Introduce automatic Generation of Delegating Lenses: Improves Validation Support for Sealed Class Hierarchies

core/src/commonMain/kotlin/dev/fritz2/core/lens.kt

@@ -7,7 +7,8 @@ package dev.fritz2.core
 annotation class Lenses
 
 /**
- * Describes a focus point into a data structure, i.e. a property of a given complex entity
+ * Describes a focus point into a data structure, i.e. a property of a given complex entity for read and write
+ * access.
  *
  * @property id identifies the focus of this lens
  */
@@ -37,9 +38,9 @@ interface Lens<P, T> {
      */
     suspend fun apply(parent: P, mapper: suspend (T) -> T): P = set(parent, mapper(get(parent)))
 
-
     /**
-     * appends to [Lens]es so that the resulting [Lens] points from the parent of the [Lens] this is called on to the target of [other]
+     * appends to [Lens]es so that the resulting [Lens] points from the parent of the [Lens] this is called on to
+     * the target of [other]
      *
      * @param other [Lens] to append to this one
      */
@@ -56,9 +57,11 @@ interface Lens<P, T> {
      */
     fun withNullParent(): Lens<P?, T> = object : Lens<P?, T> {
         override val id: String = [email protected]
+
         override fun get(parent: P?): T =
             if (parent != null) [email protected](parent)
             else throw NullPointerException("get called with null parent on not-nullable lens@$id")
+
         override fun set(parent: P?, value: T): P? =
             if (parent != null) [email protected](parent, value)
             else throw NullPointerException("set called with null parent on not-nullable lens@$id")
@@ -176,5 +179,5 @@ fun <K, V> lensForElement(key: K): Lens<Map<K, V>, V> = object : Lens<Map<K, V>,
 internal fun <T> defaultLens(id: String, default: T): Lens<T?, T> = object : Lens<T?, T> {
     override val id: String = id
     override fun get(parent: T?): T = parent ?: default
-    override fun set(parent: T?, value: T): T?  = value.takeUnless { it == default }
+    override fun set(parent: T?, value: T): T? = value.takeUnless { it == default }
 }

core/src/commonTest/kotlin/dev/fritz2/core/inspector.kt

@@ -72,8 +72,16 @@ class InspectorTests {
         assertEquals(personList[0].name, p1NameInspector.data, "sub sub model data for element not correct")
 
         val p1StreetInspector = p1Inspector.map(addressLens).map(streetLens)
-        assertEquals(".${personList[0].id}.address.street", p1StreetInspector.path, "sub sub sub model id for element not correct")
-        assertEquals(personList[0].address.street, p1StreetInspector.data, "sub sub sub model data for element not correct")
+        assertEquals(
+            ".${personList[0].id}.address.street",
+            p1StreetInspector.path,
+            "sub sub sub model id for element not correct"
+        )
+        assertEquals(
+            personList[0].address.street,
+            p1StreetInspector.data,
+            "sub sub sub model data for element not correct"
+        )
     }
 
     @Test
@@ -92,12 +100,24 @@ class InspectorTests {
             assertEquals(personList[i], it.data, "[$i] sub model data for element not correct")
 
             val p1NameInspector = it.map(nameLens)
-            assertEquals(".${personList[i].id}.name", p1NameInspector.path, "[$i] sub sub model id for element not correct")
+            assertEquals(
+                ".${personList[i].id}.name",
+                p1NameInspector.path,
+                "[$i] sub sub model id for element not correct"
+            )
             assertEquals(personList[i].name, p1NameInspector.data, "[$i] sub sub model data for element not correct")
 
             val p1StreetInspector = it.map(addressLens).map(streetLens)
-            assertEquals(".${personList[i].id}.address.street", p1StreetInspector.path, "[$i] sub sub sub model id for element not correct")
-            assertEquals(personList[i].address.street, p1StreetInspector.data, "[$i] sub sub sub model data for element not correct")
+            assertEquals(
+                ".${personList[i].id}.address.street",
+                p1StreetInspector.path,
+                "[$i] sub sub sub model id for element not correct"
+            )
+            assertEquals(
+                personList[i].address.street,
+                p1StreetInspector.data,
+                "[$i] sub sub sub model data for element not correct"
+            )
 
             i++
         }
@@ -123,7 +143,11 @@ class InspectorTests {
 
         val p1StreetInspector = p1Inspector.map(addressLens).map(streetLens)
         assertEquals(".0.address.street", p1StreetInspector.path, "sub sub sub model id for element not correct")
-        assertEquals(personList[0].address.street, p1StreetInspector.data, "sub sub sub model data for element not correct")
+        assertEquals(
+            personList[0].address.street,
+            p1StreetInspector.data,
+            "sub sub sub model data for element not correct"
+        )
     }
 
     @Test
@@ -146,8 +170,16 @@ class InspectorTests {
             assertEquals(personList[i].name, p1NameInspector.data, "[$i] sub sub model data for element not correct")
 
             val p1StreetInspector = it.map(addressLens).map(streetLens)
-            assertEquals(".$i.address.street", p1StreetInspector.path, "[$i] sub sub sub model id for element not correct")
-            assertEquals(personList[i].address.street, p1StreetInspector.data, "[$i] sub sub sub model data for element not correct")
+            assertEquals(
+                ".$i.address.street",
+                p1StreetInspector.path,
+                "[$i] sub sub sub model id for element not correct"
+            )
+            assertEquals(
+                personList[i].address.street,
+                p1StreetInspector.data,
+                "[$i] sub sub sub model data for element not correct"
+            )
 
             i++
         }
@@ -173,7 +205,11 @@ class InspectorTests {
 
         val p1StreetInspector = p1Inspector.map(addressLens).map(streetLens)
         assertEquals(".2.address.street", p1StreetInspector.path, "sub sub sub model id for element not correct")
-        assertEquals(personList[2]?.address?.street, p1StreetInspector.data, "sub sub sub model data for element not correct")
+        assertEquals(
+            personList[2]?.address?.street,
+            p1StreetInspector.data,
+            "sub sub sub model data for element not correct"
+        )
     }
 
     @Test
@@ -197,8 +233,16 @@ class InspectorTests {
             assertEquals(personList[i]?.name, p1NameInspector.data, "[$i] sub sub model data for element not correct")
 
             val p1StreetInspector = inspector.map(addressLens).map(streetLens)
-            assertEquals(".$i.address.street", p1StreetInspector.path, "[$i] sub sub sub model id for element not correct")
-            assertEquals(personList[i]?.address?.street, p1StreetInspector.data, "[$i] sub sub sub model data for element not correct")
+            assertEquals(
+                ".$i.address.street",
+                p1StreetInspector.path,
+                "[$i] sub sub sub model id for element not correct"
+            )
+            assertEquals(
+                personList[i]?.address?.street,
+                p1StreetInspector.data,
+                "[$i] sub sub sub model data for element not correct"
+            )
 
             i++
         }

core/src/commonTest/kotlin/dev/fritz2/core/lens.kt

@@ -12,7 +12,6 @@ class LensesTests {
     private val heightLens = lensOf(Size::height.name, Size::height) { p, v -> p.copy(height = v) }
     private val ageLens = lensOf(Tree::age.name, Tree::age) { p, v -> p.copy(age = v) }
     private val sizeLens = lensOf(Tree::size.name, Tree::size) { p, v -> p.copy(size = v) }
-    private val tagLens = lensOf(Tree::tags.name, Tree::tags) { p, v -> p.copy(tags = v) }
 
     @Test
     fun testFormatLens() {
@@ -89,10 +88,19 @@ class LensesTests {
         val notNullLens: Lens<PostalAddress?, String> = streetLens.withNullParent()
 
         assertEquals(someStreet, notNullLens.get(addressWithCo), "not null lens does get value on non null parent")
-        assertFailsWith(NullPointerException::class, "not null lens does not throw exception when get on null parent") { notNullLens.get(null) }
+        assertFailsWith(
+            NullPointerException::class,
+            "not null lens does not throw exception when get on null parent"
+        ) { notNullLens.get(null) }
 
-        assertEquals(newValue, notNullLens.set(addressWithCo, newValue)?.street, "not null lens does set value on non null parent")
-        assertFailsWith(NullPointerException::class, "not null lens does not throw exception when set on null parent") { notNullLens.set(null, newValue)?.street }
+        assertEquals(
+            newValue,
+            notNullLens.set(addressWithCo, newValue)?.street,
+            "not null lens does set value on non null parent"
+        )
+        assertFailsWith(
+            NullPointerException::class,
+            "not null lens does not throw exception when set on null parent"
+        ) { notNullLens.set(null, newValue)?.street }
     }
-
-}
+}

lenses-annotation-processor/src/jvmMain/kotlin/dev/fritz2/lens/LenseablePropertiesDeterminer.kt

@@ -0,0 +1,19 @@
+package dev.fritz2.lens
+
+import com.google.devtools.ksp.getDeclaredProperties
+import com.google.devtools.ksp.isPublic
+import com.google.devtools.ksp.symbol.KSClassDeclaration
+import com.google.devtools.ksp.symbol.KSPropertyDeclaration
+
+internal fun interface LenseablePropertiesDeterminer {
+    fun determine(classDeclaration: KSClassDeclaration): List<KSPropertyDeclaration>
+}
+
+internal val determineLensablePropertiesInConstructor = LenseablePropertiesDeterminer { classDeclaration ->
+    val allPublicCtorProps = classDeclaration.primaryConstructor!!.parameters.filter { it.isVal }.map { it.name }
+    classDeclaration.getDeclaredProperties()
+        .filter { it.isPublic() && allPublicCtorProps.contains(it.simpleName) }.toList()
+}
+internal val determineLensablePropertiesInBody = LenseablePropertiesDeterminer { classDeclaration ->
+    classDeclaration.getDeclaredProperties().filter { it.isPublic() }.toList()
+}