Module org.apache.jena.base
Package org.apache.jena.atlas.lib

Class Trie<T>

java.lang.Object
org.apache.jena.atlas.lib.Trie<T>
Type Parameters:
T - Type of the value stored.
public final class Trie<T> extends Object
An implementation of a classic Trie, this is a mapping from strings to some value type optimized for fast prefix search and match. If you do not need prefix search then you should typically use a standard Map instead.

The empty or null string may be used as a special key to refer to the root node of the trie.

A Trie cannot store null values since null is used as an internal marker to indicate that there is no value associated with a key. This is necessary because the nature of the data structure means that adding a key potentially adds multiple keys many of which will not be associated with a value.

  • Constructor Summary

    Constructors
    Constructor
    Description
    Trie()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    add(String key, T value)
    Adds a value to the trie overwriting any existing value
    void
    clear()
    Clear the Trie completely.
    boolean
    contains(String key)
    Gets whether a key exists in the trie and has a non-null value mapped to it
    boolean
    contains(String key, boolean requireValue)
    Gets whether a key exists in the trie and meets the given value criteria
    boolean
    contains(String key, T value)
    Gets whether a key value pair are present in the trie
    T
    get(String key)
    Gets the value associated with a key
    boolean
    isEmpty()
    Test whether the Trie is empty.
    T
    longestMatch(String key)
    Finds the longest match for a given key i.e. returns the value associated with the longest prefix of the key that has a value
    List<T>
    partialSearch(String key)
    Performs a search and returns any value associated with any partial or whole prefix of the key
    List<T>
    prefixSearch(String prefix)
    Performs a prefix search and returns all values mapped under the given prefix.
    void
    remove(String key)
    Removes a value from the trie
    T
    shortestMatch(String key)
    Finds the shortest match for a given key i.e. returns the value associated with the shortest prefix of the key that has a value

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • Trie

      public Trie()

  • Method Details

    • add

      public void add(String key, T value)
      Adds a value to the trie overwriting any existing value

      Note that a null value is treated as if the key does not actually exist in the tree so trying to add a null is a no-op. If you want to remove a key use the remove(String) method instead.

      Parameters:
      key - Key
      value - Value

    • remove

      public void remove(String key)
      Removes a value from the trie

      This doesn't actually remove the key per-se rather sets the value associated with the key to null.

      Parameters:
      key - Key

    • clear

      public void clear()
      Clear the Trie completely.

    • isEmpty

      public boolean isEmpty()
      Test whether the Trie is empty.

    • contains

      public boolean contains(String key)
      Gets whether a key exists in the trie and has a non-null value mapped to it
      Parameters:
      key - Key
      Returns:
      True if the key exists and has a non-null value mapped to it

    • contains

      public boolean contains(String key, boolean requireValue)
      Gets whether a key exists in the trie and meets the given value criteria
      Parameters:
      key - Key
      requireValue - If true a key must have a non-null value associated with it to be considered to be contained in the tree, if false then the key must merely map to a node in the trie
      Returns:
      True if the key exists and the value criteria is met, false otherwise

    • contains

      public boolean contains(String key, T value)
      Gets whether a key value pair are present in the trie
      Parameters:
      key - Key
      value - Value
      Returns:
      True if the key value pair exists in the trie, false otherwise

    • get

      public T get(String key)
      Gets the value associated with a key
      Parameters:
      key - Key
      Returns:
      Value

    • prefixSearch

      public List<T> prefixSearch(String prefix)
      Performs a prefix search and returns all values mapped under the given prefix. The entirety of the prefix must be matched, if you only want part of the prefix to be matched use the partialSearch(String) method instead.
      Parameters:
      prefix - Prefix
      Returns:
      List of values associated with the given key

    • partialSearch

      public List<T> partialSearch(String key)
      Performs a search and returns any value associated with any partial or whole prefix of the key
      Parameters:
      key - Key
      Returns:
      List of values associated with any partial prefix of the key

    • shortestMatch

      public T shortestMatch(String key)
      Finds the shortest match for a given key i.e. returns the value associated with the shortest prefix of the key that has a value
      Parameters:
      key - Key
      Returns:
      Shortest Match or null if no possible matches

    • longestMatch

      public T longestMatch(String key)
      Finds the longest match for a given key i.e. returns the value associated with the longest prefix of the key that has a value
      Parameters:
      key - Key
      Returns:
      Longest Match or null if no possible matches