Refactored to lazy mapping

Hakky54 · Nov 10, 2024 · 6cf7a62 · 6cf7a62
1 parent 7251d2e
commit 6cf7a62
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Showing 3 changed files with 41 additions and 18 deletions.
diff --git a/sslcontext-kickstart/src/main/java/nl/altindag/ssl/SSLFactory.java b/sslcontext-kickstart/src/main/java/nl/altindag/ssl/SSLFactory.java
@@ -167,7 +167,7 @@ public SSLEngine getSSLEngine(String peerHost, Integer peerPort) {
      * source in a functional way.
      */
     public <T> Box<T> map(Function<SSLFactory, T> mapper) {
-        return new Box<>(this).map(mapper);
+        return Box.of(this).map(mapper);
     }
 
     public static Builder builder() {

diff --git a/sslcontext-kickstart/src/main/java/nl/altindag/ssl/util/Box.java b/sslcontext-kickstart/src/main/java/nl/altindag/ssl/util/Box.java
@@ -17,27 +17,48 @@
 
 import nl.altindag.ssl.exception.GenericException;
 
+import java.util.function.Supplier;
+
 /**
  * @author Hakan Altindag
  */
-public final class Box<T> {
+@FunctionalInterface
+public interface Box<T> {
 
-    private final T value;
+    ValueHolder<T> container();
 
-    public Box(T value) {
-        this.value = value;
+    static <T> Box<T> of(T value) {
+        return () -> ValueHolder.wrap(() -> value);
     }
 
-    public <U> Box<U> map(Function<? super T, ? extends U> mapper) {
-        try {
-            return new Box<>(mapper.apply(value));
-        } catch (Exception e) {
-            throw new GenericException(e);
-        }
+    default <R> Box<R> map(Function<? super T, ? extends R> mapper) {
+        return () -> ValueHolder.wrap(() -> {
+            final T value = container().get();
+
+            try {
+                return mapper.apply(value);
+            } catch (Exception e) {
+                throw new GenericException(e);
+            }
+        });
+    }
+
+    default T get() {
+        return container().get();
     }
 
-    public T get() {
-        return value;
+    @FunctionalInterface
+    interface ValueHolder<T> {
+
+        Supplier<T> valueSupplier();
+
+        default T get() {
+            return valueSupplier().get();
+        }
+
+        static <U> ValueHolder<U> wrap(Supplier<U> supplier) {
+            return () -> supplier;
+        }
     }
 
-}
+}
diff --git a/sslcontext-kickstart/src/test/java/nl/altindag/ssl/util/BoxShould.java b/sslcontext-kickstart/src/test/java/nl/altindag/ssl/util/BoxShould.java
@@ -27,10 +27,12 @@ class BoxShould {
 
     @Test
     void wrapAnyExceptionInGenericException() {
-        Box<String> stringBox = new Box<>("");
-        assertThatThrownBy(() -> stringBox.map(value -> {
-            throw new RuntimeException("KABOOM");
-        }))
+        Box<String> stringBox = Box.of("")
+                .map(value -> {
+                    throw new RuntimeException("KABOOM");
+                });
+
+        assertThatThrownBy(stringBox::get)
                 .isInstanceOf(GenericException.class)
                 .hasRootCauseMessage("KABOOM");
     }