/**
 * HTTP entity tag values and metadata-based generator layers.
 *
 * ETags are validators for a specific representation of a resource. Servers put
 * them in `ETag` response headers so clients and intermediaries can revalidate
 * cached content with `If-None-Match`, or protect writes with preconditions such
 * as `If-Match`.
 *
 * @stability unstable
 * @since 4.0.0
 */
import * as Context from "../Context.ts";
import * as Effect from "../Effect.ts";
import type * as FileSystem from "../FileSystem.ts";
import * as Layer from "../Layer.ts";
import type * as Body from "./HttpBody.ts";
/**
 * Represents an HTTP entity tag, either weak or strong.
 *
 * @stability unstable
 * @category models
 * @since 4.0.0
 */
export type Etag = Weak | Strong;
/**
 * Weak HTTP entity tag.
 *
 * **Details**
 *
 * The `value` is the raw tag value without the surrounding quotes or `W/` prefix.
 *
 * @stability unstable
 * @category models
 * @since 4.0.0
 */
export interface Weak {
    readonly _tag: "Weak";
    readonly value: string;
}
/**
 * Strong HTTP entity tag.
 *
 * **Details**
 *
 * The `value` is the raw tag value without the surrounding quotes.
 *
 * @stability unstable
 * @category models
 * @since 4.0.0
 */
export interface Strong {
    readonly _tag: "Strong";
    readonly value: string;
}
/**
 * Formats an `Etag` as an HTTP header value, including quotes and the `W/` prefix for weak tags.
 *
 * @stability unstable
 * @category converting
 * @since 4.0.0
 */
export declare const toString: (self: Etag) => string;
declare const Generator_base: Context.ServiceClass<Generator, "effect/http/Etag/Generator", {
    readonly fromFileInfo: (info: FileSystem.File.Info) => Effect.Effect<Etag>;
    readonly fromFileWeb: (file: Body.HttpBody.FileLike) => Effect.Effect<Etag>;
}>;
/**
 * Service for generating ETags from filesystem file information or Web `File`-like metadata.
 *
 * @stability unstable
 * @category services
 * @since 4.0.0
 */
export declare class Generator extends Generator_base {
}
/**
 * Layer that provides a `Generator` which produces strong ETags from file size
 * and modification time metadata.
 *
 * **When to use**
 *
 * Use when you need the `Generator` service to produce strong ETags and file
 * size plus modification time reliably change for every byte-level change.
 *
 * **Gotchas**
 *
 * This layer marks metadata-derived tags as strong. If the underlying storage
 * can update file contents without changing the recorded size or modification
 * time, those tags can stop representing byte-for-byte identity.
 *
 * @see {@link layerWeak} for weak metadata-derived ETags when byte-for-byte identity is not required
 * @see {@link Generator} for the service provided by this layer
 *
 * @stability unstable
 * @category layers
 * @since 4.0.0
 */
export declare const layer: Layer.Layer<Generator>;
/**
 * Layer that provides a `Generator` which produces weak ETags from file size and modification time metadata.
 *
 * @stability unstable
 * @category layers
 * @since 4.0.0
 */
export declare const layerWeak: Layer.Layer<Generator>;
export {};
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