Reading ontologies

Readers 

Ontologies can be read from files, memory buffers or input streams (see UIStream) through the CowlManager object. Cowl can attempt ontology deserialization via multiple readers, and you can control which reader is used in a number of ways:

At compile-time: readers included in the compiled library can be selected by setting the COWL_READERS CMake variable. Built-in readers are exposed through cowl_reader_*() functions.
At run-time, globally: you can set the default reader by calling cowl_set_reader().
At run-time, locally: you can specify which reader you want CowlManager to use via cowl_manager_set_reader().

You can integrate additional readers by providing suitably populated CowlReader instances. When implementing one, use the provided CowlIStream object to handle detected OWL constructs. If you need to manage prefixed IRIs, you can do so through the CowlSymTable instance available by calling cowl_istream_get_sym_table(). Refer to the built-in readers if you need guidance.

struct CowlReader

Defines a reader.

Public Members

char const *name: Name of the reader.

cowl_ret (*read)(UIStream *istream, CowlIStream *stream)

Pointer to a function that reads an ontology from an input stream.

Note

This member is mandatory.

Param state:: Reader state.
Param istream:: Input stream.
Param stream:: Ontology input stream.
Return:: Return code.

CowlReader cowl_reader_functional(void)

Returns the functional syntax reader.

Returns:: Functional syntax reader.

Handling imports 

Cowl delegates locating and loading imported ontologies to the end user via the CowlImportLoader interface. Import loaders can be either provided locally to specific objects (such as via cowl_manager_set_import_loader()), or you can opt to specify a global import loader via cowl_set_import_loader(). If you do both, Cowl prioritizes local loaders, as you would expect.

struct CowlImportLoader

Provides a mechanism for generic handling of ontology imports.

The load_ontology function should return the ontology that has the specified CowlIRI. Imports retrieval and loading is deliberately left to the implementor.

Public Members

void *ctx: Loader context, can be anything.

CowlOntology *(*load_ontology)(void *ctx, CowlIRI *iri)

Pointer to a function that returns the ontology having the specified IRI.

Param ctx:: Loader context.
Param iri:: IRI of the ontology to load.
Return:: The imported ontology, or NULL on error.

void (*free)(void *ctx)

Pointer to a resource deallocator function for the context.

Note

Can be NULL if the context does not need to release resources.

Param ctx:: Loader context.