change: Refactor AllVoidCompositeHandler into SequenceHandler.

src/index.ts

@@ -181,10 +181,10 @@ export * from './util/locking/SingleThreadedResourceLocker';
 export * from './util/locking/WrappedExpiringResourceLocker';
 
 // Util
-export * from './util/AllVoidCompositeHandler';
 export * from './util/AsyncHandler';
 export * from './util/FirstCompositeHandler';
 export * from './util/HeaderUtil';
 export * from './util/PathUtil';
 export * from './util/QuadUtil';
+export * from './util/SequenceHandler';
 export * from './util/StreamUtil';

src/util/AllVoidCompositeHandler.ts

@@ -1,24 +0,0 @@
-import { AsyncHandler } from './AsyncHandler';
-
-/**
- * A composite handler that runs all of its handlers independent of their result.
- * The `canHandle` check of this handler will always succeed.
- */
-export class AllVoidCompositeHandler<TIn> extends AsyncHandler<TIn> {
-  private readonly handlers: AsyncHandler<TIn>[];
-
-  public constructor(handlers: AsyncHandler<TIn>[]) {
-    super();
-    this.handlers = handlers;
-  }
-
-  public async handle(input: TIn): Promise<void> {
-    for (const handler of this.handlers) {
-      try {
-        await handler.handleSafe(input);
-      } catch {
-        // Ignore errors
-      }
-    }
-  }
-}

src/util/AsyncHandler.ts

@@ -1,7 +1,7 @@
 /**
  * Simple interface for classes that can potentially handle a specific kind of data asynchronously.
  */
-export abstract class AsyncHandler<TInput = void, TOutput = void> {
+export abstract class AsyncHandler<TIn = void, TOut = void> {
   /**
    * Checks if the input data can be handled by this class.
    * Throws an error if it can't handle the data.
@@ -10,7 +10,7 @@ export abstract class AsyncHandler<TInput = void, TOutput = void> {
    * @returns A promise resolving if this input can be handled, rejecting with an Error if not.
    */
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
-  public async canHandle(input: TInput): Promise<void> {
+  public async canHandle(input: TIn): Promise<void> {
     // Support any input by default
   }
 
@@ -20,7 +20,7 @@ export abstract class AsyncHandler<TInput = void, TOutput = void> {
    *
    * @returns A promise resolving when the handling is finished. Return value depends on the given type.
    */
-  public abstract handle(input: TInput): Promise<TOutput>;
+  public abstract handle(input: TIn): Promise<TOut>;
 
   /**
    * Helper function that first runs the canHandle function followed by the handle function.
@@ -30,7 +30,7 @@ export abstract class AsyncHandler<TInput = void, TOutput = void> {
    *
    * @returns The result of the handle function of the handler.
    */
-  public async handleSafe(data: TInput): Promise<TOutput> {
+  public async handleSafe(data: TIn): Promise<TOut> {
     await this.canHandle(data);
 
     return this.handle(data);

src/util/SequenceHandler.ts

@@ -0,0 +1,32 @@
+import { AsyncHandler } from './AsyncHandler';
+
+/**
+ * A composite handler that will try to run all supporting handlers sequentially
+ * and return the value of the last supported handler.
+ * The `canHandle` check of this handler will always succeed.
+ */
+export class SequenceHandler<TIn = void, TOut = void> extends AsyncHandler<TIn, TOut | undefined> {
+  private readonly handlers: AsyncHandler<TIn, TOut>[];
+
+  public constructor(handlers: AsyncHandler<TIn, TOut>[]) {
+    super();
+    this.handlers = [ ...handlers ];
+  }
+
+  public async handle(input: TIn): Promise<TOut | undefined> {
+    let result: TOut | undefined;
+    for (const handler of this.handlers) {
+      let supported: boolean;
+      try {
+        await handler.canHandle(input);
+        supported = true;
+      } catch {
+        supported = false;
+      }
+      if (supported) {
+        result = await handler.handle(input);
+      }
+    }
+    return result;
+  }
+}