    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.text.similarity;
    018
    019import org.apache.commons.lang3.Validate;
    020
    021/**
    022 * This stores a {@link EditDistance} implementation and a {@link CharSequence} "left" string.
    023 * The {@link #apply(CharSequence right)} method accepts the "right" string and invokes the
    024 * comparison function for the pair of strings.
    025 *
    026 * <p>
    027 * The following is an example which finds the most similar string:
    028 * </p>
    029 * <pre>
    030 * EditDistance&lt;Integer&gt; editDistance = new LevenshteinDistance();
    031 * String target = "Apache";
    032 * EditDistanceFrom&lt;Integer&gt; editDistanceFrom =
    033 *     new EditDistanceFrom&lt;Integer&gt;(editDistance, target);
    034 * String mostSimilar = null;
    035 * Integer shortestDistance = null;
    036 *
    037 * for (String test : new String[] { "Appaloosa", "a patchy", "apple" }) {
    038 *     Integer distance = editDistanceFrom.apply(test);
    039 *     if (shortestDistance == null || distance &lt; shortestDistance) {
    040 *         shortestDistance = distance;
    041 *         mostSimilar = test;
    042 *     }
    043 * }
    044 *
    045 * System.out.println("The string most similar to \"" + target + "\" "
    046 *     + "is \"" + mostSimilar + "\" because "
    047 *     + "its distance is only " + shortestDistance + ".");
    048 * </pre>
    049 *
    050 * @param <R> This is the type of similarity score used by the EditDistance function.
    051 * @since 1.0
    052 */
    053public class EditDistanceFrom<R> {
    054
    055    /**
    056     * Edit distance.
    057     */
    058    private final EditDistance<R> editDistance;
    059    /**
    060     * Left parameter used in distance function.
    061     */
    062    private final CharSequence left;
    063
    064    /**
    065     * This accepts the edit distance implementation and the "left" string.
    066     *
    067     * @param editDistance This may not be null.
    068     * @param left This may be null here,
    069     *             but the EditDistance#compare(CharSequence left, CharSequence right)
    070     *             implementation may not accept nulls.
    071     */
    072    public EditDistanceFrom(final EditDistance<R> editDistance, final CharSequence left) {
    073        Validate.isTrue(editDistance != null, "The edit distance may not be null.");
    074
    075        this.editDistance = editDistance;
    076        this.left = left;
    077    }
    078
    079    /**
    080     * This compares "left" field against the "right" parameter
    081     * using the "edit distance" implementation.
    082     *
    083     * @param right the second CharSequence
    084     * @return The similarity score between two CharSequences
    085     */
    086    public R apply(final CharSequence right) {
    087        return editDistance.apply(left, right);
    088    }
    089
    090    /**
    091     * Gets the edit distance.
    092     *
    093     * @return The edit distance
    094     */
    095    public EditDistance<R> getEditDistance() {
    096        return editDistance;
    097    }
    098
    099    /**
    100     * Gets the left parameter.
    101     *
    102     * @return The left parameter
    103     */
    104    public CharSequence getLeft() {
    105        return left;
    106    }
    107
    108}