feat(uml): implement part of generalization hierarchy

clazz.uml

@@ -0,0 +1,106 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<uml:Model xmi:version="20131001" xmlns:xmi="http://www.omg.org/spec/XMI/20131001" xmlns:uml="http://www.eclipse.org/uml2/5.0.0/UML" xmi:id="_Cfp0UGmxEe2kLe5KTNzRtw" name="clazz">
+  <packagedElement xmi:type="uml:Class" xmi:id="_QE0EkK7gEe2EZoZ5sgiBCg" name="asd">
+    <ownedAttribute xmi:id="_bM_S4K7gEe2EZoZ5sgiBCg" name="NewProperty1" type="_9pVK8LK0Ee24ffphK9Na6g">
+      <lowerValue xmi:type="uml:LiteralInteger" xmi:id="_bM_58K7gEe2EZoZ5sgiBCg" value="3"/>
+      <upperValue xmi:type="uml:LiteralUnlimitedNatural" xmi:id="_bNAhAK7gEe2EZoZ5sgiBCg" value="4"/>
+    </ownedAttribute>
+    <ownedAttribute xmi:id="_g69BoK7oEe2EZoZ5sgiBCg" name="NewProperty2">
+      <lowerValue xmi:type="uml:LiteralInteger" xmi:id="_g69Boa7oEe2EZoZ5sgiBCg" value="1"/>
+      <upperValue xmi:type="uml:LiteralUnlimitedNatural" xmi:id="_g69Boq7oEe2EZoZ5sgiBCg" value="*"/>
+    </ownedAttribute>
+    <ownedAttribute xmi:id="_O3oC8bK1Ee24ffphK9Na6g" name="NewClass1" type="_MHjIALK1Ee24ffphK9Na6g" aggregation="shared" association="_O3oC8LK1Ee24ffphK9Na6g">
+      <lowerValue xmi:type="uml:LiteralInteger" xmi:id="_O3oqALK1Ee24ffphK9Na6g" value="1"/>
+      <upperValue xmi:type="uml:LiteralUnlimitedNatural" xmi:id="_O3oqAbK1Ee24ffphK9Na6g" value="1"/>
+    </ownedAttribute>
+    <ownedAttribute xmi:id="_UahDwbK1Ee24ffphK9Na6g" name="NewClass3" type="_Mg74YLK1Ee24ffphK9Na6g" association="_UahDwLK1Ee24ffphK9Na6g">
+      <lowerValue xmi:type="uml:LiteralInteger" xmi:id="_Uahq0LK1Ee24ffphK9Na6g" value="1"/>
+      <upperValue xmi:type="uml:LiteralUnlimitedNatural" xmi:id="_Uahq0bK1Ee24ffphK9Na6g" value="1"/>
+    </ownedAttribute>
+    <ownedAttribute xmi:id="_VYMM8bK1Ee24ffphK9Na6g" name="new Class 4" type="_M-U_ALK1Ee24ffphK9Na6g" aggregation="composite" association="_VYMM8LK1Ee24ffphK9Na6g">
+      <lowerValue xmi:type="uml:LiteralInteger" xmi:id="_VYM0ALK1Ee24ffphK9Na6g" value="1"/>
+      <upperValue xmi:type="uml:LiteralUnlimitedNatural" xmi:id="_VYM0AbK1Ee24ffphK9Na6g" value="1"/>
+    </ownedAttribute>
+    <interfaceRealization xmi:id="_ay8lcLK1Ee24ffphK9Na6g" client="_QE0EkK7gEe2EZoZ5sgiBCg" supplier="_9pVK8LK0Ee24ffphK9Na6g" contract="_9pVK8LK0Ee24ffphK9Na6g"/>
+    <ownedOperation xmi:id="_Cr6ZsK70Ee2EZoZ5sgiBCg" name="NewOperation3"/>
+    <ownedOperation xmi:id="_r0YL0K70Ee2EZoZ5sgiBCg" name="NewOperation1">
+      <ownedParameter xmi:id="_Pf5kMbFSEe2z_s-Al402-w" name="NewParameter1" type="_QE0EkK7gEe2EZoZ5sgiBCg" direction="return"/>
+      <ownedParameter xmi:id="_TnD78LFUEe2z_s-Al402-w" name="NewParameter2" type="_W7vZ8K79Ee2EZoZ5sgiBCg" direction="return"/>
+      <ownedParameter xmi:id="_YG02YLFVEe2z_s-Al402-w" name="NewParameter3" type="_9pVK8LK0Ee24ffphK9Na6g"/>
+      <ownedParameter xmi:id="_huGJQbFuEe21bf9NlKs9Kg" name="NewParameter4"/>
+    </ownedOperation>
+  </packagedElement>
+  <packagedElement xmi:type="uml:DataType" xmi:id="_W7vZ8K79Ee2EZoZ5sgiBCg" name="NewDataType1"/>
+  <packagedElement xmi:type="uml:Class" xmi:id="_7Y-R4LK0Ee24ffphK9Na6g" name="NewClass2" isAbstract="true"/>
+  <packagedElement xmi:type="uml:Enumeration" xmi:id="_8Q6mgLK0Ee24ffphK9Na6g" name="NewEnumeration1">
+    <ownedLiteral xmi:id="__G-0sLK0Ee24ffphK9Na6g" name="NewEnumerationLiteral1"/>
+  </packagedElement>
+  <packagedElement xmi:type="uml:Interface" xmi:id="_9pVK8LK0Ee24ffphK9Na6g" name="NewInterface1"/>
+  <packagedElement xmi:type="uml:Package" xmi:id="_99xw8LK0Ee24ffphK9Na6g" name="NewPackage3" visibility="public">
+    <packageImport xmi:id="_dxJb8LK1Ee24ffphK9Na6g" importedPackage="_dDtuMLK1Ee24ffphK9Na6g"/>
+    <packageMerge xmi:id="_e5mRwLK1Ee24ffphK9Na6g" mergedPackage="_ed5NMLK1Ee24ffphK9Na6g"/>
+    <packagedElement xmi:type="uml:Package" xmi:id="_AmwlYLK1Ee24ffphK9Na6g" name="NewPackage1"/>
+  </packagedElement>
+  <packagedElement xmi:type="uml:PrimitiveType" xmi:id="_-da6ULK0Ee24ffphK9Na6g" name="NewPrimitiveType1">
+    <ownedAttribute xmi:id="_ipeAULK2Ee24ffphK9Na6g" name="NewProperty1" isStatic="true" isDerived="true">
+      <lowerValue xmi:type="uml:LiteralInteger" xmi:id="_ipenYLK2Ee24ffphK9Na6g" value="1"/>
+      <upperValue xmi:type="uml:LiteralUnlimitedNatural" xmi:id="_ipenYbK2Ee24ffphK9Na6g" value="1"/>
+    </ownedAttribute>
+  </packagedElement>
+  <packagedElement xmi:type="uml:Abstraction" xmi:id="_J2H38LK1Ee24ffphK9Na6g" client="_QE0EkK7gEe2EZoZ5sgiBCg" supplier="_7Y-R4LK0Ee24ffphK9Na6g"/>
+  <packagedElement xmi:type="uml:Class" xmi:id="_MHjIALK1Ee24ffphK9Na6g" name="NewClass1">
+    <ownedAttribute xmi:id="_O3oqArK1Ee24ffphK9Na6g" name="asd" type="_QE0EkK7gEe2EZoZ5sgiBCg" association="_O3oC8LK1Ee24ffphK9Na6g">
+      <lowerValue xmi:type="uml:LiteralInteger" xmi:id="_O3oqA7K1Ee24ffphK9Na6g" value="1"/>
+      <upperValue xmi:type="uml:LiteralUnlimitedNatural" xmi:id="_O3oqBLK1Ee24ffphK9Na6g" value="1"/>
+    </ownedAttribute>
+  </packagedElement>
+  <packagedElement xmi:type="uml:Class" xmi:id="_Mg74YLK1Ee24ffphK9Na6g" name="NewClass3">
+    <ownedAttribute xmi:id="_UaiR4LK1Ee24ffphK9Na6g" name="asd" type="_QE0EkK7gEe2EZoZ5sgiBCg" association="_UahDwLK1Ee24ffphK9Na6g">
+      <lowerValue xmi:type="uml:LiteralInteger" xmi:id="_UaiR4bK1Ee24ffphK9Na6g" value="1"/>
+      <upperValue xmi:type="uml:LiteralUnlimitedNatural" xmi:id="_UaiR4rK1Ee24ffphK9Na6g" value="1"/>
+    </ownedAttribute>
+  </packagedElement>
+  <packagedElement xmi:type="uml:Class" xmi:id="_M-U_ALK1Ee24ffphK9Na6g" name="NewClass4">
+    <substitution xmi:id="_Gt7igLK2Ee24ffphK9Na6g" client="_M-U_ALK1Ee24ffphK9Na6g" supplier="_EWMPELK2Ee24ffphK9Na6g" contract="_EWMPELK2Ee24ffphK9Na6g"/>
+    <ownedAttribute xmi:id="_VYM0ArK1Ee24ffphK9Na6g" name="asd" type="_QE0EkK7gEe2EZoZ5sgiBCg" association="_VYMM8LK1Ee24ffphK9Na6g">
+      <lowerValue xmi:type="uml:LiteralInteger" xmi:id="_VYNbELK1Ee24ffphK9Na6g" value="1"/>
+      <upperValue xmi:type="uml:LiteralUnlimitedNatural" xmi:id="_VYNbEbK1Ee24ffphK9Na6g" value="1"/>
+    </ownedAttribute>
+  </packagedElement>
+  <packagedElement xmi:type="uml:Class" xmi:id="_Nbk7sLK1Ee24ffphK9Na6g" name="NewClass5"/>
+  <packagedElement xmi:type="uml:Association" xmi:id="_O3oC8LK1Ee24ffphK9Na6g" memberEnd="_O3oC8bK1Ee24ffphK9Na6g _O3oqArK1Ee24ffphK9Na6g"/>
+  <packagedElement xmi:type="uml:Association" xmi:id="_UahDwLK1Ee24ffphK9Na6g" memberEnd="_UahDwbK1Ee24ffphK9Na6g _UaiR4LK1Ee24ffphK9Na6g"/>
+  <packagedElement xmi:type="uml:Association" xmi:id="_VYMM8LK1Ee24ffphK9Na6g" memberEnd="_VYMM8bK1Ee24ffphK9Na6g _VYM0ArK1Ee24ffphK9Na6g"/>
+  <packagedElement xmi:type="uml:Dependency" xmi:id="_XCaTELK1Ee24ffphK9Na6g" client="_QE0EkK7gEe2EZoZ5sgiBCg" supplier="_Nbk7sLK1Ee24ffphK9Na6g"/>
+  <packagedElement xmi:type="uml:Package" xmi:id="_dDtuMLK1Ee24ffphK9Na6g" name="NewPackage1">
+    <packageImport xmi:id="_wZ60QLK9Ee2fn9jN03lZYw" importedPackage="_ed5NMLK1Ee24ffphK9Na6g"/>
+  </packagedElement>
+  <packagedElement xmi:type="uml:Package" xmi:id="_ed5NMLK1Ee24ffphK9Na6g" name="NewPackage2"/>
+  <packagedElement xmi:type="uml:Realization" xmi:id="_ghLTkLK1Ee24ffphK9Na6g" client="_QE0EkK7gEe2EZoZ5sgiBCg" supplier="_9pVK8LK0Ee24ffphK9Na6g"/>
+  <packagedElement xmi:type="uml:Class" xmi:id="_D0YigLK2Ee24ffphK9Na6g" name="NewClass6"/>
+  <packagedElement xmi:type="uml:Class" xmi:id="_EWMPELK2Ee24ffphK9Na6g" name="NewClass7"/>
+  <packagedElement xmi:type="uml:Usage" xmi:id="_FGLhkLK2Ee24ffphK9Na6g" client="_Mg74YLK1Ee24ffphK9Na6g" supplier="_D0YigLK2Ee24ffphK9Na6g"/>
+  <packagedElement xmi:type="uml:Class" xmi:id="_LjfcIbSLEe2pkZx4lGC8Ew" name="asd2">
+    <ownedAttribute xmi:id="_ItfSANIcEe2rY5KN6ehSig" name="NewClass8" type="_j12MQL0cEe2besM683MlUA" association="_ItM-INIcEe2rY5KN6ehSig">
+      <lowerValue xmi:type="uml:LiteralInteger" xmi:id="_Itf5ENIcEe2rY5KN6ehSig" value="1"/>
+      <upperValue xmi:type="uml:LiteralUnlimitedNatural" xmi:id="_ItggINIcEe2rY5KN6ehSig" value="1"/>
+    </ownedAttribute>
+  </packagedElement>
+  <packagedElement xmi:type="uml:Class" xmi:id="_j12MQL0cEe2besM683MlUA" name="NewClass8" isAbstract="true">
+    <ownedAttribute xmi:id="_ItggIdIcEe2rY5KN6ehSig" name="asd2" type="_LjfcIbSLEe2pkZx4lGC8Ew" association="_ItM-INIcEe2rY5KN6ehSig">
+      <lowerValue xmi:type="uml:LiteralInteger" xmi:id="_ItggItIcEe2rY5KN6ehSig" value="1"/>
+      <upperValue xmi:type="uml:LiteralUnlimitedNatural" xmi:id="_IthHMNIcEe2rY5KN6ehSig" value="1"/>
+    </ownedAttribute>
+  </packagedElement>
+  <packagedElement xmi:type="uml:Class" xmi:id="_Uk2g0cymEe2SqIqlz0mqiA" name="NewClass9">
+    <ownedAttribute xmi:id="_uKNqAc1tEe2aWMTUBOnCiQ" name="NewProperty1" type="_j12MQL0cEe2besM683MlUA">
+      <lowerValue xmi:type="uml:LiteralInteger" xmi:id="_uK1VEM1tEe2aWMTUBOnCiQ" value="3"/>
+      <upperValue xmi:type="uml:LiteralUnlimitedNatural" xmi:id="_uK1VEc1tEe2aWMTUBOnCiQ" value="5"/>
+    </ownedAttribute>
+    <ownedOperation xmi:id="_45WxkM5PEe2J1pPdCxXkdw" name="NewOperation1" visibility="public">
+      <ownedParameter xmi:id="_8YNeEM5PEe2J1pPdCxXkdw" name="NewParameter1" type="_MHjIALK1Ee24ffphK9Na6g"/>
+      <ownedParameter xmi:id="_e-0x0dI3Ee2XPc95mjsJSg" name="NewParameter2" type="_j12MQL0cEe2besM683MlUA" direction="return"/>
+    </ownedOperation>
+  </packagedElement>
+  <packagedElement xmi:type="uml:Association" xmi:id="_ItM-INIcEe2rY5KN6ehSig" memberEnd="_ItfSANIcEe2rY5KN6ehSig _ItggIdIcEe2rY5KN6ehSig"/>
+</uml:Model>

packages/uml-parser/src/refiners/class.ts

@@ -1,7 +1,8 @@
 import { Uml } from '../uml'
 
-import { UmlElement } from './umlElement'
+import { Element } from './element'
 
-export const Class = new UmlElement(
+// TODO
+export const Class = Element.extend(
   (node) => Uml.getType(node) === Uml.Types.Class,
 )

packages/uml-parser/src/refiners/classifier.ts

@@ -0,0 +1,9 @@
+import { extendMultiple } from './element'
+import { Namespace } from './namespace'
+import { RedefinableElement } from './redefinableElement'
+
+// TODO
+export const Classifier = extendMultiple(
+  [Namespace, RedefinableElement],
+  () => false,
+)

packages/uml-parser/src/refiners/dependency.ts

@@ -2,9 +2,13 @@ import type { GraphNode } from '@cm2ml/ir'
 
 import { Uml } from '../uml'
 
+import { extendMultiple } from './element'
 import { PackageableElement } from './packageableElement'
+import { DirectedRelationship } from './relationship'
 
-export const Dependency = PackageableElement.extend(
+// TODO
+export const Dependency = extendMultiple(
+  [DirectedRelationship, PackageableElement],
   (node: GraphNode) => Uml.getType(node) === Uml.Types.Dependency,
   (node: GraphNode) => {
     const clientId = node.getAttribute(Uml.Attributes.client)?.value.literal

packages/uml-parser/src/refiners/element.ts

@@ -0,0 +1,53 @@
+import type { GraphNode } from '@cm2ml/ir'
+
+export class UmlElement {
+  readonly #isAssignable: (node: GraphNode) => boolean
+  readonly #refine?: (node: GraphNode) => void
+  private readonly subtypes: UmlElement[] = []
+
+  public constructor(
+    private readonly parents: UmlElement[],
+    isAssignable: (node: GraphNode) => boolean,
+    refine: ((node: GraphNode) => void) | undefined,
+  ) {
+    this.#isAssignable = isAssignable
+    this.#refine = refine
+  }
+
+  public isAssignable(node: GraphNode): boolean {
+    return (
+      this.#isAssignable(node) ||
+      this.subtypes.some((r) => r.isAssignable(node))
+    )
+  }
+
+  public refine(node: GraphNode): void {
+    this.parents.forEach((parent) => parent.refine(node))
+    this.#refine?.(node)
+  }
+
+  private extendBy(subtype: UmlElement) {
+    this.subtypes.push(subtype)
+  }
+
+  public extend(
+    isAssignable: (node: GraphNode) => boolean,
+    refine?: (node: GraphNode) => void,
+  ) {
+    return UmlElement.extendMultiple([this], isAssignable, refine)
+  }
+
+  public static extendMultiple(
+    parents: UmlElement[],
+    isAssignable: (node: GraphNode) => boolean,
+    refine?: (node: GraphNode) => void,
+  ) {
+    const newType = new UmlElement(parents, isAssignable, refine)
+    parents.forEach((p) => p.extendBy(newType))
+    return newType
+  }
+}
+
+export const extendMultiple = UmlElement.extendMultiple
+
+export const Element = new UmlElement([], () => true, undefined)

packages/uml-parser/src/refiners/elementImport.ts

@@ -1,7 +1,8 @@
 import { Uml } from '../uml'
 
-import { UmlElement } from './umlElement'
+import { Element } from './element'
 
-export const ElementImport = new UmlElement(
+// TODO
+export const ElementImport = Element.extend(
   (node) => node.tag === Uml.Tags.elementImport,
 )

packages/uml-parser/src/refiners/feature.ts

@@ -0,0 +1,4 @@
+import { RedefinableElement } from './redefinableElement'
+
+// TODO
+export const Feature = RedefinableElement.extend(() => false)

packages/uml-parser/src/refiners/generalization.ts

@@ -1,17 +1,17 @@
 import { Stream } from '@yeger/streams'
 
-import { Uml } from '../uml'
+import { Uml, copyAttributes } from '../uml'
 
 import { DirectedRelationship } from './relationship'
 
 export const Generalization = DirectedRelationship.extend(
   (node) => node.tag === Uml.Tags.generalization,
-  (node) => {
-    const specfic = node.parent
+  (generalization) => {
+    const specfic = generalization.parent
     if (!specfic) {
       throw new Error('Missing parent for generalization')
     }
-    const generalChild = Stream.from(node.children).find(
+    const generalChild = Stream.from(generalization.children).find(
       (child) => child.tag === Uml.Tags.general,
     )
     if (!generalChild) {
@@ -21,11 +21,16 @@ export const Generalization = DirectedRelationship.extend(
     if (!generalId) {
       throw new Error('Missing idref attribute on general')
     }
-    const general = node.model.getNodeById(generalId)
+    const general = generalization.model.getNodeById(generalId)
     if (!general) {
       throw new Error(`Could not find general with id ${generalId}`)
     }
-    node.model.addEdge('generalization', specfic, general)
-    node.model.removeNode(node)
+    const generalizationEdge = generalization.model.addEdge(
+      'generalization',
+      specfic,
+      general,
+    )
+    copyAttributes(generalization, generalizationEdge)
+    generalization.model.removeNode(generalization)
   },
 )

packages/uml-parser/src/refiners/index.ts

@@ -4,15 +4,18 @@ import { Uml, type UmlTag, type UmlType } from '../uml'
 
 import { Class } from './class'
 import { Dependency } from './dependency'
+import type { UmlElement } from './element'
 import { Generalization } from './generalization'
 import { Model } from './model'
+import { OwnedAttribute } from './ownedAttribute'
 import { Package } from './package'
 import { PackageableElement } from './packageableElement'
-import type { UmlElement } from './umlElement'
+import { Property } from './property'
 
 // TODO: Make non-partial?
 const UmlTagRefiners: Partial<Record<UmlTag, UmlElement>> = {
   generalization: Generalization,
+  ownedAttribute: OwnedAttribute,
   packagedElement: PackageableElement,
 }
 
@@ -22,6 +25,7 @@ const UmlTypeRefiners: Partial<Record<UmlType, UmlElement>> = {
   [Uml.Types.Dependency]: Dependency,
   [Uml.Types.Model]: Model,
   [Uml.Types.Package]: Package,
+  [Uml.Types.Property]: Property,
 }
 
 export function getRefiner(node: GraphNode) {

packages/uml-parser/src/refiners/model.ts

@@ -1,7 +1,8 @@
 import { Uml } from '../uml'
 
-import { UmlElement } from './umlElement'
+import { Element } from './element'
 
-export const Model = new UmlElement(
+// TODO
+export const Model = Element.extend(
   (node) => Uml.getType(node) === Uml.Types.Model,
 )

packages/uml-parser/src/refiners/namedElement.ts

@@ -0,0 +1,8 @@
+import { Uml } from '../uml'
+
+import { Element } from './element'
+
+// TODO
+export const NamedElement = Element.extend(
+  (node) => node.tag === Uml.Tags.packagedElement,
+)

packages/uml-parser/src/refiners/namespace.ts

@@ -0,0 +1,4 @@
+import { NamedElement } from './namedElement'
+
+// TODO
+export const Namespace = NamedElement.extend(() => false)

packages/uml-parser/src/refiners/ownedAttribute.ts

@@ -0,0 +1,8 @@
+import { Uml } from '../uml'
+
+import { Element } from './element'
+
+// TODO
+export const OwnedAttribute = Element.extend(
+  (node) => node.tag === Uml.Tags.ownedAttribute,
+)

packages/uml-parser/src/refiners/package.ts

@@ -1,6 +1,6 @@
-import type { Attributable, GraphNode } from '@cm2ml/ir'
+import type { GraphNode } from '@cm2ml/ir'
 
-import { Uml } from '../uml'
+import { Uml, copyAttributes } from '../uml'
 
 import { ElementImport } from './elementImport'
 import { PackageableElement } from './packageableElement'
@@ -99,9 +99,3 @@ function addPackageMerge(node: GraphNode, packageMerge: GraphNode) {
   copyAttributes(packageMerge, packageMergeEdge)
   node.model.removeNode(packageMerge)
 }
-
-function copyAttributes(source: Attributable, target: Attributable) {
-  source.attributes.forEach((attribute) => {
-    target.addAttribute(attribute)
-  })
-}

packages/uml-parser/src/refiners/packageImport.ts

@@ -1,7 +1,8 @@
 import { Uml } from '../uml'
 
-import { UmlElement } from './umlElement'
+import { Element } from './element'
 
-export const PackageImport = new UmlElement(
+// TODO
+export const PackageImport = Element.extend(
   (node) => node.tag === Uml.Tags.packageImport,
 )

packages/uml-parser/src/refiners/packageMerge.ts

@@ -1,7 +1,8 @@
 import { Uml } from '../uml'
 
-import { UmlElement } from './umlElement'
+import { Element } from './element'
 
-export const PackageMerge = new UmlElement(
+// TODO
+export const PackageMerge = Element.extend(
   (node) => node.tag === Uml.Tags.packageMerge,
 )

packages/uml-parser/src/refiners/packageableElement.ts

@@ -1,7 +1,8 @@
 import { Uml } from '../uml'
 
-import { UmlElement } from './umlElement'
+import { Element } from './element'
 
-export const PackageableElement = new UmlElement(
+// TODO
+export const PackageableElement = Element.extend(
   (node) => node.tag === Uml.Tags.packagedElement,
 )

packages/uml-parser/src/refiners/property.ts

@@ -0,0 +1,8 @@
+import { Uml } from '../uml'
+
+import { Element } from './element'
+
+// TODO
+export const Property = Element.extend(
+  (node) => Uml.getType(node) === Uml.Types.Property,
+)

packages/uml-parser/src/refiners/redefinableElement.ts

@@ -0,0 +1,4 @@
+import { NamedElement } from './namedElement'
+
+// TODO
+export const RedefinableElement = NamedElement.extend(() => false)

packages/uml-parser/src/refiners/relationship.ts

@@ -1,7 +1,7 @@
-import { UmlElement } from './umlElement'
+import { Element } from './element'
 
 // TODO
-export const Relationship = new UmlElement(() => false)
+export const Relationship = Element.extend(() => false)
 
 // TODO
 export const DirectedRelationship = Relationship.extend(() => false)