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-rw-r--r--packages/0x.js/src/utils/promisify.ts24
1 files changed, 24 insertions, 0 deletions
diff --git a/packages/0x.js/src/utils/promisify.ts b/packages/0x.js/src/utils/promisify.ts
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index 000000000..8021a3c9f
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+++ b/packages/0x.js/src/utils/promisify.ts
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+import * as _ from 'lodash';
+
+/**
+ * Transforms callback-based function -- func(arg1, arg2 .. argN, callback) -- into
+ * an ES6-compatible Promise. Promisify provides a default callback of the form (error, result)
+ * and rejects when `error` is not null. You can also supply settings object as the second argument.
+ */
+export function promisify<T>(
+ originalFn: (
+ ...args: any[],
+ // HACK: This can't be properly typed without variadic kinds https://github.com/Microsoft/TypeScript/issues/5453
+ ) => void,
+ target: any,
+): (...callArgs: any[]) => Promise<T> {
+ const promisifiedFunction = (...callArgs: any[]): Promise<T> => {
+ return new Promise<T>((resolve, reject) => {
+ const callback = (err: Error|null, data?: T) => {
+ _.isNull(err) ? resolve(data) : reject(err);
+ };
+ originalFn.apply(target, [...callArgs, callback]);
+ });
+ };
+ return promisifiedFunction;
+}