Allow StdSerializers to output primitives and array structures.

konf-core/src/main/kotlin/com/uchuhimo/konf/source/Source.kt

@@ -476,10 +476,9 @@ internal fun Any?.toCompatibleValue(mapper: ObjectMapper): Any {
         is LongArray -> this.toList()
         is DoubleArray -> this.toList()
         is FloatArray -> this.toList()
-        is List<*> -> this.map { it!!.toCompatibleValue(mapper) }
-        is Set<*> -> this.map { it!!.toCompatibleValue(mapper) }
-        is Array<*> -> this.map { it!!.toCompatibleValue(mapper) }
-        is Map<*, *> -> this.mapValues { (_, value) -> value!!.toCompatibleValue(mapper) }
+        is Iterable<*> -> this.map { it.toCompatibleValue(mapper) }
+        is Array<*> -> this.map { it.toCompatibleValue(mapper) }
+        is Map<*, *> -> this.mapValues { (_, value) -> value.toCompatibleValue(mapper) }
         is Char -> this.toString()
         is String,
         is Boolean,
@@ -495,10 +494,7 @@ internal fun Any?.toCompatibleValue(mapper: ObjectMapper): Any {
             if (this == null) {
                 "null"
             } else {
-                val result = mapper.convertValue(this, Map::class.java).mapValues { (_, value) ->
-                    value.toCompatibleValue(mapper)
-                }
-                result
+                mapper.convertValue(this, Any::class.java).toCompatibleValue(mapper)
             }
         }
     }

konf-core/src/test/kotlin/com/uchuhimo/konf/source/serializer/PrimitiveStdSerializerSpec.kt

@@ -0,0 +1,89 @@
+/*
+ * Copyright 2017-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.uchuhimo.konf.source.serializer
+
+import com.fasterxml.jackson.core.JsonGenerator
+import com.fasterxml.jackson.core.JsonParser
+import com.fasterxml.jackson.databind.DeserializationContext
+import com.fasterxml.jackson.databind.SerializerProvider
+import com.fasterxml.jackson.databind.deser.std.StdDeserializer
+import com.fasterxml.jackson.databind.module.SimpleModule
+import com.fasterxml.jackson.databind.ser.std.StdSerializer
+import com.uchuhimo.konf.Config
+import com.uchuhimo.konf.ConfigSpec
+import com.uchuhimo.konf.source.json.toJson
+import org.jetbrains.spek.api.Spek
+import org.jetbrains.spek.api.dsl.given
+import org.jetbrains.spek.api.dsl.on
+import org.junit.jupiter.api.assertDoesNotThrow
+import java.io.StringReader
+import java.io.StringWriter
+import kotlin.test.assertEquals
+
+object PrimitiveStdSerializerSpec : Spek({
+    val config = Config {
+        addSpec(WrappedStringSpec)
+        mapper.registerModule(SimpleModule().apply {
+            addSerializer(WrappedString::class.java, WrappedStringStdSerializer())
+            addDeserializer(WrappedString::class.java, WrappedStringStdDeserializer())
+        })
+    }
+
+    given("a config") {
+        on("write json") {
+            val writer = StringWriter()
+            assertDoesNotThrow {
+                config.toJson.toWriter(writer)
+            }
+            assert(writer.toString().contains("\"wrapped-string\" : \"value\""))
+        }
+
+        val json = """
+            {
+              "wrapped-string" : "1234"
+            }
+        """.trimIndent()
+        given("json") {
+            on("read json") {
+                val read = config.from.json.reader(StringReader(json))
+                assertEquals(WrappedString("1234"), read[WrappedStringSpec.wrappedString])
+            }
+        }
+    }
+
+})
+
+private object WrappedStringSpec : ConfigSpec("") {
+
+    val wrappedString by optional(name = "wrapped-string", default = WrappedString("value"))
+}
+
+private class WrappedStringStdSerializer : StdSerializer<WrappedString>(WrappedString::class.java) {
+
+    override fun serialize(value: WrappedString, gen: JsonGenerator, provider: SerializerProvider) {
+        gen.writeString(value.string)
+    }
+}
+
+private class WrappedStringStdDeserializer : StdDeserializer<WrappedString>(WrappedString::class.java) {
+
+    override fun deserialize(p: JsonParser, ctxt: DeserializationContext): WrappedString {
+        return WrappedString(p.valueAsString)
+    }
+}
+
+private data class WrappedString(val string: String)