} ]] ; then
		die -q "#targets != #possible paths; this is possibly a bug"
	fi

	for (( i = 0; i < ${#targets[@]}; i++ )) ; do
		line="${targets[i]}"

		# find out the current version
		if [[ "${cur}" = "$(id2path ${targets[i]})" ]] ; then
			targets[i]=$(highlight_marker "${line}")
		else
			targets[i]=${line}
		fi
	done

	write_numbered_list -m "(none found)" "${targets[@]}"
}


### set action ###
describe_set() {
	echo "Switches to an llvm profile"
}

describe_set_options() {
	echo "target : Target name or number (from 'list' action)"
}

describe_set_parameters() {
	echo "<target>"
}

do_set() {
	[[ -z ${@} ]] && die -q "Parameter expected."

	local target=$(check_target ${1})

	if [[ ! -f "$ENVDLLVMFILE" ]] ; then
		touch "$ENVDLLVMFILE"
	fi

	if [[ ${target} = "invalid" ]] ; then
		die -q "Can't use that profile. No suitable LLVM version found."
	fi

	update_env "${target}" || die -q "Could not update env file"
}


### show action
describe_show() {
	echo "Print the currently active llvm version"
}


do_show() {
	if [[ -n "${@}" ]] ; then
		die -q "This function does not expect any arguments"
	fi

	local version=""

	if [[ -L "${ENVDLLVMFILE}" ]] ; then
		version=$(path2id $(load_config "${ENVDLLVMFILE}" "PATH") )
	else
		write_kv_list_entry "(none)"
		return 1
	fi
	write_list_start "Current llvm version:"
	write_kv_list_entry ${version} ""
}

# vim: ts=4 sw=4 noet fdm=marker