src.it.unimi.dsi.big.util.PrefixMap Maven / Gradle / Ivy
/*
* DSI utilities
*
* Copyright (C) 2004-2023 Sebastiano Vigna
*
* This program and the accompanying materials are made available under the
* terms of the GNU Lesser General Public License v2.1 or later,
* which is available at
* http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html,
* or the Apache Software License 2.0, which is available at
* https://www.apache.org/licenses/LICENSE-2.0.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE.
*
* SPDX-License-Identifier: LGPL-2.1-or-later OR Apache-2.0
*/
package it.unimi.dsi.big.util;
import it.unimi.dsi.fastutil.Size64;
import it.unimi.dsi.fastutil.objects.Object2ObjectFunction;
import it.unimi.dsi.util.LongInterval;
/** A map from prefixes to string intervals (and possibly vice versa).
*
* Instances of this class provide the services of a {@link StringMap}, but by assuming
* the strings are lexicographically ordered, they can provide further information by
* exposing a {@linkplain #rangeMap() function from string prefixes to intervals} and a
* {@linkplain #prefixMap() function from intervals to string prefixes}.
*
*
In the first case, given a prefix, we can ask for the range of strings starting
* with that prefix, expressed as a {@link LongInterval}. This information is very useful to
* satisfy prefix queries (e.g., monitor*) with a brute-force approach.
*
*
Optionally, a prefix map may provide the opposite service: given an interval of terms, it
* may provide the maximum common prefix. This feature can be checked for by calling
* {@link #prefixMap()}.
*
* @author Sebastiano Vigna
* @since 2.0
*/
public interface PrefixMap extends StringMap, Size64 {
/** Returns a function mapping prefixes to ranges of strings.
*
* @return a function mapping prefixes to ranges of strings.
*/
Object2ObjectFunction rangeMap();
/** Returns a function mapping ranges of strings to common prefixes (optional operation).
*
* @return a function mapping ranges of strings to common prefixes, or {@code null} if this
* map does not support prefixes.
*/
Object2ObjectFunction prefixMap();
}