node_fns.mk revision b6c1cf6de79035f58b512f4400db458c8401379a 
1#
2# Copyright (C) 2007 The Android Open Source Project
3#
4# Licensed under the Apache License, Version 2.0 (the "License");
5# you may not use this file except in compliance with the License.
6# You may obtain a copy of the License at
7#
8#      http://www.apache.org/licenses/LICENSE-2.0
9#
10# Unless required by applicable law or agreed to in writing, software
11# distributed under the License is distributed on an "AS IS" BASIS,
12# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13# See the License for the specific language governing permissions and
14# limitations under the License.
15#
16
17#
18# Clears a list of variables using ":=".
19#
20# E.g.,
21#   $(call clear-var-list,A B C)
22# would be the same as:
23#   A :=
24#   B :=
25#   C :=
26#
27# $(1): list of variable names to clear
28#
29define clear-var-list
30$(foreach v,$(1),$(eval $(v):=))
31endef
32
33#
34# Copies a list of variables into another list of variables.
35# The target list is the same as the source list, but has
36# a dotted prefix affixed to it.
37#
38# E.g.,
39#   $(call copy-var-list, PREFIX, A B)
40# would be the same as:
41#   PREFIX.A := $(A)
42#   PREFIX.B := $(B)
43#
44# $(1): destination prefix
45# $(2): list of variable names to copy
46#
47define copy-var-list
48$(foreach v,$(2),$(eval $(strip $(1)).$(v):=$($(v))))
49endef
50
51#
52# Moves a list of variables into another list of variables.
53# The variable names differ by a prefix.  After moving, the
54# source variable is cleared.
55#
56# NOTE: Spaces are not allowed around the prefixes.
57#
58# E.g.,
59#   $(call move-var-list,SRC,DST,A B)
60# would be the same as:
61#   DST.A := $(SRC.A)
62#   SRC.A :=
63#   DST.B := $(SRC.B)
64#   SRC.B :=
65#
66# $(1): source prefix
67# $(2): destination prefix
68# $(3): list of variable names to move
69#
70define move-var-list
71$(foreach v,$(3), \
72  $(eval $(2).$(v) := $($(1).$(v))) \
73  $(eval $(1).$(v) :=) \
74 )
75endef
76
77#
78# $(1): haystack
79# $(2): needle
80#
81# Guarantees that needle appears at most once in haystack,
82# without changing the order of other elements in haystack.
83# If needle appears multiple times, only the first occurrance
84# will survive.
85#
86# How it works:
87#
88# - Stick everything in haystack into a single word,
89#   with "|||" separating the words.
90# - Replace occurrances of "|||$(needle)|||" with "||| |||",
91#   breaking haystack back into multiple words, with spaces
92#   where needle appeared.
93# - Add needle between the first and second words of haystack.
94# - Replace "|||" with spaces, breaking haystack back into
95#   individual words.
96#
97empty :=
98space := $(empty) $(empty)
99define uniq-word
100$(strip \
101  $(if $(filter $(2),$(1)), \
102    $(eval h := |||$(subst $(space),|||,$(strip $(1)))|||) \
103    $(eval h := $(subst |||$(strip $(2))|||,|||$(space)|||,$(h))) \
104    $(eval h := $(word 1,$(h)) $(2) $(wordlist 2,9999,$(h))) \
105    $(subst |||,$(space),$(h)) \
106   , \
107    $(1) \
108 ))
109endef
110
111INHERIT_TAG := @inherit:
112
113#
114# Walks through the list of variables, each qualified by the prefix,
115# and finds instances of words beginning with INHERIT_TAG.  Scrape
116# off INHERIT_TAG from each matching word, and return the sorted,
117# unique set of those words.
118#
119# E.g., given
120#   PREFIX.A := A $(INHERIT_TAG)aaa B C
121#   PREFIX.B := B $(INHERIT_TAG)aaa C $(INHERIT_TAG)bbb D E
122# Then
123#   $(call get-inherited-nodes,PREFIX,A B)
124# returns
125#   aaa bbb
126#
127# $(1): variable prefix
128# $(2): list of variables to check
129#
130define get-inherited-nodes
131$(sort \
132  $(subst $(INHERIT_TAG),, \
133    $(filter $(INHERIT_TAG)%, \
134      $(foreach v,$(2),$($(1).$(v))) \
135 )))
136endef
137
138#
139# for each variable ( (prefix + name) * vars ):
140#   get list of inherited words; if not empty:
141#     for each inherit:
142#       replace the first occurrence with (prefix + inherited + var)
143#       clear the source var so we can't inherit the value twice
144#
145# $(1): context prefix
146# $(2): name of this node
147# $(3): list of variable names
148#
149define _expand-inherited-values
150  $(foreach v,$(3), \
151    $(eval ### "Shorthand for the name of the target variable") \
152    $(eval _eiv_tv := $(1).$(2).$(v)) \
153    $(eval ### "Get the list of nodes that this variable inherits") \
154    $(eval _eiv_i := \
155        $(sort \
156            $(patsubst $(INHERIT_TAG)%,%, \
157                $(filter $(INHERIT_TAG)%, $($(_eiv_tv)) \
158     )))) \
159    $(foreach i,$(_eiv_i), \
160      $(eval ### "Make sure that this inherit appears only once") \
161      $(eval $(_eiv_tv) := \
162          $(call uniq-word,$($(_eiv_tv)),$(INHERIT_TAG)$(i))) \
163      $(eval ### "Expand the inherit tag") \
164      $(eval $(_eiv_tv) := \
165          $(patsubst $(INHERIT_TAG)$(i),$($(1).$(i).$(v)), \
166              $($(_eiv_tv)))) \
167      $(eval ### "Clear the child so DAGs don't create duplicate entries" ) \
168      $(eval $(1).$(i).$(v) :=) \
169      $(eval ### "If we just inherited ourselves, it's a cycle.") \
170      $(if $(filter $(INHERIT_TAG)$(2),$($(_eiv_tv))), \
171        $(warning Cycle detected between "$(2)" and "$(i)" for context "$(1)") \
172        $(error import of "$(2)" failed) \
173      ) \
174     ) \
175   ) \
176   $(eval _eiv_tv :=) \
177   $(eval _eiv_i :=)
178endef
179
180#
181# $(1): context prefix
182# $(2): makefile representing this node
183# $(3): list of node variable names
184#
185#TODO: keep a debug stack to make error messages more helpful
186define _import-node
187  $(call clear-var-list, $(3))
188  $(eval include $(2))
189  $(call copy-var-list, $(1).$(2), $(3))
190  $(call clear-var-list, $(3))
191
192  $(eval $(1).$(2).inherited := \
193      $(call get-inherited-nodes,$(1).$(2),$(3)))
194  $(call _import-nodes-inner,$(1),$($(1).$(2).inherited),$(3))
195
196  $(call _expand-inherited-values,$(1),$(2),$(3))
197
198  $(eval $(1).$(2).inherited :=)
199endef
200
201#
202# $(1): context prefix
203# $(2): list of makefiles representing nodes to import
204# $(3): list of node variable names
205#
206#TODO: Make the "does not exist" message more helpful;
207#      should print out the name of the file trying to include it.
208define _import-nodes-inner
209  $(foreach _in,$(2), \
210    $(if $(wildcard $(_in)), \
211      $(if $($(1).$(_in).seen), \
212        $(eval ### "skipping already-imported $(_in)") \
213       , \
214        $(eval $(1).$(_in).seen := true) \
215        $(call _import-node,$(1),$(strip $(_in)),$(3)) \
216       ) \
217     , \
218      $(error $(1): "$(_in)" does not exist) \
219     ) \
220   )
221endef
222
223#
224# $(1): output list variable name, like "PRODUCTS" or "DEVICES"
225# $(2): list of makefiles representing nodes to import
226# $(3): list of node variable names
227#
228define import-nodes
229$(if \
230  $(foreach _in,$(2), \
231    $(eval _node_import_context := _nic.$(1).[[$(_in)]]) \
232    $(call _import-nodes-inner,$(_node_import_context),$(_in),$(3)) \
233    $(call move-var-list,$(_node_import_context).$(_in),$(1).$(_in),$(3)) \
234    $(eval _node_import_context :=) \
235    $(eval $(1) := $($(1)) $(_in)) \
236   ) \
237,)
238endef
239