prolog.implementation
Class Relation

java.lang.Object
  |
  +--prolog.implementation.Relation

All Implemented Interfaces:

java.lang.Cloneable, IRelation

public class Relation

extends java.lang.Object

implements IRelation, java.lang.Cloneable

The base class of a relation between some atoms, like a row in a database. This interface is used to store and get facts but also to store and get parameters e.g. in a statement

prolog: myFact(joe,dan).

in this example, the relation would contain the atoms "joe" and "dan"

Field Summary

protected java.util.List

values the list where all atoms of the relation are stored

Constructor Summary

Relation()
costructor

Relation(IRelation r)
copy constructor

Method Summary

void	add(java.lang.Object value) adds a atom to this relation
java.util.Map	buildMap() builds a indexmap. a indexmap contains the atom as key and the index as integer. this function is only used for parameter matching.
boolean	equals(java.lang.Object o)
void	genXml(java.io.Writer out, ISymbolTable table) generates xml describing this relation
IAtom	get(int index) returns the atom at the specified index
int	getValueCount() returns the number of atoms contained in this relation
java.util.Iterator	getValues() returns an iterator over all atoms contained in this relation
java.lang.String	toString()
java.lang.String	toString(int[] parameterNames, ISymbolTable table) returns a string representation of this object with decoded symbols in prolog syntax used for query results e.g.
java.lang.String	toString(ISymbolTable table) returns a string representation of this object with decoded symbols

Methods inherited from class java.lang.Object

, clone, finalize, getClass, hashCode, notify, notifyAll, registerNatives, wait, wait, wait

Field Detail

values

protected java.util.List values

the list where all atoms of the relation are stored

Constructor Detail

Relation

public Relation()

costructor

Relation

public Relation(IRelation r)

copy constructor

Parameters:

r - - relation to copy

Method Detail

add

public void add(java.lang.Object value)

adds a atom to this relation

Parameters:

value - - the atom to be added

getValueCount

public int getValueCount()

returns the number of atoms contained in this relation

Specified by:

getValueCount in interface IRelation

Returns:

number of atoms

buildMap

public java.util.Map buildMap()

builds a indexmap. a indexmap contains the atom as key and the index as integer. this function is only used for parameter matching.

Specified by:

buildMap in interface IRelation

Returns:

the created indexmap

get

public IAtom get(int index)

returns the atom at the specified index

Specified by:

get in interface IRelation

Parameters:

index - of the atom to be returned

Returns:

atom at the specified index

getValues

public java.util.Iterator getValues()

returns an iterator over all atoms contained in this relation

Specified by:

getValues in interface IRelation

Returns:

iterator over the values in this relation

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

Returns:

a string representation of this object

toString

public java.lang.String toString(ISymbolTable table)

returns a string representation of this object with decoded symbols

Specified by:

toString in interface IRelation

Parameters:

table - - the symboltable used to decode

Returns:

the string representation

toString

public java.lang.String toString(int[] parameterNames,
                                 ISymbolTable table)

returns a string representation of this object with decoded symbols in prolog syntax used for query results e.g. X=a, Y=b

Specified by:

toString in interface IRelation

Parameters:

table - - the symboltable used to decode

parameterNames - - the names of the parameters in this relation

Returns:

the string representation

genXml

public void genXml(java.io.Writer out,
                   ISymbolTable table)
            throws java.io.IOException

generates xml describing this relation

Specified by:

genXml in interface IRelation

Parameters:

out - the writer where o append the xml

table - the symboltable if the xml should be decoded

Throws:

java.io.IOException - if writing xml fails