Clean up scheme and descriptor logic

build.gradle.kts

@@ -8,7 +8,7 @@ plugins {
 
 allprojects {
     group = "space.kscience"
-    version = "0.7.2-dev-2"
+    version = "0.8.0-dev-1"
 }
 
 subprojects {

dataforge-context/src/jvmMain/kotlin/space/kscience/dataforge/descriptors/annotations.kt

@@ -1,126 +0,0 @@
-/*
- * Copyright  2018 Alexander Nozik.
- *
- * 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 space.kscience.dataforge.descriptors
-
-//@MustBeDocumented
-//annotation class Attribute(
-//    val key: String,
-//    val value: String
-//)
-//
-//@MustBeDocumented
-//annotation class Attributes(
-//    val attrs: Array<Attribute>
-//)
-//
-//@MustBeDocumented
-//annotation class ItemDef(
-//    val info: String = "",
-//    val multiple: Boolean = false,
-//    val required: Boolean = false
-//)
-//
-//@Target(AnnotationTarget.PROPERTY)
-//@MustBeDocumented
-//annotation class ValueDef(
-//    val type: Array<ValueType> = [ValueType.STRING],
-//    val def: String = "",
-//    val allowed: Array<String> = [],
-//    val enumeration: KClass<*> = Any::class
-//)
-
-///**
-// * Description text for meta property, node or whole object
-// */
-//@Target(AnnotationTarget.CLASS, AnnotationTarget.PROPERTY)
-//@Retention(AnnotationRetention.RUNTIME)
-//@MustBeDocumented
-//annotation class Description(val value: String)
-//
-///**
-// * Annotation for value property which states that lists are expected
-// */
-//@Target(AnnotationTarget.PROPERTY)
-//@Retention(AnnotationRetention.RUNTIME)
-//@MustBeDocumented
-//annotation class Multiple
-//
-///**
-// * Descriptor target
-// * The DataForge path to the resource containing the description. Following targets are supported:
-// *  1. resource
-// *  1. file
-// *  1. class
-// *  1. method
-// *  1. property
-// *
-// *
-// * Does not work if [type] is provided
-// */
-//@Target(AnnotationTarget.CLASS, AnnotationTarget.PROPERTY, AnnotationTarget.VALUE_PARAMETER)
-//@Retention(AnnotationRetention.RUNTIME)
-//@MustBeDocumented
-//annotation class Descriptor(val value: String)
-//
-//
-///**
-// * Aggregator class for descriptor nodes
-// */
-//@Target(AnnotationTarget.CLASS, AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION, AnnotationTarget.VALUE_PARAMETER)
-//@Retention(AnnotationRetention.RUNTIME)
-//@MustBeDocumented
-//annotation class DescriptorNodes(vararg val nodes: NodeDef)
-//
-///**
-// * Aggregator class for descriptor values
-// */
-//@Target(AnnotationTarget.CLASS, AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION, AnnotationTarget.VALUE_PARAMETER)
-//@Retention(AnnotationRetention.RUNTIME)
-//@MustBeDocumented
-//annotation class DescriptorValues(vararg val nodes: ValueDef)
-//
-///**
-// * Alternative name for property descriptor declaration
-// */
-//@Target(AnnotationTarget.PROPERTY, AnnotationTarget.VALUE_PARAMETER)
-//@Retention(AnnotationRetention.RUNTIME)
-//@MustBeDocumented
-//annotation class DescriptorName(val name: String)
-//
-//@Target(AnnotationTarget.PROPERTY)
-//@Retention(AnnotationRetention.RUNTIME)
-//@MustBeDocumented
-//annotation class DescriptorValue(val def: ValueDef)
-////TODO enter fields directly?
-//
-//@Target(AnnotationTarget.PROPERTY)
-//@Retention(AnnotationRetention.RUNTIME)
-//@MustBeDocumented
-//annotation class ValueProperty(
-//    val name: String = "",
-//    val type: Array<ValueType> = arrayOf(ValueType.STRING),
-//    val multiple: Boolean = false,
-//    val def: String = "",
-//    val enumeration: KClass<*> = Any::class,
-//    val tags: Array<String> = emptyArray()
-//)
-//
-//
-//@Target(AnnotationTarget.PROPERTY)
-//@Retention(AnnotationRetention.RUNTIME)
-//@MustBeDocumented
-//annotation class NodeProperty(val name: String = "")

dataforge-context/src/jvmMain/kotlin/space/kscience/dataforge/descriptors/reflectiveDescriptors.kt

@@ -1,53 +1,124 @@
 package space.kscience.dataforge.descriptors
 
+import kotlinx.serialization.ExperimentalSerializationApi
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.decodeFromStream
+import org.slf4j.LoggerFactory
+import space.kscience.dataforge.meta.Scheme
+import space.kscience.dataforge.meta.SchemeSpec
+import space.kscience.dataforge.meta.ValueType
+import space.kscience.dataforge.meta.descriptors.MetaDescriptor
+import space.kscience.dataforge.meta.descriptors.MetaDescriptorBuilder
+import space.kscience.dataforge.meta.descriptors.node
+import java.net.URL
+import kotlin.reflect.KClass
+import kotlin.reflect.full.isSubclassOf
+import kotlin.reflect.full.memberProperties
+import kotlin.reflect.typeOf
 
-//inline fun <reified T : Scheme> T.buildDescriptor(): NodeDescriptor = NodeDescriptor {
-//    T::class.apply {
-//        findAnnotation<ItemDef>()?.let { def ->
-//            info = def.info
-//            required = def.required
-//            multiple = def.multiple
-//        }
-//        findAnnotation<Attribute>()?.let { attr ->
-//            attributes {
-//                this[attr.key] = attr.value.parseValue()
-//            }
-//        }
-//        findAnnotation<Attributes>()?.attrs?.forEach { attr ->
-//            attributes {
-//                this[attr.key] = attr.value.parseValue()
-//            }
-//        }
-//    }
-//    T::class.memberProperties.forEach { property ->
-//        val delegate = property.getDelegate(this@buildDescriptor)
-//
-//        val descriptor: ItemDescriptor = when (delegate) {
-//            is ConfigurableDelegate -> buildPropertyDescriptor(property, delegate)
-//            is ReadWriteDelegateWrapper<*, *> -> {
-//                if (delegate.delegate is ConfigurableDelegate) {
-//                    buildPropertyDescriptor(property, delegate.delegate as ConfigurableDelegate)
-//                } else {
-//                    return@forEach
-//                }
-//            }
-//            else -> return@forEach
-//        }
-//        defineItem(property.name, descriptor)
-//    }
-//}
 
-//inline fun <T : Scheme, reified V : Any?> buildPropertyDescriptor(
+/**
-//    property: KProperty1<T, V>,
+ * Description text for meta property, node or whole object
-//    delegate: ConfigurableDelegate
+ */
-//): ItemDescriptor {
+@Target(AnnotationTarget.CLASS, AnnotationTarget.PROPERTY)
-//    when {
+@Retention(AnnotationRetention.RUNTIME)
-//        V::class.isSubclassOf(Scheme::class) -> NodeDescriptor {
+@MustBeDocumented
-//            default = delegate.default.node
+public annotation class Description(val value: String)
-//        }
+
-//        V::class.isSubclassOf(Meta::class) -> NodeDescriptor {
+@Target(AnnotationTarget.PROPERTY)
-//            default = delegate.default.node
+@Retention(AnnotationRetention.RUNTIME)
-//        }
+@MustBeDocumented
-//
+public annotation class Multiple()
-//    }
+
-//}
+@Target(AnnotationTarget.CLASS, AnnotationTarget.PROPERTY)
+@Retention(AnnotationRetention.RUNTIME)
+@MustBeDocumented
+public annotation class DescriptorResource(val resourceName: String)
+
+@Target(AnnotationTarget.CLASS, AnnotationTarget.PROPERTY)
+@Retention(AnnotationRetention.RUNTIME)
+@MustBeDocumented
+public annotation class DescriptorUrl(val url: String)
+
+
+@OptIn(ExperimentalSerializationApi::class)
+private fun MetaDescriptorBuilder.loadDescriptorFromUrl(url: URL) {
+    url.openStream().use {
+        from(Json.decodeFromStream(MetaDescriptor.serializer(), it))
+    }
+}
+
+private fun MetaDescriptorBuilder.loadDescriptorFromResource(resource: DescriptorResource) {
+    val url = {}.javaClass.getResource(resource.resourceName)
+    if (url != null) {
+        loadDescriptorFromUrl(url)
+    } else {
+        LoggerFactory.getLogger("System")
+            .error("Can't find descriptor resource with name ${resource.resourceName}")
+    }
+}
+
+
+public fun <T : Any> MetaDescriptor.Companion.forClass(
+    kClass: KClass<T>,
+    mod: MetaDescriptorBuilder.() -> Unit = {},
+): MetaDescriptor = MetaDescriptor {
+    when {
+        kClass.isSubclassOf(Number::class) -> valueType(ValueType.NUMBER)
+        kClass == String::class -> ValueType.STRING
+        kClass == Boolean::class -> ValueType.BOOLEAN
+        kClass == DoubleArray::class -> ValueType.LIST
+    }
+
+    kClass.annotations.forEach {
+        when (it) {
+            is Description -> description = it.value
+
+            is DescriptorResource -> loadDescriptorFromResource(it)
+
+            is DescriptorUrl -> loadDescriptorFromUrl(URL(it.url))
+        }
+    }
+    kClass.memberProperties.forEach { property ->
+
+        var flag = false
+
+        val descriptor = MetaDescriptor {
+            //use base type descriptor as a base
+            (property.returnType.classifier as? KClass<*>)?.let {
+                from(forClass(it))
+            }
+            property.annotations.forEach {
+                when (it) {
+                    is Description -> {
+                        description = it.value
+                        flag = true
+                    }
+
+                    is Multiple -> {
+                        multiple = true
+                        flag = true
+                    }
+
+                    is DescriptorResource -> {
+                        loadDescriptorFromResource(it)
+                        flag = true
+                    }
+
+                    is DescriptorUrl -> {
+                        loadDescriptorFromUrl(URL(it.url))
+                        flag = true
+                    }
+                }
+            }
+        }
+        if (flag) {
+            node(property.name, descriptor)
+        }
+    }
+    mod()
+}
+
+@Suppress("UNCHECKED_CAST")
+public inline fun <reified T : Scheme> SchemeSpec<T>.autoDescriptor( noinline mod: MetaDescriptorBuilder.() -> Unit = {}): MetaDescriptor =
+    MetaDescriptor.forClass(typeOf<T>().classifier as KClass<T>, mod)

dataforge-context/src/jvmTest/kotlin/space/kscience/dataforge/descriptors/TestAutoDescriptors.kt

@@ -0,0 +1,29 @@
+package space.kscience.dataforge.descriptors
+
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.junit.jupiter.api.Test
+import space.kscience.dataforge.meta.*
+import space.kscience.dataforge.meta.descriptors.MetaDescriptor
+import space.kscience.dataforge.meta.transformations.MetaConverter
+
+private class TestScheme: Scheme(){
+
+    @Description("A")
+    val a by string()
+
+    @Description("B")
+    val b by int()
+
+    companion object: SchemeSpec<TestScheme>(::TestScheme){
+        override val descriptor: MetaDescriptor = autoDescriptor()
+    }
+}
+
+class TestAutoDescriptors {
+    @Test
+    fun autoDescriptor(){
+        val autoDescriptor = MetaDescriptor.forClass(TestScheme::class)
+        println(Json{prettyPrint = true}.encodeToString(autoDescriptor))
+    }
+}

dataforge-io/src/commonMain/kotlin/space/kscience/dataforge/io/Binary.kt

@@ -71,6 +71,11 @@ internal class ByteArrayBinary(
 
     override fun view(offset: Int, binarySize: Int): ByteArrayBinary =
         ByteArrayBinary(array, start + offset, binarySize)
+
+    override fun toString(): String =
+        "ByteArrayBinary(array=$array, start=$start, size=$size)"
+
+
 }
 
 public fun ByteArray.asBinary(): Binary = ByteArrayBinary(this)

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

@@ -15,28 +15,38 @@ import space.kscience.dataforge.names.*
 public open class Scheme : Described, MetaRepr, MutableMetaProvider, Configurable {
 
     /**
-     * Meta to be mutated by this schme
+     * Meta to be mutated by this scheme
      */
-    private var targetMeta: MutableMeta = MutableMeta()
+    private var target: MutableMeta? = null
+        get() {
+            // automatic initialization of target if it is missing
+            if (field == null) {
+                field = MutableMeta()
+            }
+            return field
+        }
 
     /**
      * Default values provided by this scheme
      */
-    private var defaultMeta: Meta? = null
+    private var prototype: Meta? = null
 
     final override val meta: ObservableMutableMeta = SchemeMeta(Name.EMPTY)
 
     final override var descriptor: MetaDescriptor? = null
-        internal set
+        private set
 
-    internal fun wrap(
+    /**
-        newMeta: MutableMeta,
+     * This method must be called before the scheme could be used
-        preserveDefault: Boolean = false,
+     */
+    internal fun initialize(
+        target: MutableMeta,
+        prototype: Meta,
+        descriptor: MetaDescriptor?,
     ) {
-        if (preserveDefault) {
+        this.target = target
-            defaultMeta = targetMeta.seal()
+        this.prototype = prototype
-        }
+        this.descriptor = descriptor
-        targetMeta = newMeta
     }
 
     /**
@@ -47,11 +57,11 @@ public open class Scheme : Described, MetaRepr, MutableMetaProvider, Configurabl
         return descriptor?.validate(meta) ?: true
     }
 
-    override fun get(name: Name): MutableMeta? = meta.get(name)
+    override fun get(name: Name): MutableMeta? = meta[name]
 
     override fun set(name: Name, node: Meta?) {
         if (validate(name, meta)) {
-            meta.set(name, node)
+            meta[name] = node
         } else {
             error("Validation failed for node $node at $name")
         }
@@ -68,14 +78,16 @@ public open class Scheme : Described, MetaRepr, MutableMetaProvider, Configurabl
 
     private val listeners: MutableList<MetaListener> = mutableListOf()
 
+    override fun toString(): String = meta.toString()
+
     private inner class SchemeMeta(val pathName: Name) : ObservableMutableMeta {
         override var value: Value?
-            get() = targetMeta[pathName]?.value
+            get() = target[pathName]?.value
-                ?: defaultMeta?.get(pathName)?.value
+                ?: prototype?.get(pathName)?.value
                 ?: descriptor?.get(pathName)?.defaultValue
             set(value) {
-                val oldValue = targetMeta[pathName]?.value
+                val oldValue = target[pathName]?.value
-                targetMeta[pathName] = value
+                target!![pathName] = value
                 if (oldValue != value) {
                     invalidate(Name.EMPTY)
                 }
@@ -83,8 +95,8 @@ public open class Scheme : Described, MetaRepr, MutableMetaProvider, Configurabl
 
         override val items: Map<NameToken, ObservableMutableMeta>
             get() {
-                val targetKeys = targetMeta[pathName]?.items?.keys ?: emptySet()
+                val targetKeys = target[pathName]?.items?.keys ?: emptySet()
-                val defaultKeys = defaultMeta?.get(pathName)?.items?.keys ?: emptySet()
+                val defaultKeys = prototype?.get(pathName)?.items?.keys ?: emptySet()
                 return (targetKeys + defaultKeys).associateWith { SchemeMeta(pathName + it) }
             }
 
@@ -111,7 +123,7 @@ public open class Scheme : Described, MetaRepr, MutableMetaProvider, Configurabl
         override fun hashCode(): Int = Meta.hashCode(this)
 
         override fun set(name: Name, node: Meta?) {
-            targetMeta.set(name, node)
+            target!![name] = node
             invalidate(name)
         }
 
@@ -119,7 +131,6 @@ public open class Scheme : Described, MetaRepr, MutableMetaProvider, Configurabl
 
         @DFExperimental
         override fun attach(name: Name, node: ObservableMutableMeta) {
-            //TODO implement zero-copy attachment
             set(name, node)
             node.onChange(this) { changeName ->
                 set(name + changeName, this[changeName])
@@ -131,10 +142,11 @@ public open class Scheme : Described, MetaRepr, MutableMetaProvider, Configurabl
 
 /**
  * Relocate scheme target onto given [MutableMeta]. Old provider does not get updates anymore.
- * Current state of the scheme used as a default.
+ * The Current state of the scheme that os used as a default.
  */
+@DFExperimental
 public fun <T : Scheme> T.retarget(provider: MutableMeta): T = apply {
-    wrap(provider, true)
+    initialize(provider, meta.seal(), descriptor)
 }
 
 /**
@@ -155,19 +167,18 @@ public open class SchemeSpec<out T : Scheme>(
     private val builder: () -> T,
 ) : Specification<T> {
 
+    override val descriptor: MetaDescriptor? get() = null
+
     override fun read(source: Meta): T = builder().also {
-        it.wrap(MutableMeta().withDefault(source))
+        it.initialize(MutableMeta(), source, descriptor)
     }
 
     override fun write(target: MutableMeta): T = empty().also {
-        it.wrap(target)
+        it.initialize(target, Meta.EMPTY, descriptor)
     }
 
-    //TODO Generate descriptor from Scheme class
-    override val descriptor: MetaDescriptor? get() = null
-
     override fun empty(): T = builder().also {
-        it.descriptor = descriptor
+        it.initialize(MutableMeta(), Meta.EMPTY, descriptor)
     }
 
     @Suppress("OVERRIDE_BY_INLINE")

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

@@ -44,38 +44,27 @@ public class MetaDescriptorBuilder @PublishedApi internal constructor() {
         attributes.apply(block)
     }
 
-    public fun item(name: Name, block: MetaDescriptorBuilder.() -> Unit = {}): MetaDescriptorBuilder {
+    internal fun node(
-        return when (name.length) {
+        name: Name,
-            0 -> apply(block)
+        descriptorBuilder: MetaDescriptorBuilder,
+    ): Unit {
+        when (name.length) {
+            0 -> error("Can't set descriptor to root")
             1 -> {
-                val target = MetaDescriptorBuilder().apply(block)
+                children[name.first().body] = descriptorBuilder
-                children[name.first().body] = target
-                target
             }
 
-            else -> {
+            else -> children.getOrPut(name.first().body) {
-                children.getOrPut(name.first().body) { MetaDescriptorBuilder() }.item(name.cutFirst(), block)
+                MetaDescriptorBuilder()
-            }
+            }.node(name.cutFirst(), descriptorBuilder)
         }
     }
 
-    public fun node(
+    internal fun node(
         name: Name,
-        descriptor: MetaDescriptor,
+        descriptorBuilder: MetaDescriptor,
-        block: MetaDescriptorBuilder.() -> Unit = {},
+    ): Unit {
-    ): MetaDescriptorBuilder = when (name.length) {
+        node(name, descriptorBuilder.toBuilder())
-        0 -> error("Can't set descriptor to root")
-        1 -> {
-            val item = descriptor.toBuilder().apply {
-                valueRestriction = ValueRestriction.ABSENT
-            }.apply(block)
-            children[name.first().body] = item
-            item
-        }
-
-        else -> children.getOrPut(name.first().body) {
-            MetaDescriptorBuilder()
-        }.node(name.cutFirst(), descriptor, block)
     }
 
     public var allowedValues: List<Value>
@@ -89,6 +78,17 @@ public class MetaDescriptorBuilder @PublishedApi internal constructor() {
         allowedValues = values.map { Value.of(it) }
     }
 
+    public fun from(descriptor: MetaDescriptor) {
+        description = descriptor.description
+        children.putAll(descriptor.children.mapValues { it.value.toBuilder() })
+        multiple = descriptor.multiple
+        valueRestriction = descriptor.valueRestriction
+        valueTypes = descriptor.valueTypes
+        indexKey = descriptor.indexKey
+        default = descriptor.defaultValue
+        attributes.update(descriptor.attributes)
+    }
+
     @PublishedApi
     internal fun build(): MetaDescriptor = MetaDescriptor(
         description = description,
@@ -102,40 +102,27 @@ public class MetaDescriptorBuilder @PublishedApi internal constructor() {
     )
 }
 
-public fun MetaDescriptorBuilder.item(name: String, block: MetaDescriptorBuilder.() -> Unit): MetaDescriptorBuilder =
+//public fun MetaDescriptorBuilder.item(name: String, block: MetaDescriptorBuilder.() -> Unit): MetaDescriptorBuilder =
-    item(Name.parse(name), block)
+//    item(Name.parse(name), block)
 
 public inline fun MetaDescriptor(block: MetaDescriptorBuilder.() -> Unit): MetaDescriptor =
     MetaDescriptorBuilder().apply(block).build()
 
 /**
- * Create and configure child value descriptor
+ * Create and configure child node descriptor
- */
-public fun MetaDescriptorBuilder.value(
-    name: Name,
-    type: ValueType,
-    vararg additionalTypes: ValueType,
-    block: MetaDescriptorBuilder.() -> Unit = {},
-): MetaDescriptorBuilder = item(name) {
-    valueType(type, *additionalTypes)
-    block()
-}
-
-public fun MetaDescriptorBuilder.value(
-    name: String,
-    type: ValueType,
-    vararg additionalTypes: ValueType,
-    block: MetaDescriptorBuilder.() -> Unit = {},
-): MetaDescriptorBuilder = value(Name.parse(name), type, additionalTypes = additionalTypes, block)
-
-/**
- * Create and configure child value descriptor
  */
 public fun MetaDescriptorBuilder.node(
-    name: Name, block: MetaDescriptorBuilder.() -> Unit,
+    name: Name,
-): MetaDescriptorBuilder = item(name) {
+    block: MetaDescriptorBuilder.() -> Unit,
-    valueRestriction = ValueRestriction.ABSENT
+) {
-    block()
+    node(
+        name,
+        MetaDescriptorBuilder().apply(block)
+    )
+}
+
+public fun MetaDescriptorBuilder.node(name: String, descriptor: MetaDescriptor) {
+    node(Name.parse(name), descriptor)
 }
 
 public fun MetaDescriptorBuilder.node(name: String, block: MetaDescriptorBuilder.() -> Unit) {
@@ -144,30 +131,16 @@ public fun MetaDescriptorBuilder.node(name: String, block: MetaDescriptorBuilder
 
 public fun MetaDescriptorBuilder.node(
     key: String,
-    described: Described,
+    base: Described,
     block: MetaDescriptorBuilder.() -> Unit = {},
 ) {
-    described.descriptor?.let {
+    node(Name.parse(key), base.descriptor?.toBuilder()?.apply(block) ?: MetaDescriptorBuilder())
-        node(Name.parse(key), it, block)
-    }
 }
 
 public fun MetaDescriptorBuilder.required() {
     valueRestriction = ValueRestriction.REQUIRED
 }
 
-public inline fun <reified E : Enum<E>> MetaDescriptorBuilder.enum(
-    key: Name,
-    default: E?,
-    crossinline modifier: MetaDescriptorBuilder.() -> Unit = {},
-): MetaDescriptorBuilder = value(key, ValueType.STRING) {
-    default?.let {
-        this.default = default.asValue()
-    }
-    allowedValues = enumValues<E>().map { it.asValue() }
-    modifier()
-}
-
 private fun MetaDescriptor.toBuilder(): MetaDescriptorBuilder = MetaDescriptorBuilder().apply {
     description = this@toBuilder.description
     children = this@toBuilder.children.mapValuesTo(LinkedHashMap()) { it.value.toBuilder() }
@@ -179,6 +152,40 @@ private fun MetaDescriptor.toBuilder(): MetaDescriptorBuilder = MetaDescriptorBu
     attributes = this@toBuilder.attributes.toMutableMeta()
 }
 
+
+/**
+ * Create and configure child value descriptor
+ */
+public fun MetaDescriptorBuilder.value(
+    name: Name,
+    type: ValueType,
+    vararg additionalTypes: ValueType,
+    block: MetaDescriptorBuilder.() -> Unit = {},
+): Unit = node(name) {
+    valueType(type, *additionalTypes)
+    block()
+}
+
+public fun MetaDescriptorBuilder.value(
+    name: String,
+    type: ValueType,
+    vararg additionalTypes: ValueType,
+    block: MetaDescriptorBuilder.() -> Unit = {},
+): Unit = value(Name.parse(name), type, additionalTypes = additionalTypes, block)
+
+
+public inline fun <reified E : Enum<E>> MetaDescriptorBuilder.enum(
+    key: Name,
+    default: E?,
+    crossinline modifier: MetaDescriptorBuilder.() -> Unit = {},
+): Unit = value(key, ValueType.STRING) {
+    default?.let {
+        this.default = default.asValue()
+    }
+    allowedValues = enumValues<E>().map { it.asValue() }
+    modifier()
+}
+
 /**
  * Make a deep copy of this descriptor applying given transformation [block]
  */

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

@@ -9,7 +9,7 @@ import kotlin.reflect.typeOf
 public inline fun <S : Scheme, reified T> MetaDescriptorBuilder.value(
     property: KProperty1<S, T>,
     noinline block: MetaDescriptorBuilder.() -> Unit = {},
-): MetaDescriptorBuilder = when (typeOf<T>()) {
+): Unit = when (typeOf<T>()) {
     typeOf<Number>(), typeOf<Int>(), typeOf<Double>(), typeOf<Short>(), typeOf<Long>(), typeOf<Float>() ->
         value(property.name, ValueType.NUMBER) {
             block()
@@ -34,7 +34,7 @@ public inline fun <S : Scheme, reified T> MetaDescriptorBuilder.value(
         multiple = true
         block()
     }
-    else -> item(property.name, block)
+    else -> node(property.name, block)
 }
 
 public inline fun <S : Scheme, reified T : Scheme> MetaDescriptorBuilder.scheme(

dataforge-meta/src/commonTest/kotlin/space/kscience/dataforge/meta/JsonMetaTest.kt

@@ -2,7 +2,7 @@ package space.kscience.dataforge.meta
 
 import kotlinx.serialization.json.*
 import space.kscience.dataforge.meta.descriptors.MetaDescriptor
-import space.kscience.dataforge.meta.descriptors.item
+import space.kscience.dataforge.meta.descriptors.node
 import kotlin.test.Test
 import kotlin.test.assertEquals
 
@@ -32,7 +32,7 @@ class JsonMetaTest {
     }
 
     val descriptor = MetaDescriptor {
-        item("nodeArray") {
+        node("nodeArray") {
             indexKey = "index"
         }
     }