net.sf.saxon.value
Class Cardinality

java.lang.Object
  net.sf.saxon.value.Cardinality

public final class Cardinality
extends Object

This class contains static methods to manipulate the cardinality property of a type. Cardinality of expressions is denoted by one of the values ONE_OR_MORE, ZERO_OR_MORE, ZERO_OR_ONE, EXACTLY_ONE, or EMPTY. These are combinations of the three bit-significant values ALLOWS_ZERO, ALLOWS_ONE, and ALLOWS_MANY.

Method Summary

static boolean	allowsMany(int cardinality) Determine whether multiple occurrences are allowed
static boolean	allowsZero(int cardinality) Determine whether empty sequence is allowed
static boolean	expectsMany(Expression expression) Determine whether multiple occurrences are not only allowed, but likely.
static String	getOccurrenceIndicator(int cardinality) Get the occurence indicator representing the cardinality
static int	multiply(int c1, int c2) Multiply two cardinalities
static boolean	subsumes(int c1, int c2) Test if one cardinality subsumes another.
static int	sum(int c1, int c2) Add two cardinalities
static String	toString(int cardinality) Display the cardinality as a string
static int	union(int c1, int c2) Form the union of two cardinalities.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

allowsMany

public static boolean allowsMany(int cardinality)

Determine whether multiple occurrences are allowed

Parameters:

cardinality - the cardinality of a sequence

Returns:

true if the cardinality allows the sequence to contain more than one item

expectsMany

public static boolean expectsMany(Expression expression)

Determine whether multiple occurrences are not only allowed, but likely. This returns false for an expression that is the atomization of a singleton node, since in that case it's quite unusual for the typed value to be a non-singleton sequence.

Parameters:

expression - an expression

Returns:

true if multiple occurrences are not only allowed, but likely. Return false if multiple occurrences are unlikely, even though they might be allowed. This is typically the case for the atomized sequence that is obtained by atomizing a singleton node.

allowsZero

public static boolean allowsZero(int cardinality)

Determine whether empty sequence is allowed

Parameters:

cardinality - the cardinality of a sequence

Returns:

true if the cardinality allows the sequence to be empty

union

public static int union(int c1,
                        int c2)

Form the union of two cardinalities. The cardinality of the expression "if (c) then e1 else e2" is the union of the cardinalities of e1 and e2.

Parameters:

c1 - a cardinality

c2 - another cardinality

Returns:

the cardinality that allows both c1 and c2

sum

public static int sum(int c1,
                      int c2)

Add two cardinalities

Parameters:

c1 - the first cardinality

c2 - the second cardinality

Returns:

the cardinality of a sequence formed by concatenating the sequences whose cardinalities are c1 and c2

subsumes

public static boolean subsumes(int c1,
                               int c2)

Test if one cardinality subsumes another. Cardinality c1 subsumes c2 if every option permitted by c2 is also permitted by c1.

Parameters:

c1 - a cardinality

c2 - another cardinality

Returns:

true if if every option permitted by c2 is also permitted by c1.

multiply

public static int multiply(int c1,
                           int c2)

Multiply two cardinalities

Parameters:

c1 - the first cardinality

c2 - the second cardinality

Returns:

the product of the cardinalities, that is, the cardinality of the sequence "for $x in S1 return S2", where c1 is the cardinality of S1 and c2 is the cardinality of S2

toString

public static String toString(int cardinality)

Display the cardinality as a string

Parameters:

cardinality - the cardinality value to be displayed

Returns:

the representation as a string, for example "zero or one", "zero or more"

getOccurrenceIndicator

public static String getOccurrenceIndicator(int cardinality)

Get the occurence indicator representing the cardinality

Parameters:

cardinality - the cardinality value

Returns:

the occurrence indicator, for example "*", "+", "?", "".