Support auto-constructing for builtin types

backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/setting/Setting.kt

@@ -14,16 +14,12 @@ package net.mamoe.mirai.console.setting
 import kotlinx.serialization.*
 import kotlinx.serialization.builtins.MapSerializer
 import kotlinx.serialization.builtins.serializer
-import net.mamoe.mirai.console.setting.internal.isOdd
-import net.mamoe.mirai.console.setting.internal.typeOf0
-import net.mamoe.mirai.console.setting.internal.valueFromKTypeImpl
-import net.mamoe.mirai.console.setting.internal.valueImpl
+import net.mamoe.mirai.console.setting.internal.*
 import net.mamoe.yamlkt.YamlNullableDynamicSerializer
 import kotlin.internal.LowPriorityInOverloadResolution
 import kotlin.reflect.KProperty
 import kotlin.reflect.KType
 import kotlin.reflect.full.findAnnotation
-import kotlin.reflect.jvm.isAccessible
 
 
 // TODO: 2020/6/21 move to JvmPlugin to inherit SettingStorage and CoroutineScope for saving
@@ -170,9 +166,7 @@ fun Setting.value(default: String): SerializerAwareValue<String> = valueImpl(def
  */
 @Suppress("UNCHECKED_CAST")
 @LowPriorityInOverloadResolution
-inline fun <reified T> Setting.value(default: T): SerializerAwareValue<T> =
-    value<T>().apply { value = default }
-
+inline fun <reified T> Setting.value(default: T): SerializerAwareValue<T> = valueFromKType(typeOf0<T>(), default)
 
 /**
  * Creates a [Value] with reified type, and set default value by reflection to its no-arg public constructor.
@@ -183,11 +177,7 @@ inline fun <reified T> Setting.value(default: T): SerializerAwareValue<T> =
  * (typically annotated with [kotlinx.serialization.Serializable])
  */
 @LowPriorityInOverloadResolution
-inline fun <reified T> Setting.value(): SerializerAwareValue<T> =
-    value(
-        T::class.constructors.find { it.parameters.isEmpty() && it.isAccessible }?.call()
-            ?: throw IllegalArgumentException("Cannot construct a default value for given type ${typeOf0<T>()}")
-    )
+inline fun <reified T> Setting.value(): SerializerAwareValue<T> = value(T::class.createInstance() as T)
 
 /**
  * Creates a [Value] with specified [KType], and set default value.

backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/setting/internal/Setting.value composite impl.kt

@@ -21,6 +21,7 @@ import net.mamoe.yamlkt.YamlDynamicSerializer
 import net.mamoe.yamlkt.YamlNullableDynamicSerializer
 import kotlin.reflect.KClass
 import kotlin.reflect.KType
+import kotlin.reflect.full.createInstance as createInstanceKotlin
 
 private val primitiveCollectionsImplemented by lazy {
     false
@@ -40,7 +41,7 @@ internal fun Setting.valueFromKTypeImpl(type: KType): SerializerAwareValue<*> {
         return valueImplPrimitive(classifier) as SerializerAwareValue<*>
     }
 
-    // 复合类型
+    // TODO: 2020/6/24 优化性能: 预先根据类型生成 V -> Value<V> 的 mapper
 
     when (classifier) {
         MutableMap::class,
@@ -102,12 +103,36 @@ internal fun Setting.valueFromKTypeImpl(type: KType): SerializerAwareValue<*> {
     }
 }
 
+@PublishedApi
+internal fun KClass<*>.createInstance(): Any? {
+    return when (this) {
+        MutableMap::class,
+        Map::class,
+        LinkedHashMap::class,
+        HashMap::class
+        -> mutableMapOf<Any?, Any?>()
+
+        MutableList::class,
+        List::class,
+        ArrayList::class
+        -> mutableListOf<Any?>()
+
+        MutableSet::class,
+        Set::class,
+        LinkedHashSet::class,
+        HashSet::class
+        -> mutableSetOf<Any?>()
+
+        else -> createInstanceKotlin()
+    }
+}
+
 internal fun KClass<*>.isPrimitiveOrBuiltInSerializableValue(): Boolean {
     when (this) {
         Byte::class, Short::class, Int::class, Long::class,
         Boolean::class,
         Char::class, String::class,
-        Pair::class, Triple::class
+        Pair::class, Triple::class // TODO: 2020/6/24 支持 PairValue, TripleValue
         -> return true
     }