Memoize version lookups in VersionGem::Api

CHANGELOG.md

@@ -28,6 +28,9 @@ Please file a bug if you notice a violation of semantic versioning.
 
 ### Fixed
 
+- `_to_a` now memoizes the split version string, so `VERSION` is split once instead of on every component lookup
+- `pre` now caches a `nil` pre-release, so versions without a suffix no longer re-run the lookup on every call
+
 ### Security
 
 ## [1.1.17] - 2026-10-25

lib/version_gem/api.rb

@@ -35,7 +35,9 @@ def patch
     #
     # @return [String, NilClass]
     def pre
-      @pre ||= _to_a[3]
+      return @pre if defined?(@pre)
+
+      @pre = _to_a[3]
     end
 
     # The version number as a hash
@@ -63,7 +65,7 @@ def to_a
     #
     # @return [Array<String>]
     def _to_a
-      @_to_a = self::VERSION.split(".")
+      @_to_a ||= self::VERSION.split(".")
     end
   end
 end

spec/version_gem/api_spec.rb

@@ -34,4 +34,33 @@
       expect(under_test.to_a).to(eq([12, 34, 56, "pre-78"]))
     end
   end
+
+  context "when memoizing lookups" do
+    let(:version_string) { "1.2.3.pre-78".dup }
+    let(:version_module) do
+      Module.new.tap do |mod|
+        mod.const_set(:VERSION, version_string)
+        mod.extend(described_class)
+      end
+    end
+
+    it "splits the version string only once across component lookups" do
+      expect(version_string).to(receive(:split).once.and_call_original)
+
+      version_module.major
+      version_module.minor
+      version_module.patch
+      version_module.pre
+    end
+
+    context "without a pre-release" do
+      let(:version_string) { "1.2.3".dup }
+
+      it "looks up the pre-release only once" do
+        expect(version_module).to(receive(:_to_a).once.and_call_original)
+
+        3.times { version_module.pre }
+      end
+    end
+  end
 end