import type { PropertyType } from './constants';
import type { Document } from './document';
import type { ReaderContext, WriterContext } from './io';
import { ExtensionProperty } from './properties';
/**
 * # Extension
 *
 * *Base class for all Extensions.*
 *
 * Extensions enhance a glTF {@link Document} with additional features and schema, beyond the core
 * glTF specification. Common extensions may be imported from the `@gltf-transform/extensions`
 * package, or custom extensions may be created by extending this base class.
 *
 * An extension is added to a Document by calling {@link Document.createExtension} with the
 * extension constructor. The extension object may then be used to construct
 * {@link ExtensionProperty} instances, which are attached to properties throughout the Document
 * as prescribed by the extension itself.
 *
 * For more information on available extensions and their usage, see [Extensions](/extensions).
 *
 * Reference:
 * - [glTF → Extensions](https://github.com/KhronosGroup/gltf/blob/main/specification/2.0/README.md#specifying-extensions)
 * - [glTF Extension Registry](https://github.com/KhronosGroup/gltf/blob/main/extensions)
 *
 * @category Extensions
 */
export declare abstract class Extension {
    /** Official name of the extension. */
    static EXTENSION_NAME: string;
    /** Official name of the extension. */
    readonly extensionName: string;
    /**
     * Before reading, extension should be called for these {@link Property} types. *Most
     * extensions don't need to implement this.*
     * @hidden
     */
    readonly prereadTypes: PropertyType[];
    /**
     * Before writing, extension should be called for these {@link Property} types. *Most
     * extensions don't need to implement this.*
     * @hidden
     */
    readonly prewriteTypes: PropertyType[];
    /** @hidden Dependency IDs needed to read this extension, to be installed before I/O. */
    readonly readDependencies: string[];
    /** @hidden Dependency IDs needed to write this extension, to be installed before I/O. */
    readonly writeDependencies: string[];
    /** @hidden */
    protected readonly document: Document;
    /** @hidden */
    protected required: boolean;
    /** @hidden */
    protected properties: Set<ExtensionProperty>;
    /** @hidden */
    private _listener;
    /** @hidden */
    constructor(document: Document);
    /** Disables and removes the extension from the Document. */
    dispose(): void;
    /** @hidden Performs first-time setup for the extension. Must be idempotent. */
    static register(): void;
    /**
     * Indicates to the client whether it is OK to load the asset when this extension is not
     * recognized. Optional extensions are generally preferred, if there is not a good reason
     * to require a client to completely fail when an extension isn't known.
     */
    isRequired(): boolean;
    /**
     * Indicates to the client whether it is OK to load the asset when this extension is not
     * recognized. Optional extensions are generally preferred, if there is not a good reason
     * to require a client to completely fail when an extension isn't known.
     */
    setRequired(required: boolean): this;
    /**
     * Lists all {@link ExtensionProperty} instances associated with, or created by, this
     * extension. Includes only instances that are attached to the Document's graph; detached
     * instances will be excluded.
     */
    listProperties(): ExtensionProperty[];
    /**********************************************************************************************
     * I/O implementation.
     */
    /** @hidden Installs dependencies required by the extension. */
    install(key: string, dependency: unknown): this;
    /**
     * Used by the {@link PlatformIO} utilities when reading a glTF asset. This method may
     * optionally be implemented by an extension, and should then support any property type
     * declared by the Extension's {@link Extension.prereadTypes} list. The Extension will
     * be given a ReaderContext instance, and is expected to update either the context or its
     * {@link JSONDocument} with resources known to the Extension. *Most extensions don't need to
     * implement this.*
     * @hidden
     */
    preread(_readerContext: ReaderContext, _propertyType: PropertyType): this;
    /**
     * Used by the {@link PlatformIO} utilities when writing a glTF asset. This method may
     * optionally be implemented by an extension, and should then support any property type
     * declared by the Extension's {@link Extension.prewriteTypes} list. The Extension will
     * be given a WriterContext instance, and is expected to update either the context or its
     * {@link JSONDocument} with resources known to the Extension. *Most extensions don't need to
     * implement this.*
     * @hidden
     */
    prewrite(_writerContext: WriterContext, _propertyType: PropertyType): this;
    /**
     * Used by the {@link PlatformIO} utilities when reading a glTF asset. This method must be
     * implemented by each extension in order to support reading files. The extension will be
     * given a ReaderContext instance, and should update the current {@link Document} accordingly.
     * @hidden
     */
    abstract read(readerContext: ReaderContext): this;
    /**
     * Used by the {@link PlatformIO} utilities when writing a glTF asset. This method must be
     * implemented by each extension in order to support writing files. The extension will be
     * given a WriterContext instance, and should modify the {@link JSONDocument} output
     * accordingly. Adding the extension name to the `extensionsUsed` and `extensionsRequired` list
     * is done automatically, and should not be included here.
     * @hidden
     */
    abstract write(writerContext: WriterContext): this;
}