/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.tomcat.util.buf;
/**
* This class implements some basic ASCII character handling functions.
*/
public final class Ascii {
/*
* Character translation tables.
*/
private static final byte[] toLower = new byte[256];
/*
* Character type tables.
*/
private static final boolean[] isDigit = new boolean[256];
private static final long OVERFLOW_LIMIT = Long.MAX_VALUE / 10;
/*
* Initialize character translation and type tables.
*/
static {
for (int i = 0; i < 256; i++) {
toLower[i] = (byte) i;
}
for (int lc = 'a'; lc <= 'z'; lc++) {
int uc = lc + 'A' - 'a';
toLower[uc] = (byte) lc;
}
for (int d = '0'; d <= '9'; d++) {
isDigit[d] = true;
}
}
/**
* Returns the lower case equivalent of the specified ASCII character.
*
* @param c The char
*
* @return the lower case equivalent char
*/
public static int toLower(int c) {
return toLower[c & 0xff] & 0xff;
}
/**
* @return <code>true</code> if the specified ASCII character is a digit.
*
* @param c The char
*/
private static boolean isDigit(int c) {
return isDigit[c & 0xff];
}
/**
* Parses an unsigned long from the specified sub array of bytes.
*
* @param b the bytes to parse
* @param off the start offset of the bytes
* @param len the length of the bytes
*
* @return the long value
*
* @exception NumberFormatException if the long format was invalid
*/
public static long parseLong(byte[] b, int off, int len) throws NumberFormatException {
int c;
if (b == null || len <= 0 || !isDigit(c = b[off++])) {
throw new NumberFormatException();
}
long n = c - '0';
while (--len > 0) {
if (isDigit(c = b[off++]) && (n < OVERFLOW_LIMIT || (n == OVERFLOW_LIMIT && (c - '0') < 8))) {
n = n * 10 + c - '0';
} else {
throw new NumberFormatException();
}
}
return n;
}
}