Max P.
b83aa330b3
- Replace standard imports with type-only imports to improve clarity and align with TypeScript best practices. - Ensure consistency across modules by modifying all relevant files.
58 lines
2.0 KiB
TypeScript
58 lines
2.0 KiB
TypeScript
import type { IContext } from '../Interfaces/mod.ts';
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/**
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* Represents a final request handler responsible for producing an HTTP response.
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*
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* The handler is the terminal stage of the middleware pipeline and is responsible
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* for processing the incoming request and generating the final `Response`.
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*
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* It receives the fully-typed request context, which includes the original request,
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* parsed route parameters, query parameters, and any shared state populated by prior middleware.
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*
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* @template TContext The specific context type for this handler, including typed `state`, `params`, and `query`.
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*/
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type Handler<TContext extends IContext = IContext> = (
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ctx: TContext,
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) => Promise<Response>;
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/**
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* Represents a handler function with an associated name.
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*
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* This is useful for debugging, logging, or when you need to reference
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* the handler by name in your application.
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*
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* @template TContext The specific context type for this handler, including typed `state`, `params`, and `query`.
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*/
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type NamedHandler<TContext extends IContext = IContext> =
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& Handler<TContext>
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& { name?: string };
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export type { NamedHandler as Handler };
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/**
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* Type guard to determine whether a given value is a valid `IHandler` function.
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*
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* This function checks whether the input is a function and whether it returns
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* a `Promise<Response>` when called. Due to TypeScript's structural typing and
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* the lack of runtime type information, only minimal runtime validation is possible.
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*
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* @param value - The value to test.
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* @returns `true` if the value is a function that appears to conform to `IHandler`.
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*
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* @example
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* ```ts
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* const candidate = async (ctx: IContext) => new Response("ok");
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* if (isHandler(candidate)) {
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* // candidate is now typed as IHandler<IContext>
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* }
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* ```
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*/
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export function isHandler<TContext extends IContext = IContext>(
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value: unknown,
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): value is Handler<TContext> {
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return (
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typeof value === 'function' &&
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value.length === 1 // ctx
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);
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}
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