## URI

URI — URI class

## Synopsis

    typedef             librdf_uri;
    librdf_uri*         librdf_new_uri                      (librdf_world *world,
                                                             unsigned char *uri_string);
    librdf_uri*         librdf_new_uri_from_uri             (librdf_uri *old_uri);
    librdf_uri*         librdf_new_uri_from_uri_local_name  (librdf_uri *old_uri,
                                                             unsigned char *local_name);
    void                librdf_free_uri                     (librdf_uri *uri);
    unsigned char*      librdf_uri_as_string                (librdf_uri *uri);
    unsigned char*      librdf_uri_as_counted_string        (librdf_uri *uri,
                                                             size_t *len_p);
    void                librdf_uri_print                    (librdf_uri *uri,
                                                             FILE *fh);
    unsigned char*      librdf_uri_to_string                (librdf_uri *uri);
    unsigned char*      librdf_uri_to_counted_string        (librdf_uri *uri,
                                                             size_t *len_p);
    int                 librdf_uri_equals                   (librdf_uri *first_uri,
                                                             librdf_uri *second_uri);
    int                 librdf_uri_is_file_uri              (librdf_uri *uri);
    const char*         librdf_uri_to_filename              (librdf_uri *uri);
    librdf_uri*         librdf_new_uri_normalised_to_base   (unsigned char *uri_string,
                                                             librdf_uri *source_uri,
                                                             librdf_uri *base_uri);
    librdf_uri*         librdf_new_uri_relative_to_base     (librdf_uri *base_uri,
                                                             unsigned char *uri_string);
    librdf_uri*         librdf_new_uri_from_filename        (librdf_world *world,
                                                             const char *filename);
    int                 librdf_uri_compare                  (librdf_uri *uri1,
                                                             librdf_uri *uri2);
    int                 (*librdf_uri_filter_func)           (void *user_data,
                                                             librdf_uri *uri);

## Description

A class for absolute URIs and relative URI computation utility functions. Only absolute URIs are provided, with no current access to internals of URIs such as URI scheme, path, authority. Relative URIs can be generated against some base or turned to and from local filenames.

## Details

### librdf_uri

    typedef struct librdf_uri_s librdf_uri;

Redland URI class.

### librdf_new_uri ()

    librdf_uri*         librdf_new_uri                      (librdf_world *world,
                                                             unsigned char *uri_string);

Constructor - create a new librdf_uri object from a URI string.

A new URI is constructed from a copy of the string. If the string is a NULL pointer or empty (0 length) then the result is NULL.

`world` : | redland world object
`uri_string` : | URI in string form
Returns : | a new librdf_uri object or NULL on failure

### librdf_new_uri_from_uri ()

    librdf_uri*         librdf_new_uri_from_uri             (librdf_uri *old_uri);

Copy constructor - create a new librdf_uri object from an existing librdf_uri object.

`old_uri` : | librdf_uri object
Returns : | a new librdf_uri object or NULL on failure

### librdf_new_uri_from_uri_local_name ()

    librdf_uri*         librdf_new_uri_from_uri_local_name  (librdf_uri *old_uri,
                                                             unsigned char *local_name);

Copy constructor - create a new librdf_uri object from an existing librdf_uri object and a local name.

`old_uri` : | librdf_uri object
`local_name` : | local name to append to URI
Returns : | a new librdf_uri object or NULL on failure

### librdf_free_uri ()

    void                librdf_free_uri                     (librdf_uri *uri);

Destructor - destroy a librdf_uri object.

`uri` : | librdf_uri object

### librdf_uri_as_string ()

    unsigned char*      librdf_uri_as_string                (librdf_uri *uri);

Get a pointer to the string representation of the URI.

Returns a shared pointer to the URI string representation. Note: does not allocate a new string so the caller must not free it.

`uri` : | librdf_uri object
Returns : | string representation of URI

### librdf_uri_as_counted_string ()

    unsigned char*      librdf_uri_as_counted_string        (librdf_uri *uri,
                                                             size_t *len_p);

Get a pointer to the string representation of the URI with length.

Returns a shared pointer to the URI string representation. Note: does not allocate a new string so the caller must not free it.

`uri` : | librdf_uri object
`len_p` : | pointer to location to store length
Returns : | string representation of URI

### librdf_uri_print ()

    void                librdf_uri_print                    (librdf_uri *uri,
                                                             FILE *fh);

Print the URI to the given file handle.

`uri` : | librdf_uri object
`fh` : | file handle

### librdf_uri_to_string ()

    unsigned char*      librdf_uri_to_string                (librdf_uri *uri);

Format the URI as a string.

Note: this method allocates a new string since this is a _to_ method and the caller must free the resulting memory.

`uri` : | librdf_uri object
Returns : | string representation of the URI or NULL on failure

### librdf_uri_to_counted_string ()

    unsigned char*      librdf_uri_to_counted_string        (librdf_uri *uri,
                                                             size_t *len_p);

Format the URI as a counted string.

Note: this method allocates a new string since this is a _to_ method and the caller must free the resulting memory.

`uri` : | librdf_uri object
`len_p` : | pointer to location to store length
Returns : | string representation of the URI or NULL on failure

### librdf_uri_equals ()

    int                 librdf_uri_equals                   (librdf_uri *first_uri,
                                                             librdf_uri *second_uri);

Compare two librdf_uri objects for equality.

`first_uri` : | librdf_uri object 1
`second_uri` : | librdf_uri object 2
Returns : | non 0 if the objects are equal

### librdf_uri_is_file_uri ()

    int                 librdf_uri_is_file_uri              (librdf_uri *uri);

Test if a URI points to a filename.

`uri` : | librdf_uri object
Returns : | Non zero if the URI points to a file

### librdf_uri_to_filename ()

    const char*         librdf_uri_to_filename              (librdf_uri *uri);

Return pointer to filename of URI.

Returns a pointer to a newly allocated buffer that the caller must free. This will fail if the URI is not a file: URI. This can be checked with librdf_uri_is_file_uri

`uri` : | librdf_uri object
Returns : | pointer to filename or NULL on failure

### librdf_new_uri_normalised_to_base ()

    librdf_uri*         librdf_new_uri_normalised_to_base   (unsigned char *uri_string,
                                                             librdf_uri *source_uri,
                                                             librdf_uri *base_uri);

Constructor - create a new librdf_uri object from a URI string stripped of the source URI, made relative to the base URI.

`uri_string` : | URI in string form
`source_uri` : | source URI to remove
`base_uri` : | base URI to add
Returns : | a new librdf_uri object or NULL on failure

### librdf_new_uri_relative_to_base ()

    librdf_uri*         librdf_new_uri_relative_to_base     (librdf_uri *base_uri,
                                                             unsigned char *uri_string);

Constructor - create a new librdf_uri object from a URI string relative to a base URI.

An empty uri_string or NULL is equivalent to librdf_new_uri_from_uri(base_uri)

`base_uri` : | absolute base URI
`uri_string` : | relative URI string
Returns : | a new librdf_uri object or NULL on failure

### librdf_new_uri_from_filename ()

    librdf_uri*         librdf_new_uri_from_filename        (librdf_world *world,
                                                             const char *filename);

Constructor - create a new librdf_uri object from a filename.

`world` : | Redland librdf_world object
`filename` : | filename
Returns : | a new librdf_uri object or NULL on failure

### librdf_uri_compare ()

    int                 librdf_uri_compare                  (librdf_uri *uri1,
                                                             librdf_uri *uri2);

Compare two librdf_uri objects lexicographically.

A NULL URI is always less than (never equal to) a non-NULL URI.

`uri1` : | librdf_uri object 1 or NULL
`uri2` : | librdf_uri object 2 or NULL
Returns : | <0 if `uri1` is less than `uri2`, 0 if equal, >0 if `uri1` is greater than `uri2`

### librdf_uri_filter_func ()

    int                 (*librdf_uri_filter_func)           (void *user_data,
                                                             librdf_uri *uri);

Callback function for `librdf_parser_set_uri_filter()`

`user_data` : | user data
`uri` : | librdf_uri URI to check
Returns : | non-0 to filter the URI