Mega Code Archive
ASCII character handling functions
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/*
* 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.
*/
/**
* This class implements some basic ASCII character handling functions.
*
* @author dac@eng.sun.com
* @author James Todd [gonzo@eng.sun.com]
*/
public final class Ascii {
/*
* Character translation tables.
*/
private static final byte[] toUpper = new byte[256];
private static final byte[] toLower = new byte[256];
/*
* Character type tables.
*/
private static final boolean[] isAlpha = new boolean[256];
private static final boolean[] isUpper = new boolean[256];
private static final boolean[] isLower = new boolean[256];
private static final boolean[] isWhite = new boolean[256];
private static final boolean[] isDigit = new boolean[256];
/*
* Initialize character translation and type tables.
*/
static {
for (int i = 0; i < 256; i++) {
toUpper[i] = (byte)i;
toLower[i] = (byte)i;
}
for (int lc = 'a'; lc <= 'z'; lc++) {
int uc = lc + 'A' - 'a';
toUpper[lc] = (byte)uc;
toLower[uc] = (byte)lc;
isAlpha[lc] = true;
isAlpha[uc] = true;
isLower[lc] = true;
isUpper[uc] = true;
}
isWhite[ ' '] = true;
isWhite['\t'] = true;
isWhite['\r'] = true;
isWhite['\n'] = true;
isWhite['\f'] = true;
isWhite['\b'] = true;
for (int d = '0'; d <= '9'; d++) {
isDigit[d] = true;
}
}
/**
* Returns the upper case equivalent of the specified ASCII character.
*/
public static int toUpper(int c) {
return toUpper[c & 0xff] & 0xff;
}
/**
* Returns the lower case equivalent of the specified ASCII character.
*/
public static int toLower(int c) {
return toLower[c & 0xff] & 0xff;
}
/**
* Returns true if the specified ASCII character is upper or lower case.
*/
public static boolean isAlpha(int c) {
return isAlpha[c & 0xff];
}
/**
* Returns true if the specified ASCII character is upper case.
*/
public static boolean isUpper(int c) {
return isUpper[c & 0xff];
}
/**
* Returns true if the specified ASCII character is lower case.
*/
public static boolean isLower(int c) {
return isLower[c & 0xff];
}
/**
* Returns true if the specified ASCII character is white space.
*/
public static boolean isWhite(int c) {
return isWhite[c & 0xff];
}
/**
* Returns true if the specified ASCII character is a digit.
*/
public static boolean isDigit(int c) {
return isDigit[c & 0xff];
}
/**
* Parses an unsigned integer from the specified subarray of bytes.
* @param b the bytes to parse
* @param off the start offset of the bytes
* @param len the length of the bytes
* @exception NumberFormatException if the integer format was invalid
*/
public static int parseInt(byte[] b, int off, int len)
throws NumberFormatException
{
int c;
if (b == null || len <= 0 || !isDigit(c = b[off++])) {
throw new NumberFormatException();
}
int n = c - '0';
while (--len > 0) {
if (!isDigit(c = b[off++])) {
throw new NumberFormatException();
}
n = n * 10 + c - '0';
}
return n;
}
public static int parseInt(char[] b, int off, int len)
throws NumberFormatException
{
int c;
if (b == null || len <= 0 || !isDigit(c = b[off++])) {
throw new NumberFormatException();
}
int n = c - '0';
while (--len > 0) {
if (!isDigit(c = b[off++])) {
throw new NumberFormatException();
}
n = n * 10 + c - '0';
}
return n;
}
/**
* Parses an unsigned long from the specified subarray of bytes.
* @param b the bytes to parse
* @param off the start offset of the bytes
* @param len the length of the bytes
* @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';
long m;
while (--len > 0) {
if (!isDigit(c = b[off++])) {
throw new NumberFormatException();
}
m = n * 10 + c - '0';
if (m < n) {
// Overflow
throw new NumberFormatException();
} else {
n = m;
}
}
return n;
}
public static long parseLong(char[] 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';
long m;
while (--len > 0) {
if (!isDigit(c = b[off++])) {
throw new NumberFormatException();
}
m = n * 10 + c - '0';
if (m < n) {
// Overflow
throw new NumberFormatException();
} else {
n = m;
}
}
return n;
}
}
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