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cdde9e894d
Features of interest: Allow setting target local variables (similar to gmake) In META_MODE .MAKE.META.CMP_FILTER can be used for filtering commands before comparion. contrib/bmake/mk/cc-wrap.mk is an example of using these See ChangeLog for the gory details.
42 lines
1.4 KiB
Makefile
42 lines
1.4 KiB
Makefile
# $NetBSD: hanoi-include.mk,v 1.2 2022/01/08 22:13:43 rillig Exp $
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#
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# Implements the Towers of Hanoi puzzle, thereby demonstrating a bunch of
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# more or less useful programming techniques:
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#
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# * default assignment using the ?= assignment operator
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# * including the same file recursively (rather unusual)
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# * extracting the current value of a variable using the .for loop
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# * using shell commands for calculations since make is a text processor
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# * using the :: dependency operator for adding commands to a target
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# * on-the-fly variable assignment expressions using the ::= modifier
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#
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# usage:
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# env N=3 make -f hanoi-include.mk
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# endless loop:
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# make -f hanoi-include.mk N=3
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N?= 5 # Move this number of disks ...
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FROM?= A # ... from this stack ...
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VIA?= B # ... via this stack ...
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TO?= C # ... to this stack.
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.if $N == 1
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. for from to in ${FROM} ${TO}
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all::
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@echo "Move the upper disk from stack ${from} to stack ${to}."
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. endfor
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.else
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_:= ${N::!=expr $N - 1} ${TMP::=${VIA}} ${VIA::=${TO}} ${TO::=${TMP}}
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. include "${.PARSEDIR}/${.PARSEFILE}"
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_:= ${N::!=expr $N + 1} ${TMP::=${VIA}} ${VIA::=${TO}} ${TO::=${TMP}}
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. for from to in ${FROM} ${TO}
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all::
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@echo "Move the upper disk from stack ${from} to stack ${to}."
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. endfor
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_:= ${N::!=expr $N - 1} ${TMP::=${VIA}} ${VIA::=${FROM}} ${FROM::=${TMP}}
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. include "${.PARSEDIR}/${.PARSEFILE}"
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_:= ${N::!=expr $N + 1} ${TMP::=${VIA}} ${VIA::=${FROM}} ${FROM::=${TMP}}
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.endif
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