de.up.ling.irtg.automata

Class Rule

java.lang.Object

de.up.ling.irtg.automata.Rule

All Implemented Interfaces:

Serializable, Comparable<Rule>

public class Rule
extends Object
implements Serializable, Comparable<Rule>

A rule in a tree automaton.

A rule consists of a parent state, a label (or terminal symbol), an array of child states, and a weight. The states and labels are represented as int values for efficiency reasons; they can be resolved to human-readable values by looking them up using TreeAutomaton.getStateForId(int) (for states) or Signature.resolveSymbolId(int) using the tree automaton's signature (for labels).

In order to create new rule objects, do not instantiate Rules directly. Instead, call TreeAutomaton.createRule(java.lang.Object, java.lang.String, java.util.List) or one of its variants. This gives the containing TreeAutomaton a chance to update its internal data structures if necessary.

If it is not specified, the weight is set to 1.0. You can destructively modify a rule's weight; this is useful, for instance, in implementing the EM algorithm. As a consequence, equals(java.lang.Object) and hashCode() ignore the weight, i.e. a rule remains equals to itself after you change the weight.

Author:

koller

See Also:

Serialized Form

Method Summary

Modifier and Type	Method and Description
int	compareTo(Rule o)
boolean	equals(Object obj) Compares two rules for equality.
static Collection<Integer>	extractParentStates(Collection<Rule> rules)
int	getArity()
int[]	getChildren()
Object	getExtra() Retrieves the auxiliary information from this rule.
int	getLabel()
String	getLabel(TreeAutomaton auto)
int	getParent()
double	getWeight()
int	hashCode()
boolean	isLoop()
static List<String>	rulesToStrings(Collection<Rule> rules, TreeAutomaton auto)
void	setExtra(Object extra) Stores auxiliary information within this rule.
void	setWeight(double weight)
String	toString()
String	toString(TreeAutomaton auto)
String	toString(TreeAutomaton auto, boolean parentIsFinal)

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Method Detail

getChildren

public int[] getChildren()

getLabel

public int getLabel()

getLabel

public String getLabel(TreeAutomaton auto)

getParent

public int getParent()

getWeight

public double getWeight()

setWeight

public void setWeight(double weight)

getExtra

public Object getExtra()

Retrieves the auxiliary information from this rule.

Returns:

See Also:

setExtra(java.lang.Object)

setExtra

public void setExtra(Object extra)

Stores auxiliary information within this rule. Do not use this unless you know what you're doing.

Parameters:

extra -

getArity

public int getArity()

toString

public String toString()

Overrides:

toString in class Object

toString

public String toString(TreeAutomaton auto)

toString

public String toString(TreeAutomaton auto,
                       boolean parentIsFinal)

rulesToStrings

public static List<String> rulesToStrings(Collection<Rule> rules,
                                          TreeAutomaton auto)

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Compares two rules for equality. Rule weights are ignored in the comparison. Notice that this implementation of equals is only meaningful if the two rules belong to the same automaton, as otherwise states might be encoded by different interners.

Overrides:

equals in class Object

Parameters:

obj -

Returns:

compareTo

public int compareTo(Rule o)

Specified by:

compareTo in interface Comparable<Rule>

extractParentStates

public static Collection<Integer> extractParentStates(Collection<Rule> rules)

isLoop

public boolean isLoop()