/*
* Copyright (C) 2006 The Guava Authors
*
* 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.common.base;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import java.io.Serializable;
import javax.annotation.Nullable;
/**
* Utility class for converting between various ASCII case formats. Behavior is undefined for
* non-ASCII input.
*
* @author Mike Bostock
* @since 1.0
*/
@GwtCompatible
public enum CaseFormat {
/**
* Hyphenated variable naming convention, e.g., "lower-hyphen".
*/
LOWER_HYPHEN(CharMatcher.is('-'), "-") {
@Override String normalizeWord(String word) {
return Ascii.toLowerCase(word);
}
@Override String convert(CaseFormat format, String s) {
if (format == LOWER_UNDERSCORE) {
return s.replace('-', '_');
}
if (format == UPPER_UNDERSCORE) {
return Ascii.toUpperCase(s.replace('-', '_'));
}
return super.convert(format, s);
}
},
/**
* C++ variable naming convention, e.g., "lower_underscore".
*/
LOWER_UNDERSCORE(CharMatcher.is('_'), "_") {
@Override String normalizeWord(String word) {
return Ascii.toLowerCase(word);
}
@Override String convert(CaseFormat format, String s) {
if (format == LOWER_HYPHEN) {
return s.replace('_', '-');
}
if (format == UPPER_UNDERSCORE) {
return Ascii.toUpperCase(s);
}
return super.convert(format, s);
}
},
/**
* Java variable naming convention, e.g., "lowerCamel".
*/
LOWER_CAMEL(CharMatcher.inRange('A', 'Z'), "") {
@Override String normalizeWord(String word) {
return firstCharOnlyToUpper(word);
}
},
/**
* Java and C++ class naming convention, e.g., "UpperCamel".
*/
UPPER_CAMEL(CharMatcher.inRange('A', 'Z'), "") {
@Override String normalizeWord(String word) {
return firstCharOnlyToUpper(word);
}
},
/**
* Java and C++ constant naming convention, e.g., "UPPER_UNDERSCORE".
*/
UPPER_UNDERSCORE(CharMatcher.is('_'), "_") {
@Override String normalizeWord(String word) {
return Ascii.toUpperCase(word);
}
@Override String convert(CaseFormat format, String s) {
if (format == LOWER_HYPHEN) {
return Ascii.toLowerCase(s.replace('_', '-'));
}
if (format == LOWER_UNDERSCORE) {
return Ascii.toLowerCase(s);
}
return super.convert(format, s);
}
};
private final CharMatcher wordBoundary;
private final String wordSeparator;
CaseFormat(CharMatcher wordBoundary, String wordSeparator) {
this.wordBoundary = wordBoundary;
this.wordSeparator = wordSeparator;
}
/**
* Converts the specified {@code String str} from this format to the specified {@code format}. A
* "best effort" approach is taken; if {@code str} does not conform to the assumed format, then
* the behavior of this method is undefined but we make a reasonable effort at converting anyway.
*/
public final String to(CaseFormat format, String str) {
checkNotNull(format);
checkNotNull(str);
return (format == this) ? str : convert(format, str);
}
/**
* Enum values can override for performance reasons.
*/
String convert(CaseFormat format, String s) {
// deal with camel conversion
StringBuilder out = null;
int i = 0;
int j = -1;
while ((j = wordBoundary.indexIn(s, ++j)) != -1) {
if (i == 0) {
// include some extra space for separators
out = new StringBuilder(s.length() + 4 * wordSeparator.length());
out.append(format.normalizeFirstWord(s.substring(i, j)));
} else {
out.append(format.normalizeWord(s.substring(i, j)));
}
out.append(format.wordSeparator);
i = j + wordSeparator.length();
}
return (i == 0)
? format.normalizeFirstWord(s)
: out.append(format.normalizeWord(s.substring(i))).toString();
}
/**
* Returns a {@code Converter} that converts strings from this format to {@code targetFormat}.
*
* @since 16.0
*/
@Beta
public Converter<String, String> converterTo(CaseFormat targetFormat) {
return new StringConverter(this, targetFormat);
}
private static final class StringConverter
extends Converter<String, String> implements Serializable {
private final CaseFormat sourceFormat;
private final CaseFormat targetFormat;
StringConverter(CaseFormat sourceFormat, CaseFormat targetFormat) {
this.sourceFormat = checkNotNull(sourceFormat);
this.targetFormat = checkNotNull(targetFormat);
}
@Override protected String doForward(String s) {
// TODO(kevinb): remove null boilerplate (convert() will do it automatically)
return s == null ? null : sourceFormat.to(targetFormat, s);
}
@Override protected String doBackward(String s) {
// TODO(kevinb): remove null boilerplate (convert() will do it automatically)
return s == null ? null : targetFormat.to(sourceFormat, s);
}
@Override public boolean equals(@Nullable Object object) {
if (object instanceof StringConverter) {
StringConverter that = (StringConverter) object;
return sourceFormat.equals(that.sourceFormat)
&& targetFormat.equals(that.targetFormat);
}
return false;
}
@Override public int hashCode() {
return sourceFormat.hashCode() ^ targetFormat.hashCode();
}
@Override public String toString() {
return sourceFormat + ".converterTo(" + targetFormat + ")";
}
private static final long serialVersionUID = 0L;
}
abstract String normalizeWord(String word);
private String normalizeFirstWord(String word) {
return (this == LOWER_CAMEL) ? Ascii.toLowerCase(word) : normalizeWord(word);
}
private static String firstCharOnlyToUpper(String word) {
return (word.isEmpty())
? word
: new StringBuilder(word.length())
.append(Ascii.toUpperCase(word.charAt(0)))
.append(Ascii.toLowerCase(word.substring(1)))
.toString();
}
}