/*
* Copyright 2017 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.names;
import static com.google.common.collect.ImmutableList.toImmutableList;
import com.google.common.collect.ImmutableList;
import java.util.Arrays;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
/** Utility functions for dealing with Java naming conventions */
public class NamingConventions {
private static final Pattern ONLY_UNDERSCORES = Pattern.compile("^_+$");
private static final String UNDERSCORE = "_";
private static final String CASE_TRANSITION = "(?<=[a-z0-9])(?=[A-Z])";
private static final String TRAILING_DIGITS = "(?<![0-9_])(?=[0-9]+$)";
private static final Pattern TERM_SPLITTER =
Pattern.compile(String.format("%s|%s|%s", UNDERSCORE, CASE_TRANSITION, TRAILING_DIGITS));
/**
* Split a Java name into terms based on either Camel Case or Underscores. We also split digits at
* the end of the name into a separate term so as to treat PERSON1 and PERSON_1 as the same thing.
*
* @param identifierName to split
* @return a list of the terms in the name, in order and converted to lowercase
*/
public static ImmutableList<String> splitToLowercaseTerms(String identifierName) {
if (ONLY_UNDERSCORES.matcher(identifierName).matches()) {
// Degenerate case of names which contain only underscore
return ImmutableList.of(identifierName);
}
return Arrays.stream(TERM_SPLITTER.split(identifierName))
.map(String::toLowerCase)
.collect(toImmutableList());
}
public static String convertToLowerUnderscore(String identifierName) {
return splitToLowercaseTerms(identifierName).stream().collect(Collectors.joining("_"));
}
}