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/*
* 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 com.google.common.annotations.GwtCompatible;
/**
* Utility class for converting between various ASCII case formats.
*
* @author Mike Bostock
* @since 1.0
*/
@GwtCompatible
public enum CaseFormat {
/**
* Hyphenated variable naming convention, e.g., "lower-hyphen".
*/
LOWER_HYPHEN(CharMatcher.is('-'), "-"),
/**
* C++ variable naming convention, e.g., "lower_underscore".
*/
LOWER_UNDERSCORE(CharMatcher.is('_'), "_"),
/**
* Java variable naming convention, e.g., "lowerCamel".
*/
LOWER_CAMEL(CharMatcher.inRange('A', 'Z'), ""),
/**
* Java and C++ class naming convention, e.g., "UpperCamel".
*/
UPPER_CAMEL(CharMatcher.inRange('A', 'Z'), ""),
/**
* Java and C++ constant naming convention, e.g., "UPPER_UNDERSCORE".
*/
UPPER_UNDERSCORE(CharMatcher.is('_'), "_");
private final CharMatcher wordBoundary;
private final String wordSeparator;
CaseFormat(CharMatcher wordBoundary, String wordSeparator) {
this.wordBoundary = wordBoundary;
this.wordSeparator = wordSeparator;
}
/**
* Converts the specified {@code String s} from this format to the specified {@code format}. A
* "best effort" approach is taken; if {@code s} 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 String to(CaseFormat format, String s) {
if (format == null) {
throw new NullPointerException();
}
if (s == null) {
throw new NullPointerException();
}
if (format == this) {
return s;
}
/* optimize cases where no camel conversion is required */
switch (this) {
case LOWER_HYPHEN:
switch (format) {
case LOWER_UNDERSCORE:
return s.replace('-', '_');
case UPPER_UNDERSCORE:
return Ascii.toUpperCase(s.replace('-', '_'));
}
break;
case LOWER_UNDERSCORE:
switch (format) {
case LOWER_HYPHEN:
return s.replace('_', '-');
case UPPER_UNDERSCORE:
return Ascii.toUpperCase(s);
}
break;
case UPPER_UNDERSCORE:
switch (format) {
case LOWER_HYPHEN:
return Ascii.toLowerCase(s.replace('_', '-'));
case LOWER_UNDERSCORE:
return Ascii.toLowerCase(s);
}
break;
}
// otherwise, 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();
}
if (i == 0) {
return format.normalizeFirstWord(s);
}
out.append(format.normalizeWord(s.substring(i)));
return out.toString();
}
private String normalizeFirstWord(String word) {
switch (this) {
case LOWER_CAMEL:
return Ascii.toLowerCase(word);
default:
return normalizeWord(word);
}
}
private String normalizeWord(String word) {
switch (this) {
case LOWER_HYPHEN:
return Ascii.toLowerCase(word);
case LOWER_UNDERSCORE:
return Ascii.toLowerCase(word);
case LOWER_CAMEL:
return firstCharOnlyToUpper(word);
case UPPER_CAMEL:
return firstCharOnlyToUpper(word);
case UPPER_UNDERSCORE:
return Ascii.toUpperCase(word);
}
throw new RuntimeException("unknown case: " + this);
}
private static String firstCharOnlyToUpper(String word) {
int length = word.length();
if (length == 0) {
return word;
}
return new StringBuilder(length)
.append(Ascii.toUpperCase(word.charAt(0)))
.append(Ascii.toLowerCase(word.substring(1)))
.toString();
}
}
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