numeric_ext.rb: add Integer#ceildiv.

mrbgems/mruby-numeric-ext/mrblib/numeric_ext.rb

@@ -77,3 +77,23 @@ class Numeric
     (self & mask) == 0
   end
 end
+
+class Integer
+  #  call-seq:
+  #    ceildiv(other) -> integer
+  #
+  #  Returns the result of division +self+ by +other+. The
+  #  result is rounded up to the nearest integer.
+  #
+  #    3.ceildiv(3) # => 1
+  #    4.ceildiv(3) # => 2
+  #
+  #    4.ceildiv(-3) # => -1
+  #    -4.ceildiv(3) # => -1
+  #    -4.ceildiv(-3) # => 2
+  #
+  #    3.ceildiv(1.2) # => 3
+  def ceildiv(other)
+    -div(-other)
+  end
+end

mrbgems/mruby-numeric-ext/test/numeric.rb

@@ -25,3 +25,23 @@ assert('Integer#pow') do
   assert_equal(-8, (-2).pow(3))
   assert_equal(361, 9.pow(1024,1000))
 end
+
+assert('Integer#ceildiv') do
+  assert_equal(0, 0.ceildiv(3))
+  assert_equal(1, 1.ceildiv(3))
+  assert_equal(1, 3.ceildiv(3))
+  assert_equal(2, 4.ceildiv(3))
+
+  assert_equal(-1, 4.ceildiv(-3))
+  assert_equal(-1, -4.ceildiv(3))
+  assert_equal(2, -4.ceildiv(-3))
+
+#  assert_equal(3, 3.ceildiv(1.2))
+#  assert_equal(3, 3.ceildiv(6/5r))
+
+#  assert_equal(10, (10**100-11).ceildiv(10**99-1))
+#  assert_equal(11, (10**100-9).ceildiv(10**99-1))
+  assert_equal(8, 2.pow(3))
+  assert_equal(-8, (-2).pow(3))
+#  assert_equal(361, 9.pow(1024,1000))
+end