# 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 := $(.DEFAULT_GOAL)
+mg-orig-default-goal:=$(.DEFAULT_GOAL)
+
+# We use second-expansion heavily to dynamically compute prerequisites when they
+# are needed. Second-expansion lets us follow make's implicit rule search
+# instead of trying to anticipate which prerequisites it will need in advance.
+.SECONDEXPANSION:
+
# TEXT UTILITIES
-empty :=
-bs := \$(empty)
+empty:=
+bs:=\$(empty)
+pct:=%
define nl
endef
# Shell-quote: a'b => 'a'\''b'
-sq = '$(subst ','\'',$1)'
+sq='$(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 $$,$$$$,$1))
+mqas=$(subst $(nl),$$(nl),$(subst $$,$$$$,$1))
# Return nonempty if the strings are equal, empty otherwise.
# If the strings have only nice characters, you can do $(filter x$1,x$2).
-streq = $(findstring x$1,$(findstring x$2,x$1))
+streq=$(findstring x$1,$(findstring x$2,x$1))
# $(call fmt-make-assignment,foo,bar)
# Output a make assignment that stores bar in variable foo.
# The result is like `foo:=bar' but handles leading spaces, $, and
# newlines appearing in bar safely.
-fmt-make-assignment = $1:=$$(empty)$(call mqas,$2)
+fmt-make-assignment=$1:=$$(empty)$(call mqas,$2)
-# We use second-expansion heavily to dynamically compute prerequisites when they
-# are needed. Second-expansion lets us follow make's implicit rule search
-# instead of trying to anticipate which prerequisites it will need in advance.
-.SECONDEXPANSION:
# TARGET OBFUSCATION
nextoid:=/./.
newoid=$(nextoid)$(eval nextoid:=$(subst /.//////,//./,$(patsubst /.//////%,/././%,$(nextoid:.=/.))))
-# High-priority implicit rule for obfuscated targets. Works for both always-
-# exists and alternate-name targets.
+# Target-specific variables for obfuscated targets.
$(opfx)%: oid=$(word 1,$(subst $(aname), ,$@))
$(opfx)%: otgt=$(word 2,$(subst $(aname), ,$@))
+
+# High-priority implicit rule for obfuscated targets. Works for both always-
+# exists and alternate-name targets.
$(opfx)%: $$($$(oid)@opr)
$($(oid)@ocmd)
+# Make won't use the same implicit rule more than once on its stack, so provide
+# a second copy of the rule to allow two obfuscated targets on the stack.
+# Needed for $(mg-genfile-oid)$(aname)bar.g <- $(mg-scout-oid)$(aname)bar .
+# The prerequisites must look different before second-expansion so the second
+# rule isn't discarded as a duplicate.
+$(opfx)%: $$(empty) $$($$(oid)@opr)
+ $($(oid)@ocmd)
+
# MAIN BUILD LOGIC
-# Target metadata variables for bar: (*: stored in bar.g)
+# DESIGN:
+#
+# - To each generated file bar corresponds a "genfile" bar.g that contains some
+# information about how bar was generated, including the command (for rebuild on
+# command change) and the warnings (for replay).
+#
+# - bar.g's mtime is the last time Mage verified that bar was up to date. bar
+# needs to be regenerated iff a prerequisite is newer than *bar.g* (not bar).
+# If a prerequisite changes but the command gives the same contents for bar,
+# bar.g is touched but bar itself is not touched because files that depend on it
+# need not be regenerated.
+#
+# - If bar is newer than bar.g, the user has overridden it, and we should leave
+# the override in place but warn the user about it.
+#
+# - The user's Makefile defines Mage rules by calling mg-define-rule. Each Mage
+# rule becomes one underlying make rule with the same target and a little extra
+# magic. This is important so that all implicit rule competition takes place at
+# the same target. Additionally, the prerequisites are passed to an obfuscated
+# target for bar.g to see if any are newer than bar.g. This is done by the
+# single obfuscated implicit rule, keeping the number of implicit rules low.
+# Then the command script for bar checks for overrides, command change,
+# prerequisite change, etc. and acts accordingly.
+#
+# Target metadata variables for bar: (* means stored in bar.g)
#
# bar@cmd:=cat foo >bar.tmp
# Generation command as given to the shell.*
+#
# bar@warnings:=$(empty)yikes!
# Stuff the command printed to stdout or stderr.*
+#
# bar@deps:=included@x oops@
# If dependency-logging, list of filename@revision used. Revision is x for
# exists and empty for doesn't exist. Later perhaps x will be the mtime.*
+#
# bar@gloaded:=1
# Set if Mage has loaded bar.g and hasn't changed it since then.
+#
+# bar@gdeps:=foo
+# Static dependencies of bar, for checking by bar.g.
+#
+# bar@gq:=foo $(mg-scout-oid)$(aname)bar
+# $? from the rule for bar.g; used by the rule for bar.
+#
# bar@uptodate:=1
# Set when Mage makes a file or depends on it being made. Used to determine
# the next prerequisite to check for a dependency-logging command.
-# bar@generated:=1
-# Set when Mage generates a file; suppresses warning replay.
#
-# If the rule for bar is overridden, we clear the information from bar.g so that
-# it is as if bar.g didn't exist.
+## If the rule for bar is overridden, we clear the information from bar.g so
+## that it is as if bar.g didn't exist. -- Not currently needed
+#
+# Some make features with which Mage's compatibility has not been investigated:
+# - Command-line options (especially --dry-run, --question, --touch,
+# --always-make, --keep-going, --jobs, --assume-old, and --assume-new)
+# - Static pattern rules
+# - Vpath
# $(call gload,foo.o)
# Make sure foo.o's genfile, if any, has been loaded.
))
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)@ .
+# bar.g: scout bar and its dependencies and store $?. When implicit rules
+# compete for bar, we depend on the rule make uses being the last one it
+# second-expands so that $(bar@gdeps) is still correct.
+mg-genfile-oid:=$(newoid)
+mg-scout-oid:=$(newoid)
+$(mg-genfile-oid)@opr=$($(otgt:.g=)@gdeps) $(if $(wildcard $(otgt:.g=)),$(mg-scout-oid)$(aname)$(otgt:.g=),)
+$(mg-genfile-oid)@ocmd=$(eval $(otgt:.g=)@gq:=$?)
+
+# Mage-ized automatic variables.
+# $@: needs no translation
+# NOTE: $(mg@) is *eventual* target. Commands must write to temp file, $t .
+# $%: haven't thought about it much, but probably needs no translation
+mg< = $(firstword $(mg^))
+mg? = $(filter-out $(opfx)%,$($@@gq))
+mg^ = $(filter-out MG-% $(opfx)%,$^)
+mg+ = $(filter-out MG-% $(opfx)%,$+)
+# $|: needs no translation
+# $*: needs no translation
+
+# $(call mg-translate-cmd,cat $$< >$$t)
+# Replaces references to automatic variables with references to their Mage-ized
+# counterparts. There might be false matches, e.g., $$@ => $$(mg@) ;
+# to prevent that, write $$$(empty)@ instead. (c.f. autoconf empty quadrigraph)
define mg-translate-cmd
-$(subst $$@,$$(mg@),$(subst $$<,$$(mg<),$(subst $$^,$$(mg^),$(subst $$+,$$(mg+),$1))))
+$(subst $$?,$$(mg?),$(subst $$<,$$(mg<),$(subst $$^,$$(mg^),$(subst $$+,$$(mg+),$1))))
endef
-# $(call mg-define-rule,target,prerequisite,cmd)
-# Defines a rule.
-# If cmd uses $@, quote if necessary so this function sees $@, etc.
-#
-# When we generate bar from foo using a Mage rule:
-# Division of work:
-# - "bar.g: foo" generates bar if necessary.
-# - "bar: bar.g" loads new genfile and replays warnings if bar.g was
-# already up to date.
-# Cases:
-# - bar is managed and up to date => replay
-# - bar doesn't exist or is managed and out of date => generate
-# - bar is unmanaged => warn about override
+# $(call prereq-predict,target,prerequisites)
+# Expands to code that does the following at second-expansion time:
+# 1. Computes the actual prerequisites from the given prerequisite patterns by
+# translating % to $* and prepending a directory if appropriate.
+# 2. Saves both existing ($+) and newly computed prerequisites to $(bar@gdeps)
+# where the rule for bar.g can get them.
+# Factor out set-gdeps because make gets confused if the macro for the
+# prerequisites has a colon. Make replaces the first % with the stem *before
+# expansion*, so use $(pct) to protect some %s.
+set-gdeps=$(eval $@@gdeps:=$1)
+prereq-predict=$$$$(call set-gdeps,$$$$+ $(if $(findstring /,$1),$$$$(subst $$$$(pct),$$$*,$2),$$$$(addprefix $$$$(dir $$$$@),$$$$(subst $$$$(pct),$$$$*,$2))))
+
+# Used to make the rule for bar always run so we can act based on $(bar@gdeps)
+# and check for command change.
MG-FORCE:
.PHONY: MG-FORCE
-mg-scout-oid:=$(newoid)
+
+# $(call mg-define-rule,target,prerequisites,cmd)
+# Defines a rule. cmd is expanded again when it is run, at which time
+# Mage-ized automatic variables are available.
define mg-define-rule
$(eval
-# Define some target-specific variables.
-# It might look like we could use $*, but $1 most likely isn't %.
-$1.g: target = $$(@:.g=)
-$1.g: cmd = $(call mg-translate-cmd,$3)
-$1.g: mg@ = $$(target).tmp
-$1.g: mg^ = $$(filter-out MG-% $$(opfx)%,$$^)
-$1.g: mg+ = $$(filter-out MG-% $$(opfx)%,$$+)
-$1.g: mg< = $$(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)
-
-$(mg-file-from-genfile)
-)
-endef
-
-define mg-file-from-genfile
-# If the file was regenerated, load the new genfile.
-# If not, replay any warnings.
-# HMMM Maybe errors should go to stderr???
-$1: MG-FORCE | $1.g
- $$(call gload,$$@)
- $$(eval $$@@uptodate:=1)
- $$(if $$($$@@warnings),$$(if $$($$@@changed),,$$(info $$($$@@cmd) # warning replay)$$(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 $(target)),$(mg-scout-oid)$(aname)$(target),)
-
-# If the command changed, we must regenerate.
-mg-check-cmd=$(if $(call streq,$(cmd),$($(target)@cmd)),,x)
+# Store the new command.
+$1: cmd=$(call mg-translate-cmd,$3)
+# Provide variable for the temporary file. FIX
+$1: t=$$@.tmp
-# Just add additional prerequisites.
-# I don't think this can add patterns to implicit rules, but it should be able
-# to add specific prerequisites to uses of implicit rules.
-# TODO Make this work for dependency-logging commands if desired.
-define mg-define-prereq
-$(eval
-$1.g: $2
+# Rule for the target. Set $(bar@gdeps) to all prerequisites. Apply the new
+# prerequisites. The command script always runs. Depend on bar.g to get
+# $(bar@gq).
+$1: $(call prereq-predict,$1,$2) $2 MG-FORCE $(mg-genfile-oid)$(aname)$$$$@.g
+ $$(mg-rule-cmd)
)
endef
+# TODO Provide a way to define static pattern rules.
+
# Procedure to generate bar. Remember, $@ is bar.g.
# If an override:
# 1. Complain. (Should we stop "`bar' is up to date" using @:; ?)
# 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 $(mg-scout-oid)$(aname)$(target),$?),\
- $(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 $(target)@changed:=1)$(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); }
-
-# $(call mg-rule,target,static prerequisites,cmd,[dep converter])
-# Defines a rule with a dependency-logging command.
-# I haven't decided on the format for the dep converter yet.
-dlc-static-run-oid:=$(newoid)
-define mg-define-rule-dlc
-$(eval
-
-# Copied stuff from mg-define-rule to modify as necessary
-
-## 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^))
-
-#
-$1.g: MG-FORCE | $$$$(dlc-first-run-oid)$$$$(aname)$1.g $$$$(call dlc-setup-tgt,$(newoid))
-
-## Rule for the genfile. Evidently all the prerequisites we want second-expanded
-## have to go on the same rule.
-#$1.g: $2 $$$$(mg-scout-target) MG-FORCE
-# $$(mg-generate)
-
-
-$(mg-file-from-genfile)
-)
+# If not:
+# 1. If there were warnings, replay them. (HMMM To stderr?)
+# HMMM .tmp in displayed command looks ugly
+define mg-rule-cmd
+ $(if $(filter $(mg-scout-oid)$(aname)$@,$($@@gq)),\
+ $(info Mage: warning: Manually created/modified file at $@ overrides rule.)\
+ ,$(call gload,$@)$(if $($@@gq)$(if $(wildcard $@),,x)$(mg-check-cmd),\
+ $(eval $@@gloaded:=)$(info $(cmd))\
+ @trap 'rm -f $@.tmp $@.g.tmp' EXIT &&\
+ exec 3>$@.g.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 $@.g.tmp $@.g\
+ ,$(if $($@@warnings),\
+ $(info $($@@cmd) # Mage warning replay$(nl)$($@@warnings))\
+ )))
endef
-define dlc-setup-tgt
-$(eval
+# If the command changed, we must regenerate.
+mg-check-cmd=$(if $(call streq,$(cmd),$($@@cmd)),,x)
-)$1
+# Pieces of mg-generate that I factored out to make mg-generate more readable.
+mg-assign-cmd=echo $(call sq,$(call fmt-make-assignment,$@@cmd,$(cmd)))
+mg-run-cmd={ ($(cmd)) 2>&1 && { [ -r $@.tmp ] || { echo 'Mage: error: Command for $@ succeeded without creating it!'; false; }; }; }
+mg-wrap-warnings=sed -re '1s/^/$@@warnings:=$$(empty)/; 1!s/^/$@@warnings+=$$(nl)/'
+mg-maybe-move-target={ cmp -s $@ $@.tmp || echo >$@.g && mv -f $@.tmp $@; }
+
+# Just add additional prerequisites. This cannot add prerequisite patterns to
+# an implicit rule, but it can add specific prerequisites to an individual use
+# of an implicit rule. Currently, Mage picks up the target's prerequisites from
+# make, so this just attaches the given prerequisites to the target, but the
+# implementation might change in the future.
+define mg-define-prereq
+$(eval $1: $2)
endef
# END
Matt McCutchen's Web Site / mgear / mgear.git / commitdiff