Updated Aug 30, 2008 by lars.heuer
Labels:	Featured

XPathFunctions

Overview on XPath functions

XPath Functions

Retrieving a topic by its subject identifier

The function sid expects a string and returns a topic with a subject identifier equals to the the specified string.

Example:

// Find the topic "John_Lennon" and return all roles it plays

IFilter<Role> filter = XPathFilter.create("sid('http://de.wikipedia.org/wiki/John_Lennon')/role");

for (Role role: filter.match(topicMap)) {
   // ...
}

Retrieving a topic by its subject locator

The function slo expects a string and returns a topic with a subject locator equals to the the specified string.

Example:

// Find a topic with the subject locator "http://www.semagia.com/" and return all occurrences

IFilter<Occurrence> filter = XPathFilter.create("slo('http://www.semagia.com/')/occurrence");

for (Occurrence occ: filter.match(topicMap)) {
   // ...
}

Retrieving a Topic Maps construct by its item identifier

The function iid expects a string and returns a org.tmapi.core.Construct with an item identifier equals to the the specified string.

Example:

// Find a construct with the item identifier "http://www.semagia.com/map#id" and return the parent

IFilter<Construct> filter = XPathFilter.create("iid('http://www.semagia.com/map#id')/..");

Construct parent = filter.matchOne(topicMap);

Check if a statement is in the unconstrained scope

The function in-ucs expects a org.tmapi.core.Scoped instance and returns true if the statement is in the unconstrained scope, otherwise false.

Example:

// Find those names which are in the unconstrained constrained scope
IFilter<Name> filter = XPathFilter.create("name[in-ucs(.)]"); 

for (Name name: filter.match(topic)) {
// ...
}

In fact, the in-ucs function is equivalent to the following code, but requires less typing, is faster, and should be more clear:

// Find those names which are in the unconstrained constrained scope
IFilter<Name> filter = XPathFilter.create("name[count(./scope) = 0]"); 

for (Name name: filter.match(topic)) {
// ...
}

Check if a name uses the default name type

The function default-name expects a org.tmapi.core.Name instance and returns true if the name has the default name type (http://psi.topicmaps.org/iso13250/model/topic-name), otherwise false.

Example:

// Returns all string values of all names which use the default name type.
IFilter<String> filter = XPathFilter.create("name[default-name(.)]/value"); 

String defaultName = filter.matchOne(topic);