Merge pull request #2741 from FirelyTeam/feature/try-nullability

Nullability and Try-style function annotations

src/Hl7.Fhir.Base/ElementModel/DomNode.cs

@@ -6,6 +6,8 @@
  * available at https://raw.githubusercontent.com/FirelyTeam/firely-net-sdk/master/LICENSE
  */
 
+#nullable enable
+
 using Hl7.Fhir.Utility;
 using System;
 using System.Collections.Generic;
@@ -16,28 +18,28 @@ namespace Hl7.Fhir.ElementModel
 {
     public class DomNode<T> : IAnnotatable where T : DomNode<T>
     {
-        public string Name { get; set; }
+        public string Name { get; set; } = null!;
 
-        private List<T> _childList = null;
+        private List<T>? _childList;
 
         protected List<T> ChildList
         {
-            get => LazyInitializer.EnsureInitialized(ref _childList, () => new());
+            get => LazyInitializer.EnsureInitialized(ref _childList, () => [])!;
             set => _childList = value;
         }
 
-        internal IEnumerable<T> ChildrenInternal(string name = null) =>
+        internal IEnumerable<T> ChildrenInternal(string? name = null) =>
             name == null ? ChildList : ChildList.Where(c => c.Name.MatchesPrefix(name));
 
-        public T Parent { get; protected set; }
+        public T? Parent { get; protected set; }
 
-        public DomNodeList<T> this[string name] => new DomNodeList<T>(ChildrenInternal(name));
+        public DomNodeList<T> this[string name] => new (ChildrenInternal(name));
 
         public T this[int index] => ChildList[index];
 
         #region << Annotations >>
-        private AnnotationList _annotations = null;
-        protected AnnotationList AnnotationsInternal => LazyInitializer.EnsureInitialized(ref _annotations, () => new());
+        private AnnotationList? _annotations;
+        protected AnnotationList AnnotationsInternal => LazyInitializer.EnsureInitialized(ref _annotations, () => [])!;
 
         protected bool HasAnnotations => _annotations is not null && !_annotations.IsEmpty;
 

src/Hl7.Fhir.Base/ElementModel/ElementNode.cs

@@ -1,23 +1,25 @@
-
-/* 
+/* 
  * Copyright (c) 2018, Firely (info@fire.ly) and contributors
  * See the file CONTRIBUTORS for details.
  * 
  * This file is licensed under the BSD 3-Clause license
  * available at https://raw.githubusercontent.com/FirelyTeam/firely-net-sdk/master/LICENSE
  */
 
+#nullable enable
+
 using Hl7.Fhir.Specification;
 using Hl7.Fhir.Utility;
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Threading;
 using P = Hl7.Fhir.ElementModel.Types;
 
 namespace Hl7.Fhir.ElementModel
 {
-    public class ElementNode : DomNode<ElementNode>, ITypedElement, IAnnotated, IAnnotatable, IShortPathGenerator
+    public class ElementNode : DomNode<ElementNode>, ITypedElement, IAnnotated, IShortPathGenerator
     {
         /// <summary>
         /// Creates an implementation of ITypedElement that represents a primitive value
@@ -43,12 +45,12 @@ public static ITypedElement ForPrimitive(object value)
         /// <param name="value"></param>
         /// <param name="primitiveValue"></param>
         /// <returns></returns>
-        public static bool TryConvertToElementValue(object value, out object primitiveValue)
+        public static bool TryConvertToElementValue(object? value, [NotNullWhen(true)] out object? primitiveValue)
         {
             primitiveValue = conv();
             return primitiveValue is not null;
 
-            object conv()
+            object? conv()
             {
                 // NOTE: Keep Any.TryConvertToSystemValue, TypeSpecifier.TryGetNativeType and TypeSpecifier.ForNativeType in sync
                 switch (value)
@@ -94,8 +96,8 @@ public static IEnumerable<ITypedElement> CreateList(params object[] values) =>
             values switch
             {
                 null => EmptyList,
-                [var one] => [toTT(one)],
-                _ => values.Select(toTT).ToList()
+                [var one] => [toTe(one)!],
+                _ => values.Select(toTe).ToList()!
             };
 
         /// <summary>
@@ -107,10 +109,10 @@ public static IEnumerable<ITypedElement> CreateList(params object[] values) =>
         public static IEnumerable<ITypedElement> CreateList(IEnumerable<object> values) => values switch
         {
             null => EmptyList,
-            _ => values.Select(toTT).ToList()
+            _ => values.Select(toTe).ToList()!
         };
 
-        private static ITypedElement toTT(object value) => value switch
+        private static ITypedElement? toTe(object? value) => value switch
         {
             null => null,
             ITypedElement element => element,
@@ -119,26 +121,26 @@ public static IEnumerable<ITypedElement> CreateList(params object[] values) =>
 
 
         public static readonly IEnumerable<ITypedElement> EmptyList = [];
-        public IEnumerable<ITypedElement> Children(string name = null) => ChildrenInternal(name);
+        public IEnumerable<ITypedElement> Children(string? name = null) => ChildrenInternal(name);
 
-        internal ElementNode(string name, object value, string instanceType, IElementDefinitionSummary definition)
+        private ElementNode(string name, object? value, string? instanceType, IElementDefinitionSummary? definition)
         {
             Name = name ?? throw new ArgumentNullException(nameof(name));
             InstanceType = instanceType;
             Value = value;
             Definition = definition;
         }
 
-        private IReadOnlyCollection<IElementDefinitionSummary> _childDefinitions = null;
+        private IReadOnlyCollection<IElementDefinitionSummary> _childDefinitions = null!;
 
         private IReadOnlyCollection<IElementDefinitionSummary> getChildDefinitions(IStructureDefinitionSummaryProvider provider)
         {
             LazyInitializer.EnsureInitialized(ref _childDefinitions, () => this.ChildDefinitions(provider));
 
-            return _childDefinitions!;
+            return _childDefinitions;
         }
 
-        public ElementNode Add(IStructureDefinitionSummaryProvider provider, ElementNode child, string name = null)
+        public ElementNode Add(IStructureDefinitionSummaryProvider provider, ElementNode child, string? name = null)
         {
             if (provider == null) throw new ArgumentNullException(nameof(provider));
             if (child == null) throw new ArgumentNullException(nameof(child));
@@ -147,7 +149,7 @@ public ElementNode Add(IStructureDefinitionSummaryProvider provider, ElementNode
             return child;
         }
 
-        public ElementNode Add(IStructureDefinitionSummaryProvider provider, string name, object value = null, string instanceType = null)
+        public ElementNode Add(IStructureDefinitionSummaryProvider provider, string name, object? value = null, string? instanceType = null)
         {
             if (provider == null) throw new ArgumentNullException(nameof(provider));
             if (name == null) throw new ArgumentNullException(nameof(name));
@@ -182,7 +184,7 @@ public void Replace(IStructureDefinitionSummaryProvider provider, ElementNode ol
         /// <summary>
         /// Will update the child to reflect it being a child of this element, but will not yet add the child at any position within this element
         /// </summary>
-        private void importChild(IStructureDefinitionSummaryProvider provider, ElementNode child, string name, int? position = null)
+        private void importChild(IStructureDefinitionSummaryProvider provider, ElementNode child, string? name, int? position = null)
         {
             child.Name = name ?? child.Name;
             if (child.Name == null) throw Error.Argument($"The ElementNode given should have its Name property set or the '{nameof(name)}' parameter should be given.");
@@ -195,7 +197,7 @@ private void importChild(IStructureDefinitionSummaryProvider provider, ElementNo
             // we think it should be - this way you can safely first create a node representing
             // an independently created root for a resource of datatype, and then add it to the tree.
             var childDefs = getChildDefinitions(provider ?? throw Error.ArgumentNull(nameof(provider)));
-            var childDef = childDefs.Where(cd => cd.ElementName == child.Name).SingleOrDefault();
+            var childDef = childDefs.SingleOrDefault(cd => cd.ElementName == child.Name);
 
             child.Definition = childDef ?? child.Definition;    // if we don't know about the definition, stick with the old one (if any)
 
@@ -230,7 +232,7 @@ private void importChild(IStructureDefinitionSummaryProvider provider, ElementNo
 
         }
 
-        public static ElementNode Root(IStructureDefinitionSummaryProvider provider, string type, string name = null, object value = null)
+        public static ElementNode Root(IStructureDefinitionSummaryProvider provider, string type, string? name = null, object? value = null)
         {
             if (provider == null) throw Error.ArgumentNull(nameof(provider));
             if (type == null) throw Error.ArgumentNull(nameof(type));
@@ -241,13 +243,13 @@ public static ElementNode Root(IStructureDefinitionSummaryProvider provider, str
             return new ElementNode(name ?? type, value, type, definition);
         }
 
-        public static ElementNode FromElement(ITypedElement node, bool recursive = true, IEnumerable<Type> annotationsToCopy = null)
+        public static ElementNode FromElement(ITypedElement node, bool recursive = true, IEnumerable<Type>? annotationsToCopy = null)
         {
             if (node == null) throw new ArgumentNullException(nameof(node));
             return buildNode(node, recursive, annotationsToCopy, null);
         }
 
-        private static ElementNode buildNode(ITypedElement node, bool recursive, IEnumerable<Type> annotationsToCopy, ElementNode parent)
+        private static ElementNode buildNode(ITypedElement node, bool recursive, IEnumerable<Type>? annotationsToCopy, ElementNode? parent)
         {
             var me = new ElementNode(node.Name, node.Value, node.InstanceType, node.Definition)
             {
@@ -288,11 +290,11 @@ public ElementNode ShallowCopy()
             return copy;
         }
 
-        public IElementDefinitionSummary Definition { get; private set; }
+        public IElementDefinitionSummary? Definition { get; private set; }
 
-        public string InstanceType { get; private set; }
+        public string? InstanceType { get; private set; }
 
-        public object Value { get; set; }
+        public object? Value { get; set; }
 
         public IEnumerable<object> Annotations(Type type)
         {

src/Hl7.Fhir.Base/ElementModel/IBaseElementNavigator.cs

@@ -26,7 +26,7 @@ public interface IBaseElementNavigator<TDerived> where TDerived : IBaseElementNa
         /// </summary>
         /// <param name="name">Return only the children with the given name.</param>
         /// <returns></returns>
-        IEnumerable<TDerived> Children(string? name = null);
+        IEnumerable<ITypedElement> Children(string? name = null);
 
         /// <summary>
         /// Name of the node, e.g. "active", "value".
@@ -36,7 +36,7 @@ public interface IBaseElementNavigator<TDerived> where TDerived : IBaseElementNa
         /// <summary>
         /// Type of the node. If a FHIR type, this is just a simple string, otherwise a StructureDefinition url for a type defined as a logical model.
         /// </summary>
-        string InstanceType { get; }
+        string? InstanceType { get; }
 
         /// <summary>
         /// The value of the node (if it represents a primitive FHIR value)
@@ -63,7 +63,7 @@ public interface IBaseElementNavigator<TDerived> where TDerived : IBaseElementNa
         /// base64Binary    string (uuencoded)
         /// xhtml           string
         /// </remarks>
-        object Value { get; }
+        object? Value { get; }
     }
 }
 

src/Hl7.Fhir.Base/ElementModel/ITypedElement.cs

@@ -8,6 +8,9 @@
 
 using Hl7.Fhir.Specification;
 
+#nullable enable
+
+
 namespace Hl7.Fhir.ElementModel
 {
     /// <summary>
@@ -28,10 +31,10 @@ public interface ITypedElement : IBaseElementNavigator<ITypedElement>
         /// An indication of the location of this node within the data represented by the <c>ITypedElement</c>.
         /// </summary>
         /// <remarks>The format of the location is the dotted name of the property, including indices to make
-        /// sure repeated occurences of an element can be distinguished. It needs to be sufficiently precise to aid 
+        /// sure repeated occurrences of an element can be distinguished. It needs to be sufficiently precise to aid 
         /// the user in locating issues in the data.</remarks>
         string Location { get; }
 
-        IElementDefinitionSummary Definition { get; }
+        IElementDefinitionSummary? Definition { get; }
     }
 }

src/Hl7.Fhir.Base/ElementModel/PrimitiveElement.cs

@@ -54,9 +54,7 @@ public PrimitiveElement(object value, string? name = null, bool useFullTypeName
             InstanceType = useFullTypeName ? systemType.FullName : systemType.Name;
             Name = name ?? "@primitivevalue@";
         }
-
-
-
+
 
         public string Name { get; private set; }
 

src/Hl7.Fhir.Base/ElementModel/ScopedNode.cs

@@ -81,10 +81,10 @@ private ScopedNode(ScopedNode parentNode, ScopedNode? parentResource, ITypedElem
         public string Name => Current.Name;
 
         /// <inheritdoc/>
-        public string InstanceType => Current.InstanceType;
+        public string InstanceType => Current.InstanceType!;
 
         /// <inheritdoc/>
-        public object Value => Current.Value;
+        public object? Value => Current.Value;
 
         /// <inheritdoc/>
         public string Location => Current.Location;
@@ -123,7 +123,7 @@ public ITypedElement ResourceContext
         }
 
         /// <inheritdoc />
-        public IElementDefinitionSummary Definition => Current.Definition;
+        public IElementDefinitionSummary? Definition => Current.Definition;
 
         /// <summary>
         /// Get the list of container parents in a list, nearest parent first.

src/Hl7.Fhir.Base/ElementModel/TypedElementOnSourceNode.cs

@@ -39,7 +39,7 @@ public TypedElementOnSourceNode(ISourceNode source, string? type, IStructureDefi
             (InstanceType, Definition) = buildRootPosition(type);
         }
 
-        private (string instanceType, IElementDefinitionSummary? definition) buildRootPosition(string? type)
+        private (string? instanceType, IElementDefinitionSummary? definition) buildRootPosition(string? type)
         {
             var rootType = type ?? _source.GetResourceTypeIndicator();
             if (rootType == null)
@@ -48,7 +48,7 @@ public TypedElementOnSourceNode(ISourceNode source, string? type, IStructureDefi
                     throw Error.Format(nameof(type), $"Cannot determine the type of the root element at '{_source.Location}', " +
                         $"please supply a type argument.");
                 else
-                    return ("Base", null);
+                    return (null, null);
             }
 
             var elementType = Provider.Provide(rootType);
@@ -97,7 +97,7 @@ private void raiseTypeError(string message, object source, bool warning = false,
             ExceptionHandler.NotifyOrThrow(source, notification);
         }
 
-        public string InstanceType { get; private set; }
+        public string? InstanceType { get; private set; }
 
         private readonly ISourceNode _source;
 
@@ -489,7 +489,7 @@ private IEnumerable<ITypedElement> runAdditionalRules(IEnumerable<ITypedElement>
         public string ShortPath { get; private set; }
 
         public override string ToString() =>
-            $"{(($"[{InstanceType}] "))}{_source}";
+            $"{(InstanceType != null ? ($"[{InstanceType}] ") : "")}{_source}";
 
         public IEnumerable<object> Annotations(Type type)
         {