    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 * <p>
    023 * This stores a {@link EditDistance} implementation and a {@link CharSequence} "left" string.
    024 * The {@link #apply(CharSequence right)} method accepts the "right" string and invokes the
    025 * comparison function for the pair of strings.
    026 * </p>
    027 *
    028 * <p>
    029 * The following is an example which finds the most similar string:
    030 * </p>
    031 * <pre>
    032 * EditDistance&lt;Integer&gt; editDistance = new LevenshteinDistance();
    033 * String target = "Apache";
    034 * EditDistanceFrom&lt;Integer&gt; editDistanceFrom =
    035 *     new EditDistanceFrom&lt;Integer&gt;(editDistance, target);
    036 * String mostSimilar = null;
    037 * Integer shortestDistance = null;
    038 *
    039 * for (String test : new String[] { "Appaloosa", "a patchy", "apple" }) {
    040 *     Integer distance = editDistanceFrom.apply(test);
    041 *     if (shortestDistance == null || distance &lt; shortestDistance) {
    042 *         shortestDistance = distance;
    043 *         mostSimilar = test;
    044 *     }
    045 * }
    046 *
    047 * System.out.println("The string most similar to \"" + target + "\" "
    048 *     + "is \"" + mostSimilar + "\" because "
    049 *     + "its distance is only " + shortestDistance + ".");
    050 * </pre>
    051 *
    052 * @param <R> This is the type of similarity score used by the EditDistance function.
    053 * @since 1.0
    054 */
    055public class EditDistanceFrom<R> {
    056
    057    /**
    058     * Edit distance.
    059     */
    060    private final EditDistance<R> editDistance;
    061    /**
    062     * Left parameter used in distance function.
    063     */
    064    private final CharSequence left;
    065
    066    /**
    067     * <p>This accepts the edit distance implementation and the "left" string.</p>
    068     *
    069     * @param editDistance This may not be null.
    070     * @param left This may be null here,
    071     *             but the EditDistance#compare(CharSequence left, CharSequence right)
    072     *             implementation may not accept nulls.
    073     */
    074    public EditDistanceFrom(final EditDistance<R> editDistance, final CharSequence left) {
    075        Validate.isTrue(editDistance != null, "The edit distance may not be null.");
    076
    077        this.editDistance = editDistance;
    078        this.left = left;
    079    }
    080
    081    /**
    082     * <p>
    083     * This compares "left" field against the "right" parameter
    084     * using the "edit distance" implementation.
    085     * </p>
    086     *
    087     * @param right the second CharSequence
    088     * @return the similarity score between two CharSequences
    089     */
    090    public R apply(final CharSequence right) {
    091        return editDistance.apply(left, right);
    092    }
    093
    094    /**
    095     * Gets the left parameter.
    096     *
    097     * @return the left parameter
    098     */
    099    public CharSequence getLeft() {
    100        return left;
    101    }
    102
    103    /**
    104     * Gets the edit distance.
    105     *
    106     * @return the edit distance
    107     */
    108    public EditDistance<R> getEditDistance() {
    109        return editDistance;
    110    }
    111
    112}