[Feature] Resolve positional @feature.index and bare xmi:id URI fragments (#106)

ECoreNetto.Tests/Resource/PositionalAndIdFragmentTestFixture.cs

@@ -0,0 +1,263 @@
+// ------------------------------------------------------------------------------------------------
+// <copyright file="PositionalAndIdFragmentTestFixture.cs" company="Starion Group S.A.">
+//
+//   Copyright 2017-2026 Starion Group S.A.
+//   SPDX-License-Identifier: Apache-2.0
+//
+// </copyright>
+// ------------------------------------------------------------------------------------------------
+
+namespace ECoreNetto.Tests.Resource
+{
+    using System;
+    using System.IO;
+    using System.Linq;
+
+    using ECoreNetto.Resource;
+
+    using NUnit.Framework;
+
+    /// <summary>
+    /// Suite of tests for the EMF URI-fragment-resolution items of issue #106: positional
+    /// <c>//@feature.index</c> fragments (resolved by structural navigation) and bare <c>xmi:id</c>
+    /// fragments (resolved through an id-to-object map), both same-file and cross-file.
+    /// </summary>
+    [TestFixture]
+    public class PositionalAndIdFragmentTestFixture
+    {
+        private ResourceSet resourceSet = null!;
+
+        [SetUp]
+        public void SetUp()
+        {
+            this.resourceSet = new ResourceSet();
+        }
+
+        [Test]
+        public void Verify_that_same_file_positional_fragments_resolve()
+        {
+            var root = this.Load("positional.ecore", PositionalModel);
+
+            var alpha = Class(root, "Alpha");
+            var beta = Class(root, "Beta");
+            var text = root.EClassifiers.OfType<EDataType>().Single(c => c.Name == "Text");
+
+            var toBeta = alpha.EStructuralFeatures.OfType<EReference>().Single(r => r.Name == "toBeta");
+            var label = beta.EStructuralFeatures.OfType<EAttribute>().Single(a => a.Name == "label");
+
+            Assert.Multiple(() =>
+            {
+                // eType="#//@eClassifiers.1" -> the second classifier, Beta
+                Assert.That(toBeta.EType, Is.SameAs(beta));
+
+                // eType="#//@eClassifiers.2" -> the third classifier, the Text data type
+                Assert.That(label.EType, Is.SameAs(text));
+            });
+        }
+
+        [Test]
+        public void Verify_that_a_deep_positional_fragment_resolves_to_a_structural_feature()
+        {
+            var root = this.Load("positional.ecore", PositionalModel);
+            var resource = this.resourceSet.Resources.Single();
+
+            var toBeta = Class(root, "Alpha").EStructuralFeatures.Single(f => f.Name == "toBeta");
+
+            var resolved = resource.GetEObject("positional.ecore#//@eClassifiers.0/@eStructuralFeatures.0");
+
+            Assert.That(resolved, Is.SameAs(toBeta));
+        }
+
+        [Test]
+        public void Verify_that_out_of_range_and_unknown_positional_fragments_do_not_resolve()
+        {
+            this.Load("positional.ecore", PositionalModel);
+            var resource = this.resourceSet.Resources.Single();
+
+            Assert.Multiple(() =>
+            {
+                // index beyond the number of classifiers
+                Assert.That(resource.GetEObject("positional.ecore#//@eClassifiers.99"), Is.Null);
+
+                // a containment feature that Alpha does not have
+                Assert.That(resource.GetEObject("positional.ecore#//@eClassifiers.0/@eOperations.0"), Is.Null);
+
+                // an unknown containment feature name
+                Assert.That(resource.GetEObject("positional.ecore#//@eClassifiers.0/@bogus.0"), Is.Null);
+
+                // a navigation segment that is not of the '@feature.index' form
+                Assert.That(resource.GetEObject("positional.ecore#//@eClassifiers.0/plain"), Is.Null);
+
+                // an '@feature' segment without an index
+                Assert.That(resource.GetEObject("positional.ecore#//@eClassifiers"), Is.Null);
+
+                // an '@feature.index' segment with a non-numeric index
+                Assert.That(resource.GetEObject("positional.ecore#//@eClassifiers.x"), Is.Null);
+
+                // a name-based path that does not exist (structural navigation is only for '@' segments)
+                Assert.That(resource.GetEObject("positional.ecore#//NoSuchClass"), Is.Null);
+
+                // an empty in-document fragment
+                Assert.That(resource.GetEObject("positional.ecore#"), Is.Null);
+
+                // an unknown xmi:id
+                Assert.That(resource.GetEObject("#_missing"), Is.Null);
+            });
+        }
+
+        [Test]
+        public void Verify_that_positional_fragments_navigate_every_containment_feature()
+        {
+            this.Load("rich.ecore", RichModel);
+            var resource = this.resourceSet.Resources.Single();
+
+            EObject? Resolve(string fragment) => resource.GetEObject($"rich.ecore#{fragment}");
+
+            Assert.Multiple(() =>
+            {
+                Assert.That(((EPackage)Resolve("//@eSubpackages.0")!).Name, Is.EqualTo("sub"));
+                Assert.That(((EClass)Resolve("//@eSubpackages.0/@eClassifiers.0")!).Name, Is.EqualTo("InSub"));
+                Assert.That(Resolve("//@eClassifiers.0/@eAnnotations.0"), Is.InstanceOf<EAnnotation>());
+                Assert.That(((ETypeParameter)Resolve("//@eClassifiers.0/@eTypeParameters.0")!).Name, Is.EqualTo("T"));
+                Assert.That(Resolve("//@eClassifiers.0/@eTypeParameters.0/@eBounds.0"), Is.InstanceOf<EGenericType>());
+                Assert.That(((EOperation)Resolve("//@eClassifiers.0/@eOperations.0")!).Name, Is.EqualTo("doIt"));
+                Assert.That(((ETypeParameter)Resolve("//@eClassifiers.0/@eOperations.0/@eTypeParameters.0")!).Name, Is.EqualTo("U"));
+                Assert.That(((EParameter)Resolve("//@eClassifiers.0/@eOperations.0/@eParameters.0")!).Name, Is.EqualTo("arg"));
+                Assert.That(Resolve("//@eClassifiers.0/@eOperations.0/@eGenericExceptions.0"), Is.InstanceOf<EGenericType>());
+                Assert.That(Resolve("//@eClassifiers.1/@eGenericSuperTypes.0"), Is.InstanceOf<EGenericType>());
+                Assert.That(((EEnumLiteral)Resolve("//@eClassifiers.2/@eLiterals.0")!).Name, Is.EqualTo("RED"));
+            });
+        }
+
+        [Test]
+        public void Verify_that_a_same_file_xmi_id_fragment_resolves()
+        {
+            var root = this.Load("ids.ecore", XmiIdModel);
+
+            var node = Class(root, "Node");
+            var parent = node.EStructuralFeatures.OfType<EReference>().Single(r => r.Name == "parent");
+
+            // eType="#_node" is an intrinsic xmi:id reference; Node registers the id first, so a later
+            // duplicate xmi:id does not override it and the reference resolves back to Node
+            Assert.That(parent.EType, Is.SameAs(node));
+        }
+
+        [Test]
+        public void Verify_that_cross_file_positional_and_xmi_id_fragments_resolve()
+        {
+            // the target file must sit next to the source so the demand-load can find and load it; it is
+            // written to disk only (not pre-registered as a resource), mirroring real cross-file loading
+            WriteFile("target.ecore", TargetModel);
+            var root = this.Load("source.ecore", SourceModel);
+
+            var source = Class(root, "SourceClass");
+            var viaPosition = source.EStructuralFeatures.OfType<EReference>().Single(r => r.Name == "viaPosition");
+            var viaId = source.EStructuralFeatures.OfType<EReference>().Single(r => r.Name == "viaId");
+
+            Assert.Multiple(() =>
+            {
+                Assert.That(viaPosition.EType, Is.Not.Null);
+                Assert.That(viaPosition.EType!.Name, Is.EqualTo("TargetClass"));
+
+                // both forms address the same object in the target resource
+                Assert.That(viaId.EType, Is.SameAs(viaPosition.EType));
+            });
+        }
+
+        private static EClass Class(EPackage root, string name)
+        {
+            return root.EClassifiers.OfType<EClass>().Single(c => c.Name == name);
+        }
+
+        private static void WriteFile(string fileName, string content)
+        {
+            var path = Path.Combine(TestContext.CurrentContext.TestDirectory, fileName);
+            File.WriteAllText(path, content);
+        }
+
+        private Resource CreateResource(string fileName, string content)
+        {
+            var path = Path.Combine(TestContext.CurrentContext.TestDirectory, fileName);
+            File.WriteAllText(path, content);
+
+            return this.resourceSet.CreateResource(new Uri(path));
+        }
+
+        private EPackage Load(string fileName, string content)
+        {
+            var resource = this.CreateResource(fileName, content);
+            var root = resource.Load(null);
+
+            Assert.That(resource.Errors, Is.Empty, string.Join("; ", resource.Errors.Select(e => e.Message)));
+
+            return root;
+        }
+
+        private const string Header =
+            "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n" +
+            "<ecore:EPackage xmi:version=\"2.0\" xmlns:xmi=\"http://www.omg.org/XMI\" " +
+            "xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" " +
+            "xmlns:ecore=\"http://www.eclipse.org/emf/2002/Ecore\" ";
+
+        private const string PositionalModel =
+            Header +
+            "name=\"positional\" nsURI=\"positional\" nsPrefix=\"positional\">\r\n" +
+            "  <eClassifiers xsi:type=\"ecore:EClass\" name=\"Alpha\">\r\n" +
+            "    <eStructuralFeatures xsi:type=\"ecore:EReference\" name=\"toBeta\" eType=\"#//@eClassifiers.1\"/>\r\n" +
+            "  </eClassifiers>\r\n" +
+            "  <eClassifiers xsi:type=\"ecore:EClass\" name=\"Beta\">\r\n" +
+            "    <eStructuralFeatures xsi:type=\"ecore:EAttribute\" name=\"label\" eType=\"#//@eClassifiers.2\"/>\r\n" +
+            "  </eClassifiers>\r\n" +
+            "  <eClassifiers xsi:type=\"ecore:EDataType\" name=\"Text\" instanceClassName=\"java.lang.String\"/>\r\n" +
+            "</ecore:EPackage>";
+
+        private const string RichModel =
+            Header +
+            "name=\"rich\" nsURI=\"rich\" nsPrefix=\"rich\">\r\n" +
+            "  <eSubpackages name=\"sub\" nsURI=\"sub\" nsPrefix=\"sub\">\r\n" +
+            "    <eClassifiers xsi:type=\"ecore:EClass\" name=\"InSub\"/>\r\n" +
+            "  </eSubpackages>\r\n" +
+            "  <eClassifiers xsi:type=\"ecore:EClass\" name=\"Container\">\r\n" +
+            "    <eAnnotations source=\"http://example.org/a\"/>\r\n" +
+            "    <eTypeParameters name=\"T\">\r\n" +
+            "      <eBounds eClassifier=\"#//Container\"/>\r\n" +
+            "    </eTypeParameters>\r\n" +
+            "    <eOperations name=\"doIt\">\r\n" +
+            "      <eTypeParameters name=\"U\"/>\r\n" +
+            "      <eParameters name=\"arg\" eType=\"#//Container\"/>\r\n" +
+            "      <eGenericExceptions eClassifier=\"#//Container\"/>\r\n" +
+            "    </eOperations>\r\n" +
+            "  </eClassifiers>\r\n" +
+            "  <eClassifiers xsi:type=\"ecore:EClass\" name=\"Derived\">\r\n" +
+            "    <eGenericSuperTypes eClassifier=\"#//Container\"/>\r\n" +
+            "  </eClassifiers>\r\n" +
+            "  <eClassifiers xsi:type=\"ecore:EEnum\" name=\"Color\">\r\n" +
+            "    <eLiterals name=\"RED\" value=\"0\"/>\r\n" +
+            "  </eClassifiers>\r\n" +
+            "</ecore:EPackage>";
+
+        private const string XmiIdModel =
+            Header +
+            "name=\"ids\" nsURI=\"ids\" nsPrefix=\"ids\">\r\n" +
+            "  <eClassifiers xsi:type=\"ecore:EClass\" name=\"Node\" xmi:id=\"_node\">\r\n" +
+            "    <eStructuralFeatures xsi:type=\"ecore:EReference\" name=\"parent\" eType=\"#_node\"/>\r\n" +
+            "  </eClassifiers>\r\n" +
+            "  <eClassifiers xsi:type=\"ecore:EClass\" name=\"Other\" xmi:id=\"_node\"/>\r\n" +
+            "</ecore:EPackage>";
+
+        private const string TargetModel =
+            Header +
+            "name=\"target\" nsURI=\"target\" nsPrefix=\"target\">\r\n" +
+            "  <eClassifiers xsi:type=\"ecore:EClass\" name=\"TargetClass\" xmi:id=\"_target\"/>\r\n" +
+            "</ecore:EPackage>";
+
+        private const string SourceModel =
+            Header +
+            "name=\"source\" nsURI=\"source\" nsPrefix=\"source\">\r\n" +
+            "  <eClassifiers xsi:type=\"ecore:EClass\" name=\"SourceClass\">\r\n" +
+            "    <eStructuralFeatures xsi:type=\"ecore:EReference\" name=\"viaPosition\" eType=\"target.ecore#//@eClassifiers.0\"/>\r\n" +
+            "    <eStructuralFeatures xsi:type=\"ecore:EReference\" name=\"viaId\" eType=\"target.ecore#_target\"/>\r\n" +
+            "  </eClassifiers>\r\n" +
+            "</ecore:EPackage>";
+    }
+}

ECoreNetto/ModelElement/EObject.cs

@@ -128,7 +128,7 @@
         /// <returns>
         /// The <see cref="EStructuralFeature"/> that actually contains the object.
         /// </returns>
         public EStructuralFeature EContainingFeature()
         {
             throw new NotImplementedException();
         }
@@ -141,7 +141,7 @@
         /// <returns>
         /// The feature that properly contains the object.
         /// </returns>
         public EReference EContainmentFeature()
         {
             throw new NotImplementedException();
         }
@@ -156,7 +156,7 @@
         /// <returns>
         /// A list view of the content objects.
         /// </returns>
         public IEnumerable<EObject> EContents()
         {
             throw new NotImplementedException();
         }
@@ -167,7 +167,7 @@
         /// <returns>
         /// A tree iterator that iterates over all contents.
         /// </returns>
         public IEnumerable<EObject> EAllContents()
         {
             throw new NotImplementedException();
         }
@@ -183,7 +183,7 @@
         /// <returns>
         /// true if this object is a proxy or false, otherwise.
         /// </returns>
         public bool EIsProxy()
         {
             throw new NotImplementedException();
         }
@@ -199,7 +199,7 @@
         /// <returns>
         /// A list view of the cross referenced objects. 
         /// </returns>
         public IEnumerable<EObject> ECrossReferences()
         {
             throw new NotImplementedException();
         }
@@ -238,7 +238,7 @@
         /// <exception cref="ArgumentException">
         /// If the <see cref="EStructuralFeature"/> is not one the meta class's features and is also not affiliated with one of the meta class's features. 
         /// </exception>        
         public object EGet(EStructuralFeature feature, bool resolve)
         {
             throw new NotImplementedException();
         }
@@ -266,7 +266,7 @@
         /// <exception cref="InvalidCastException">
         /// If there is a type conflict.
         /// </exception>
         public void ESet(EStructuralFeature feature, object newValue)
         {
             throw new NotImplementedException();
         }
@@ -290,7 +290,7 @@
         /// <exception cref="ArgumentException">
         /// If the feature is not one the meta class's <see cref="EStructuralFeature"/>s.
         /// </exception>
         public bool EIsSet(EStructuralFeature feature)
         {
             throw new NotImplementedException();
         }
@@ -309,7 +309,7 @@
         /// <exception cref="ArgumentException">
         /// If the feature is not one the meta class's <see cref="EStructuralFeature"/>s, or it isn't changeable.
         /// </exception>
         public void EUnSet(EStructuralFeature feature)
         {
             throw new NotImplementedException();
         }
@@ -347,9 +347,23 @@
         public virtual void ReadXml(XmlNode element)
         {
             this.SaveAttributes(element);
+            this.RegisterXmiId();
             this.ReadChildNodes(element);
         }
 
+        /// <summary>
+        /// Registers this object in its <see cref="EResource"/> under its intrinsic <c>xmi:id</c>, when it
+        /// carries one, so that a reference of the bare <c>xmi:id</c> form (a URI fragment without a leading
+        /// slash, resolved by EMF through <c>getEObjectByID</c>) can be resolved to this object.
+        /// </summary>
+        private void RegisterXmiId()
+        {
+            if (this.Attributes.TryGetValue("xmi:id", out var id) && !string.IsNullOrEmpty(id))
+            {
+                this.EResource.RegisterEObjectId(id, this);
+            }
+        }
+
         /// <summary>
         /// Set the properties of this <see cref="EObject"/>
         /// </summary>