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Michael Wittenced465c2011-04-02 21:46:09 +00001# This allows us to work with the newline character:
2define newline
3
4
5endef
6newline := $(newline)
7
8# nl-escape
9#
10# Usage: escape = $(call nl-escape[,escape])
11#
12# This is used as the common way to specify
13# what should replace a newline when escaping
14# newlines; the default is a bizarre string.
15#
16nl-escape = $(or $(1),m822df3020w6a44id34bt574ctac44eb9f4n)
17
18# escape-nl
19#
20# Usage: escaped-text = $(call escape-nl,text[,escape])
21#
22# GNU make's $(shell ...) function converts to a
23# single space each newline character in the output
24# produced during the expansion; this may not be
25# desirable.
26#
27# The only solution is to change each newline into
28# something that won't be converted, so that the
29# information can be recovered later with
30# $(call unescape-nl...)
31#
32escape-nl = $(subst $(newline),$(call nl-escape,$(2)),$(1))
33
34# unescape-nl
35#
36# Usage: text = $(call unescape-nl,escaped-text[,escape])
37#
38# See escape-nl.
39#
40unescape-nl = $(subst $(call nl-escape,$(2)),$(newline),$(1))
41
42# shell-escape-nl
43#
44# Usage: $(shell some-command | $(call shell-escape-nl[,escape]))
45#
46# Use this to escape newlines from within a shell call;
47# the default escape is a bizarre string.
48#
49# NOTE: The escape is used directly as a string constant
50# in an `awk' program that is delimited by shell
51# single-quotes, so be wary of the characters
52# that are chosen.
53#
54define shell-escape-nl
55awk 'NR==1 {t=$$0} NR>1 {t=t "$(nl-escape)" $$0} END {printf t}'
56endef
57
58# shell-unescape-nl
59#
60# Usage: $(shell some-command | $(call shell-unescape-nl[,escape]))
61#
62# Use this to unescape newlines from within a shell call;
63# the default escape is a bizarre string.
64#
65# NOTE: The escape is used directly as an extended regular
66# expression constant in an `awk' program that is
67# delimited by shell single-quotes, so be wary
68# of the characters that are chosen.
69#
70# (The bash shell has a bug where `{gsub(...),...}' is
71# misinterpreted as a brace expansion; this can be
72# overcome by putting a space between `{' and `gsub').
73#
74define shell-unescape-nl
75awk 'NR==1 {t=$$0} NR>1 {t=t "\n" $$0} END { gsub(/$(nl-escape)/,"\n",t); printf t }'
76endef
77
78# escape-for-shell-sq
79#
80# Usage: embeddable-text = $(call escape-for-shell-sq,text)
81#
82# This function produces text that is suitable for
83# embedding in a shell string that is delimited by
84# single-quotes.
85#
86escape-for-shell-sq = $(subst ','\'',$(1))
87
88# shell-sq
89#
90# Usage: single-quoted-and-escaped-text = $(call shell-sq,text)
91#
92shell-sq = '$(escape-for-shell-sq)'
93
94# shell-wordify
95#
96# Usage: wordified-text = $(call shell-wordify,text)
97#
98# For instance:
99#
100# |define text
101# |hello
102# |world
103# |endef
104# |
105# |target:
106# | echo $(call shell-wordify,$(text))
107#
108# At least GNU make gets confused by expanding a newline
109# within the context of a command line of a makefile rule
110# (this is in constrast to a `$(shell ...)' function call,
111# which can handle it just fine).
112#
113# This function avoids the problem by producing a string
114# that works as a shell word, regardless of whether or
115# not it contains a newline.
116#
117# If the text to be wordified contains a newline, then
118# an intrictate shell command substitution is constructed
119# to render the text as a single line; when the shell
120# processes the resulting escaped text, it transforms
121# it into the original unescaped text.
122#
123# If the text does not contain a newline, then this function
124# produces the same results as the `$(shell-sq)' function.
125#
126shell-wordify = $(if $(findstring $(newline),$(1)),$(_sw-esc-nl),$(shell-sq))
127define _sw-esc-nl
128"$$(echo $(call escape-nl,$(shell-sq),$(2)) | $(call shell-unescape-nl,$(2)))"
129endef
130
131# is-absolute
132#
133# Usage: bool-value = $(call is-absolute,path)
134#
135is-absolute = $(shell echo $(shell-sq) | grep ^/ -q && echo y)
136
137# lookup
138#
139# Usage: absolute-executable-path-or-empty = $(call lookup,path)
140#
141# (It's necessary to use `sh -c' because GNU make messes up by
142# trying too hard and getting things wrong).
143#
144lookup = $(call unescape-nl,$(shell sh -c $(_l-sh)))
145_l-sh = $(call shell-sq,command -v $(shell-sq) | $(call shell-escape-nl,))
146
147# is-executable
148#
149# Usage: bool-value = $(call is-executable,path)
150#
151# (It's necessary to use `sh -c' because GNU make messes up by
152# trying too hard and getting things wrong).
153#
154is-executable = $(call _is-executable-helper,$(shell-sq))
155_is-executable-helper = $(shell sh -c $(_is-executable-sh))
156_is-executable-sh = $(call shell-sq,test -f $(1) -a -x $(1) && echo y)
157
158# get-executable
159#
160# Usage: absolute-executable-path-or-empty = $(call get-executable,path)
161#
162# The goal is to get an absolute path for an executable;
163# the `command -v' is defined by POSIX, but it's not
164# necessarily very portable, so it's only used if
165# relative path resolution is requested, as determined
166# by the presence of a leading `/'.
167#
168get-executable = $(if $(1),$(if $(is-absolute),$(_ge-abspath),$(lookup)))
169_ge-abspath = $(if $(is-executable),$(1))
170
171# get-supplied-or-default-executable
172#
173# Usage: absolute-executable-path-or-empty = $(call get-executable-or-default,variable,default)
174#
175define get-executable-or-default
176$(if $($(1)),$(call _ge_attempt,$($(1)),$(1)),$(call _ge_attempt,$(2)))
177endef
178_ge_attempt = $(or $(get-executable),$(_gea_warn),$(call _gea_err,$(2)))
179_gea_warn = $(warning The path '$(1)' is not executable.)
180_gea_err = $(if $(1),$(error Please set '$(1)' appropriately))
Michael Witten7fbd0652011-04-12 20:27:59 +0000181
182# try-cc
183# Usage: option = $(call try-cc, source-to-build, cc-options)
184try-cc = $(shell sh -c \
185 'TMP="$(OUTPUT)$(TMPOUT).$$$$"; \
186 echo "$(1)" | \
187 $(CC) -x c - $(2) -o "$$TMP" > /dev/null 2>&1 && echo y; \
188 rm -f "$$TMP"')