defiler/API.md

The API consists of two classes, File and Defiler.

A File represents a physical file on the disk, or a generated virtual file with no particular corresponding file in the filesystem, or a partially or fully transformed physical or virtual/generated file.

A Defiler represents a set of watched files on the disk, plus a set of generated files, plus a set of transforms to execute on them.

File

Constructor

new File(path)

A new File instance to serve as the representation of a physical file, a generated file, or a transformed file. path is the relative path to the file, from some understood root.

Properties

path

The file's path can be retrieved or updated by getting and setting path.

paths

An array of all paths this file has had, in chronological order. Setting path automatically updates this.

ext

The file's extension (including the preceding .) can be retrieved or updated by getting and setting path. The ext and path properties are kept in sync.

bytes

The file's contents can be updated by getting or setting bytes, which is a Buffer.

text

The file's contents can also be updated by getting of setting text, which is a string. Mutating the bytes Buffer will not be reflected in text, but reassigning the entire bytes or text properties will keep the other in sync.

Defiler

Constructor

new Defiler()

A new Defiler instance to represent a collection of watched physical files and generated files, and transforms to run on them.

Properties

ready

A Promise that's resolved once we've completed the initial wave of processing. This remains unchanged as later watches or changes are triggered.

origFiles

A map of (original) relative paths to File instances for the original physical files.

files

A map of original relative paths to File instances for the transformed files.

origPaths

A sorted array of the relative paths of all of the physical files. This can be used whether or not we've completed the initial wave of processing.

Configuration

add({ dir, read = true, watch = true, debounce = 10 })

Register an input directory.

• dir - the directory to watch
• read - (optional) whether to actually read in the contents of the files in this directory. If false, the files will still be run through all of the transforms, but they will have null bytes and text
• watch - (optional) whether to actually watch this directory for changes. If false, the files will still be run through all of the transforms, but any changes to them will not be
• debounce - (optional) The length of the timeout in milliseconds to use to debounce incoming events from fs.watch. Multiple events are often emitted for a single change, and events can also be emitted before fs.stat reports the changes. Defiler will wait until debounce milliseconds have passed since the last fs.watch event for a file before handling it. Defaults to 10ms, which Works On My Machine.

Returns the Defiler instance for chaining.

add({ transform, if })

Register a new transform to be applied to all files.

• transform({ defiler, path, file, get }) - a transformer function, which is passed an object containing the Defiler instance, the original path of the file, the File instance to mutate, and a function get(path) which calls the get(path, dependent) method (see below) with the appropriate dependent (that is, the current file's path), as a convenience. The function can return a Promise to indicate when it's done
• if({ defiler, path, file }) - (optional) a function that, if present, will be called (before calling the main transform) with an object containing the Defiler instance, the original path of the file, and the File instance. If the function returns false or a Promise resolving to false, the transform is skipped

Returns the Defiler instance for chaining.

add({ path, generator })

Register a new generated file, not directly sourced from a physical file.

• path - the relative path of the file to register the generator for
• generator({ defiler, file, get }) - a generator function, which is passed an object containing the Defiler instance, a new File instance to mutate containing only a path, and a function get(path) which calls the get(path, dependent) method (see below) with the appropriate dependent (that is, the current file's path), as a convenience. The function can return a Promise to indicate when it's done

Returns the Defiler instance for chaining.

Execution

exec()

Start the Defiler running. No additional configuration (registering input directories, transforms, or generated files) can happen after this.

Returns the Defiler instance for chaining.

Operation

get(path, dependent)

Wait for a file or array of files to be ready, and retrieve the File instance(s).

• path - the path, or array of paths, to wait for to become available
• dependent - (optional) a path of a file to re-process if any of the file or files given in path change. Typically, this is the path to the file you are currently transforming or generating

Returns a Promise resolving to the File instance or an array of File instances.

This can be asked for physical or generated files. If you ask for one or more physical files during the initial wave of processing before everything has been read in and processed, it will wait for the file or files to be ready (and transformed). Requesting something that is neither a known physical file nor a registered generated file will not throw an error, but will instead simply return undefined.

If a path dependent is passed, dependent is registered as depending on the file or files in path. When the file or files in path change, the file at dependent will be automatically re-transformed (using refile, below). If you're calling get inside a transform or generator, dependent should typically be the path of the file you're transforming or generating.

Typically, you would not call this directly, and would instead call the get function passed to the transform or generator callback, which then calls this method with the appropriate dependent.

refile(path)

Manually re-transform a File. This can be from a physical file or a generated one. Returns a Promise to indicate when all processing is complete. Re-transforming a physical file will use the version of it that was last read into memory. Re-transforming a generated file will call its generator again.

Returns a Promise to indicate when all processing is complete.

Typically, you would not need to call this directly, as it would be automatically handled by the dependencies registered by get.

addFile(file)

Manually insert a non-physical File, running it through all the transforms.

For convenience, you can also call this with a plain old JavaScript object, and a new File instance will be created for you with fields Object.assigned from the object.

Returns a Promise to indicate when all processing is complete.

Events

Defiler extends Node's EventEmitter, and emits four kinds of events.

origFile({ defiler, file })

An origFile event is emitted when the original version of a physical file has been read in. It's emitted with an object containing the Defiler instance and the File instance.

file({ defiler, path, file })

A file event is emitted after all transforms on a file are complete. It's emitted with an object containing the Defiler instance, the file's original relative path, and the fully transformed File instance.

deleted({ defiler, path })

A deleted event is emitted when a watched physical file has been deleted. It's emitted with an object containing the Defiler instance and the (original) relative path to the file.

error({ defiler, path, file, error })

An error event is emitted if a file transform or a file generator throws an exception or returns a Promise that rejects. It's emitted with an object containing the Defiler instance, the file's original relative path, the File instance that caused the error, and the thrown error.