Add pattern matching support to Gem::Version

lib/rubygems/version.rb

@@ -336,6 +336,65 @@ def segments # :nodoc:
     _segments.dup
   end
 
+  ##
+  # Deconstructs the version into an array for pattern matching.
+  # Returns the version segments as an array.
+  #
+  #   Gem::Version.new("3.2.1").deconstruct      #=> [3, 2, 1]
+  #   Gem::Version.new("3.2.0.rc.2").deconstruct #=> [3, 2, 0, "rc", 2]
+  #
+  # This enables array pattern matching on version segments:
+  #
+  #   case Gem::Version.new("3.2.1")
+  #   in [major, minor, build]
+  #     # major => 3, minor => 2, build => 1
+  #   end
+  #
+  #   case Gem::Version.new("3.2.0.rc.2")
+  #   in [major, minor, build, pre, *]
+  #     # Matches prerelease versions
+  #   end
+  alias_method :deconstruct, :segments
+
+  ##
+  # Deconstructs the version into a hash for pattern matching.
+  # Returns a hash with keys +:major+, +:minor+, and +:build+.
+  #
+  # Note: RubyGems does not enforce a specific versioning scheme, and the
+  # names "major", "minor", and "build" are conventional.
+  #
+  #   Gem::Version.new("3.2.1").deconstruct_keys(nil)  #=> { major: 3, minor: 2, build: 1 }
+  #   Gem::Version.new("3.2").deconstruct_keys(nil)    #=> { major: 3, minor: 2, build: nil }
+  #   Gem::Version.new("3").deconstruct_keys(nil)      #=> { major: 3, minor: nil, build: nil }
+  #
+  # This enables hash pattern matching:
+  #
+  #   case Gem::Version.new("3.2.1")
+  #   in major: 3, minor: 2, build: 1
+  #     # Matches exactly 3.2.1
+  #   end
+  #
+  # Important: Hash pattern matching checks each segment independently, which
+  # differs from version comparison semantics:
+  #
+  #   # This matches "3.2" but NOT "4.0" (since 0 < 2)
+  #   case Gem::Version.new("4.0")
+  #   in major: (3..), minor: (2..)
+  #     "matches"
+  #   else
+  #     "no match"  # => "no match"
+  #   end
+  #
+  #   # However, version comparison shows 4.0 > 3.2
+  #   Gem::Version.new("4.0") >= Gem::Version.new("3.2")  #=> true
+  #
+  # For version comparison logic, use standard comparison operators or array
+  # patterns instead of hash patterns with ranges.
+  def deconstruct_keys(keys)
+    major, minor, build = segments
+    { major:, minor:, build: }
+  end
+
   ##
   # A recommended version for use with a ~> Requirement.
 

test/rubygems/test_gem_version.rb

@@ -226,6 +226,65 @@ def test_frozen_version
     assert_version_equal v("2"), v.bump
   end
 
+  def test_deconstruct
+    version = v("3.2.1")
+    major, minor, patch = version.deconstruct
+    assert_equal 3, major
+    assert_equal 2, minor
+    assert_equal 1, patch
+  end
+
+  def test_deconstruct_keys
+    version = v("3.2.1")
+    assert_equal({ major: 3, minor: 2, build: 1 }, version.deconstruct_keys(nil))
+  end
+
+  def test_deconstruct_keys_two_segments
+    version = v("3.2")
+    assert_equal({ major: 3, minor: 2, build: nil }, version.deconstruct_keys(nil))
+  end
+
+  def test_deconstruct_keys_one_segment
+    version = v("3")
+    assert_equal({ major: 3, minor: nil, build: nil }, version.deconstruct_keys(nil))
+  end
+
+  def test_pattern_matching_array
+    case v("3.2.1")
+    in [major, minor, build]
+      assert_equal 3, major
+      assert_equal 2, minor
+      assert_equal 1, build
+    else
+      flunk "Array pattern did not match"
+    end
+  end
+
+  def test_pattern_matching_hash
+    result =
+      case v("3.2.1")
+      in major: 3.., minor: 2.. then "matched"
+      else "no match"
+      end
+    assert_equal "matched", result
+  end
+
+  def test_pattern_matching_hash_vs_comparison
+    # Hash pattern checks each segment independently
+    version = v("4.0")
+    result =
+      case version
+      in major: (3..), minor: (2..)
+        "matched"
+      else
+        "no match"
+      end
+    assert_equal "no match", result
+
+    # But version comparison shows 4.0 > 3.2
+    assert_operator v("4.0"), :>=, v("3.2")
+  end
+
   # Asserts that +version+ is a prerelease.
 
   def assert_prerelease(version)