org.zedlib
Class HashFun

java.lang.Object
  java.util.AbstractCollection
      java.util.AbstractSet
          java.util.HashSet
              org.zedlib.HashSet
                  org.zedlib.HashRel
                      org.zedlib.HashFun

All Implemented Interfaces:

Cloneable, Collection, Function, Relation, Serializable, Set, Set

Direct Known Subclasses:

HashBag, HashSeq

public class HashFun

extends HashRel

implements Function

This class provides similar functionality to java.util.Map, however, it is properly descended from a Set (org.zedlib.Set, hence implements the java.util.Set interface). It does not implement the java.util.Map interface because of conflicts between the java.util.Map and java.util.Set interfaces. If X and Y are sets, X → Y is the set of partial functions from X to Y. These are relations which relate each member x of X to at most one member of Y.

Author:

Brad Long

See Also:

Serialized Form

Constructor Summary

HashFun()

HashFun(Collection c)
Constructs a function containing all elements in the supplied collection of maplets.

HashFun(Collection c1, Collection c2)
Constructs a function between two collections.

HashFun(Function f)
Constructs a function from a given function.

HashFun(Map m)
Constructs a function from a given java.util.Map.

Method Summary

boolean	add(Maplet m) Adds a maplet to this function.
boolean	containsKey(Object key) An alternative for domain().contains(key).
boolean	containsValue(Object value) An alternative for range().contains(value).
protected Set	getInstance()
protected Set	getInstance(Set s)
Maplet	getMaplet(Object key) Returns the maplet that a given key participates in.
Object	getValue(Object key) Returns the value that a given key maps to.
Object	put(Maplet m) Adds a maplet to this function.
Object	put(Object x, Object y) Adds two objects representing a maplet to this function.

Methods inherited from class org.zedlib.HashRel

add, add, addAll, addAll, buildRelation, composition, domain, domainAntiRestriction, domainRestriction, image, inverse, isFunction, isInjection, isReflexive, override, range, rangeAntiRestriction, rangeRestriction, toString, transitiveClosure

Methods inherited from class org.zedlib.HashSet

cartesianProduct, difference, difference, identity, intersection, intersection, isProperSubsetOf, isSubsetOf, isSupersetOf, union, union

Methods inherited from class java.util.HashSet

clear, clone, contains, isEmpty, iterator, remove, size

Methods inherited from class java.util.AbstractSet

equals, hashCode, removeAll

Methods inherited from class java.util.AbstractCollection

containsAll, retainAll, toArray, toArray

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.zedlib.Relation

add, addAll, composition, domain, domainAntiRestriction, domainRestriction, image, inverse, isFunction, isInjection, isReflexive, override, range, rangeAntiRestriction, rangeRestriction, transitiveClosure

Methods inherited from interface org.zedlib.Set

cartesianProduct, difference, identity, intersection, isSubsetOf, isSupersetOf, union

Methods inherited from interface java.util.Set

add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray

Constructor Detail

HashFun

public HashFun()

HashFun

public HashFun(Collection c1,
               Collection c2)

Constructs a function between two collections. Each maplet is created by traversing the iterators of each collection and associating each element of c1 with an element from c2. Duplicate elements in c1 are ignored, therefore requiring the number of unique elements in c1 to equal the number of elements in c2. This provides the same logical abstraction as java.util.Map but is properly contained in the collections hierarchy.

Parameters:

c1 - any collection

c2 - any collection

Throws:

IllegalArgumentException - if the collections do not contain the same number of unique elements

HashFun

public HashFun(Collection c)

Constructs a function containing all elements in the supplied collection of maplets.

Throws:

ClassCastException - if the collection does not contain maplets

HashFun

public HashFun(Map m)

Constructs a function from a given java.util.Map.

HashFun

public HashFun(Function f)

Constructs a function from a given function.

Method Detail

getInstance

protected Set getInstance()

Overrides:

getInstance in class HashRel

getInstance

protected Set getInstance(Set s)

Overrides:

getInstance in class HashRel

add

public boolean add(Maplet m)

Adds a maplet to this function. Existing maplets with the same x in (x,y) are overwritten with the given maplet.

Specified by:

add in interface Relation

Overrides:

add in class HashRel

Parameters:

m - the maplet to add to the function

Returns:

true if the maplet was added to this function

put

public Object put(Object x,
                  Object y)

Adds two objects representing a maplet to this function. Existing maplets with the same x in (x,y) are overwritten with the given maplet.

Parameters:

x - the key to add to the function; x in the maplet (x,y)

y - the value to add to the function; y in the maplet (x,y)

Returns:

the object, y in (x,y), that was replaced or null if there was no maplet having a key of x in the function.

put

public Object put(Maplet m)

Adds a maplet to this function. Existing maplets with the same x in (x,y) are overwritten with the given maplet.

Specified by:

put in interface Function

Parameters:

m - the maplet to add to the function

Returns:

the object, y in (x,y), that was replaced or null if there was no maplet having a key of x in the function.

getValue

public Object getValue(Object key)

Returns the value that a given key maps to.

Parameters:

key - the key (x) with which to obtain its corresponding (y) value

Returns:

the object that the given key maps to

getMaplet

public Maplet getMaplet(Object key)

Returns the maplet that a given key participates in.

Specified by:

getMaplet in interface Function

Parameters:

key - the key (x) with which to obtain its corresponding (y) value

Returns:

the maplet that the given key participates in

containsValue

public boolean containsValue(Object value)

An alternative for range().contains(value).

Specified by:

containsValue in interface Function

Parameters:

value - the object to check for existence in the range of this function

Returns:

true if a given value, y, is contained in the range of this function

containsKey

public boolean containsKey(Object key)

An alternative for domain().contains(key).

Specified by:

containsKey in interface Function

Parameters:

key - the object to check for existence in the domain of this function

Returns:

true if a given value, x, is contained in the domain of this function