# NB: don"t use ANY quotes ('/") for put()/add()/set() arguments!
# shell will get confused by ' or args get spammed with "

# pay attention to the context functions get called in:
# e.g. features.in/syslinux/config.mk introduces conditionals

# this one adds whatever is given as an argument
put = $(and $(1),$(put_body))
define put_body
{ $(log_body); \
printf '%s\n' '$(1)' >> "$(CONFIG)"; }
endef

# these three take two args
# add() just appends an additive rule...
add = $(and $(1),$(2),$(add_body))
define add_body
{ $(log_body); \
printf '%s += %s\n' '$(1)' '$(2)' >> "$(CONFIG)"; }
endef

# ...set() comments out any previous definition
# and then appends an assigning rule...
set = $(and $(1),$(2),$(set_body))
define set_body
{ $(log_body); \
subst 's|^$(1)[ 	]*[+?]*=.*$$|#& # overridden by $@|' "$(CONFIG)"; \
printf '%s = %s\n' '$(1)' '$(2)' >> "$(CONFIG)"; }
endef

# try() appends a conditionally-assigning rule
try = $(and $(1),$(2),$(try_body))
define try_body
{ $(log_body); \
printf '%s ?= %s\n' '$(1)' '$(2)' >> "$(CONFIG)"; }
endef

# if the rule being executed isn't logged yet, log it
define log_body
{ grep -q '^# $@$$' "$(CONFIG)" || printf '# %s\n' '$@' >> "$(CONFIG)"; }
endef

# convert tag list into a list of relative package list paths
tags = $(and $(strip $(1)),$(addprefix tagged/,$(shell echo "$(1)" | bin/tags2lists pkg.in/lists/tagged)))