Add fast cast for recursive generics

dataforge-meta/src/commonMain/kotlin/space/kscience/dataforge/meta/Meta.kt

@@ -3,6 +3,7 @@ package space.kscience.dataforge.meta
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.json.Json
 import space.kscience.dataforge.misc.Type
+import space.kscience.dataforge.misc.unsafeCast
 import space.kscience.dataforge.names.*
 import space.kscience.dataforge.values.*
 
@@ -139,13 +140,6 @@ public fun Meta.getIndexed(name: Name): Map<String?, Meta> {
  */
 public interface TypedMeta<out M : TypedMeta<M>> : Meta {
 
-    /**
-     * Access self as a recursive type instance
-     */
-    @Suppress("UNCHECKED_CAST")
-    public val self: M
-        get() = this as M
-
     override val items: Map<NameToken, M>
 
     override fun getMeta(name: Name): M? {
@@ -161,6 +155,11 @@ public interface TypedMeta<out M : TypedMeta<M>> : Meta {
     override fun toMeta(): Meta = this
 }
 
+/**
+ * Access self as a recursive type instance
+ */
+public inline val <M : TypedMeta<M>> TypedMeta<M>.self: M get() = unsafeCast()
+
 //public typealias Meta = TypedMeta<*>
 
 public operator fun <M : TypedMeta<M>> TypedMeta<M>.get(token: NameToken): M? = items[token]

dataforge-meta/src/commonMain/kotlin/space/kscience/dataforge/meta/descriptors/MetaDescriptor.kt

@@ -51,6 +51,20 @@ public data class MetaDescriptor(
     public val defaultValue: Value? = null,
     public val attributes: Meta = Meta.EMPTY,
 ) {
+    /**
+     * A node constructed of default values for this descriptor and its children
+     */
+    public val defaultNode: Meta by lazy {
+        Meta {
+            defaultValue?.let { defaultValue ->
+                this.value = defaultValue
+            }
+            children.forEach { (key, descriptor) ->
+                set(key, descriptor.defaultNode)
+            }
+        }
+    }
+
     public companion object {
         internal const val ALLOWED_VALUES_KEY = "allowedValues"
     }
@@ -68,19 +82,6 @@ public operator fun MetaDescriptor.get(name: Name): MetaDescriptor? = when (name
 
 public operator fun MetaDescriptor.get(name: String): MetaDescriptor? = get(Name.parse(name))
 
-/**
- * A node constructed of default values for this descriptor and its children
- */
-public val MetaDescriptor.defaultNode: Meta
-    get() = Meta {
-        defaultValue?.let { defaultValue ->
-            this.value = defaultValue
-        }
-        children.forEach { (key, descriptor) ->
-            set(key, descriptor.defaultNode)
-        }
-    }
-
 public fun MetaDescriptor.validate(value: Value?): Boolean = if (value == null) {
     valueRequirement != ValueRequirement.REQUIRED
 } else {

dataforge-meta/src/commonMain/kotlin/space/kscience/dataforge/misc/cast.kt

@@ -0,0 +1,3 @@
+package space.kscience.dataforge.misc
+
+public expect inline fun <T> Any?.unsafeCast(): T

dataforge-meta/src/jsMain/kotlin/space/kscience/dataforge/misc/castJs.kt

@@ -0,0 +1,5 @@
+package space.kscience.dataforge.misc
+import kotlin.js.unsafeCast as unsafeCastJs
+
+@Suppress("UNCHECKED_CAST", "NOTHING_TO_INLINE")
+public actual inline fun <T> Any?.unsafeCast(): T = this.unsafeCastJs<T>()

dataforge-meta/src/jvmMain/kotlin/space/kscience/dataforge/misc/castJvm.kt

@@ -0,0 +1,4 @@
+package space.kscience.dataforge.misc
+
+@Suppress("UNCHECKED_CAST", "NOTHING_TO_INLINE")
+public actual inline fun <T> Any?.unsafeCast(): T = this as T

dataforge-meta/src/nativeMain/kotlin/space/kscience/dataforge/misc/castNative.kt

@@ -0,0 +1,4 @@
+package space.kscience.dataforge.misc
+
+@Suppress("UNCHECKED_CAST", "NOTHING_TO_INLINE")
+public actual inline fun <T> Any?.unsafeCast(): T = this as T