feat: add optional support

shapeshift/src/main/kotlin/dev/krud/shapeshift/ShapeShift.kt

@@ -14,6 +14,7 @@ import dev.krud.shapeshift.MappingDecoratorRegistration.Companion.id
 import dev.krud.shapeshift.MappingTransformerRegistration.Companion.id
 import dev.krud.shapeshift.condition.MappingCondition
 import dev.krud.shapeshift.condition.MappingConditionContext
+import dev.krud.shapeshift.container.ContainerAdapter
 import dev.krud.shapeshift.decorator.MappingDecorator
 import dev.krud.shapeshift.decorator.MappingDecoratorContext
 import dev.krud.shapeshift.dto.MappingStructure
@@ -35,7 +36,8 @@ class ShapeShift internal constructor(
     val mappingDefinitionResolvers: Set<MappingDefinitionResolver>,
     val defaultMappingStrategy: MappingStrategy,
     val decoratorRegistrations: Set<MappingDecoratorRegistration<out Any, out Any>>,
-    val objectSuppliers: Map<Class<*>, Supplier<*>>
+    val objectSuppliers: Map<Class<*>, Supplier<*>>,
+    val containerAdapters: Map<Class<*>, ContainerAdapter<out Any>>
 ) {
     val transformerRegistrations: MutableList<MappingTransformerRegistration<out Any, out Any>> = mutableListOf()
     internal val transformersByTypeCache: MutableMap<Class<out MappingTransformer<out Any?, out Any?>>, MappingTransformerRegistration<out Any?, out Any?>> =
@@ -116,14 +118,15 @@ class ShapeShift internal constructor(
         toPair.field.isAccessible = true
 
         val mappingStrategy = resolvedMappedField.effectiveMappingStrategy(defaultMappingStrategy)
-        val fromValue = fromPair.field.getValue(fromPair.target)
+        var fromValue = fromPair.field.getValue(fromPair.target)
         val shouldMapValue = when (mappingStrategy) {
             MappingStrategy.NONE -> error("Mapping strategy is set to NONE")
             MappingStrategy.MAP_ALL -> true
             MappingStrategy.MAP_NOT_NULL -> fromValue != null
         }
 
         if (shouldMapValue) {
+            fromValue = fromPair.field.getEffectiveValue(fromPair.target)
             try {
                 if (!resolvedMappedField.conditionMatches(fromValue)) {
                     return
@@ -142,12 +145,12 @@ class ShapeShift internal constructor(
                 }
 
                 if (valueToSet == null) {
-                    toPair.field.setValue(toPair.target, null)
+                    toPair.field.setEffectiveValue(toPair.target, null)
                 } else {
                     if (!toPair.type.isAssignableFrom(valueToSet::class.java)) {
                         error("Type mismatch: Expected ${toPair.type} but got ${valueToSet::class.java}")
                     }
-                    toPair.field.setValue(toPair.target, valueToSet)
+                    toPair.field.setEffectiveValue(toPair.target, valueToSet)
                 }
             } catch (e: Exception) {
                 val newException =
@@ -199,7 +202,7 @@ class ShapeShift internal constructor(
         val fieldType = field.type.kotlin.javaObjectType
 
         if (nodes.size == 1) {
-            return ObjectFieldTrio(target, field, fieldType)
+            return ObjectFieldTrio(target, field, field.getTrueType())
         }
         field.isAccessible = true
         var subTarget = field.get(target)
@@ -290,6 +293,33 @@ class ShapeShift internal constructor(
         error("Could not find a no-arg constructor or object supplier for class $clazz")
     }
 
+    private val Field.isContainer: Boolean get() = type in containerAdapters
+
+    private fun Field.getEffectiveValue(target: Any): Any? {
+        val value = getValue(target)
+        if (isContainer) {
+            return (containerAdapters[type] as ContainerAdapter<Any?>).unwrapValue(value)
+        }
+        return value
+    }
+
+    private fun Field.setEffectiveValue(target: Any, value: Any?) {
+        val value = if (isContainer) {
+            (containerAdapters[type] as ContainerAdapter<Any?>).wrapValue(value)
+        } else {
+            value
+        }
+        setValue(target, value)
+    }
+
+    private fun Field.getTrueType(): Class<*> {
+        return if (isContainer) {
+            (containerAdapters[type] as ContainerAdapter<Any?>).getTrueType(this)
+        } else {
+            type.kotlin.javaObjectType
+        }
+    }
+
     companion object {
         enum class SourceType {
             FROM,

shapeshift/src/main/kotlin/dev/krud/shapeshift/ShapeShiftBuilder.kt

@@ -12,6 +12,8 @@ package dev.krud.shapeshift
 
 import dev.krud.shapeshift.MappingDecoratorRegistration.Companion.toRegistration
 import dev.krud.shapeshift.MappingTransformerRegistration.Companion.toRegistration
+import dev.krud.shapeshift.container.ContainerAdapter
+import dev.krud.shapeshift.container.OptionalContainerAdapter
 import dev.krud.shapeshift.decorator.MappingDecorator
 import dev.krud.shapeshift.dsl.KotlinDslMappingDefinitionBuilder
 import dev.krud.shapeshift.resolver.MappingDefinition
@@ -37,7 +39,9 @@ import dev.krud.shapeshift.transformer.StringToIntMappingTransformer
 import dev.krud.shapeshift.transformer.StringToLongMappingTransformer
 import dev.krud.shapeshift.transformer.StringToShortMappingTransformer
 import dev.krud.shapeshift.transformer.base.MappingTransformer
+import java.util.*
 import java.util.function.Supplier
+import javax.swing.text.html.Option
 
 /**
  * A builder used to create a new ShapeShift instance.
@@ -51,6 +55,7 @@ class ShapeShiftBuilder {
     private var defaultMappingStrategy: MappingStrategy = MappingStrategy.MAP_NOT_NULL
     private val mappingDefinitions: MutableList<MappingDefinition> = mutableListOf()
     private val objectSuppliers: MutableMap<Class<*>, Supplier<*>> = mutableMapOf()
+    private val containerAdapters: MutableMap<Class<*>, ContainerAdapter<out Any>> = mutableMapOf()
 
     init {
         // Add default annotation resolver
@@ -60,6 +65,9 @@ class ShapeShiftBuilder {
         DEFAULT_TRANSFORMERS.forEach {
             withTransformer(it)
         }
+
+        // Default container adapters
+        containerAdapters[Optional::class.java] = OptionalContainerAdapter()
     }
 
     /**
@@ -174,7 +182,7 @@ class ShapeShiftBuilder {
             resolvers += StaticMappingDefinitionResolver(mappingDefinitions)
         }
 
-        return ShapeShift(transformerRegistrations, resolvers, defaultMappingStrategy, decoratorRegistrations, objectSuppliers)
+        return ShapeShift(transformerRegistrations, resolvers, defaultMappingStrategy, decoratorRegistrations, objectSuppliers, containerAdapters)
     }
 
     companion object {

shapeshift/src/main/kotlin/dev/krud/shapeshift/container/ContainerAdapter.kt

@@ -0,0 +1,24 @@
+/*
+ * Copyright KRUD 2024
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package dev.krud.shapeshift.container
+
+import java.lang.reflect.Field
+
+interface ContainerAdapter<ContainerType> {
+
+    val containerClazz: Class<ContainerType>
+
+    fun getTrueType(field: Field): Class<*>
+
+    fun unwrapValue(container: ContainerType): Any?
+
+    fun wrapValue(value: Any?): ContainerType
+}

shapeshift/src/main/kotlin/dev/krud/shapeshift/container/OptionalContainerAdapter.kt

@@ -0,0 +1,31 @@
+/*
+ * Copyright KRUD 2024
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package dev.krud.shapeshift.container
+
+import dev.krud.shapeshift.util.getGenericAtPosition
+import java.lang.reflect.Field
+import java.util.*
+
+class OptionalContainerAdapter: ContainerAdapter<Optional<*>> {
+    override val containerClazz: Class<Optional<*>> = Optional::class.java
+
+    override fun getTrueType(field: Field): Class<*> {
+        return field.getGenericAtPosition(0)
+    }
+
+    override fun unwrapValue(container: Optional<*>): Any? {
+        return container.orElse(null)
+    }
+
+    override fun wrapValue(value: Any?): Optional<*> {
+        return Optional.ofNullable(value)
+    }
+}

shapeshift/src/main/kotlin/dev/krud/shapeshift/util/ReflectionUtils.kt

@@ -13,6 +13,8 @@
 package dev.krud.shapeshift.util
 
 import java.lang.reflect.Field
+import java.lang.reflect.ParameterizedType
+
 
 data class ClassPair<From, To>(val from: Class<out From>, val to: Class<out To>)
 
@@ -45,4 +47,12 @@ internal fun Class<*>.getDeclaredFieldRecursive(name: String): Field {
         }
     }
     throw NoSuchFieldException(name)
+}
+
+internal fun Field.getGenericAtPosition(position: Int): Class<*> {
+    if (genericType !is ParameterizedType) {
+        error("Type ${this.type} is not parameterized")
+    }
+    val typeArgument = (genericType as ParameterizedType).actualTypeArguments[position] as Class<*>
+    return typeArgument
 }

shapeshift/src/test/kotlin/dev/krud/shapeshift/ValueContainerTest.kt

@@ -0,0 +1,63 @@
+package dev.krud.shapeshift
+
+import dev.krud.shapeshift.resolver.annotation.DefaultMappingTarget
+import dev.krud.shapeshift.resolver.annotation.MappedField
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import strikt.api.expect
+import strikt.assertions.isEqualTo
+import java.util.*
+import javax.swing.text.html.Option
+
+class ValueContainerTest {
+
+    internal lateinit var shapeShift: ShapeShift
+
+    @BeforeEach
+    internal fun setUp() {
+        shapeShift = ShapeShiftBuilder().build()
+    }
+
+    @Test
+    fun `contained values should be unwrapped, transformed and rewrapped`() {
+        val toWrapped = shapeShift.map<FromWrapped, ToWrapped>(FromWrapped())
+        expect {
+            that(toWrapped.someField).isEqualTo(Optional.of("ABCD"))
+            that(toWrapped.someField2).isEqualTo(Optional.of(123))
+        }
+    }
+
+    @Test
+    fun `empty but non-null container should set null`() {
+        val toNullable = shapeShift.map<FromNullable, ToNullable>(FromNullable())
+        println()
+    }
+
+
+    @DefaultMappingTarget(ToWrapped::class)
+    class FromWrapped {
+        @MappedField
+        var someField: Optional<String>? = Optional.of("ABCD")
+
+        @MappedField
+        var someField2: Optional<String>? = Optional.of("123")
+    }
+
+    class ToWrapped {
+        var someField: Optional<String>? = null
+        var someField2: Optional<Int>? = null
+    }
+
+    @DefaultMappingTarget(ToNullable::class)
+    class FromNullable {
+        @MappedField
+        var someField: Optional<String>? = Optional.empty()
+        @MappedField
+        var someField2: Optional<String>? = null
+    }
+
+    class ToNullable {
+        var someField: String? = "ABCD"
+        var someField2: String? = "ABCD"
+    }
+}