Initial Contribution

1 files changed, 238 insertions, 0 deletions

diff --git a/core/node_fns.mk b/core/node_fns.mk
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+#
+# 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) := \
+          $(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
+#
+#TODO: keep a debug stack to make error messages more helpful
+define _import-node
+  $(call clear-var-list, $(3))
+  $(eval include $(2))
+  $(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 :=)
+endef
+
+#
+# $(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)]]) \
+    $(call _import-nodes-inner,$(_node_import_context),$(_in),$(3)) \
+    $(call move-var-list,$(_node_import_context).$(_in),$(1).$(_in),$(3)) \
+    $(eval _node_import_context :=) \
+    $(eval $(1) := $($(1)) $(_in)) \
+   ) \
+,)
+endef