Add Range#overlap?

README.md

@@ -114,6 +114,7 @@ itself, JRuby and Rubinius.
 #### Range
 
 - `reverse_each` (with correct handling of endless Ranges)
+- `overlap?`
 
 ## Ruby 3.2 backports
 

lib/backports/3.3.0/range.rb

@@ -0,0 +1,3 @@
+require 'backports/tools/require_relative_dir'
+
+Backports.require_relative_dir

lib/backports/3.3.0/range/overlap.rb

@@ -0,0 +1,18 @@
+unless Range.method_defined? :overlap?
+  class Range
+    def overlap?(other)
+      raise TypeError, "wrong argument type #{other.class} (expected Range)" unless other.is_a?(Range)
+
+      [
+        [other.begin, self.end, exclude_end?],
+        [self.begin, other.end, other.exclude_end?],
+        [self.begin, self.end, exclude_end?],
+        [other.begin, other.end, other.exclude_end?],
+      ].all? do |from, to, excl|
+        less = (from || -Float::INFINITY) <=> (to || Float::INFINITY)
+        less = +1 if less == 0 && excl
+        less && less <= 0
+      end
+    end
+  end
+end

test/overlap_test.rb

@@ -0,0 +1,67 @@
+require './test/test_helper'
+require 'backports/3.3.0/range/overlap'
+
+class OverlapTest < Test::Unit::TestCase
+  def test_overlap?
+    assert_not_operator(0..2, :overlap?, -2..-1)
+    assert_not_operator(0..2, :overlap?, -2...0)
+    assert_operator(0..2, :overlap?, -1..0)
+    assert_operator(0..2, :overlap?, 1..2)
+    assert_operator(0..2, :overlap?, 2..3)
+    assert_not_operator(0..2, :overlap?, 3..4)
+    assert_not_operator(0...2, :overlap?, 2..3)
+
+    assert_operator(nil..0, :overlap?, -1..0)
+    assert_operator(nil...0, :overlap?, -1..0)
+    assert_operator(nil..0, :overlap?, 0..1)
+    assert_operator(nil..0, :overlap?, ..1)
+    assert_not_operator(nil..0, :overlap?, 1..2)
+    assert_not_operator(nil...0, :overlap?, 0..1)
+
+    assert_not_operator(0.., :overlap?, -2..-1)
+    assert_not_operator(0.., :overlap?, ...0)
+    assert_operator(0.., :overlap?, -1..0)
+    assert_operator(0.., :overlap?, ..0)
+    assert_operator(0.., :overlap?, 0..1)
+    assert_operator(0.., :overlap?, 1..2)
+    assert_operator(0.., :overlap?, 1..nil)
+
+    assert_not_operator((1..3), :overlap?, ('a'..'d'))
+
+    assert_raise(TypeError) { (0..nil).overlap?(1) }
+    assert_raise(TypeError) { (0..nil).overlap?(nil) }
+
+    assert_operator((1..3), :overlap?, (2..4))
+    assert_operator((1...3), :overlap?, (2..3))
+    assert_operator((2..3), :overlap?, (1..2))
+    assert_operator((nil..3), :overlap?, (3..nil))
+    assert_operator((nil..nil), :overlap?, (3..nil))
+    assert_operator((nil...nil), :overlap?, (nil..nil))
+
+    assert_raise(TypeError) { (1..3).overlap?(1) }
+
+    assert_not_operator((1..2), :overlap?, (2...2))
+    assert_not_operator((2...2), :overlap?, (1..2))
+
+    assert_not_operator((4..1), :overlap?, (2..3))
+    assert_not_operator((4..1), :overlap?, (nil..3))
+    assert_not_operator((4..1), :overlap?, (2..nil))
+
+    assert_not_operator((1..4), :overlap?, (3..2))
+    assert_not_operator((nil..4), :overlap?, (3..2))
+    assert_not_operator((1..nil), :overlap?, (3..2))
+
+    assert_not_operator((4..5), :overlap?, (2..3))
+    assert_not_operator((4..5), :overlap?, (2...4))
+
+    assert_not_operator((1..2), :overlap?, (3..4))
+    assert_not_operator((1...3), :overlap?, (3..4))
+
+    assert_not_operator((4..5), :overlap?, (2..3))
+    assert_not_operator((4..5), :overlap?, (2...4))
+
+    assert_not_operator((1..2), :overlap?, (3..4))
+    assert_not_operator((1...3), :overlap?, (3..4))
+    assert_not_operator((nil...3), :overlap?, (3..nil))
+  end
+end