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rose-ash/lib/smalltalk/tests/programs/life.st
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smalltalk: Conway Life + dynamic-array literal {…}; classic corpus complete
2026-04-25 07:31:47 +00:00

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1.7 KiB
Smalltalk

"Conway's Game of Life — 2D grid stepped by the standard rules:
live with 2 or 3 neighbours stays alive; dead with exactly 3 becomes alive.
Classic-corpus program for the Smalltalk-on-SX runtime. The canonical
'glider gun' demo (~36 cells, period-30 emission) is correct but too slow
to verify on the spec interpreter without JIT — block, blinker, glider
cover the rule arithmetic and edge handling."
Object subclass: #Life
instanceVariableNames: 'rows cols cells'!
!Life methodsFor: 'init'!
rows: r cols: c
rows := r. cols := c.
cells := Array new: r * c.
1 to: r * c do: [:i | cells at: i put: 0].
^ self! !
!Life methodsFor: 'access'!
rows ^ rows!
cols ^ cols!
at: r at: c
((r < 1) or: [r > rows]) ifTrue: [^ 0].
((c < 1) or: [c > cols]) ifTrue: [^ 0].
^ cells at: (r - 1) * cols + c!
at: r at: c put: v
cells at: (r - 1) * cols + c put: v.
^ v! !
!Life methodsFor: 'step'!
neighbors: r at: c
| sum |
sum := 0.
-1 to: 1 do: [:dr |
-1 to: 1 do: [:dc |
((dr = 0) and: [dc = 0]) ifFalse: [
sum := sum + (self at: r + dr at: c + dc)]]].
^ sum!
step
| next |
next := Array new: rows * cols.
1 to: rows * cols do: [:i | next at: i put: 0].
1 to: rows do: [:r |
1 to: cols do: [:c |
| n alive lives |
n := self neighbors: r at: c.
alive := (self at: r at: c) = 1.
lives := alive
ifTrue: [(n = 2) or: [n = 3]]
ifFalse: [n = 3].
lives ifTrue: [next at: (r - 1) * cols + c put: 1]]].
cells := next.
^ self!
stepN: n
n timesRepeat: [self step].
^ self! !
!Life methodsFor: 'measure'!
livingCount
| sum |
sum := 0.
1 to: rows * cols do: [:i | (cells at: i) = 1 ifTrue: [sum := sum + 1]].
^ sum! !