安卓makefile全域性變數建立流程分析
阿新 • • 發佈:2019-02-02
- #
- # Copyright (C) 2007 The Android Open Source Project
- #
- # Licensed under the Apache License, Version 2.0 (the "License");
- # you may not use this file except in compliance with the License.
- # You may obtain a copy of the License at
- #
- # http://www.apache.org/licenses/LICENSE-2.0
- #
- # Unless required by applicable law or agreed to in writing, software
- # distributed under the License is distributed on an "AS IS" BASIS,
- # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- # See the License for the specific language governing permissions and
- # limitations under the License.
- #
- #
- # Clears a list of variables using ":=".
- #
- # E.g.,
- # $(call clear-var-list,A B C)
- # would be the same as:
- # A :=
- # B :=
- # C :=
- #
- # $(1): list of variable names to clear
- #
- define clear-var-list
- $(foreach v,$(1),$(eval $(v):=))
- endef
- #
- # Copies a list of variables into another list of variables.
- # The target list is the same as the source list, but has
- # a dotted prefix affixed to it.
- #
- # E.g.,
- # $(call copy-var-list, PREFIX, A B)
- # would be the same as:
- # PREFIX.A := $(A)
- # PREFIX.B := $(B)
- #
- # $(1): destination prefix
- # $(2): list of variable names to copy
- #
- define copy-var-list
- $(foreach v,$(2),$(eval $(strip $(1)).$(v):=$($(v))))
- endef
- #
- # Moves a list of variables into another list of variables.
- # The variable names differ by a prefix. After moving, the
- # source variable is cleared.
- #
- # NOTE: Spaces are not allowed around the prefixes.
- #
- # E.g.,
- # $(call move-var-list,SRC,DST,A B)
- # would be the same as:
- # DST.A := $(SRC.A)
- # SRC.A :=
- # DST.B := $(SRC.B)
- # SRC.B :=
- #
- # $(1): source prefix
- # $(2): destination prefix
- # $(3): list of variable names to move
- #
- define move-var-list
- $(foreach v,$(3), \
- $(eval $(2).$(v) := $($(1).$(v))) \
- $(eval $(1).$(v) :=) \
- )
- endef
- #
- # $(1): haystack
- # $(2): needle
- #
- # Guarantees that needle appears at most once in haystack,
- # without changing the order of other elements in haystack.
- # If needle appears multiple times, only the first occurrance
- # will survive.
- #
- # How it works:
- #
- # - Stick everything in haystack into a single word,
- # with "|||" separating the words.
- # - Replace occurrances of "|||$(needle)|||" with "||| |||",
- # breaking haystack back into multiple words, with spaces
- # where needle appeared.
- # - Add needle between the first and second words of haystack.
- # - Replace "|||" with spaces, breaking haystack back into
- # individual words.
- #
- empty :=
- space := $(empty) $(empty)
- define uniq-word
- $(strip \
- $(if $(filter $(2),$(1)), \
- $(eval h := |||$(subst $(space),|||,$(strip $(1)))|||) \
- $(eval h := $(subst |||$(strip $(2))|||,|||$(space)|||,$(h))) \
- $(eval h := $(word 1,$(h)) $(2) $(wordlist 2,9999,$(h))) \
- $(subst |||,$(space),$(h)) \
- , \
- $(1) \
- ))
- endef
- INHERIT_TAG := @inherit:
- #
- # Walks through the list of variables, each qualified by the prefix,
- # and finds instances of words beginning with INHERIT_TAG. Scrape
- # off INHERIT_TAG from each matching word, and return the sorted,
- # unique set of those words.
- #
- # E.g., given
- # PREFIX.A := A $(INHERIT_TAG)aaa B C
- # PREFIX.B := B $(INHERIT_TAG)aaa C $(INHERIT_TAG)bbb D E
- # Then
- # $(call get-inherited-nodes,PREFIX,A B)
- # returns
- # aaa bbb
- #
- # $(1): variable prefix
- # $(2): list of variables to check
- #
- define get-inherited-nodes
- $(sort \
- $(subst $(INHERIT_TAG),, \
- $(filter $(INHERIT_TAG)%, \
- $(foreach v,$(2),$($(1).$(v))) \
- )))
- endef
- #
- # for each variable ( (prefix + name) * vars ):
- # get list of inherited words; if not empty:
- # for each inherit:
- # replace the first occurrence with (prefix + inherited + var)
- # clear the source var so we can't inherit the value twice
- #
- # $(1): context prefix
- # $(2): name of this node
- # $(3): list of variable names
- #
- define _expand-inherited-values
- $(foreach v,$(3), \
- $(eval ### "Shorthand for the name of the target variable") \
- $(eval _eiv_tv := $(1).$(2).$(v)) \
- $(eval ### "Get the list of nodes that this variable inherits") \
- $(eval _eiv_i := \
- $(sort \
- $(patsubst $(INHERIT_TAG)%,%, \
- $(filter $(INHERIT_TAG)%, $($(_eiv_tv)) \
- )))) \
- $(foreach i,$(_eiv_i), \
- $(eval ### "Make sure that this inherit appears only once") \
- $(eval $(_eiv_tv) := \
- $(call uniq-word,$($(_eiv_tv)),$(INHERIT_TAG)$(i))) \
- $(eval ### "Expand the inherit tag") \
- $(eval $(_eiv_tv) := \
- $(strip \
- $(patsubst $(INHERIT_TAG)$(i),$($(1).$(i).$(v)), \
- $($(_eiv_tv))))) \
- $(eval ### "Clear the child so DAGs don't create duplicate entries" ) \
- $(eval $(1).$(i).$(v) :=) \
- $(eval ### "If we just inherited ourselves, it's a cycle.") \
- $(if $(filter $(INHERIT_TAG)$(2),$($(_eiv_tv))), \
- $(warning Cycle detected between "$(2)" and "$(i)" for context "$(1)") \
- $(error import of "$(2)" failed) \
- ) \
- ) \
- ) \
- $(eval _eiv_tv :=) \
- $(eval _eiv_i :=)
- endef
- #
- # $(1): context prefix
- # $(2): makefile representing this node
- # $(3): list of node variable names
- #
- # _include_stack contains the list of included files, with the most recent files first.
- define _import-node
- $(eval _include_stack := $(2) $$(_include_stack))
- $(call clear-var-list, $(3))
- $(eval LOCAL_PATH := $(patsubst %/,%,$(dir $(2))))
- $(eval MAKEFILE_LIST :=)
- $(eval include $(2))
- $(eval _included := $(filter-out $(2),$(MAKEFILE_LIST)))
- $(eval MAKEFILE_LIST :=)
- $(eval LOCAL_PATH :=)
- $(call copy-var-list, $(1).$(2), $(3))
- $(call clear-var-list, $(3))
- $(eval $(1).$(2).inherited := \
- $(call get-inherited-nodes,$(1).$(2),$(3)))
- $(call _import-nodes-inner,$(1),$($(1).$(2).inherited),$(3))
- $(call _expand-inherited-values,$(1),$(2),$(3))
- $(eval $(1).$(2).inherited :=)
- $(eval _include_stack := $(wordlist 2,9999,$$(_include_stack)))
- endef
- #
- # This will generate a warning for _included above
- # $(if $(_included), \
- # $(eval $(warning product spec file: $(2)))\
- # $(foreach _inc,$(_included),$(eval $(warning $(space)$(space)$(space)includes: $(_inc)))),)
- #
- #
- # $(1): context prefix
- # $(2): list of makefiles representing nodes to import
- # $(3): list of node variable names
- #
- #TODO: Make the "does not exist" message more helpful;
- # should print out the name of the file trying to include it.
- define _import-nodes-inner
- $(foreach _in,$(2), \
- $(if $(wildcard $(_in)), \
- $(if $($(1).$(_in).seen), \
- $(eval ### "skipping already-imported $(_in)") \
- , \
- $(eval $(1).$(_in).seen := true) \
- $(call _import-node,$(1),$(strip $(_in)),$(3)) \
- ) \
- , \
- $(error $(1): "$(_in)" does not exist) \
- ) \
- )
- endef
- #
- # $(1): output list variable name, like "PRODUCTS" or "DEVICES"
- # $(2): list of makefiles representing nodes to import
- # $(3): list of node variable names
- #
- define import-nodes
- $(if \
- $(foreach _in,$(2), \
- $(eval _node_import_context := _nic.$(1).[[$(_in)]]) \
- $(if $(_include_stack),$(eval $(error ASSERTION FAILED: _include_stack \
- should be empty here: $(_include_stack))),) \
- $(eval _include_stack := ) \
- $(call _import-nodes-inner,$(_node_import_context),$(_in),$(3)) \
- $(call move-var-list,$(_node_import_context).$(_in),$(1).$(_in),$(3)) \
- $(eval _node_import_context :=) \
- $(eval $(1) := $($(1)) $(_in)) \
- $(if $(_include_stack),$(eval $(error ASSERTION FAILED: _include_stack \
- should be empty here: $(_include_stack))),) \
- ) \
- ,)
- endef