Lens.eachOption

solita · Mar 28, 2024 · f14ee89 · f14ee89
1 parent 12e4b38
commit f14ee89
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Showing 2 changed files with 27 additions and 1 deletion.
diff --git a/pom.xml b/pom.xml
@@ -2,7 +2,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>fi.solita.utils</groupId>
     <artifactId>functional-utils</artifactId>
-    <version>0.12.47</version>
+    <version>0.12.48</version>
     <build>
         <resources>
                 <resource>

diff --git a/src/main/java/fi/solita/utils/functional/lens/Lens.java b/src/main/java/fi/solita/utils/functional/lens/Lens.java
@@ -67,6 +67,32 @@ public Option<E> apply(Option<E> c) {
         );
     }
 
+    public static final <D,E,S> Lens<D,Option<S>> eachOption(final Lens<D,Option<E>> lens, final Lens<E,S> lens2) {
+        return new Lens<D,Option<S>>(
+            new Apply<D, Option<S>>() {
+                @Override
+                public Option<S> apply(D t) {
+                    return t == null ? null : lens.apply(t).map(lens2);
+                }
+            },
+            new Function2<D, Apply<Option<S>,Option<S>>, D>() {
+                @Override
+                public D apply(D d, final Apply<Option<S>, Option<S>> f) {
+                    return lens.modify(d, new Apply<Option<E>,Option<E>>() {
+                        public Option<E> apply(Option<E> c) {
+                            return c == null ? null : !c.isDefined() ? c : Some(lens2.modify(c.get(), new Apply<S, S>() {
+                                @Override
+                                public S apply(S t) {
+                                    return f.apply(Some(t)).get();
+                                }
+                            }));
+                        };
+                    });
+                }
+            }
+        );
+    }
+
     /**
      * @return a setter targetting each member of the collection behind {@code setter}.
      */