/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */
import { UpdateRecorder } from './update-recorder';
/**
 * A workspace path semantically is equivalent to the `Path` type provided by the
 * Angular devkit. Paths denoted with such a type are guaranteed to be representing
 * paths of a given virtual file system. This means that the root of a path can be
 * different, and does not necessarily need to match the root in the real file system.
 *
 * For example: Consider we have a project in `/home/<..>/my-project`. Then a path
 * like `/package.json` could actually refer to the `package.json` file in `my-project`.
 * Note that in the real file system this would not match though.
 *
 * One wonder why another type has been declared for such paths, when there already
 * is the `Path` type provided by the devkit. We do this for a couple of reasons:
 *
 *   1. The update-tool cannot have a dependency on the Angular devkit as that one
 *      is not synced into g3. We want to be able to run migrations in g3 if needed.
 */
export declare type WorkspacePath = string & {
    __PRIVATE_DEVKIT_PATH: void;
};
/** Interface that describes a directory. */
export interface DirectoryEntry {
    /** List of directories inside the directory. */
    directories: string[];
    /** List of files inside the directory. */
    files: string[];
}
/**
 * Abstraction of the file system that migrations can use to record and apply
 * changes. This is necessary to support virtual file systems as used in the CLI devkit.
 */
export declare abstract class FileSystem {
    /** Checks whether the given file or directory exists. */
    abstract exists(path: WorkspacePath): boolean;
    /** Gets the contents of the given file. */
    abstract read(filePath: WorkspacePath): string | null;
    /** Reads the given directory to retrieve children. */
    abstract readDirectory(dirPath: WorkspacePath): DirectoryEntry;
    /**
     * Creates an update recorder for the given file. Edits can be recorded and
     * committed in batches. Changes are not applied automatically because otherwise
     * migrations would need to re-read files, or account for shifted file contents.
     */
    abstract edit(filePath: WorkspacePath): UpdateRecorder;
    /** Applies all changes which have been recorded in update recorders. */
    abstract commitEdits(): void;
    /** Creates a new file with the given content. */
    abstract create(filePath: WorkspacePath, content: string): void;
    /** Overwrites an existing file with the given content. */
    abstract overwrite(filePath: WorkspacePath, content: string): void;
    /** Deletes the given file. */
    abstract delete(filePath: WorkspacePath): void;
    /**
     * Resolves given paths to a resolved path in the file system. For example, the devkit
     * tree considers the actual workspace directory as file system root.
     *
     * Follows the same semantics as the native path `resolve` method. i.e. segments
     * are processed in reverse. The last segment is considered the target and the
     * function will iterate from the target through other segments until it finds an
     * absolute path segment.
     */
    abstract resolve(...segments: string[]): WorkspacePath;
}