Data commit

Task/Conways-Game-of-Life/UNIX-Shell/conways-game-of-life.sh

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+# Shells only have 1-dimensional arrays, so each row is one string
+function main {
+  typeset blinker=(000 111 000)
+  run list 4 "${blinker[@]}"
+}
+
+function run {
+  typeset mode=$1 # screen or list
+  shift
+  typeset -i limit=0
+  if (( $1 > 1 )); then
+    limit=$1
+    shift
+  fi
+  if [[ mode == screen ]]; then
+    clear
+  fi
+  typeset universe=("$@")
+  typeset -i generation=0
+  while (( !limit || generation < limit )); do
+    if [[ mode == screen ]]; then
+      printf '\e[H'
+    else
+      printf '\n'
+    fi
+    printf 'Generation %d\n' "$generation"
+    disp "${universe[@]}" | tr '01' '.@'
+    universe=($(next_generation "${universe[@]}"))
+    (( generation += 1 ))
+    sleep 0.125
+  done
+}
+
+# display a matrix
+function disp {
+  # remove sed for more compact display
+  printf '%s\n' "$@" | sed 's/./ &/g'
+}
+
+# center a matrix within a given size by padding with 0s
+function center {
+  typeset height=$1 width=$2
+  shift 2
+  typeset -i offset_i offset_j i j
+  if (( $# > height || ${#1} > width )); then
+    printf >&2 'Source larger than target.\n'
+    return 1
+  fi
+  (( offset_i = (height - $#) / 2 ))
+  (( offset_j = (width - ${#1}) / 2 ))
+  typeset prefix zeroes suffix
+  for (( j=0; j<width; ++j )); do
+    zeroes+=0
+    if (( j < offset_j )); then
+      prefix+=0
+    elif (( j >= offset_j+${#1} )); then
+      suffix+=0
+    fi
+  done
+  for (( i=0; i<offset_i; ++i )); do
+    printf '%s\n' "$zeroes"
+  done
+  while (( $# )); do
+    printf '%s%s%s\n' "$prefix" "$1" "$suffix"
+    shift
+    (( i++ ))
+  done
+  while (( i++ < height )); do
+    printf '%s\n' "$zeroes"
+  done
+}
+
+# compute the next generation
+# the grid is finite; pass -t to treat as torus (wraparound), otherwise it's
+# bounded by always-dead cells
+next_generation() {
+  typeset -i torus=0
+  if [[ $1 == -t ]]; then
+    torus=1
+    shift
+  fi
+  # cache cells in an associative array
+  # (for fast lookup when counting neighbors)
+  typeset -A cells
+  typeset -i i=0 j=0 height=$# width=${#1}
+  while (( $# )); do
+    row=$1
+    shift
+    for (( j=0; j<${#row}; ++j )); do
+      cells[$i,$j]=${row:$j:1}
+    done
+    (( i+=1 ))
+  done
+  typeset -i di dj ni nj n cell
+  for (( i=0; i<height; ++i )); do
+    for (( j=0; j<width; ++j )); do
+      n=0
+      for (( di=-1; di<2; ++di )); do
+        (( ni = i + di ))
+        if (( torus )); then
+          (( ni = (ni + height) % height ))
+        fi
+        for (( dj=-1; dj<2; ++dj )); do
+          (( nj = j + dj ))
+          if (( torus )); then
+            (( nj = (nj + width) % width ))
+          fi
+          if (( (di || dj) && ni >= 0 && nj >= 0 && ni < height && nj < width  )); then
+            (( n += ${cells[$ni,$nj]} ))
+          fi
+        done
+      done
+      printf '%d' "$(( ( n == 3 ) || ( ${cells[$i,$j]} && n==2 ) ))"
+    done
+    printf '\n'
+  done
+}
+
+main "$@"