Loader Object

To be compatible with the parsing/loading functions in @loaders.gl/core such as parse and load, a parser needs to be described by a "loader object" conforming to the following specification.

Loader Object Format v1.0

Common Fields

Field	Type	Default	Description
name	String	Required	Short name of the loader ('OBJ', 'PLY' etc)
extension	String	Required	Three letter (typically) extension used by files of this format
extensions	String[]	Required	Array of file extension strings supported by this loader
category	String	Optional	Indicates the type/shape of data
parse | worker	Function	null	Every non-worker loader should expose a parse function.

Note: Only one of extension or extensions is required. If both are supplied, extensions will be used.

Test Function

| Field | Type | Default | Description | | ---------- | ---------- | -------- | --------------------------------------------------------------------------------------------- | ------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | test | Function | String | String[] | null | Guesses if a binary format file is of this format by examining the first bytes in the file. If the test is specified as a string or array of strings, the initial bytes are expected to be "magic bytes" matching one of the provided strings. | | testText | Function | null | Guesses if a text format file is of this format by examining the first characters in the file |

Parser Functions

Each (non-worker) loader should define a parse function. Additional parsing functions can be exposed depending on the loaders capabilities, to optimize for text parsing, synchronous parsing, streaming parsing, etc:

Parser function field	Type	Default	Description
parse	Function	null	Asynchronously parses binary data (e.g. file contents) asynchronously (ArrayBuffer).
parseInBatches (Experimental)	Function	null	Parses binary data chunks (ArrayBuffer) to output data "batches"
parseSync	Function	null	Atomically and synchronously parses binary data (e.g. file contents) (ArrayBuffer)
parseTextSync	Function	null	Atomically and synchronously parses a text file (String)

Synchronous parsers are more flexible as they can support synchronous parsing which can simplify application logic and debugging, and iterator-based parsers are more flexible as they can support batched loading of large data sets in addition to atomic loading.

You are encouraged to provide the most capable parser function you can (e.g. parseSync or parseToIterator if possible). Unless you are writing a completely new loader from scratch, the appropriate choice often depends on the capabilities of an existing external "loader" that you are working with.

Parser Function Signatures

• async parse(data : ArrayBuffer, options : Object, context : Object) : Object
• parseSync(data : ArrayBuffer, options : Object, context : Object) : Object
• parseInBatches(data : AsyncIterator, options : Object, context : Object) : AsyncIterator

The context parameter will contain the foolowing fields

• parse or parseSync
• url if available