feat(deasync): make the deasync module an optional dependency since n…

…ot all environments support it

package.json

@@ -62,14 +62,14 @@
     "@types/node": "12.7.4",
     "@types/object-path": "0.11.0",
     "chalk": "2.4.2",
-    "deasync": "0.1.15",
     "object-path": "0.11.4",
     "tslib": "1.10.0",
     "typescript": "3.6.2"
   },
   "optionalDependencies": {
     "@types/jsdom": "12.2.4",
-    "jsdom": "15.1.1"
+    "jsdom": "15.1.1",
+    "deasync": "0.1.15"
   },
   "main": "./dist/cjs/index.js",
   "module": "./dist/esm/index.js",

src/index.ts

@@ -24,6 +24,7 @@ export {MaxOpDurationExceededError} from "./interpreter/error/policy-error/max-o
 export {NetworkError} from "./interpreter/error/policy-error/network-error/network-error";
 export {NonDeterministicError} from "./interpreter/error/policy-error/non-deterministic-error/non-deterministic-error";
 export {ProcessError} from "./interpreter/error/policy-error/process-error/process-error";
+export {AsyncNotSupportedError} from "./interpreter/error/async-not-supported-error/async-not-supported-error";
 
 // Reporting
 export {BindingReportCallback, IReportingOptions, ReportingOptions} from "./interpreter/reporting/i-reporting-options";

src/interpreter/error/async-not-supported-error/async-not-supported-error.ts

@@ -0,0 +1,13 @@
+import {EvaluationError} from "../evaluation-error/evaluation-error";
+import {IAsyncNotSupportedErrorOptions} from "./i-async-not-supported-error-options";
+import {createEmptyStatement} from "typescript";
+
+/**
+ * An Error that can be thrown when an async operation is attempted but can't be computed
+ */
+export class AsyncNotSupportedError extends EvaluationError {
+
+	constructor ({message = `It is not possible to evaluate asynchronously: Optional dependency 'deasync' must be installed.'`}: IAsyncNotSupportedErrorOptions) {
+		super({message, node: createEmptyStatement()});
+	}
+}

src/interpreter/error/async-not-supported-error/i-async-not-supported-error-options.ts

@@ -0,0 +1,4 @@
+import {IEvaluationErrorOptions} from "../evaluation-error/i-evaluation-error-options";
+
+export interface IAsyncNotSupportedErrorOptions extends Omit<IEvaluationErrorOptions, "node"> {
+}

src/interpreter/util/await/sync-await.ts

@@ -1,11 +1,25 @@
-import {loopWhile} from "deasync";
+import {AsyncNotSupportedError} from "../../error/async-not-supported-error/async-not-supported-error";
+
+let loopWhile: (typeof import("deasync").loopWhile)|undefined;
+
+try {
+	// tslint:disable-next-line:no-require-imports no-var-requires
+	const importedModule = require("deasync") as typeof import("deasync");
+	loopWhile = importedModule.loopWhile;
+} catch {
+	// This is OK
+}
 
 /**
  * A synchronous way to await a result
  * @param {Promise<T>} promise
  * @return {T}
  */
 export function syncAwait<T> (promise: Promise<T>): T {
+	if (loopWhile === undefined) {
+		// Throw this error if for some reason the deasync module wasn't installed
+		throw new AsyncNotSupportedError({});
+	}
 	let done = false;
 	let rejected = false;
 	let resolveResult: unknown;