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// Copyright 2008 Google Inc.
//
// 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.gwtorm.client;
/** Common utility functions for {@link Key} implementors. */
public class KeyUtil {
private static Encoder ENCODER_IMPL = new StandardKeyEncoder();
/**
* Determine if two keys are equal, supporting null references.
*
* @param <T> type of the key entity.
* @param a first key to test; may be null.
* @param b second key to test; may be null.
* @return true if both <code>a</code> and <code>b</code> are null, or if both are not-null and
* <code>a.equals(b)</code> is true. Otherwise false.
*/
public static <T extends Key<?>> boolean eq(final T a, final T b) {
if (a == b) {
return true;
}
if (a == null || b == null) {
return false;
}
return a.equals(b);
}
/**
* Encode a string to be safe for use within a URL like string.
*
* <p>The returned encoded string has URL component characters escaped with hex escapes (e.g. ' '
* is '+' and '%' is '%25'). The special character '/' is left literal. The comma character (',')
* is always encoded, permitting multiple encoded string values to be joined together safely.
*
* @param e the string to encode, must not be null.
* @return the encoded string.
*/
public static String encode(final String e) {
return ENCODER_IMPL.encode(e);
}
/**
* Decode a string previously encoded by {@link #encode(String)}.
*
* @param e the string to decode, must not be null.
* @return the decoded string.
*/
public static String decode(final String e) {
return ENCODER_IMPL.decode(e);
}
/**
* Split a string along the last comma and parse into the parent.
*
* @param parent parent key; <code>parent.fromString(in[0..comma])</code>.
* @param in the input string.
* @return text (if any) after the last comma in the input.
*/
public static String parseFromString(final Key<?> parent, final String in) {
final int comma = in.lastIndexOf(',');
if (comma < 0 && parent == null) {
return decode(in);
}
if (comma < 0 && parent != null) {
throw new IllegalArgumentException("Not enough components: " + in);
}
assert (parent != null);
parent.fromString(in.substring(0, comma));
return decode(in.substring(comma + 1));
}
public abstract static class Encoder {
public abstract String encode(String e);
public abstract String decode(String e);
}
private KeyUtil() {}
}