Implement basic execution system and UI

This is a rather large commit that includes all of the following:
- React UI with code editor, runtime renderer and input-output panes
- Language providers for a sample language and Brainfuck
- Implementation of code execution in a web worker
- All-at-once unabortable execution of program fully functional

engines/execution-controller.ts

@@ -0,0 +1,60 @@
+import { LanguageEngine, StepExecutionResult } from "./types";
+
+type ExecuteAllArgs<RS> = {
+  /** Interval between two execution steps, in milliseconds */
+  interval?: number;
+  /**
+   * Pass to run in streaming-response mode.
+   * Callback is called with exeuction result on every execution step.
+   */
+  onResult?: (result: StepExecutionResult<RS>) => void;
+};
+
+class ExecutionController<RS> {
+  private _engine: LanguageEngine<RS>;
+  private _result: StepExecutionResult<RS> | null;
+
+  /**
+   * Create a new ExecutionController.
+   * @param engine Language engine to use for execution
+   */
+  constructor(engine: LanguageEngine<RS>) {
+    this._engine = engine;
+    this._engine.resetState();
+    this._result = null;
+  }
+
+  /**
+   * Reset execution state in controller and engine.
+   * Clears out state from the current execution cycle.
+   */
+  resetState() {
+    this._engine.resetState();
+    this._result = null;
+  }
+
+  /**
+   * Load code and user input into the engine to prepare for execution.
+   * @param code Code content, lines separated by `\n`
+   * @param input User input, lines separated by '\n'
+   */
+  prepare(code: string, input: string) {
+    this._engine.prepare(code, input);
+  }
+
+  async executeAll({ interval, onResult }: ExecuteAllArgs<RS>) {
+    while (true) {
+      this._result = this._engine.executeStep();
+      onResult && onResult(this._result);
+      if (!this._result.nextStepLocation) break;
+      if (interval) await this.sleep(interval);
+    }
+    return this._result;
+  }
+
+  private async sleep(millis: number) {
+    return new Promise<void>((resolve) => setTimeout(resolve, millis));
+  }
+}
+
+export default ExecutionController;