First check-in of the code from the Obsidian Prj project.

src/DIContainer.ts

@@ -0,0 +1,96 @@
+import { ImplementsStatic } from './helper/ImplementsStatic';
+import { ITSInjex, ITSInjex_ } from './interfaces/IDIContainer';
+
+/**
+ * Dependency Entry Interface
+ */
+interface IDependency {
+    /**
+     * The dependency itself
+     */
+    dependency: unknown;
+    /**
+     * If true, the dependency is deprecated => a warning
+     * is logged when the dependency is resolved
+     */
+    deprecated?: boolean;
+}
+
+/**
+ * Dependency Injection Container
+ */
+@ImplementsStatic<ITSInjex_>()
+export class DIContainer implements ITSInjex {
+    private static _instance: DIContainer;
+    private readonly _dependencies = new Map<string, IDependency>();
+
+    /**
+     * Private constructor to prevent direct instantiation.
+     */
+    private constructor() {}
+
+    //#region IDIContainer_
+
+    /**
+     * Retrieves the singleton instance of DependencyRegistry.
+     * @returns The singleton instance.
+     */
+    public static getInstance(): ITSInjex {
+        if (this._instance == null) {
+            this._instance = new DIContainer();
+        }
+
+        return this._instance;
+    }
+
+    //#endregion
+
+    //#region IDIContainer
+
+    /**
+     * Register a dependency
+     * @param identifier The identifier of the dependency
+     * @param dependency The dependency to register
+     * @param deprecated If true, the dependency is deprecated => a warning
+     * is logged when the dependency is resolved
+     */
+    public register<T>(
+        identifier: string,
+        dependency: T,
+        deprecated = false,
+    ): void {
+        this._dependencies.set(identifier, {
+            dependency: dependency,
+            deprecated: deprecated,
+        });
+    }
+
+    /**
+     * Resolve a dependency
+     * @param identifier The identifier of the dependency
+     * @param necessary If true, throws an error if the dependency is not found
+     * @returns The resolved dependency or undefined if the dependency is not found (if necessary is false)
+     * @throws Error if the dependency is not found (if necessary is true)
+     */
+    public resolve<T>(identifier: string, necessary = true): T | undefined {
+        const dependency = this._dependencies.get(identifier);
+
+        if (necessary && !dependency) {
+            throw new Error(`Dependency ${identifier} not found`);
+        } else if (!dependency) {
+            return undefined;
+        }
+
+        if (dependency.deprecated) {
+            // eslint-disable-next-line no-console
+            console.warn(`Dependency ${identifier} is deprecated`);
+
+            // Remove the deprecation warning; it should only be logged once.
+            dependency.deprecated = false;
+        }
+
+        return dependency.dependency as T;
+    }
+
+    //#endregion
+}