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Diffstat (limited to 'unit-tests/hanoi-include.mk')
| -rw-r--r-- | unit-tests/hanoi-include.mk | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/unit-tests/hanoi-include.mk b/unit-tests/hanoi-include.mk new file mode 100644 index 0000000000000..3ad0a751845ae --- /dev/null +++ b/unit-tests/hanoi-include.mk @@ -0,0 +1,41 @@ +# $NetBSD: hanoi-include.mk,v 1.1 2020/10/03 17:30:54 rillig Exp $ +# +# Implements the Towers of Hanoi puzzle, thereby demonstrating a bunch of +# useful programming techniques: +# +# * default assignment using the ?= assignment operator +# * including the same file recursively +# * extracting the current value of a variable using the .for loop +# * using shell commands for calculations since make is a text processor +# * using the :: dependency operator for adding commands to a target +# * on-the-fly variable assignment expressions using the ::= modifier +# +# usage: +# env N=3 make -f hanoi-include.mk +# endless loop: +# make -f hanoi-include.mk N=3 + +N?= 5 # Move this number of disks ... +FROM?= A # ... from this stack ... +VIA?= B # ... via this stack ... +TO?= C # ... to this stack. + +.if $N == 1 +. for from to in ${FROM} ${TO} +all:: + @echo "Move the upper disk from stack ${from} to stack ${to}." +. endfor +.else +_:= ${N::!=expr $N - 1} ${TMP::=${VIA}} ${VIA::=${TO}} ${TO::=${TMP}} +. include "${.PARSEDIR}/${.PARSEFILE}" +_:= ${N::!=expr $N + 1} ${TMP::=${VIA}} ${VIA::=${TO}} ${TO::=${TMP}} + +. for from to in ${FROM} ${TO} +all:: + @echo "Move the upper disk from stack ${from} to stack ${to}." +. endfor + +_:= ${N::!=expr $N - 1} ${TMP::=${VIA}} ${VIA::=${FROM}} ${FROM::=${TMP}} +. include "${.PARSEDIR}/${.PARSEFILE}" +_:= ${N::!=expr $N + 1} ${TMP::=${VIA}} ${VIA::=${FROM}} ${FROM::=${TMP}} +.endif |