Merge pull request #4560 from lopopolo/range-max-min-hang

Specialize Enumerable#max and Enumerable#min for Range

3 files changed, 167 insertions, 0 deletions

diff --git a/mrbgems/mruby-range-ext/mrblib/range.rb b/mrbgems/mruby-range-ext/mrblib/range.rb
index de7925ba7..a149a57dc 100644
--- a/mrbgems/mruby-range-ext/mrblib/range.rb
+++ b/mrbgems/mruby-range-ext/mrblib/range.rb
@@ -25,4 +25,43 @@ class Range
     end
     ary
   end
+
+  def max(&block)
+    val = self.first
+    last = self.last
+    return super if block
+
+    # fast path for numerics
+    if (val.kind_of?(Fixnum) || val.kind_of?(Float)) && (last.kind_of?(Fixnum) || last.kind_of?(Float))
+      raise TypeError if exclude_end? && !last.kind_of?(Fixnum)
+      return nil if val > last
+      return nil if val == last && exclude_end?
+
+      max = last
+      max -= 1 if exclude_end?
+      return max
+    end
+
+    # delegate to Enumerable
+    super
+  end
+
+  def min(&block)
+    val = self.first
+    last = self.last
+    return super if block
+
+    # fast path for numerics
+    if (val.kind_of?(Fixnum) || val.kind_of?(Float)) && (last.kind_of?(Fixnum) || last.kind_of?(Float))
+      raise TypeError if exclude_end? && !last.kind_of?(Fixnum)
+      return nil if val > last
+      return nil if val == last && exclude_end?
+
+      min = val
+      return min
+    end
+
+    # delegate to Enumerable
+    super
+  end
 end
diff --git a/mrbgems/mruby-range-ext/test/range.rb b/mrbgems/mruby-range-ext/test/range.rb
index efcbdabe4..b56d6b58e 100644
--- a/mrbgems/mruby-range-ext/test/range.rb
+++ b/mrbgems/mruby-range-ext/test/range.rb
@@ -30,3 +30,105 @@ assert('Range#size') do
   assert_equal Float::INFINITY, (0..Float::INFINITY).size
   assert_nil ('a'..'z').size
 end
+
+assert('Range#max') do
+  # returns the maximum value in the range when called with no arguments
+  assert_equal 10, (1..10).max
+  assert_equal 9, (1...10).max
+  assert_equal 4294967295, (0...2**32).max
+
+  # returns the maximum value in the Float range when called with no arguments
+  assert_equal 908.1111, (303.20..908.1111).max
+
+  # raises TypeError when called on an exclusive range and a non Integer value
+  assert_raise(TypeError) { (303.20...908.1111).max }
+
+  # returns nil when the endpoint is less than the start point
+  assert_equal nil, (100..10).max
+
+  # returns nil when the endpoint equals the start point and the range is exclusive
+  assert_equal nil, (5...5).max
+
+  # returns the endpoint when the endpoint equals the start point and the range is inclusive
+  assert_equal 5, (5..5).max
+
+  # returns nil when the endpoint is less than the start point in a Float range
+  assert_equal nil, (3003.20..908.1111).max
+end
+
+assert('Range#max given a block') do
+  # passes each pair of values in the range to the block
+  acc = []
+  (1..10).max do |a, b|
+    acc << a
+    acc << b
+    a
+  end
+  (1..10).each do |value|
+    assert_true acc.include?(value)
+  end
+
+  # passes each pair of elements to the block in reversed order
+  acc = []
+  (1..5).max do |a, b|
+    acc << [a, b]
+    a
+  end
+  assert_equal [[2, 1], [3, 2], [4, 3], [5, 4]], acc
+
+  # returns the element the block determines to be the maximum
+  assert_equal 1, ((1..3).max { |_a, _b| -3 })
+
+  # returns nil when the endpoint is less than the start point
+  assert_equal nil, ((100..10).max { |x, y| x <=> y })
+  assert_equal nil, ((5...5).max { |x, y| x <=> y })
+end
+
+assert('Range#min') do
+  # returns the minimum value in the range when called with no arguments
+  assert_equal 1, (1..10).min
+  assert_equal 1, (1...10).min
+
+  # returns the minimum value in the Float range when called with no arguments
+  assert_equal 303.20, (303.20..908.1111).min
+
+  # returns nil when the start point is greater than the endpoint
+  assert_equal nil, (100..10).min
+
+  # returns nil when the endpoint equals the start point and the range is exclusive
+  assert_equal nil, (5...5).max
+
+  # returns the endpoint when the endpoint equals the start point and the range is inclusive
+  assert_equal 5, (5..5).max
+
+  # returns nil when the start point is greater than the endpoint in a Float range
+  assert_equal nil, (3003.20..908.1111).max
+end
+
+assert('Range#min given a block') do
+  # passes each pair of values in the range to the block
+  acc = []
+  (1..10).min do |a, b|
+    acc << a
+    acc << b
+    a
+  end
+  (1..10).each do |value|
+    assert_true acc.include?(value)
+  end
+
+  # passes each pair of elements to the block in reversed order
+  acc = []
+  (1..5).min do |a, b|
+    acc << [a, b]
+    a
+  end
+  assert_equal [[2, 1], [3, 1], [4, 1], [5, 1]], acc
+
+  # returns the element the block determines to be the minimum
+  assert_equal 3, ((1..3).min { |_a, _b| -3 })
+
+  # returns nil when the start point is greater than the endpoint
+  assert_equal nil, ((100..10).min { |x, y| x <=> y })
+  assert_equal nil, ((5...5).min { |x, y| x <=> y })
+end
diff --git a/mrbgems/mruby-string-ext/test/range.rb b/mrbgems/mruby-string-ext/test/range.rb
new file mode 100644
index 000000000..80c286850
--- /dev/null
+++ b/mrbgems/mruby-string-ext/test/range.rb
@@ -0,0 +1,26 @@
+assert('Range#max') do
+  # returns the maximum value in the range when called with no arguments
+  assert_equal 'l', ('f'..'l').max
+  assert_equal 'e', ('a'...'f').max
+
+  # returns nil when the endpoint is less than the start point
+  assert_equal nil, ('z'..'l').max
+end
+
+assert('Range#max given a block') do
+  # returns nil when the endpoint is less than the start point
+  assert_equal nil, (('z'..'l').max { |x, y| x <=> y })
+end
+
+assert('Range#min') do
+  # returns the minimum value in the range when called with no arguments
+  assert_equal 'f', ('f'..'l').min
+
+  # returns nil when the start point is greater than the endpoint
+  assert_equal nil, ('z'..'l').min
+end
+
+assert('Range#min given a block') do
+  # returns nil when the start point is greater than the endpoint
+  assert_equal nil, (('z'..'l').min { |x, y| x <=> y })
+end