grafast/dist/steps/get.d.ts

Cutting edge GraphQL planning and execution engine

import type { Step } from "../step.js";
/**
 * If your step class has a `get` method you should implement this so users
 * benefit from type safety.
 *
 * e.g.
 * ```ts
 * class MyStep extends Step {
 *   __inferGet?: {
 *     [TKey in keyof MyData]: MySpecialStep<MyData[TKey]>;
 *   };
 *   get<TKey extends keyof MyData>(key: TKey): MySpecialStep<MyData[TKey]> {
 *     // ...
 *   }
 * }
 * ```
 */
interface HasInferredGet<TStepByKey extends Record<string, Step>> {
    /**
     * TypeScript hack so we can infer the type of getting each key; this key
     * won't actually have a value
     */
    __inferGet?: TStepByKey;
}
/**
 * Determines the keys that a given step represents
 *
 * 1. If it implements HasInferredGet, get the explicit keys
 * 2. Otherwise, if it has a get method, figure out which attributes it accepts
 * 3. Otherwise, determine the type the Step encodes and extract the keys of that
 */
type StepGetKeys<TStep extends Step> = TStep extends HasInferredGet<infer UStepByKey> ? keyof UStepByKey : TStep extends {
    get(attr: infer U): any;
} ? U : TStep extends Step<infer UData | null | undefined> ? keyof UData : never;
/**
 * Determines the type of the step returned from `get(step, attr)`.
 *
 * 1. If it implements HasInferredGet, get a step representing that specific attribute
 * 2. Otherwise, if it has a get method, return the ReturnType of that method
 * 3. Otherwise, determine the type the Step encodes and return a Step representing the relevant key of that
 */
type GetResult<TStep extends Step, TAttr extends StepGetKeys<TStep>> = TStep extends HasInferredGet<infer UStepByKey> ? TAttr extends keyof UStepByKey ? UStepByKey[TAttr] : never : TStep extends {
    get(attr: any): infer UGetStep;
} ? UGetStep : TStep extends Step<infer UData | null | undefined> ? TAttr extends keyof UData ? Step<UData[TAttr]> : never : never;
/**
 * Call `$step.get(attr)` if possible, falling back to `access($step, attr)`.
 */
export declare function get<TStep extends Step, TAttr extends StepGetKeys<TStep> & string>($step: TStep, attr: TAttr): GetResult<TStep, TAttr>;
export {};
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