net.sf.saxon.functions

Class StandardFunction


public abstract class StandardFunction
extends java.lang.Object

This class contains static data tables defining the properties of standard functions. "Standard functions" here means the XPath 2.0 functions, the XSLT 2.0 functions, and a few selected extension functions which need special recognition.

Nested Class Summary

static class
StandardFunction.Entry
An entry in the table describing the properties of a function

Field Summary

protected static ItemType
SAME_AS_FIRST_ARGUMENT

Method Summary

static void
arg(StandardFunction.Entry e, int a, ItemType type, int cardinality, Value resultIfEmpty)
Add information to a function entry about the argument types of the function
static StandardFunction.Entry
getFunction(String name, int arity)
Get the table entry for the function with a given name
static StandardFunction.Entry
makeEntry(String name, Class implementationClass, int opcode, int minArguments, int maxArguments, ItemType itemType, int cardinality)
Make a table entry describing the signature of a function, with a reference to the implementation class.

Field Details

SAME_AS_FIRST_ARGUMENT

protected static ItemType SAME_AS_FIRST_ARGUMENT

Method Details

arg

public static void arg(StandardFunction.Entry e,
                       int a,
                       ItemType type,
                       int cardinality,
                       Value resultIfEmpty)
Add information to a function entry about the argument types of the function
Parameters:
e - the entry for the function
a - the position of the argument, counting from zero
type - the item type of the argument
cardinality - the cardinality of the argument
resultIfEmpty - the value returned by the function if an empty sequence appears as the value, when this result is unaffected by any other arguments

getFunction

public static StandardFunction.Entry getFunction(String name,
                                                 int arity)
Get the table entry for the function with a given name
Parameters:
name - the name of the function. This may be an unprefixed local-name for functions in the system namespace, or may use the conventional prefix "saxon:" in the case of Saxon extension functions that are specially recognized
Returns:
if the function name is known, an Entry containing information about the function. Otherwise, null

makeEntry

public static StandardFunction.Entry makeEntry(String name,
                                               Class implementationClass,
                                               int opcode,
                                               int minArguments,
                                               int maxArguments,
                                               ItemType itemType,
                                               int cardinality)
Make a table entry describing the signature of a function, with a reference to the implementation class.
Parameters:
name - the function name
implementationClass - the class used to implement the function
opcode - identifies the function when a single class implements several functions
minArguments - the minimum number of arguments required
maxArguments - the maximum number of arguments allowed
itemType - the item type of the result of the function
cardinality - the cardinality of the result of the function
Returns:
the entry describing the function. The entry is incomplete, it does not yet contain information about the function arguments.