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Concurrent Radix Trees and Concurrent Suffix Trees for Java.
/**
* Copyright 2012-2013 Niall Gallagher
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.googlecode.concurrenttrees.radix;
import com.googlecode.concurrenttrees.common.KeyValuePair;
/**
* API of a radix tree, that is a tree which allows values to be looked up based on prefixes of the keys
* with which they were associated, as well as based on exact matches for keys. A radix tree essentially allows
* "equals" and "starts with" lookup.
*
* See documentation on each method for details.
*
* @param The type of the values associated with keys in the tree
*
* @author Niall Gallagher
*/
public interface RadixTree {
/**
* Associates the given value with the given key; replacing any previous value associated with the key.
* Returns the previous value associated with the key, if any.
*
* This operation is performed atomically.
*
* @param key The key with which the specified value should be associated
* @param value The value to associate with the key, which cannot be null
* @return The previous value associated with the key, if there was one, otherwise null
*/
O put(CharSequence key, O value);
/**
* If a value is not already associated with the given key in the tree, associates the given value with the
* key; otherwise if an existing value is already associated, returns the existing value and does not overwrite it.
*
* This operation is performed atomically.
*
* @param key The key with which the specified value should be associated
* @param value The value to associate with the key, which cannot be null
* @return The existing value associated with the key, if there was one; otherwise null in which case the new
* value was successfully associated
*/
O putIfAbsent(CharSequence key, O value);
/**
* Removes the value associated with the given key (exact match).
* If no value is associated with the key, does nothing.
*
* @param key The key for which an associated value should be removed
* @return True if a value was removed (and therefore was associated with the key), false if no value was
* associated/removed
*/
boolean remove(CharSequence key);
/**
* Returns the value associated with the given key (exact match), or returns null if no such value
* is associated with the key.
*
* @param key The key with which a sought value might be associated
* @return The value associated with the given key (exact match), or null if no value was associated with the key
*/
O getValueForExactKey(CharSequence key);
/**
* Returns a lazy iterable which returns the set of keys in the tree which start with the given prefix.
*
* This is inclusive - if the given prefix is an exact match for a key in the tree, that key is also
* returned.
*
* @param prefix A prefix of sought keys in the tree
* @return The set of keys in the tree which start with the given prefix, inclusive
*/
Iterable getKeysStartingWith(CharSequence prefix);
/**
* Returns a lazy iterable which returns the set of values associated with keys in the tree which start with the
* given prefix.
*
* This is inclusive - if the given prefix is an exact match for a key in the tree, the value associated
* with that key is also returned.
*
* Note that although the same value might originally have been associated with multiple keys, the set returned
* does not contain duplicates (as determined by the value objects' implementation of {@link Object#equals(Object)}).
*
* @param prefix A prefix of keys in the tree for which associated values are sought
* @return The set of values associated with keys in the tree which start with the given prefix, inclusive
*/
Iterable getValuesForKeysStartingWith(CharSequence prefix);
/**
* Returns a lazy iterable which returns the set of {@link KeyValuePair}s for keys and their associated values
* in the tree, where the keys start with the given prefix.
*
* This is inclusive - if the given prefix is an exact match for a key in the tree, the {@link KeyValuePair}
* for that key is also returned.
*
* @param prefix A prefix of keys in the tree for which associated {@link KeyValuePair}s are sought
* @return The set of {@link KeyValuePair}s for keys in the tree which start with the given prefix, inclusive
*/
Iterable> getKeyValuePairsForKeysStartingWith(CharSequence prefix);
/**
* Returns a lazy iterable which returns the set of keys in the tree which are the closest match for the given
* candidate key.
*
* Example:
* Tree contains: {@code Ford Focus}, {@code Ford Mondeo}, {@code BMW M3}
* getClosestKeys("Ford F150") -> returns {@code Ford Focus}, {@code Ford Mondeo}
*
* This is inclusive - if the given candidate is an exact match for a key in the tree, that key is also
* returned.
*
* @param candidate A candidate key
* @return The set of keys in the tree which most closely match the candidate key, inclusive
*/
Iterable getClosestKeys(CharSequence candidate);
/**
* Returns a lazy iterable which returns the set of values associated with keys in the tree which are the closest
* match for the given candidate key.
*
* See {#getClosestKeys} for more details.
*
* @param candidate A candidate key
* @return The set of values associated with keys in the tree which most closely match the candidate key, inclusive
*/
Iterable getValuesForClosestKeys(CharSequence candidate);
/**
* Returns a lazy iterable which returns the set of {@link KeyValuePair}s for keys and their associated values in
* the tree which are the closest match for the given candidate key.
*
* See {#getClosestKeys} for more details.
*
* @param candidate A candidate key
* @return The set of {@link KeyValuePair}s for keys and their associated values in the tree which most closely
* match the candidate key, inclusive
*/
Iterable> getKeyValuePairsForClosestKeys(CharSequence candidate);
/**
* Counts the number of keys/values stored in the tree.
*
* In the current implementation, this is an expensive operation, having O(n) time complexity.
*
* @return The number of keys/values stored in the tree
*/
int size();
}