[mgear/mgear.git] / src / mage.mk

# Mage Build Tool by Matt McCutchen
# http://www.kepreon.com/~matt/mage/

# Remember the original default goal so we can restore it at the end of mage.mk.
mg-orig-default-goal := $(.DEFAULT_GOAL)

# TEXT UTILITIES
empty :=
bs := \$(empty)
define nl


endef
# Shell-quote: a'b => 'a'\''b'
sq = '$(subst ','\'',$1)'
# Make-quote: a$\nb => a$$$(nl)b
# This is enough to assign the value, *but not to use it as an argument!*
mqas = $(subst $(nl),$$(nl),$(subst $$,$$$$,$1))
# Return nonempty if the strings are equal, empty otherwise.
# If the strings have only nice characters, you can do $(filter x$1,x$2).
streq = $(findstring x$1,$(findstring x$2,x$1))

# $(call fmt-make-assignment,foo,bar)
# Output a make assignment that stores bar in variable foo.
# The result is like `foo:=bar' but handles leading spaces, $, and
# newlines appearing in bar safely.
fmt-make-assignment = $1:=$$(empty)$(call mqas,$2)

# OBFUSCATION

# Coming soon.

# High-priority implicit rule to ensure that we don't try to actually update
# obfuscated targets.  TEMP
/./proc/self/cwd/%:
	

# MAIN BUILD LOGIC

# bar.g file format:
#     bar@cmd:=cat foo >bar.tmp
#     bar@warnings:=$(empty)yikes!
# And if dependency-logging:
# List of filename@revision, revision is x for exists and empty for doesn't
# exist.  Later perhaps x will be the mtime.
#     bar@deps:=included@x oops@
# If bar is overridden, we clear all three variables.

# $(call gload,foo.o)
# Make sure foo.o's genfile, if any, has been loaded.
define gload
$(if $($1@gloaded),,$(eval 
$1@cmd:=
$1@warnings:=
$1@deps:=
-include $1.g
$1@gloaded:=1
))
endef

# $(call mg-translate-cmd,touch $$@)
# Translates $@, $<, $^, $+, $* to Mage-ized variables if necessary.
# We won't support $%, $?, $|.
# There might be false matches, e.g., $$@ => $$(mg@) ;
# to prevent that, do $$$(empty)@ .
define mg-translate-cmd
$(subst $$@,$$(mg@),$(subst $$<,$$(mg<),$(subst $$^,$$(mg^),$(subst $$+,$$(mg+),$1))))
endef

# OOOH!!! .SECONDEXPANSION does let us watch the implicit rule search as it
# happens.
.SECONDEXPANSION:

# $(call mg-rule,target,prerequisite,cmd)
# Defines a rule.
# If cmd uses $@, quote if necessary so this function sees $@, etc.
# 
# When we generate bar from foo using a Mage rule:
# Division of work:
# - "bar.g: foo" generates bar if necessary.
# - "bar: bar.g" loads new genfile and replays warnings if bar.g was
#   already up to date.
# Cases:
# - bar is managed and up to date => replay
# - bar doesn't exist or is managed and out of date => generate
# - bar is unmanaged => warn about override 
MG-FORCE:
.PHONY: MG-FORCE
define mg-define-rule
$(eval 

# Define some target-specific variables.
# It might look like we could use $*, but $1 most likely isn't %.
$1.g: target = $$(@:.g=)
$1.g: cmd = $(call mg-translate-cmd,$3)
$1.g: mg@ = $$(target).tmp
$1.g: mg^ = $$(filter-out MG-% /./%,$$^)
$1.g: mg+ = $$(filter-out MG-% /./%,$$+)
$1.g: mg< = $$(firstword $$(mg^))

# Rule for the genfile.  Evidently all the prerequisites we want second-expanded
# have to go on the same rule.
$1.g: $2 $$$$(mg-scout-target) MG-FORCE
	$$(mg-generate)

# If the file was regenerated, load the new genfile.
# If not, replay any warnings.
## We don't have to worry about .DELETE_ON_ERROR deleting the target because
## it is only touched if we *successfully* regenerate it.
# - No longer applies because we don't remember errors.
# HMMM Maybe errors should go to stderr???
$1: MG-FORCE | $1.g
	$$(call gload,$$@)
	$$(if $$($$@@warnings),$$(if $$($$@@built),,$$(info $$($$@@cmd) # warning replay)$$(info $$($$@@warnings))),)
)
endef

# If the target is unmanaged, we must run the rule; we'll see that the
# obfuscated target is in $? and complain.
mg-scout-target=$(if $(wildcard $(target)),/./proc/self/cwd/$(target),)

# If the command changed, we must regenerate.
mg-check-cmd=$(if $(call streq,$(cmd),$($(target)@cmd)),,x)

# Just add additional prerequisites.
# I don't think this works for implicit rules.
define mg-define-prereq
$(eval 
$1.g: $2
)
endef

# Procedure to generate bar.  Remember, $@ is bar.g.
# If an override:
#     1. Complain.  (Should we stop "`bar' is up to date" using @:; ?)
#     2. Clear out the warnings so we don't replay them.
# Otherwise, check prereqs, command, and nonexistence to decide whether bar
# needs to be regenerated.  If so:
#     1. Set a flag so Mage knows to reread the genfile when make runs target
#        "bar".
#     2. Echo the command being run.
#     On error, skip to 8:
#        3. Open the new genfile bar.g.tmp for writing.
#        4. Store the command in bar.g.tmp.
#        5. Run the command to bar.tmp, storing warnings in bar.g.tmp.
#        6. If bar.tmp differs from bar:
#           a. Clear and touch bar.g (so bar doesn't become an override if we're
#              killed between steps 6b and 7).
#           b. Move in the new bar.
#        7. Now that bar is known to be up to date, move in the new bar.g.
#     8. Defensively remove both temporary files and exit with the exit code
#        from before the removal. (trap EXIT)
define mg-generate
	$(call gload,$(target))\
	$(if $(filter /./proc/self/cwd/$(target),$?),\
		$(info mage: warning: Manually created/modified file at $(target) overrides rule.)\
		$(eval $(target)@cmd:=)$(eval $(target)@warnings:=)$(eval $(target)@deps:=)\
	,\
	$(if $?$(if $(wildcard $(target)),,x)$(mg-check-cmd),\
	$(eval $(target)@gloaded:=)$(eval $(target)@built:=1)$(info $(cmd))\
	@trap 'rm -f $(target).tmp $@.tmp' EXIT &&\
	exec 3>$@.tmp && $(mg-assign-cmd) >&3 &&\
	set -o pipefail && { $(mg-run-cmd) | tee /dev/fd/4 | $(mg-wrap-warnings) >&3; } 4>&1 &&\
	$(mg-maybe-move-target) && mv -f $@.tmp $@\
	))
endef

# Pieces of mg-generate that I factored out to make mg-generate more readable.
mg-assign-cmd=echo $(call sq,$(call fmt-make-assignment,$(target)@cmd,$(cmd)))
mg-run-cmd={ ($(cmd)) 2>&1 && { [ -r $(target).tmp ] || { echo 'mage: error: Command for $(target) succeeded without creating it!'; false; }; }; }
mg-wrap-warnings=sed -re '1s/^/$(target)@warnings:=$$(empty)/; 1!s/^/$(target)@warnings+=$$(nl)/'
mg-maybe-move-target={ cmp -s $(target) $(target).tmp || echo >$@ && mv -f $(target).tmp $(target); }

# END

# We don't want anything we defined to become the default goal.
.DEFAULT_GOAL := $(mg-orig-default-goal)
Commit	Line	Data
ac64c802 MM	1	# Mage Build Tool by Matt McCutchen
ac64c802 MM	2	# http://www.kepreon.com/~matt/mage/
00804b7c	3
ac64c802 MM	4	# Remember the original default goal so we can restore it at the end of mage.mk.
	5	mg-orig-default-goal := $(.DEFAULT_GOAL)
	6
	7	# TEXT UTILITIES
00804b7c MM	8	empty :=
	9	bs := \$(empty)
	10	define nl
	11
	12
	13	endef
	14	# Shell-quote: a'b => 'a'\''b'
	15	sq = '$(subst ','\'',$1)'
	16	# Make-quote: a$\nb => a$$$(nl)b
	17	# This is enough to assign the value, but not to use it as an argument!
	18	mqas = $(subst $(nl),$$(nl),$(subst $$,$$$$,$1))
	19	# Return nonempty if the strings are equal, empty otherwise.
	20	# If the strings have only nice characters, you can do $(filter x$1,x$2).
	21	streq = $(findstring x$1,$(findstring x$2,x$1))
	22
	23	# $(call fmt-make-assignment,foo,bar)
	24	# Output a make assignment that stores bar in variable foo.
	25	# The result is like `foo:=bar' but handles leading spaces, $, and
	26	# newlines appearing in bar safely.
	27	fmt-make-assignment = $1:=$$(empty)$(call mqas,$2)
	28
ac64c802	29	# OBFUSCATION
00804b7c	30
ac64c802 MM	31	# Coming soon.
	32
	33	# High-priority implicit rule to ensure that we don't try to actually update
	34	# obfuscated targets. TEMP
	35	/./proc/self/cwd/%:
	36
00804b7c	37
ac64c802 MM	38	# MAIN BUILD LOGIC
	39
	40	# bar.g file format:
	41	# bar@cmd:=cat foo >bar.tmp
	42	# bar@warnings:=$(empty)yikes!
	43	# And if dependency-logging:
	44	# List of filename@revision, revision is x for exists and empty for doesn't
	45	# exist. Later perhaps x will be the mtime.
	46	# bar@deps:=included@x oops@
	47	# If bar is overridden, we clear all three variables.
	48
	49	# $(call gload,foo.o)
00804b7c	50	# Make sure foo.o's genfile, if any, has been loaded.
ac64c802 MM	51	define gload
	52	$(if $($1@gloaded),,$(eval
	53	$1@cmd:=
	54	$1@warnings:=
	55	$1@deps:=
00804b7c	56	-include $1.g
ac64c802	57	$1@gloaded:=1
00804b7c MM	58	))
	59	endef
	60
	61	# $(call mg-translate-cmd,touch $$@)
ac64c802 MM	62	# Translates $@, $<, $^, $+, $* to Mage-ized variables if necessary.
	63	# We won't support $%, $?, $\|.
	64	# There might be false matches, e.g., $$@ => $$(mg@) ;
00804b7c MM	65	# to prevent that, do $$$(empty)@ .
	66	define mg-translate-cmd
	67	$(subst $$@,$$(mg@),$(subst $$<,$$(mg<),$(subst $$^,$$(mg^),$(subst $$+,$$(mg+),$1))))
	68	endef
	69
	70	# OOOH!!! .SECONDEXPANSION does let us watch the implicit rule search as it
	71	# happens.
	72	.SECONDEXPANSION:
	73
	74	# $(call mg-rule,target,prerequisite,cmd)
	75	# Defines a rule.
	76	# If cmd uses $@, quote if necessary so this function sees $@, etc.
	77	#
ac64c802	78	# When we generate bar from foo using a Mage rule:
00804b7c	79	# Division of work:
ac64c802 MM	80	# - "bar.g: foo" generates bar if necessary.
	81	# - "bar: bar.g" loads new genfile and replays warnings if bar.g was
	82	# already up to date.
00804b7c MM	83	# Cases:
00804b7c MM	84	# - bar is managed and up to date => replay
ac64c802	85	# - bar doesn't exist or is managed and out of date => generate
00804b7c	86	# - bar is unmanaged => warn about override
ac64c802	87	MG-FORCE:
ce8fee85	88	.PHONY: MG-FORCE
ac64c802	89	define mg-define-rule
00804b7c MM	90	$(eval
	91
	92	# Define some target-specific variables.
	93	# It might look like we could use $*, but $1 most likely isn't %.
	94	$1.g: target = $$(@:.g=)
	95	$1.g: cmd = $(call mg-translate-cmd,$3)
	96	$1.g: mg@ = $$(target).tmp
ac64c802 MM	97	$1.g: mg^ = $$(filter-out MG-% /./%,$$^)
ac64c802 MM	98	$1.g: mg+ = $$(filter-out MG-% /./%,$$+)
00804b7c MM	99	$1.g: mg< = $$(firstword $$(mg^))
00804b7c MM	100
ac64c802 MM	101	# Rule for the genfile. Evidently all the prerequisites we want second-expanded
	102	# have to go on the same rule.
	103	$1.g: $2 $$$$(mg-scout-target) MG-FORCE
	104	$$(mg-generate)
	105
	106	# If the file was regenerated, load the new genfile.
	107	# If not, replay any warnings.
	108	## We don't have to worry about .DELETE_ON_ERROR deleting the target because
	109	## it is only touched if we successfully regenerate it.
	110	# - No longer applies because we don't remember errors.
	111	# HMMM Maybe errors should go to stderr???
	112	$1: MG-FORCE \| $1.g
	113	$$(call gload,$$@)
	114	$$(if $$($$@@warnings),$$(if $$($$@@built),,$$(info $$($$@@cmd) # warning replay)$$(info $$($$@@warnings))),)
	115	)
	116	endef
00804b7c	117
00804b7c MM	118	# If the target is unmanaged, we must run the rule; we'll see that the
00804b7c MM	119	# obfuscated target is in $? and complain.
ac64c802	120	mg-scout-target=$(if $(wildcard $(target)),/./proc/self/cwd/$(target),)
00804b7c MM	121
00804b7c MM	122	# If the command changed, we must regenerate.
ac64c802	123	mg-check-cmd=$(if $(call streq,$(cmd),$($(target)@cmd)),,x)
00804b7c MM	124
00804b7c MM	125	# Just add additional prerequisites.
ac64c802 MM	126	# I don't think this works for implicit rules.
ac64c802 MM	127	define mg-define-prereq
00804b7c MM	128	$(eval
	129	$1.g: $2
	130	)
	131	endef
	132
ac64c802	133	# Procedure to generate bar. Remember, $@ is bar.g.
00804b7c	134	# If an override:
ac64c802 MM	135	# 1. Complain. (Should we stop "`bar' is up to date" using @:; ?)
	136	# 2. Clear out the warnings so we don't replay them.
	137	# Otherwise, check prereqs, command, and nonexistence to decide whether bar
	138	# needs to be regenerated. If so:
	139	# 1. Set a flag so Mage knows to reread the genfile when make runs target
	140	# "bar".
	141	# 2. Echo the command being run.
	142	# On error, skip to 8:
	143	# 3. Open the new genfile bar.g.tmp for writing.
	144	# 4. Store the command in bar.g.tmp.
	145	# 5. Run the command to bar.tmp, storing warnings in bar.g.tmp.
	146	# 6. If bar.tmp differs from bar:
	147	# a. Clear and touch bar.g (so bar doesn't become an override if we're
	148	# killed between steps 6b and 7).
	149	# b. Move in the new bar.
	150	# 7. Now that bar is known to be up to date, move in the new bar.g.
	151	# 8. Defensively remove both temporary files and exit with the exit code
	152	# from before the removal. (trap EXIT)
	153	define mg-generate
	154	$(call gload,$(target))\
	155	$(if $(filter /./proc/self/cwd/$(target),$?),\
00804b7c	156	$(info mage: warning: Manually created/modified file at $(target) overrides rule.)\
ac64c802	157	$(eval $(target)@cmd:=)$(eval $(target)@warnings:=)$(eval $(target)@deps:=)\
00804b7c	158	,\
ac64c802 MM	159	$(if $?$(if $(wildcard $(target)),,x)$(mg-check-cmd),\
	160	$(eval $(target)@gloaded:=)$(eval $(target)@built:=1)$(info $(cmd))\
	161	@trap 'rm -f $(target).tmp $@.tmp' EXIT &&\
	162	exec 3>$@.tmp && $(mg-assign-cmd) >&3 &&\
	163	set -o pipefail && { $(mg-run-cmd) \| tee /dev/fd/4 \| $(mg-wrap-warnings) >&3; } 4>&1 &&\
	164	$(mg-maybe-move-target) && mv -f $@.tmp $@\
	165	))
00804b7c MM	166	endef
00804b7c MM	167
ac64c802 MM	168	# Pieces of mg-generate that I factored out to make mg-generate more readable.
	169	mg-assign-cmd=echo $(call sq,$(call fmt-make-assignment,$(target)@cmd,$(cmd)))
	170	mg-run-cmd={ ($(cmd)) 2>&1 && { [ -r $(target).tmp ] \|\| { echo 'mage: error: Command for $(target) succeeded without creating it!'; false; }; }; }
	171	mg-wrap-warnings=sed -re '1s/^/$(target)@warnings:=$$(empty)/; 1!s/^/$(target)@warnings+=$$(nl)/'
	172	mg-maybe-move-target={ cmp -s $(target) $(target).tmp \|\| echo >$@ && mv -f $(target).tmp $(target); }
	173
	174	# END
	175
00804b7c	176	# We don't want anything we defined to become the default goal.
ac64c802	177	.DEFAULT_GOAL := $(mg-orig-default-goal)