Package adams.core

Class Trie

java.lang.Object

adams.core.Trie

All Implemented Interfaces:

Serializable, Cloneable, Iterable<String>, Collection<String>

public class Trie
extends Object
implements Serializable, Cloneable, Collection<String>

A class representing a Trie data structure for strings. See also Trie on WikiPedia.

Author:

fracpete (fracpete at waikato dot ac dot nz)

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Trie.TrieIterator	Represents an iterator over a trie
static class	Trie.TrieNode	Represents a node in the trie.

Field Summary

Fields

Modifier and Type	Field	Description
protected int	m_HashCode	the hash code
protected boolean	m_RecalcHashCode	whether the structure got modified and the hash code needs to be re-calculated
protected Trie.TrieNode	m_Root	the root node

Constructor Summary

Constructors

Constructor	Description
Trie()	initializes the data structure

Method Summary

Modifier and Type	Method	Description
boolean	add(String o)	Ensures that this collection contains the specified element.
boolean	addAll(Collection<? extends String> c)	Adds all of the elements in the specified collection to this collection
void	clear()	Removes all of the elements from this collection
Object	clone()	returns a deep copy of itself
boolean	contains(Object o)	Returns true if this collection contains the specified element.
boolean	containsAll(Collection<?> c)	Returns true if this collection contains all of the elements in the specified collection.
boolean	containsPrefix(String prefix)	checks whether the given prefix is stored in the trie
boolean	equals(Object o)	Compares the specified object with this collection for equality.
String	getCommonPrefix()	returns the common prefix for all the nodes
Trie.TrieNode	getRoot()	returns the root node of the trie
List<String>	getWithPrefix(String prefix)	returns all stored strings that match the given prefix
int	hashCode()	Returns the hash code value for this collection.
boolean	isEmpty()	Returns true if this collection contains no elements.
Iterator<String>	iterator()	Returns an iterator over the elements in this collection.
static void	main(String[] args)	Only for testing (prints the built Trie).
boolean	remove(Object o)	Removes a single instance of the specified element from this collection, if it is present.
boolean	removeAll(Collection<?> c)	Removes all this collection's elements that are also contained in the specified collection
boolean	retainAll(Collection<?> c)	Retains only the elements in this collection that are contained in the specified collection
int	size()	Returns the number of elements in this collection.
Object[]	toArray()	Returns an array containing all of the elements in this collection.
<T> T[]	toArray(T[] a)	Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.
String	toString()	returns the trie in string representation
protected String	toString(Trie.TrieNode node)	returns the node as String

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

parallelStream, removeIf, spliterator, stream, toArray

Methods inherited from interface java.lang.Iterable

forEach

Field Detail

m_Root

protected Trie.TrieNode m_Root

the root node

m_HashCode

protected int m_HashCode

the hash code

m_RecalcHashCode

protected boolean m_RecalcHashCode

whether the structure got modified and the hash code needs to be re-calculated

Constructor Detail

Trie

public Trie()

initializes the data structure

Method Detail

add

public boolean add(String o)

Ensures that this collection contains the specified element.

Specified by:

add in interface Collection<String>

Parameters:

o - the string to add

Returns:

true if the structure changed

addAll

public boolean addAll(Collection<? extends String> c)

Adds all of the elements in the specified collection to this collection

Specified by:

addAll in interface Collection<String>

Parameters:

c - the collection to add

clear

public void clear()

Removes all of the elements from this collection

Specified by:

clear in interface Collection<String>

clone

public Object clone()

returns a deep copy of itself

Overrides:

clone in class Object

Returns:

a copy of itself

contains

public boolean contains(Object o)

Returns true if this collection contains the specified element.

Specified by:

contains in interface Collection<String>

Parameters:

o - the object to check for in trie

Returns:

true if found

containsAll

public boolean containsAll(Collection<?> c)

Returns true if this collection contains all of the elements in the specified collection.

Specified by:

containsAll in interface Collection<String>

Parameters:

c - the collection to look for in the trie

Returns:

true if all elements were found

containsPrefix

public boolean containsPrefix(String prefix)

checks whether the given prefix is stored in the trie

Parameters:

prefix - the prefix to check

Returns:

true if the prefix is part of the trie

equals

public boolean equals(Object o)

Compares the specified object with this collection for equality.

Specified by:

equals in interface Collection<String>

Overrides:

equals in class Object

Parameters:

o - the object to check for equality

getCommonPrefix

public String getCommonPrefix()

returns the common prefix for all the nodes

Returns:

the result of the search

getRoot

public Trie.TrieNode getRoot()

returns the root node of the trie

Returns:

the root node

getWithPrefix

public List<String> getWithPrefix(String prefix)

returns all stored strings that match the given prefix

Parameters:

prefix - the prefix that all strings must have

Returns:

all strings that match the prefix

hashCode

public int hashCode()

Returns the hash code value for this collection.

Specified by:

hashCode in interface Collection<String>

Overrides:

hashCode in class Object

Returns:

the hash code

isEmpty

public boolean isEmpty()

Returns true if this collection contains no elements.

Specified by:

isEmpty in interface Collection<String>

Returns:

true if empty

iterator

public Iterator<String> iterator()

Returns an iterator over the elements in this collection.

Specified by:

iterator in interface Collection<String>

Specified by:

iterator in interface Iterable<String>

Returns:

returns an iterator over all the stored strings

remove

public boolean remove(Object o)

Removes a single instance of the specified element from this collection, if it is present.

Specified by:

remove in interface Collection<String>

Parameters:

o - the object to remove

Returns:

true if this collection changed as a result of the call

removeAll

public boolean removeAll(Collection<?> c)

Removes all this collection's elements that are also contained in the specified collection

Specified by:

removeAll in interface Collection<String>

Parameters:

c - the collection to remove

Returns:

true if the collection changed

retainAll

public boolean retainAll(Collection<?> c)

Retains only the elements in this collection that are contained in the specified collection

Specified by:

retainAll in interface Collection<String>

Parameters:

c - the collection to use as reference

Returns:

true if this collection changed as a result of the call

size

public int size()

Returns the number of elements in this collection.

Specified by:

size in interface Collection<String>

Returns:

the number of nodes in the tree

toArray

public Object[] toArray()

Returns an array containing all of the elements in this collection.

Specified by:

toArray in interface Collection<String>

Returns:

the stored strings as array

toArray

public <T> T[] toArray(T[] a)

Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.

Specified by:

toArray in interface Collection<String>

Parameters:

a - the array into which the elements of this collection are to be stored

Returns:

an array containing the elements of this collection

toString

protected String toString(Trie.TrieNode node)

returns the node as String

Parameters:

node - the node to turn into a string

Returns:

the node as string

toString

public String toString()

returns the trie in string representation

Overrides:

toString in class Object

Returns:

the trie as string

main

public static void main(String[] args)

Only for testing (prints the built Trie). Arguments are added to the Trie. If not arguments provided then a few default strings are uses for building.

Parameters:

args - commandline arguments