1 # This allows us to work with the newline character:
2 define newline
3
4
5 endef
6 newline := $(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 #
16 nl-escape = $(if $(1),$(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 #
32 escape-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 #
40 unescape-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 #
54 define shell-escape-nl
55 awk 'NR==1 {t=$$0} NR>1 {t=t "$(nl-escape)" $$0} END {printf t}'
56 endef
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 #
74 define shell-unescape-nl
75 awk 'NR==1 {t=$$0} NR>1 {t=t "\n" $$0} END { gsub(/$(nl-escape)/,"\n",t); printf t }'
76 endef
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 #
86 escape-for-shell-sq = $(subst ','\'',$(1))
87
88 # shell-sq
89 #
90 # Usage: single-quoted-and-escaped-text = $(call shell-sq,text)
91 #
92 shell-sq = '$(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 #
126 shell-wordify = $(if $(findstring $(newline),$(1)),$(_sw-esc-nl),$(shell-sq))
127 define _sw-esc-nl
128 "$$(echo $(call escape-nl,$(shell-sq),$(2)) | $(call shell-unescape-nl,$(2)))"
129 endef
130
131 # is-absolute
132 #
133 # Usage: bool-value = $(call is-absolute,path)
134 #
135 is-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 #
144 lookup = $(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 #
154 is-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 #
168 get-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 #
175 define get-executable-or-default
176 $(if $($(1)),$(call _ge_attempt,$($(1)),$(1)),$(call _ge_attempt,$(2)))
177 endef
178 _ge_attempt = $(or $(get-executable),$(call _gea_err,$(2)))
179 _gea_err = $(if $(1),$(error Please set '$(1)' appropriately))
180
181 # version-ge3
182 #
183 # Usage $(call version-ge3,2.6.4,$(FLEX_VERSION))
184 #
185 # To compare if a 3 component version is greater or equal to another, first use
186 # was to check the flex version to see if we can use compiler warnings as
187 # errors for one of the cases flex generates code C compilers complains about.
188
189 version-ge3 = $(shell echo "$(1).$(2)" | awk -F'.' '{ printf("%d\n", (10000000 * $$1 + 10000 * $$2 + $$3) >= (10000000 * $$4 + 10000 * $$5 + $$6)) }')
190
191 # version-lt3
192 #
193 # Usage $(call version-lt3,2.6.2,$(FLEX_VERSION))
194 #
195 # To compare if a 3 component version is less thjan another, first use was to
196 # check the flex version to see if we can use compiler warnings as errors for
197 # one of the cases flex generates code C compilers complains about.
198
199 version-lt3 = $(shell echo "$(1).$(2)" | awk -F'.' '{ printf("%d\n", (10000000 * $$1 + 10000 * $$2 + $$3) < (10000000 * $$4 + 10000 * $$5 + $$6)) }')
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