Data commit

Task/Sierpinski-triangle/NetRexx/sierpinski-triangle.netrexx

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+/* NetRexx */
+options replace format comments java crossref symbols nobinary
+
+numeric digits 1000
+runSample(arg)
+return
+
+-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+method runSample(arg) public static
+  BLACK_UPPOINTING_TRIANGLE = '\u25b2'
+  parse arg ordr filr .
+  if ordr = '' | ordr = '.' then ordr = 4
+  if filr = '' | filr = '.' then filler = BLACK_UPPOINTING_TRIANGLE
+  else                           filler = filr
+  drawSierpinskiTriangle(ordr, filler)
+  return
+
+-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+method drawSierpinskiTriangle(ordr, filler = Rexx '^') public static
+  n = 1 * (2 ** ordr)
+  line = ' '.copies(2 * n)
+  line = line.overlay(filler, n + 1) -- set the top point of the triangle
+  loop row = 1 to n -- NetRexx arrays, lists etc. index from 1
+    say line.strip('t')
+    u = filler
+    loop col = 2 + n - row to n + row
+      cl = line.substr(col - 1, 1)
+      cr = line.substr(col + 1, 1)
+      if cl == cr then t = ' '
+      else             t = filler
+      line = line.overlay(u, col - 1)
+      u = t
+      end col
+      j2 = n + row - 1
+      j3 = n + row
+      line = line.overlay(t, j2 + 1)
+      line = line.overlay(filler, j3 + 1)
+    end row
+  return