5.8.2 Node

enum SerdNodeType

Type of a node.

An RDF node, in the abstract sense, can be either a resource, literal, or a blank. This type is more precise, because syntactically there are two ways to refer to a resource (by URI or CURIE). Serd also has support for variable nodes to support some features, which are not RDF nodes.

There are also two ways to refer to a blank node in syntax (by ID or anonymously), but this is handled by statement flags rather than distinct node types.

enumerator SERD_LITERAL

Literal value.

A literal optionally has either a language, or a datatype (not both).

enumerator SERD_URI

URI (absolute or relative).

Value is an unquoted URI string, which is either a relative reference with respect to the current base URI (e.g. “foo/bar”), or an absolute URI (e.g. “http://example.org/foo”). RFC3986

enumerator SERD_BLANK

A blank node.

Value is a blank node ID without any syntactic prefix, like “id3”, which is meaningful only within this serialisation. RDF 1.1 Turtle

enumerator SERD_VARIABLE

A variable node.

Value is a variable name without any syntactic prefix, like “name”, which is meaningful only within this serialisation. SPARQL 1.1 Query Language

enum SerdNodeFlag

Flags that describe the details of a node.

enumerator SERD_IS_LONG

Literal node should be triple-quoted.

enumerator SERD_HAS_DATATYPE

Literal node has datatype.

enumerator SERD_HAS_LANGUAGE

Literal node has language.

typedef struct SerdNodeImpl SerdNode

An RDF node.

typedef uint32_t SerdNodeFlags

Bitwise OR of SerdNodeFlag values.

bool serd_get_boolean(const SerdNode *node)

Return the value of node as a boolean.

This will work for booleans, and numbers of any datatype if they are 0 or 1.

Returns

The value of node as a bool, or false on error.

double serd_get_double(const SerdNode *node)

Return the value of node as a double.

This will coerce numbers of any datatype to double, if the value fits.

Returns

The value of node as a double, or NaN on error.

float serd_get_float(const SerdNode *node)

Return the value of node as a float.

This will coerce numbers of any datatype to float, if the value fits.

Returns

The value of node as a float, or NaN on error.

int64_t serd_get_integer(const SerdNode *node)

Return the value of node as a long (signed 64-bit integer).

This will coerce numbers of any datatype to long, if the value fits.

Returns

The value of node as a int64_t, or 0 on error.

size_t serd_get_base64_size(const SerdNode *node)

Return the maximum size of a decoded base64 node in bytes.

This returns an upper bound on the number of bytes that would be decoded by serd_get_base64(). This is calculated as a simple constant-time arithmetic expression based on the length of the encoded string, so may be larger than the actual size of the data due to things like additional whitespace.

SerdWriteResult serd_get_base64(const SerdNode *node, size_t buf_size, void *buf)

Decode a base64 node.

This function can be used to decode a node created with serd_new_base64().

Parameters

  • node – A literal node which is an encoded base64 string.

  • buf_size – The size of buf in bytes.

  • buf – Buffer where decoded data will be written.

Returns

On success, SerdStatus.SERD_SUCCESS is returned along with the number of bytes written. If the output buffer is too small, then SerdStatus.SERD_OVERFLOW is returned along with the number of bytes required for successful decoding.

SerdNode *serd_node_copy(SerdAllocator *allocator, const SerdNode *node)

Return a deep copy of node

void serd_node_free(SerdAllocator *allocator, SerdNode *node)

Free any data owned by node

SerdNodeType serd_node_type(const SerdNode *node)

Return the type of a node (SERD_URI, SERD_BLANK, or SERD_LITERAL)

const char *serd_node_string(const SerdNode *node)

Return the node’s string.

size_t serd_node_length(const SerdNode *node)

Return the length of the node’s string in bytes (excluding terminator)

SerdStringView serd_node_string_view(const SerdNode *node)

Return a view of the string in a node.

This is a convenience wrapper for serd_node_string() and serd_node_length() that can be used to get both in a single call.

SerdURIView serd_node_uri_view(const SerdNode *node)

Return a parsed view of the URI in a node.

It is best to check the node type before calling this function, though it is safe to call on non-URI nodes. In that case, it will return a null view with all fields zero.

Note that this parses the URI string contained in the node, so it is a good idea to keep the value if you will be using it several times in the same scope.

SerdNodeFlags serd_node_flags(const SerdNode *node)

Return the flags (string properties) of a node.

const SerdNode *serd_node_datatype(const SerdNode *node)

Return the datatype of the literal node, if present.

const SerdNode *serd_node_language(const SerdNode *node)

Return the language tag of the literal node, if present.

bool serd_node_equals(const SerdNode *a, const SerdNode *b)

Return true iff a is equal to b

int serd_node_compare(const SerdNode *a, const SerdNode *b)

Compare two nodes.

Returns less than, equal to, or greater than zero if a is less than, equal to, or greater than b, respectively. NULL is treated as less than any other node.

Nodes are ordered first by type, then by string value, then by language or datatype, if present.