/* Jackson JSON-processor.
*
* Copyright (c) 2007- Tatu Saloranta, tatu.saloranta@iki.fi
*
* Licensed under the License specified in file LICENSE, included with
* the source code and binary code bundles.
* You may not use this file except in compliance with the License.
*
* 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.codehaus.jackson;
import java.util.Arrays;
/**
* Abstract base class used to define specific details of which
* variant of Base64 encoding/decoding is to be used. Although there is
* somewhat standard basic version (so-called "MIME Base64"), other variants
* exists, see <a href="http://en.wikipedia.org/wiki/Base64">Base64 Wikipedia entry</a> for details.
*
* @author Tatu Saloranta
*
* @since 0.9.3
*/
public final class Base64Variant
{
/**
* Placeholder used by "no padding" variant, to be used when a character
* value is needed.
*/
final static char PADDING_CHAR_NONE = '\0';
/**
* Marker used to denote ascii characters that do not correspond
* to a 6-bit value (in this variant), and is not used as a padding
* character.
*/
public final static int BASE64_VALUE_INVALID = -1;
/**
* Marker used to denote ascii character (in decoding table) that
* is the padding character using this variant (if any).
*/
public final static int BASE64_VALUE_PADDING = -2;
/*
////////////////////////////////////////////////////
// Encoding/decoding tables
////////////////////////////////////////////////////
*/
/**
* Decoding table used for base 64 decoding.
*/
private final int[] _asciiToBase64 = new int[128];
/**
* Encoding table used for base 64 decoding when output is done
* as characters.
*/
private final char[] _base64ToAsciiC = new char[64];
/**
* Alternative encoding table used for base 64 decoding when output is done
* as ascii bytes.
*/
private final byte[] _base64ToAsciiB = new byte[64];
/*
////////////////////////////////////////////////////
// Other configuration
////////////////////////////////////////////////////
*/
/**
* Symbolic name of variant; used for diagnostics/debugging.
*/
final String _name;
/**
* Whether this variant uses padding or not.
*/
final boolean _usesPadding;
/**
* Characted used for padding, if any ({@link #PADDING_CHAR_NONE} if not).
*/
final char _paddingChar;
/**
* Maximum number of encoded base64 characters to output during encoding
* before adding a linefeed, if line length is to be limited
* ({@link java.lang.Integer#MAX_VALUE} if not limited).
*<p>
* Note: for some output modes (when writing attributes) linefeeds may
* need to be avoided, and this value ignored.
*/
final int _maxLineLength;
/*
////////////////////////////////////////////////////
// Life-cycle
////////////////////////////////////////////////////
*/
public Base64Variant(String name, String base64Alphabet, boolean usesPadding, char paddingChar, int maxLineLength)
{
_name = name;
_usesPadding = usesPadding;
_paddingChar = paddingChar;
_maxLineLength = maxLineLength;
// Ok and then we need to create codec tables.
// First the main encoding table:
int alphaLen = base64Alphabet.length();
if (alphaLen != 64) {
throw new IllegalArgumentException("Base64Alphabet length must be exactly 64 (was "+alphaLen+")");
}
// And then secondary encoding table and decoding table:
base64Alphabet.getChars(0, alphaLen, _base64ToAsciiC, 0);
Arrays.fill(_asciiToBase64, BASE64_VALUE_INVALID);
for (int i = 0; i < alphaLen; ++i) {
char alpha = _base64ToAsciiC[i];
_base64ToAsciiB[i] = (byte) alpha;
_asciiToBase64[alpha] = i;
}
// Plus if we use padding, add that in too
if (usesPadding) {
_asciiToBase64[(int) paddingChar] = BASE64_VALUE_PADDING;
}
}
/**
* "Copy constructor" that can be used when the base alphabet is identical
* to one used by another variant except for the maximum line length
* (and obviously, name).
*/
public Base64Variant(Base64Variant base, String name, int maxLineLength)
{
this(base, name, base._usesPadding, base._paddingChar, maxLineLength);
}
/**
* "Copy constructor" that can be used when the base alphabet is identical
* to one used by another variant, but other details (padding, maximum
* line length) differ
*/
public Base64Variant(Base64Variant base, String name, boolean usesPadding, char paddingChar, int maxLineLength)
{
_name = name;
byte[] srcB = base._base64ToAsciiB;
System.arraycopy(srcB, 0, this._base64ToAsciiB, 0, srcB.length);
char[] srcC = base._base64ToAsciiC;
System.arraycopy(srcC, 0, this._base64ToAsciiC, 0, srcC.length);
int[] srcV = base._asciiToBase64;
System.arraycopy(srcV, 0, this._asciiToBase64, 0, srcV.length);
_usesPadding = usesPadding;
_paddingChar = paddingChar;
_maxLineLength = maxLineLength;
}
/*
////////////////////////////////////////////////////
// Public accessors
////////////////////////////////////////////////////
*/
public String getName() { return _name; }
public boolean usesPadding() { return _usesPadding; }
public boolean usesPaddingChar(char c) { return c == _paddingChar; }
public boolean usesPaddingChar(int ch) { return ch == (int) _paddingChar; }
public char getPaddingChar() { return _paddingChar; }
public byte getPaddingByte() { return (byte)_paddingChar; }
public int getMaxLineLength() { return _maxLineLength; }
/*
////////////////////////////////////////////////////
// Decoding support
////////////////////////////////////////////////////
*/
/**
* @return 6-bit decoded value, if valid character;
*/
public int decodeBase64Char(char c)
{
int ch = (int) c;
return (ch <= 127) ? _asciiToBase64[ch] : BASE64_VALUE_INVALID;
}
public int decodeBase64Char(int ch)
{
return (ch <= 127) ? _asciiToBase64[ch] : BASE64_VALUE_INVALID;
}
public int decodeBase64Byte(byte b)
{
int ch = (int) b;
return (ch <= 127) ? _asciiToBase64[ch] : BASE64_VALUE_INVALID;
}
/*
////////////////////////////////////////////////////
// Encoding support
////////////////////////////////////////////////////
*/
public char encodeBase64BitsAsChar(int value)
{
/* Let's assume caller has done necessary checks; this
* method must be fast and inlinable
*/
return _base64ToAsciiC[value];
}
/**
* Method that encodes given right-aligned (LSB) 24-bit value
* into 4 base64 characters, stored in given result buffer.
*/
public int encodeBase64Chunk(int b24, char[] buffer, int ptr)
{
buffer[ptr++] = _base64ToAsciiC[(b24 >> 18) & 0x3F];
buffer[ptr++] = _base64ToAsciiC[(b24 >> 12) & 0x3F];
buffer[ptr++] = _base64ToAsciiC[(b24 >> 6) & 0x3F];
buffer[ptr++] = _base64ToAsciiC[b24 & 0x3F];
return ptr;
}
public void encodeBase64Chunk(StringBuilder sb, int b24)
{
sb.append(_base64ToAsciiC[(b24 >> 18) & 0x3F]);
sb.append(_base64ToAsciiC[(b24 >> 12) & 0x3F]);
sb.append(_base64ToAsciiC[(b24 >> 6) & 0x3F]);
sb.append(_base64ToAsciiC[b24 & 0x3F]);
}
/**
* Method that outputs partial chunk (which only encodes one
* or two bytes of data). Data given is still aligned same as if
* it as full data; that is, missing data is at the "right end"
* (LSB) of int.
*
* @param outputBytes Number of encoded bytes included (either 1 or 2)
*/
public int encodeBase64Partial(int bits, int outputBytes, char[] buffer, int outPtr)
{
buffer[outPtr++] = _base64ToAsciiC[(bits >> 18) & 0x3F];
buffer[outPtr++] = _base64ToAsciiC[(bits >> 12) & 0x3F];
if (_usesPadding) {
buffer[outPtr++] = (outputBytes == 2) ?
_base64ToAsciiC[(bits >> 6) & 0x3F] : _paddingChar;
buffer[outPtr++] = _paddingChar;
} else {
if (outputBytes == 2) {
buffer[outPtr++] = _base64ToAsciiC[(bits >> 6) & 0x3F];
}
}
return outPtr;
}
public void encodeBase64Partial(StringBuilder sb, int bits, int outputBytes)
{
sb.append(_base64ToAsciiC[(bits >> 18) & 0x3F]);
sb.append(_base64ToAsciiC[(bits >> 12) & 0x3F]);
if (_usesPadding) {
sb.append((outputBytes == 2) ?
_base64ToAsciiC[(bits >> 6) & 0x3F] : _paddingChar);
sb.append(_paddingChar);
} else {
if (outputBytes == 2) {
sb.append(_base64ToAsciiC[(bits >> 6) & 0x3F]);
}
}
}
public byte encodeBase64BitsAsByte(int value)
{
// As with above, assuming it is 6-bit value
return _base64ToAsciiB[value];
}
/**
* Method that encodes given right-aligned (LSB) 24-bit value
* into 4 base64 bytes (ascii), stored in given result buffer.
*/
public int encodeBase64Chunk(int b24, byte[] buffer, int ptr)
{
buffer[ptr++] = _base64ToAsciiB[(b24 >> 18) & 0x3F];
buffer[ptr++] = _base64ToAsciiB[(b24 >> 12) & 0x3F];
buffer[ptr++] = _base64ToAsciiB[(b24 >> 6) & 0x3F];
buffer[ptr++] = _base64ToAsciiB[b24 & 0x3F];
return ptr;
}
/**
* Method that outputs partial chunk (which only encodes one
* or two bytes of data). Data given is still aligned same as if
* it as full data; that is, missing data is at the "right end"
* (LSB) of int.
*
* @param outputBytes Number of encoded bytes included (either 1 or 2)
*/
public int encodeBase64Partial(int bits, int outputBytes, byte[] buffer, int outPtr)
{
buffer[outPtr++] = _base64ToAsciiB[(bits >> 18) & 0x3F];
buffer[outPtr++] = _base64ToAsciiB[(bits >> 12) & 0x3F];
if (_usesPadding) {
byte pb = (byte) _paddingChar;
buffer[outPtr++] = (outputBytes == 2) ?
_base64ToAsciiB[(bits >> 6) & 0x3F] : pb;
buffer[outPtr++] = pb;
} else {
if (outputBytes == 2) {
buffer[outPtr++] = _base64ToAsciiB[(bits >> 6) & 0x3F];
}
}
return outPtr;
}
/*
////////////////////////////////////////////////////
// other methods
////////////////////////////////////////////////////
*/
// @Override
public String toString() { return _name; }
}