com.google.errorprone.bugpatterns.ArgumentParameterSimilarityMetrics.java Source code

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Here is the source code for com.google.errorprone.bugpatterns.ArgumentParameterSimilarityMetrics.java

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/*
 * Copyright 2016 Google Inc. All Rights Reserved.
 *
 * 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.google.errorprone.bugpatterns;

import static java.util.stream.Collectors.toCollection;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Sets;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.regex.Pattern;

/** Similarity metrics for the ArgumentParameter* checks. */
public class ArgumentParameterSimilarityMetrics {

    private static final Pattern ONLY_UNDERSCORES = Pattern.compile("^_+$");
    private static final Pattern UNDERSCORES_OR_CASE_TRANSITIONS = Pattern.compile("_|(?<=[a-z0-9])(?=[A-Z])");

    /**
     * The similarity metric from Section 2.1 of Liu et al., "Nomen est Omen: Exploring and Exploiting
     * Similarities between Argument and Parameter Names," ICSE 2016.
     *
     * <p>The formula is |argTerms intersect paramTerms| / (|argTerms| + |paramTerms|) * 2.
     */
    public static double computeNormalizedTermIntersection(String arg, String param) {
        // TODO(ciera): consider also using edit distance on individual words.
        Set<String> argSplit = splitStringTerms(arg);
        Set<String> paramSplit = splitStringTerms(param);
        // TODO(andrewrice): Handle the substring cases so that lenList matches listLength
        double commonTerms = Sets.intersection(argSplit, paramSplit).size() * 2;
        double totalTerms = argSplit.size() + paramSplit.size();
        return commonTerms / totalTerms;
    }

    /**
     * Divides a string into a set of terms by splitting on underscores and transitions from lower to
     * upper case.
     */
    @VisibleForTesting
    static Set<String> splitStringTerms(String name) {
        if (ONLY_UNDERSCORES.matcher(name).matches()) {
            // Degenerate case of names which contain only underscore
            return ImmutableSet.of(name);
        }
        // TODO(andrewrice): switch over to toImmutableSet if guava provides it in future
        return Arrays.stream(UNDERSCORES_OR_CASE_TRANSITIONS.split(name)).map(String::toLowerCase)
                .collect(toCollection(HashSet::new));
    }

    private ArgumentParameterSimilarityMetrics() {
    }
}