Add Kernel context and Kernel application data.

demo/DemoApp.tsx

@@ -39,6 +39,7 @@ import {Await, useAsync} from "../src/Async";
 import {NotifyErrorsBoundary} from "../src/Components/Errors/NotifyErrorsBoundary";
 import {DemoFailingComponent, DemoResetComponent} from "./DemoFailingComponent";
 import {Tip} from "../src/Components/Tips/Tip";
+import {useKernelApplicationData} from "../src/KernelContext";
 
 export function DemoApp()
 {
@@ -73,6 +74,8 @@ export function DemoApp()
 
 	const [failingComponentsCount, setFailingComponentsCount] = useState(0);
 
+	const [kernelApplicationData, setKernelApplicationData] = useKernelApplicationData("customData", "");
+
 	return (
 		<Application>
 			<MainMenu>
@@ -609,6 +612,23 @@ export function DemoApp()
 				</NotifyErrorsBoundary>
 			</Card>
 
+			<h2>
+				Global states
+			</h2>
+
+			<Card>
+				<label>
+					Kernel application custom data
+					<input type={"text"} name={"kernel-application-data"}
+					       value={kernelApplicationData}
+					       onChange={(event) => setKernelApplicationData(event.currentTarget.value)} />
+				</label>
+
+				<Buttons placement={"center"}>
+					<button type={"button"} onClick={easySubapp}>Open demo subapp to see if it works</button>
+				</Buttons>
+			</Card>
+
 		</Application>
 	);
 }

demo/DemoSubapp.tsx

@@ -1,6 +1,7 @@
 import React from "react";
 import {Subapp, useSubapp} from "../src/Components/Subapps/Subapps";
 import {Card} from "../src/Components/Card";
+import {useKernelApplicationData} from "../src/KernelContext";
 
 /**
  * A demo Subapp component.
@@ -10,6 +11,9 @@ export function DemoSubapp()
 	// Get subapp close function.
 	const {uuid, close} = useSubapp();
 
+	// Get kernel application custom data.
+	const [kernelApplicationData] = useKernelApplicationData("customData", "");
+
 	return (
 		<Subapp title={"My complex subapp"}>
 			<Card>
@@ -17,6 +21,8 @@ export function DemoSubapp()
 
 				<p>UUID : <code>{uuid}</code></p>
 
+				{kernelApplicationData && <p><strong>Kernel application data</strong>: <code>{kernelApplicationData}</code></p>}
+
 				<button onClick={close}>Close the subapp</button>
 			</Card>
 		</Subapp>

index.ts

@@ -49,4 +49,5 @@ export * from "./src/Components/Tips/Tip";
 
 export * from "./src/Async";
 export * from "./src/GlobalState";
+export * from "./src/KernelContext";
 export * from "./src/Utils";

package.json

@@ -1,5 +1,5 @@
 {
-	"version": "1.7.1",
+	"version": "1.8.0",
 	"name": "@kernelui/core",
 	"description": "Kernel UI Core.",
 	"scripts": {

src/Application/Kernel.tsx

@@ -3,6 +3,7 @@ import React from "react";
 import {createBrowserRouter, RouterProvider} from "react-router-dom";
 import {CurtainsProvider} from "../Components/Curtains/Curtains";
 import {NotificationsProvider} from "../Components/Notifications/Notifications";
+import {KernelContextProvider} from "../KernelContext";
 
 /**
  * Main Kernel UI app component which initializes everything.
@@ -14,17 +15,19 @@ export function Kernel({header, footer, router}: {
 })
 {
 	return (
-		<IconContext.Provider value={{
-			size: "1em",
-			weight: "bold",
-		}}>
-			<NotificationsProvider>
-				<CurtainsProvider>
-					{header}
-					<RouterProvider router={router} />
-					{footer}
-				</CurtainsProvider>
-			</NotificationsProvider>
-		</IconContext.Provider>
+		<KernelContextProvider>
+			<IconContext.Provider value={{
+				size: "1em",
+				weight: "bold",
+			}}>
+				<NotificationsProvider>
+					<CurtainsProvider>
+						{header}
+						<RouterProvider router={router} />
+						{footer}
+					</CurtainsProvider>
+				</NotificationsProvider>
+			</IconContext.Provider>
+		</KernelContextProvider>
 	);
 }

src/KernelContext.tsx

@@ -0,0 +1,111 @@
+import React, {useCallback, useContext, useMemo, useState} from "react";
+
+/**
+ * Application data setter function type.
+ */
+export type ApplicationDataSetter<IdentifierType extends string|symbol|number = string, ValueType = any> = (identifier: IdentifierType, value: ValueType) => void;
+
+/**
+ * Application data dispatcher function type.
+ */
+export type KernelApplicationDataDispatcher<ValueType = any> = (value: ValueType) => void;
+
+/**
+ * Kernel application data type.
+ */
+export type KernelApplicationData = Record<string, any>;
+
+/**
+ * Kernel context data.
+ */
+export interface KernelContextData
+{
+	application: {
+		data: KernelApplicationData;
+		setData: ApplicationDataSetter;
+	};
+}
+
+/**
+ * React Kernel context.
+ */
+export const KernelContext = React.createContext<KernelContextData>({
+	application: {
+		data: {},
+		setData: () => {},
+	},
+});
+
+/**
+ * Kernel context provider.
+ */
+export function KernelContextProvider({children}: React.PropsWithChildren<{}>)
+{
+	// Kernel application data initialization.
+	const [kernelApplicationData, setKernelApplicationData] = useState<KernelApplicationData>({});
+
+	/**
+	 * Change application data function.
+	 */
+	const changeApplicationData = useCallback((applicationUpdate: Partial<KernelApplicationData>) => {
+		setKernelApplicationData({
+			...kernelApplicationData,
+			...applicationUpdate,
+		});
+	}, [kernelApplicationData, setKernelApplicationData]);
+
+	/**
+	 * Application data setter function.
+	 */
+	const applicationDataSetter = useCallback((identifier: string, data: any) => (
+		changeApplicationData({
+			[identifier]: data,
+		})
+	), [changeApplicationData]);
+
+	// Initialize kernel context value.
+	const kernelContextValue = useMemo<KernelContextData>(() => ({
+		application: {
+			data: kernelApplicationData,
+			setData: applicationDataSetter,
+		},
+	}), [kernelApplicationData, applicationDataSetter]);
+
+	return (
+		<KernelContext.Provider value={kernelContextValue}>
+			{children}
+		</KernelContext.Provider>
+	);
+}
+
+/**
+ * Get kernel context data.
+ */
+export function useKernelContext(): KernelContextData
+{
+	return useContext(KernelContext);
+}
+
+/**
+ * Initialize or get kernel application data with given identifier.
+ * @param identifier Application data identifier.
+ * @param initialValue Application data initial value.
+ */
+export function useKernelApplicationData<T>(identifier: string, initialValue: T): [T, KernelApplicationDataDispatcher<T>]
+{
+	/**
+	 * Get kernel context.
+	 */
+	const kernelContext = useKernelContext();
+
+	/**
+	 * Function to set application data.
+	 */
+	const setApplicationData = useCallback(
+		(newValue: T) => kernelContext.application.setData(identifier, newValue),
+		[kernelContext.application.setData]
+	);
+
+	// Return kernel application data.
+	return [kernelContext.application.data?.[identifier] ?? initialValue, setApplicationData];
+}