| Tal4Rdf | Silex team |
|
This reference manual is work in progress.
Namespace prefixes are declared as global variables, whose name is t4rns:prefix, and whose value is the namespace URI. Note that literal values in TALES must start with the string: keyword. Note also that variable declaration are separated by semicolons.
Example:
<html xmlns:tal="http://xml.zope.org/namespaces/tal"
tal:define="
global t4rns:rdf string:http://www.w3.org/1999/02/22-rdf-syntax-ns#;
global t4rns:rdfs string:http://www.w3.org/2000/01/rdf-schema#;
global t4rns:owl string:http://www.w3.org/2002/07/owl#;
global t4rns:xsd string:http://www.w3.org/2001/XMLSchema#;
global t4rns:foaf string:http://xmlns.com/foaf/0.1/;
global t4rns:dc string:http://purl.org/dc/terms/
">
...
NB: For making this BNF less verbose, the slashes separating the tokens in the TALES expression are not represented. Note in particular that absolute paths (AbsPath) start with an empty token so that the TALES expression actually starts with a slash.
RDFPath :- AbsPath | RelPath | CompoundPath
AbsPath :- "" StartStep RelPath?
RelPath :- Step+ DataOp?
CompoundPath :- (AbsPath | RelPath) BinaryOp StartStep RelPath?
StartStep :- Curie ("or" Curie)*
Step :- XCurie ("or" XCurie)* | NodeOp
Curie :- (Any standard CURIE)
XCurie :- (Any standard or inverted (with ":-") CURIE)
DataOp :- (see list below)
NodeOp :- (see list below)
BinaryOp :- (see list below)
| type: | NodeOp |
|---|---|
| result: | node list (1 node) |
| pre-condition: | none |
Only keep the first node from the list.
NB: except in a few cases, the order of the lists is not significant, so any may return different values on different rendering of the template.
NB: if the node list is empty, any will cause an error rather than returning a single path. This allows to use it in conjunction with TAL’s | operator.
| type: | DataOp |
|---|---|
| result: | text |
| pre-condition: | none |
Same as asPath, but appends :- after each CURIE.
| type: | DataOp |
|---|---|
| result: | text |
| pre-condition: | none |
Tries to convert a node list into the corresponding path. This is useful with the question-mark syntax of TAL.
Only URI-ref nodes, that can be expressed as CURIEs with the current namespaces, are included in the list.
| type: | NodeOp |
|---|---|
| result: | node list (only blank nodes) |
| pre-condition: | none |
Only keeps the blank nodes from the node list.
| type: | BinaryOp |
|---|---|
| result: | boolean |
| pre-condition: | none |
Evaluates to true if the left hand node list and the right hand node list have at least one node in common.
NB: although intersect would have seemed a more exact name, contains seems more suited to common uses of this operator, like:
tal:condition="some_node/rdf:type/contains/owl:Class"
| type: | DataOp |
|---|---|
| result: | depends (see below) |
| pre-condition: | single literal |
Tries to convert the literal to a builtin data, according to its datatype.
| type: | NodeOp |
|---|---|
| result: | node list (0 or 1 uri-ref) |
| pre-condition: | a single literal node |
Evaluates to the datatype, if any, of the literal.
| type: | DataOp |
|---|---|
| result: | text |
| pre-condition: | a single node, blank or URI-ref |
Evaluates to the identifier part of the node, i.e. what would be used as the suffix of the CURIE.
| type: | DataOp |
|---|---|
| result: | boolean |
| pre-condition: | a single node |
Evaluates to true if and only if the node is blank.
| type: | DataOp |
|---|---|
| result: | boolean |
| pre-condition: | a single node |
Evaluates to true if and only if the node is a literal.
| type: | DataOp |
|---|---|
| result: | boolean |
| pre-condition: | a single node |
Evaluates to true if and only if the node is a URI-ref.
| type: | NodeOp |
|---|---|
| result: | node list (sorted) |
| pre-condition: | a single node, well formed rdf:List |
Iter over the items of the rdf:List.
| type: | NodeOp |
|---|---|
| result: | node list (sorted) |
| pre-condition: | a single node |
Iter over the rdf:li properties of the node.
| type: | NodeOp |
|---|---|
| result: | single URIref |
| pre-condition: | none |
Tries to extract form parameters to generate a URL applying the same template to the resource identified by this URI-ref.
TODO: make the documentation clear about what happens for graph templates, resource templates without graph, resource remplates with graph
| type: | NodeOp |
|---|---|
| result: | node list (only literals) |
| pre-condition: | non |
Only keeps the literal nodes from the node list.
| type: | DataOp |
|---|---|
| result: | text |
| pre-condition: | single node |
Evaluates to the N3 syntax for the node (useful for literals, that will render by default just as their value).
| type: | NodeOp |
|---|---|
| result: | node list (single URI-ref node) |
| pre-condition: | single node, URI-ref |
Evaluates to the namespace part of the URI-ref, as a node. Useful to check that two resources belong to the same namespace with r1/ns/contains/r2/ns.
| type: | BinaryOp |
|---|---|
| result: | text |
| pre-condition: | the first operand must evaluate to a single node, the second operand must evaluate to a single URI-ref |
Retrieve the RHS resource, and use it as a template to render the LHS resource.
NB: do not forget the TAL keyword structure whenever the invoked template produces HTML or XML tags, or those tags will be escaped and rendered as is.
| type: | NodeOp |
|---|---|
| result: | node list (only literals) |
| pre-condition: | none |
Tries to extract HTTP Accept-language information from the context, and select from the node list the literals that best match this directive.
| type: | DataOp |
|---|---|
| result: | text |
| pre-condition: | single node, literal |
Evaluates to the value of the literal.
TODO: The RDF graph. It has an attribute size returning the number of triples. It is iterable (usable with tal:repeat), and yields triples with attributes subject, predicate, object and s, p, o for short. Those attributes are nodes that can be used as any other node.
By default, a path evaluating to multiple nodes will display as one of those nodes; a path evaluating to no node will not display at all (see why). If t4r:display is set to string:strict, then a path evaluating to n nodes with n≠1 will display as the special string {n nodes}. Although less usable, this makes debugging of templates more convenient.
TODO