edu.nyu.jet.util

Class DoubleArrayTrie

java.lang.Object

edu.nyu.jet.util.DoubleArrayTrie

public class DoubleArrayTrie
extends Object

DoubleArrayTrie provides faster trie implementation which is based Double-Array Structure.

• Aoe, J. An Efficient Digital Search Algorithm by Using a Double-Array Structure. IEEE Transactions on Software Engineering. Vol. 15, 9 (Sep 1989). pp. 1066-1077.

Author:

Akira ODA

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DoubleArrayTrie.Result

Constructor Summary

Constructors

Constructor and Description
DoubleArrayTrie()

Method Summary

Methods

Modifier and Type	Method and Description
boolean	build(char[][] key, int[] value) Builds a double array trie.
List<DoubleArrayTrie.Result>	commonPrefixSearch(CharSequence key) Searches strings which are specified key's prefix.
List<DoubleArrayTrie.Result>	commonPrefixSearch(CharSequence key, int offset) Searches strings which are specified key's prefix.
List<DoubleArrayTrie.Result>	commonPrefixSearch(CharSequence key, int offset, int length) Searches strings which are specified key's prefix.
List<DoubleArrayTrie.Result>	commonPrefixSearch(CharSequence key, int offset, int length, int nodePos) Searches the value to which be associated with the specified key.
int	exactMatchSearch(CharSequence key) Searches the value to which be associated with the specified key.
int	exactMatchSearch(CharSequence key, int offset) Searches the value to which be associated with the specified key.
int	exactMatchSearch(CharSequence key, int offset, int length) Searches the value to which be associated with the specified key.
int	exactMatchSearch(CharSequence key, int offset, int length, int nodePos) Searches the value to which be associated with the specified key.
DoubleArrayTrie.Result	getLongestCommonPrefix(CharSequence key) Returns longest common prefix between strings in the trie and specified key.
DoubleArrayTrie.Result	getLongestCommonPrefix(CharSequence key, int offset) Returns longest common prefix between strings in the trie and specified key.
DoubleArrayTrie.Result	getLongestCommonPrefix(CharSequence key, int offset, int length) Returns longest common prefix between strings in the trie and specified key.
DoubleArrayTrie.Result	getLongestCommonPrefix(CharSequence key, int offset, int length, int nodePos) Returns longest common prefix between strings in the trie and specified key.
void	load(File file) Loads double array from file.
void	load(String filename) Loads double array from file.
void	save(String filename) Saves double array into file

Methods inherited from class java.lang.Object

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

Constructor Detail

DoubleArrayTrie

public DoubleArrayTrie()

Method Detail

build

public boolean build(char[][] key,
            int[] value)

Builds a double array trie. The specified array of key is must be sorted. If it is not sorted, the results is undefined.

Parameters:

key - array of each word

value - array of each value.

Returns:

true if build double array completed without errors.

save

public void save(String filename)
          throws IOException

Saves double array into file

Parameters:

filename - the named of file to save double array

Throws:

IOException - if an I/O error occurs

load

public void load(String filename)
          throws IOException

Loads double array from file.

Parameters:

filename - the system depended filename

Throws:

IOException - if an I/O error occurs

load

public void load(File file)
          throws IOException

Loads double array from file.

Parameters:

file - the file object

Throws:

IOException - if an I/O error occurs

exactMatchSearch

public int exactMatchSearch(CharSequence key,
                   int offset,
                   int length,
                   int nodePos)

Searches the value to which be associated with the specified key.

Parameters:

key - the string to be searched for

offset - starting position in the specified key

length - length of the specified key

nodePos - starting position for search in double array node

Returns:

the value to which be as sociated with the specified key, or -1 if double array does not contains specified key.

exactMatchSearch

public int exactMatchSearch(CharSequence key,
                   int offset,
                   int length)

Searches the value to which be associated with the specified key.

Parameters:

key - the string to be searched for

offset - starting position in the specified key

length - length of the specified key

Returns:

the value to which be as sociated with the specified key, or -1 if double array does not contains specified key.

exactMatchSearch

public int exactMatchSearch(CharSequence key,
                   int offset)

Searches the value to which be associated with the specified key.

Parameters:

key - the string to be searched for

offset - starting position in the specified key

Returns:

the value to which be as sociated with the specified key, -1 if double array does not contains specified key.

exactMatchSearch

public int exactMatchSearch(CharSequence key)

Searches the value to which be associated with the specified key.

Parameters:

key - the string to be searched for

Returns:

the value to which be as sociated with the specified key, -1 if double array does not contains specified key.

commonPrefixSearch

public List<DoubleArrayTrie.Result> commonPrefixSearch(CharSequence key,
                                              int offset,
                                              int length,
                                              int nodePos)

Searches the value to which be associated with the specified key.

Parameters:

key - the string to be searched for

offset - starting position in the key

length - length of key

nodePos - starting position for search in double array node.

Returns:

list of integer value which is associated with matched keys if values is specified. Otherwise, indexes of matched keys.

commonPrefixSearch

public List<DoubleArrayTrie.Result> commonPrefixSearch(CharSequence key,
                                              int offset,
                                              int length)

Searches strings which are specified key's prefix.

Parameters:

key - the string to be searched for

offset - starting position in the key

length - length of key

Returns:

list of integer value which is associated with matched keys if values is specified. Otherwise, indexes of matched keys.

commonPrefixSearch

public List<DoubleArrayTrie.Result> commonPrefixSearch(CharSequence key,
                                              int offset)

Searches strings which are specified key's prefix.

Parameters:

key - the string to be searched for

offset - starting position in the key

length - length of key

Returns:

list of integer value which is associated with matched keys if values is specified. Otherwise, indexes of matched keys.

commonPrefixSearch

public List<DoubleArrayTrie.Result> commonPrefixSearch(CharSequence key)

Searches strings which are specified key's prefix.

Parameters:

key - the string to be searched for

Returns:

list of integer value which is associated with matched keys if values is specified. Otherwise, indexes of matched keys.

getLongestCommonPrefix

public DoubleArrayTrie.Result getLongestCommonPrefix(CharSequence key,
                                            int offset,
                                            int length,
                                            int nodePos)

Returns longest common prefix between strings in the trie and specified key.

Parameters:

key - the string to be searched for

offset - offset of specified key

length - length of specified key

nodePos - starting position for search in double array node.

Returns:

DoubleArrayTrie.Result object that contains length of prefix and value which is associated with prefix.

getLongestCommonPrefix

public DoubleArrayTrie.Result getLongestCommonPrefix(CharSequence key,
                                            int offset,
                                            int length)

Returns longest common prefix between strings in the trie and specified key.

Parameters:

key - the string to be searched for

offset - offset of specified key

length - length of specified key

Returns:

DoubleArrayTrie.Result object that contains length of prefix and value which is associated with prefix.

getLongestCommonPrefix

public DoubleArrayTrie.Result getLongestCommonPrefix(CharSequence key,
                                            int offset)

Returns longest common prefix between strings in the trie and specified key.

Parameters:

key - the string to be searched for

offset - offset of specified key

Returns:

DoubleArrayTrie.Result object that contains length of prefix and value which is associated with prefix.

getLongestCommonPrefix

public DoubleArrayTrie.Result getLongestCommonPrefix(CharSequence key)

Returns longest common prefix between strings in the trie and specified key.

Parameters:

key - the string to be searched for

offset - offset of specified key

Returns:

DoubleArrayTrie.Result object that contains length of prefix and value which is associated with prefix.