com.google.debugging.sourcemap.Base64 Maven / Gradle / Ivy
/*
* Copyright 2011 The Closure Compiler 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.debugging.sourcemap;
import java.util.Arrays;
/**
* A utility class for working with Base64 values.
*/
public final class Base64 {
// This is a utility class
private Base64() {}
/**
* A map used to convert integer values in the range 0-63 to their base64
* values.
*/
private static final String BASE64_MAP =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ" +
"abcdefghijklmnopqrstuvwxyz" +
"0123456789+/";
/**
* A map used to convert base64 character into integer values.
*/
private static final int[] BASE64_DECODE_MAP = new int[256];
static {
Arrays.fill(BASE64_DECODE_MAP, -1);
for (int i = 0; i < BASE64_MAP.length(); i++) {
BASE64_DECODE_MAP[BASE64_MAP.charAt(i)] = i;
}
}
/**
* @param value A value in the range of 0-63.
* @return a base64 digit.
*/
public static char toBase64(int value) {
assert (value <= 63 && value >= 0) : "value out of range:" + value;
return BASE64_MAP.charAt(value);
}
/**
* @param c A base64 digit.
* @return A value in the range of 0-63.
*/
public static int fromBase64(char c) {
int result = BASE64_DECODE_MAP[c];
assert (result != -1) : "invalid char";
return result;
}
/**
* @param value an integer to base64 encode.
* @return the six digit long base64 encoded value of the integer.
*/
public static String base64EncodeInt(int value) {
char[] c = new char[6];
for (int i = 0; i < 5; i++) {
c[i] = Base64.toBase64((value >> (26 - i * 6)) & 0x3f);
}
c[5] = Base64.toBase64((value << 4) & 0x3f);
return new String(c);
}
}