lambda

#!/bin/bash
#


# Check the existence of the function with the given name.
#
function lambda_function_exist {
	declare -f -F $1 > /dev/null
	return $?
}

# Applies the function ITERATEE (from 2nd argument) with rest arguments
# of this function to each item in the global variable referenced by
# 1st argument.
#
# For example, when the function `lamdba_foreach` is called as below
#
#	export AAA=(x y z)
#	lamdba_foreach AAA my_func aa bb cc
#
# Above function call equals to the combination of following function calls:
#
#	my_func x aa bb cc
#	my_func y aa bb cc
#	my_func z aa bb cc
#
# When non-zero value is returned from ITERATEE when applying to one item, 
# the rest items won't be applied and the function returns that non-zero 
# value to callee immediately.
#
#
# Global Variables for Behavior Changes:
#
#	- FOREACH_REVERSE_ORDER, indicates the order of items in FOREACH_LIST to apply apply function ITERATEE.
#		- false, (by default), use original order of items in FOREACH_LIST
#		- true, use reversed order of items in FOREACH_LIST
#
#	- FOREACH_IGNORE_ERROR, ignore all non-zero values when applying ITERATEE on any item.
#		- false (by default)
#		- true
#
function lamdba_foreach {
	local -n ITEMS=$1; shift
	[ "0" == "${#ITEMS[@]}" ] && return 0
	[ "" == "${ITEMS}" ] && return 1

	local ITERATEE=$1; shift
	[ "" == "${ITERATEE}" ] && return 2
	lambda_function_exist ${ITERATEE} || return 3

	[ "" == "${FOREACH_REVERSE_ORDER}" ] && local FOREACH_REVERSE_ORDER="false"
	[ "" == "${FOREACH_IGNORE_ERROR}"  ] && local FOREACH_IGNORE_ERROR="false"

	local THE_TMP_FILE=(mktemp /tmp/XXXXXX)
	for item in "${ITEMS[@]}"; do echo "${item}" >> ${THE_TMP_FILE}; done
	if [ "true" == "${FOREACH_REVERSE_ORDER}" ]; then
		IFS=$'\n'
		local THE_LIST=($(tac ${THE_TMP_FILE}))
	else
		IFS=$'\n'
		local THE_LIST=($(cat ${THE_TMP_FILE}))
	fi
	unset IFS
	rm -f ${THE_TMP_FILE}

	for item in "${THE_LIST[@]}"; do
		# echo "applying ${ITERATEE} ${item} $@"
		${ITERATEE} ${item} $@
		local EXIT_VALUE=$?
		# echo "exit_value => ${EXIT_VALUE}"
		[ "true" == "${FOREACH_IGNORE_ERROR}" ] && continue
		[ "0" != "${EXIT_VALUE}" ] && return ${EXIT_VALUE}
	done
	return 0
}