@temporalio/common/lib/interceptors.js

Common library for code that's used across the Client, Worker, and/or Workflow

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.composeInterceptorsWith = composeInterceptorsWith;
exports.composeInterceptors = composeInterceptors;
/**
 * Shared implementation for interceptor chaining.
 *
 * The workflow package needs one small behavioral extension over the generic interceptor
 * semantics: every `next(...)` continuation it hands to workflow interceptors must first
 * restore the workflow random scope that was current when that continuation was created.
 *
 * We keep the chain-construction loop here as the single source of truth so ordering and
 * basic composition behavior cannot drift between the generic implementation used by client,
 * worker, activity, and nexus code and the workflow-specific implementation that decorates
 * `next(...)` at each boundary. The only behavior that varies between callers is the
 * `wrapNext` hook: most packages use the identity wrapper, while workflow code supplies a
 * wrapper that re-enters the captured workflow async-local random scope.
 */
function composeInterceptorsWith(interceptors, method, next, wrapNext) {
    let composedNext = next;
    for (let i = interceptors.length - 1; i >= 0; --i) {
        const interceptor = interceptors[i];
        if (interceptor?.[method] !== undefined) {
            const prev = wrapNext(composedNext);
            // We lose type safety here because Typescript can't deduce that interceptor[method] is a function that returns
            // the same type as Next<I, M>
            composedNext = ((input) => interceptor[method](input, prev));
        }
    }
    return composedNext;
}
/**
 * Compose all interceptor methods into a single function.
 *
 * Calling the composed function results in calling each of the provided interceptor, in order (from the first to
 * the last), followed by the original function provided as argument to `composeInterceptors()`.
 *
 * @param interceptors a list of interceptors
 * @param method the name of the interceptor method to compose
 * @param next the original function to be executed at the end of the interception chain
 */
// ts-prune-ignore-next (imported via lib/interceptors)
function composeInterceptors(interceptors, method, next) {
    return composeInterceptorsWith(interceptors, method, next, ((wrappedNext) => wrappedNext));
}
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