[FEATURE] Add custom hook support

.gitignore

@@ -25,6 +25,9 @@ node_modules
 *.launch
 .settings/
 *.sublime-workspace
+.nvim.lua
+.nvimrc
+.exrc
 
 # IDE - VSCode
 .vscode/*
@@ -58,4 +61,4 @@ Thumbs.db
 .cache-loader/
 
 .nx/cache
-.nx/workspace-data
+.nx/workspace-data

libs/execution/src/lib/blocks/block-execution-util.ts

@@ -62,11 +62,15 @@ export async function executeBlocks(
 
     executionContext.enterNode(block);
 
+    await executionContext.executeHooks(inputValue);
+
     const executionResult = await executeBlock(
       inputValue,
       block,
       executionContext,
     );
+    await executionContext.executeHooks(inputValue, executionResult);
+
     if (R.isErr(executionResult)) {
       return executionResult;
     }

libs/execution/src/lib/execution-context.ts

@@ -4,6 +4,7 @@
 
 // eslint-disable-next-line unicorn/prefer-node-protocol
 import { strict as assert } from 'assert';
+import { inspect } from 'node:util';
 
 import {
   type BlockDefinition,
@@ -26,13 +27,16 @@ import {
 } from '@jvalue/jayvee-language-server';
 import { assertUnreachable, isReference } from 'langium';
 
+import { type Result } from './blocks';
 import { type JayveeConstraintExtension } from './constraints';
 import {
   type DebugGranularity,
   type DebugTargets,
 } from './debugging/debug-configuration';
 import { type JayveeExecExtension } from './extension';
+import { type HookContext } from './hooks';
 import { type Logger } from './logging/logger';
+import { type IOTypeImplementation } from './types';
 
 export type StackNode =
   | BlockDefinition
@@ -55,6 +59,7 @@ export class ExecutionContext {
       debugTargets: DebugTargets;
     },
     public readonly evaluationContext: EvaluationContext,
+    public readonly hookContext: HookContext,
   ) {
     logger.setLoggingContext(pipeline.name);
   }
@@ -133,6 +138,34 @@ export class ExecutionContext {
     return property;
   }
 
+  public executeHooks(
+    input: IOTypeImplementation | null,
+    output?: Result<IOTypeImplementation | null>,
+  ) {
+    const node = this.getCurrentNode();
+    assert(
+      isBlockDefinition(node),
+      `Expected node to be \`BlockDefinition\`: ${inspect(node)}`,
+    );
+
+    const blocktype = node.type.ref?.name;
+    assert(
+      blocktype !== undefined,
+      `Expected block definition to have a blocktype: ${inspect(node)}`,
+    );
+
+    if (output === undefined) {
+      return this.hookContext.executePreBlockHooks(blocktype, input, this);
+    }
+
+    return this.hookContext.executePostBlockHooks(
+      blocktype,
+      input,
+      this,
+      output,
+    );
+  }
+
   private getDefaultPropertyValue<I extends InternalValueRepresentation>(
     propertyName: string,
     valueType: ValueType<I>,

libs/execution/src/lib/hooks/hook-context.ts

@@ -0,0 +1,161 @@
+// SPDX-FileCopyrightText: 2025 Friedrich-Alexander-Universitat Erlangen-Nurnberg
+//
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { type Result } from '../blocks';
+import { type ExecutionContext } from '../execution-context';
+import { type IOTypeImplementation } from '../types';
+
+import {
+  type HookOptions,
+  type HookPosition,
+  type PostBlockHook,
+  type PreBlockHook,
+  isPreBlockHook,
+} from './hook';
+
+const AllBlocks = '*';
+
+interface HookSpec<H extends PreBlockHook | PostBlockHook> {
+  blocking: boolean;
+  hook: H;
+}
+
+// eslint-disable-next-line @typescript-eslint/no-empty-function
+function noop() {}
+
+async function executePreBlockHooks(
+  hooks: HookSpec<PreBlockHook>[],
+  blocktype: string,
+  input: IOTypeImplementation | null,
+  context: ExecutionContext,
+) {
+  await Promise.all(
+    hooks.map(async ({ blocking, hook }) => {
+      if (blocking) {
+        await hook(blocktype, input, context);
+      } else {
+        hook(blocktype, input, context).catch(noop);
+      }
+    }),
+  );
+}
+
+async function executePostBlockHooks(
+  hooks: HookSpec<PostBlockHook>[],
+  blocktype: string,
+  input: IOTypeImplementation | null,
+  context: ExecutionContext,
+  output: Result<IOTypeImplementation | null>,
+) {
+  await Promise.all(
+    hooks.map(async ({ blocking, hook }) => {
+      if (blocking) {
+        await hook(blocktype, input, output, context);
+      } else {
+        hook(blocktype, input, output, context).catch(noop);
+      }
+    }),
+  );
+}
+
+export class HookContext {
+  private hooks: {
+    pre: Record<string, HookSpec<PreBlockHook>[]>;
+    post: Record<string, HookSpec<PostBlockHook>[]>;
+  } = { pre: {}, post: {} };
+
+  public addHook(
+    position: 'preBlock',
+    hook: PreBlockHook,
+    opts: HookOptions,
+  ): void;
+  public addHook(
+    position: 'postBlock',
+    hook: PostBlockHook,
+    opts: HookOptions,
+  ): void;
+  public addHook(
+    position: HookPosition,
+    hook: PreBlockHook | PostBlockHook,
+    opts: HookOptions,
+  ): void;
+  public addHook(
+    position: HookPosition,
+    hook: PreBlockHook | PostBlockHook,
+    opts: HookOptions,
+  ) {
+    for (const blocktype of opts.blocktypes ?? [AllBlocks]) {
+      if (isPreBlockHook(hook, position)) {
+        if (this.hooks.pre[blocktype] === undefined) {
+          this.hooks.pre[blocktype] = [];
+        }
+        this.hooks.pre[blocktype].push({
+          blocking: opts.blocking ?? false,
+          hook,
+        });
+      } else {
+        if (this.hooks.post[blocktype] === undefined) {
+          this.hooks.post[blocktype] = [];
+        }
+        this.hooks.post[blocktype].push({
+          blocking: opts.blocking ?? false,
+          hook,
+        });
+      }
+    }
+  }
+
+  public async executePreBlockHooks(
+    blocktype: string,
+    input: IOTypeImplementation | null,
+    context: ExecutionContext,
+  ) {
+    context.logger.logInfo(`Executing general pre-block-hooks`);
+    const general = executePreBlockHooks(
+      this.hooks.pre[AllBlocks] ?? [],
+      blocktype,
+      input,
+      context,
+    );
+    context.logger.logInfo(
+      `Executing pre-block-hooks for blocktype ${blocktype}`,
+    );
+    const blockSpecific = executePreBlockHooks(
+      this.hooks.pre[blocktype] ?? [],
+      blocktype,
+      input,
+      context,
+    );
+
+    await Promise.all([general, blockSpecific]);
+  }
+
+  public async executePostBlockHooks(
+    blocktype: string,
+    input: IOTypeImplementation | null,
+    context: ExecutionContext,
+    output: Result<IOTypeImplementation | null>,
+  ) {
+    context.logger.logInfo(`Executing general post-block-hooks`);
+    const general = executePostBlockHooks(
+      this.hooks.post[AllBlocks] ?? [],
+      blocktype,
+      input,
+      context,
+      output,
+    );
+    context.logger.logInfo(
+      `Executing post-block-hooks for blocktype ${blocktype}`,
+    );
+    const blockSpecific = executePostBlockHooks(
+      this.hooks.post[blocktype] ?? [],
+      blocktype,
+      input,
+      context,
+      output,
+    );
+
+    await Promise.all([general, blockSpecific]);
+  }
+}

libs/execution/src/lib/hooks/hook.ts

@@ -0,0 +1,46 @@
+// SPDX-FileCopyrightText: 2025 Friedrich-Alexander-Universitat Erlangen-Nurnberg
+//
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { type Result } from '../blocks';
+import { type ExecutionContext } from '../execution-context';
+import { type IOTypeImplementation } from '../types';
+
+/** When to execute the hook.*/
+export type HookPosition = 'preBlock' | 'postBlock';
+
+export interface HookOptions {
+  /** Whether the pipeline should await the hooks completion. `false` if omitted.*/
+  blocking?: boolean;
+  /** Optionally specify one or more blocks to limit this hook to. If omitted, the hook will be executed on all blocks*/
+  blocktypes?: string[];
+}
+
+/** This function will be executed before a block.*/
+export type PreBlockHook = (
+  blocktype: string,
+  input: IOTypeImplementation | null,
+  context: ExecutionContext,
+) => Promise<void>;
+
+export function isPreBlockHook(
+  hook: PreBlockHook | PostBlockHook,
+  position: HookPosition,
+): hook is PreBlockHook {
+  return position === 'preBlock';
+}
+
+/** This function will be executed before a block.*/
+export type PostBlockHook = (
+  blocktype: string,
+  input: IOTypeImplementation | null,
+  output: Result<IOTypeImplementation | null>,
+  context: ExecutionContext,
+) => Promise<void>;
+
+export function isPostBlockHook(
+  hook: PreBlockHook | PostBlockHook,
+  position: HookPosition,
+): hook is PostBlockHook {
+  return position === 'postBlock';
+}

libs/execution/src/lib/hooks/index.ts

@@ -0,0 +1,6 @@
+// SPDX-FileCopyrightText: 2025 Friedrich-Alexander-Universitat Erlangen-Nurnberg
+//
+// SPDX-License-Identifier: AGPL-3.0-only
+
+export * from './hook';
+export * from './hook-context';

libs/execution/src/lib/index.ts

@@ -13,3 +13,4 @@ export * from './types/value-types/visitors';
 export * from './execution-context';
 export * from './extension';
 export * from './logging';
+export * from './hooks';