Implementing 'tr' in GNU Make 3.80

[John Graham-Cumming]

Sometimes it's handy to be able to 'tr' inside GNU Make without wasting
time going to the shell.  Here's an implementation that works with GNU
Make 3.80:

# The tr function.   Has three arguments:
#
# $1   The list of characters to translate from 
# $2   The list of characters to translate to
# $3   The text to translate
#
# For example, $(call tr,A B C,1 2 3,CAPITAL) becomes 21PIT1L.

tr = $(eval __t := $3)                                                    \
     $(foreach c,                                                         \
         $(join $(addsuffix :,$1),$2),                                    \
         $(eval __t :=                                                    \
             $(subst $(word 1,$(subst :, ,$c)),$(word 2,$(subst :, ,$c)), \
                 $(__t))))$(__t)

# Common character classes for use with the tr function.  Each of
# these is actually a variable declaration and must be wrapped with
# $() or ${} to be used. 

[A-Z] := A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #
[a-z] := a b c d e f g h i j k l m n o p q r s t u v w x y z #
[0-9] := 0 1 2 3 4 5 6 7 8 9 #
[A-F] := A B C D E F #

# Upper case and lower case functions.  Each function has a single
# argument which is the text to alter

uc = $(call tr,$([a-z]),$([A-Z]),$1)
lc = $(call tr,$([A-Z]),$([a-z]),$1)

.PHONY: all
all:
        @echo $(call lc,The Quick Brown Fox)
        @echo $(call uc,The Quick Brown Fox)

John.
-- 
John Graham-Cumming

Home: http://www.jgc.org/
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