BaseEncoding.java
/*
* Copyright (C) 2012 The Guava 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.common.io;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkPositionIndexes;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.math.IntMath.divide;
import static com.google.common.math.IntMath.log2;
import static java.math.RoundingMode.CEILING;
import static java.math.RoundingMode.FLOOR;
import static java.math.RoundingMode.UNNECESSARY;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Ascii;
import com.google.common.base.Objects;
import com.google.errorprone.annotations.concurrent.LazyInit;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.Writer;
import java.util.Arrays;
import javax.annotation.CheckForNull;
/**
* A binary encoding scheme for reversibly translating between byte sequences and printable ASCII
* strings. This class includes several constants for encoding schemes specified by <a
* href="http://tools.ietf.org/html/rfc4648">RFC 4648</a>. For example, the expression:
*
* <pre>{@code
* BaseEncoding.base32().encode("foo".getBytes(Charsets.US_ASCII))
* }</pre>
*
* <p>returns the string {@code "MZXW6==="}, and
*
* <pre>{@code
* byte[] decoded = BaseEncoding.base32().decode("MZXW6===");
* }</pre>
*
* <p>...returns the ASCII bytes of the string {@code "foo"}.
*
* <p>By default, {@code BaseEncoding}'s behavior is relatively strict and in accordance with RFC
* 4648. Decoding rejects characters in the wrong case, though padding is optional. To modify
* encoding and decoding behavior, use configuration methods to obtain a new encoding with modified
* behavior:
*
* <pre>{@code
* BaseEncoding.base16().lowerCase().decode("deadbeef");
* }</pre>
*
* <p>Warning: BaseEncoding instances are immutable. Invoking a configuration method has no effect
* on the receiving instance; you must store and use the new encoding instance it returns, instead.
*
* <pre>{@code
* // Do NOT do this
* BaseEncoding hex = BaseEncoding.base16();
* hex.lowerCase(); // does nothing!
* return hex.decode("deadbeef"); // throws an IllegalArgumentException
* }</pre>
*
* <p>It is guaranteed that {@code encoding.decode(encoding.encode(x))} is always equal to {@code
* x}, but the reverse does not necessarily hold.
*
* <table>
* <caption>Encodings</caption>
* <tr>
* <th>Encoding
* <th>Alphabet
* <th>{@code char:byte} ratio
* <th>Default padding
* <th>Comments
* <tr>
* <td>{@link #base16()}
* <td>0-9 A-F
* <td>2.00
* <td>N/A
* <td>Traditional hexadecimal. Defaults to upper case.
* <tr>
* <td>{@link #base32()}
* <td>A-Z 2-7
* <td>1.60
* <td>=
* <td>Human-readable; no possibility of mixing up 0/O or 1/I. Defaults to upper case.
* <tr>
* <td>{@link #base32Hex()}
* <td>0-9 A-V
* <td>1.60
* <td>=
* <td>"Numerical" base 32; extended from the traditional hex alphabet. Defaults to upper case.
* <tr>
* <td>{@link #base64()}
* <td>A-Z a-z 0-9 + /
* <td>1.33
* <td>=
* <td>
* <tr>
* <td>{@link #base64Url()}
* <td>A-Z a-z 0-9 - _
* <td>1.33
* <td>=
* <td>Safe to use as filenames, or to pass in URLs without escaping
* </table>
*
* <p>All instances of this class are immutable, so they may be stored safely as static constants.
*
* @author Louis Wasserman
* @since 14.0
*/
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public abstract class BaseEncoding {
// TODO(lowasser): consider making encodeTo(Appendable, byte[], int, int) public.
BaseEncoding() {}
/**
* Exception indicating invalid base-encoded input encountered while decoding.
*
* @author Louis Wasserman
* @since 15.0
*/
public static final class DecodingException extends IOException {
DecodingException(String message) {
super(message);
}
DecodingException(Throwable cause) {
super(cause);
}
}
/** Encodes the specified byte array, and returns the encoded {@code String}. */
public String encode(byte[] bytes) {
return encode(bytes, 0, bytes.length);
}
/**
* Encodes the specified range of the specified byte array, and returns the encoded {@code
* String}.
*/
public final String encode(byte[] bytes, int off, int len) {
checkPositionIndexes(off, off + len, bytes.length);
StringBuilder result = new StringBuilder(maxEncodedSize(len));
try {
encodeTo(result, bytes, off, len);
} catch (IOException impossible) {
throw new AssertionError(impossible);
}
return result.toString();
}
/**
* Returns an {@code OutputStream} that encodes bytes using this encoding into the specified
* {@code Writer}. When the returned {@code OutputStream} is closed, so is the backing {@code
* Writer}.
*/
@GwtIncompatible // Writer,OutputStream
public abstract OutputStream encodingStream(Writer writer);
/**
* Returns a {@code ByteSink} that writes base-encoded bytes to the specified {@code CharSink}.
*/
@GwtIncompatible // ByteSink,CharSink
public final ByteSink encodingSink(final CharSink encodedSink) {
checkNotNull(encodedSink);
return new ByteSink() {
@Override
public OutputStream openStream() throws IOException {
return encodingStream(encodedSink.openStream());
}
};
}
// TODO(lowasser): document the extent of leniency, probably after adding ignore(CharMatcher)
private static byte[] extract(byte[] result, int length) {
if (length == result.length) {
return result;
}
byte[] trunc = new byte[length];
System.arraycopy(result, 0, trunc, 0, length);
return trunc;
}
/**
* Determines whether the specified character sequence is a valid encoded string according to this
* encoding.
*
* @since 20.0
*/
public abstract boolean canDecode(CharSequence chars);
/**
* Decodes the specified character sequence, and returns the resulting {@code byte[]}. This is the
* inverse operation to {@link #encode(byte[])}.
*
* @throws IllegalArgumentException if the input is not a valid encoded string according to this
* encoding.
*/
public final byte[] decode(CharSequence chars) {
try {
return decodeChecked(chars);
} catch (DecodingException badInput) {
throw new IllegalArgumentException(badInput);
}
}
/**
* Decodes the specified character sequence, and returns the resulting {@code byte[]}. This is the
* inverse operation to {@link #encode(byte[])}.
*
* @throws DecodingException if the input is not a valid encoded string according to this
* encoding.
*/
final byte[] decodeChecked(CharSequence chars)
throws DecodingException {
chars = trimTrailingPadding(chars);
byte[] tmp = new byte[maxDecodedSize(chars.length())];
int len = decodeTo(tmp, chars);
return extract(tmp, len);
}
/**
* Returns an {@code InputStream} that decodes base-encoded input from the specified {@code
* Reader}. The returned stream throws a {@link DecodingException} upon decoding-specific errors.
*/
@GwtIncompatible // Reader,InputStream
public abstract InputStream decodingStream(Reader reader);
/**
* Returns a {@code ByteSource} that reads base-encoded bytes from the specified {@code
* CharSource}.
*/
@GwtIncompatible // ByteSource,CharSource
public final ByteSource decodingSource(final CharSource encodedSource) {
checkNotNull(encodedSource);
return new ByteSource() {
@Override
public InputStream openStream() throws IOException {
return decodingStream(encodedSource.openStream());
}
};
}
// Implementations for encoding/decoding
abstract int maxEncodedSize(int bytes);
abstract void encodeTo(Appendable target, byte[] bytes, int off, int len) throws IOException;
abstract int maxDecodedSize(int chars);
abstract int decodeTo(byte[] target, CharSequence chars) throws DecodingException;
CharSequence trimTrailingPadding(CharSequence chars) {
return checkNotNull(chars);
}
// Modified encoding generators
/**
* Returns an encoding that behaves equivalently to this encoding, but omits any padding
* characters as specified by <a href="http://tools.ietf.org/html/rfc4648#section-3.2">RFC 4648
* section 3.2</a>, Padding of Encoded Data.
*/
public abstract BaseEncoding omitPadding();
/**
* Returns an encoding that behaves equivalently to this encoding, but uses an alternate character
* for padding.
*
* @throws IllegalArgumentException if this padding character is already used in the alphabet or a
* separator
*/
public abstract BaseEncoding withPadChar(char padChar);
/**
* Returns an encoding that behaves equivalently to this encoding, but adds a separator string
* after every {@code n} characters. Any occurrences of any characters that occur in the separator
* are skipped over in decoding.
*
* @throws IllegalArgumentException if any alphabet or padding characters appear in the separator
* string, or if {@code n <= 0}
* @throws UnsupportedOperationException if this encoding already uses a separator
*/
public abstract BaseEncoding withSeparator(String separator, int n);
/**
* Returns an encoding that behaves equivalently to this encoding, but encodes and decodes with
* uppercase letters. Padding and separator characters remain in their original case.
*
* @throws IllegalStateException if the alphabet used by this encoding contains mixed upper- and
* lower-case characters
*/
public abstract BaseEncoding upperCase();
/**
* Returns an encoding that behaves equivalently to this encoding, but encodes and decodes with
* lowercase letters. Padding and separator characters remain in their original case.
*
* @throws IllegalStateException if the alphabet used by this encoding contains mixed upper- and
* lower-case characters
*/
public abstract BaseEncoding lowerCase();
private static final BaseEncoding BASE64 =
new Base64Encoding(
"base64()", "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/", '=');
/**
* The "base64" base encoding specified by <a
* href="http://tools.ietf.org/html/rfc4648#section-4">RFC 4648 section 4</a>, Base 64 Encoding.
* (This is the same as the base 64 encoding from <a
* href="http://tools.ietf.org/html/rfc3548#section-3">RFC 3548</a>.)
*
* <p>The character {@code '='} is used for padding, but can be {@linkplain #omitPadding()
* omitted} or {@linkplain #withPadChar(char) replaced}.
*
* <p>No line feeds are added by default, as per <a
* href="http://tools.ietf.org/html/rfc4648#section-3.1">RFC 4648 section 3.1</a>, Line Feeds in
* Encoded Data. Line feeds may be added using {@link #withSeparator(String, int)}.
*/
public static BaseEncoding base64() {
return BASE64;
}
private static final BaseEncoding BASE64_URL =
new Base64Encoding(
"base64Url()", "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_", '=');
/**
* The "base64url" encoding specified by <a
* href="http://tools.ietf.org/html/rfc4648#section-5">RFC 4648 section 5</a>, Base 64 Encoding
* with URL and Filename Safe Alphabet, also sometimes referred to as the "web safe Base64." (This
* is the same as the base 64 encoding with URL and filename safe alphabet from <a
* href="http://tools.ietf.org/html/rfc3548#section-4">RFC 3548</a>.)
*
* <p>The character {@code '='} is used for padding, but can be {@linkplain #omitPadding()
* omitted} or {@linkplain #withPadChar(char) replaced}.
*
* <p>No line feeds are added by default, as per <a
* href="http://tools.ietf.org/html/rfc4648#section-3.1">RFC 4648 section 3.1</a>, Line Feeds in
* Encoded Data. Line feeds may be added using {@link #withSeparator(String, int)}.
*/
public static BaseEncoding base64Url() {
return BASE64_URL;
}
private static final BaseEncoding BASE32 =
new StandardBaseEncoding("base32()", "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567", '=');
/**
* The "base32" encoding specified by <a href="http://tools.ietf.org/html/rfc4648#section-6">RFC
* 4648 section 6</a>, Base 32 Encoding. (This is the same as the base 32 encoding from <a
* href="http://tools.ietf.org/html/rfc3548#section-5">RFC 3548</a>.)
*
* <p>The character {@code '='} is used for padding, but can be {@linkplain #omitPadding()
* omitted} or {@linkplain #withPadChar(char) replaced}.
*
* <p>No line feeds are added by default, as per <a
* href="http://tools.ietf.org/html/rfc4648#section-3.1">RFC 4648 section 3.1</a>, Line Feeds in
* Encoded Data. Line feeds may be added using {@link #withSeparator(String, int)}.
*/
public static BaseEncoding base32() {
return BASE32;
}
private static final BaseEncoding BASE32_HEX =
new StandardBaseEncoding("base32Hex()", "0123456789ABCDEFGHIJKLMNOPQRSTUV", '=');
/**
* The "base32hex" encoding specified by <a
* href="http://tools.ietf.org/html/rfc4648#section-7">RFC 4648 section 7</a>, Base 32 Encoding
* with Extended Hex Alphabet. There is no corresponding encoding in RFC 3548.
*
* <p>The character {@code '='} is used for padding, but can be {@linkplain #omitPadding()
* omitted} or {@linkplain #withPadChar(char) replaced}.
*
* <p>No line feeds are added by default, as per <a
* href="http://tools.ietf.org/html/rfc4648#section-3.1">RFC 4648 section 3.1</a>, Line Feeds in
* Encoded Data. Line feeds may be added using {@link #withSeparator(String, int)}.
*/
public static BaseEncoding base32Hex() {
return BASE32_HEX;
}
private static final BaseEncoding BASE16 = new Base16Encoding("base16()", "0123456789ABCDEF");
/**
* The "base16" encoding specified by <a href="http://tools.ietf.org/html/rfc4648#section-8">RFC
* 4648 section 8</a>, Base 16 Encoding. (This is the same as the base 16 encoding from <a
* href="http://tools.ietf.org/html/rfc3548#section-6">RFC 3548</a>.) This is commonly known as
* "hexadecimal" format.
*
* <p>No padding is necessary in base 16, so {@link #withPadChar(char)} and {@link #omitPadding()}
* have no effect.
*
* <p>No line feeds are added by default, as per <a
* href="http://tools.ietf.org/html/rfc4648#section-3.1">RFC 4648 section 3.1</a>, Line Feeds in
* Encoded Data. Line feeds may be added using {@link #withSeparator(String, int)}.
*/
public static BaseEncoding base16() {
return BASE16;
}
private static final class Alphabet {
private final String name;
// this is meant to be immutable -- don't modify it!
private final char[] chars;
final int mask;
final int bitsPerChar;
final int charsPerChunk;
final int bytesPerChunk;
private final byte[] decodabet;
private final boolean[] validPadding;
Alphabet(String name, char[] chars) {
this.name = checkNotNull(name);
this.chars = checkNotNull(chars);
try {
this.bitsPerChar = log2(chars.length, UNNECESSARY);
} catch (ArithmeticException e) {
throw new IllegalArgumentException("Illegal alphabet length " + chars.length, e);
}
/*
* e.g. for base64, bitsPerChar == 6, charsPerChunk == 4, and bytesPerChunk == 3. This makes
* for the smallest chunk size that still has charsPerChunk * bitsPerChar be a multiple of 8.
*/
int gcd = Math.min(8, Integer.lowestOneBit(bitsPerChar));
try {
this.charsPerChunk = 8 / gcd;
this.bytesPerChunk = bitsPerChar / gcd;
} catch (ArithmeticException e) {
throw new IllegalArgumentException("Illegal alphabet " + new String(chars), e);
}
this.mask = chars.length - 1;
byte[] decodabet = new byte[Ascii.MAX + 1];
Arrays.fill(decodabet, (byte) -1);
for (int i = 0; i < chars.length; i++) {
char c = chars[i];
checkArgument(c < decodabet.length, "Non-ASCII character: %s", c);
checkArgument(decodabet[c] == -1, "Duplicate character: %s", c);
decodabet[c] = (byte) i;
}
this.decodabet = decodabet;
boolean[] validPadding = new boolean[charsPerChunk];
for (int i = 0; i < bytesPerChunk; i++) {
validPadding[divide(i * 8, bitsPerChar, CEILING)] = true;
}
this.validPadding = validPadding;
}
char encode(int bits) {
return chars[bits];
}
boolean isValidPaddingStartPosition(int index) {
return validPadding[index % charsPerChunk];
}
boolean canDecode(char ch) {
return ch <= Ascii.MAX && decodabet[ch] != -1;
}
int decode(char ch) throws DecodingException {
if (ch > Ascii.MAX) {
throw new DecodingException("Unrecognized character: 0x" + Integer.toHexString(ch));
}
int result = decodabet[ch];
if (result == -1) {
if (ch <= 0x20 || ch == Ascii.MAX) {
throw new DecodingException("Unrecognized character: 0x" + Integer.toHexString(ch));
} else {
throw new DecodingException("Unrecognized character: " + ch);
}
}
return result;
}
private boolean hasLowerCase() {
for (char c : chars) {
if (Ascii.isLowerCase(c)) {
return true;
}
}
return false;
}
private boolean hasUpperCase() {
for (char c : chars) {
if (Ascii.isUpperCase(c)) {
return true;
}
}
return false;
}
Alphabet upperCase() {
if (!hasLowerCase()) {
return this;
}
checkState(!hasUpperCase(), "Cannot call upperCase() on a mixed-case alphabet");
char[] upperCased = new char[chars.length];
for (int i = 0; i < chars.length; i++) {
upperCased[i] = Ascii.toUpperCase(chars[i]);
}
return new Alphabet(name + ".upperCase()", upperCased);
}
Alphabet lowerCase() {
if (!hasUpperCase()) {
return this;
}
checkState(!hasLowerCase(), "Cannot call lowerCase() on a mixed-case alphabet");
char[] lowerCased = new char[chars.length];
for (int i = 0; i < chars.length; i++) {
lowerCased[i] = Ascii.toLowerCase(chars[i]);
}
return new Alphabet(name + ".lowerCase()", lowerCased);
}
public boolean matches(char c) {
return c < decodabet.length && decodabet[c] != -1;
}
@Override
public String toString() {
return name;
}
@Override
public boolean equals(@CheckForNull Object other) {
if (other instanceof Alphabet) {
Alphabet that = (Alphabet) other;
return Arrays.equals(this.chars, that.chars);
}
return false;
}
@Override
public int hashCode() {
return Arrays.hashCode(chars);
}
}
static class StandardBaseEncoding extends BaseEncoding {
// TODO(lowasser): provide a useful toString
final Alphabet alphabet;
@CheckForNull final Character paddingChar;
StandardBaseEncoding(String name, String alphabetChars, @CheckForNull Character paddingChar) {
this(new Alphabet(name, alphabetChars.toCharArray()), paddingChar);
}
StandardBaseEncoding(Alphabet alphabet, @CheckForNull Character paddingChar) {
this.alphabet = checkNotNull(alphabet);
checkArgument(
paddingChar == null || !alphabet.matches(paddingChar),
"Padding character %s was already in alphabet",
paddingChar);
this.paddingChar = paddingChar;
}
@Override
int maxEncodedSize(int bytes) {
return alphabet.charsPerChunk * divide(bytes, alphabet.bytesPerChunk, CEILING);
}
@GwtIncompatible // Writer,OutputStream
@Override
public OutputStream encodingStream(final Writer out) {
checkNotNull(out);
return new OutputStream() {
int bitBuffer = 0;
int bitBufferLength = 0;
int writtenChars = 0;
@Override
public void write(int b) throws IOException {
bitBuffer <<= 8;
bitBuffer |= b & 0xFF;
bitBufferLength += 8;
while (bitBufferLength >= alphabet.bitsPerChar) {
int charIndex = (bitBuffer >> (bitBufferLength - alphabet.bitsPerChar)) & alphabet.mask;
out.write(alphabet.encode(charIndex));
writtenChars++;
bitBufferLength -= alphabet.bitsPerChar;
}
}
@Override
public void flush() throws IOException {
out.flush();
}
@Override
public void close() throws IOException {
if (bitBufferLength > 0) {
int charIndex = (bitBuffer << (alphabet.bitsPerChar - bitBufferLength)) & alphabet.mask;
out.write(alphabet.encode(charIndex));
writtenChars++;
if (paddingChar != null) {
while (writtenChars % alphabet.charsPerChunk != 0) {
out.write(paddingChar.charValue());
writtenChars++;
}
}
}
out.close();
}
};
}
@Override
void encodeTo(Appendable target, byte[] bytes, int off, int len) throws IOException {
checkNotNull(target);
checkPositionIndexes(off, off + len, bytes.length);
for (int i = 0; i < len; i += alphabet.bytesPerChunk) {
encodeChunkTo(target, bytes, off + i, Math.min(alphabet.bytesPerChunk, len - i));
}
}
void encodeChunkTo(Appendable target, byte[] bytes, int off, int len) throws IOException {
checkNotNull(target);
checkPositionIndexes(off, off + len, bytes.length);
checkArgument(len <= alphabet.bytesPerChunk);
long bitBuffer = 0;
for (int i = 0; i < len; ++i) {
bitBuffer |= bytes[off + i] & 0xFF;
bitBuffer <<= 8; // Add additional zero byte in the end.
}
// Position of first character is length of bitBuffer minus bitsPerChar.
final int bitOffset = (len + 1) * 8 - alphabet.bitsPerChar;
int bitsProcessed = 0;
while (bitsProcessed < len * 8) {
int charIndex = (int) (bitBuffer >>> (bitOffset - bitsProcessed)) & alphabet.mask;
target.append(alphabet.encode(charIndex));
bitsProcessed += alphabet.bitsPerChar;
}
if (paddingChar != null) {
while (bitsProcessed < alphabet.bytesPerChunk * 8) {
target.append(paddingChar.charValue());
bitsProcessed += alphabet.bitsPerChar;
}
}
}
@Override
int maxDecodedSize(int chars) {
return (int) ((alphabet.bitsPerChar * (long) chars + 7L) / 8L);
}
@Override
CharSequence trimTrailingPadding(CharSequence chars) {
checkNotNull(chars);
if (paddingChar == null) {
return chars;
}
char padChar = paddingChar.charValue();
int l;
for (l = chars.length() - 1; l >= 0; l--) {
if (chars.charAt(l) != padChar) {
break;
}
}
return chars.subSequence(0, l + 1);
}
@Override
public boolean canDecode(CharSequence chars) {
checkNotNull(chars);
chars = trimTrailingPadding(chars);
if (!alphabet.isValidPaddingStartPosition(chars.length())) {
return false;
}
for (int i = 0; i < chars.length(); i++) {
if (!alphabet.canDecode(chars.charAt(i))) {
return false;
}
}
return true;
}
@Override
int decodeTo(byte[] target, CharSequence chars) throws DecodingException {
checkNotNull(target);
chars = trimTrailingPadding(chars);
if (!alphabet.isValidPaddingStartPosition(chars.length())) {
throw new DecodingException("Invalid input length " + chars.length());
}
int bytesWritten = 0;
for (int charIdx = 0; charIdx < chars.length(); charIdx += alphabet.charsPerChunk) {
long chunk = 0;
int charsProcessed = 0;
for (int i = 0; i < alphabet.charsPerChunk; i++) {
chunk <<= alphabet.bitsPerChar;
if (charIdx + i < chars.length()) {
chunk |= alphabet.decode(chars.charAt(charIdx + charsProcessed++));
}
}
final int minOffset = alphabet.bytesPerChunk * 8 - charsProcessed * alphabet.bitsPerChar;
for (int offset = (alphabet.bytesPerChunk - 1) * 8; offset >= minOffset; offset -= 8) {
target[bytesWritten++] = (byte) ((chunk >>> offset) & 0xFF);
}
}
return bytesWritten;
}
@Override
@GwtIncompatible // Reader,InputStream
public InputStream decodingStream(final Reader reader) {
checkNotNull(reader);
return new InputStream() {
int bitBuffer = 0;
int bitBufferLength = 0;
int readChars = 0;
boolean hitPadding = false;
@Override
public int read() throws IOException {
while (true) {
int readChar = reader.read();
if (readChar == -1) {
if (!hitPadding && !alphabet.isValidPaddingStartPosition(readChars)) {
throw new DecodingException("Invalid input length " + readChars);
}
return -1;
}
readChars++;
char ch = (char) readChar;
if (paddingChar != null && paddingChar.charValue() == ch) {
if (!hitPadding
&& (readChars == 1 || !alphabet.isValidPaddingStartPosition(readChars - 1))) {
throw new DecodingException("Padding cannot start at index " + readChars);
}
hitPadding = true;
} else if (hitPadding) {
throw new DecodingException(
"Expected padding character but found '" + ch + "' at index " + readChars);
} else {
bitBuffer <<= alphabet.bitsPerChar;
bitBuffer |= alphabet.decode(ch);
bitBufferLength += alphabet.bitsPerChar;
if (bitBufferLength >= 8) {
bitBufferLength -= 8;
return (bitBuffer >> bitBufferLength) & 0xFF;
}
}
}
}
@Override
public int read(byte[] buf, int off, int len) throws IOException {
// Overriding this to work around the fact that InputStream's default implementation of
// this method will silently swallow exceptions thrown by the single-byte read() method
// (other than on the first call to it), which in this case can cause invalid encoded
// strings to not throw an exception.
// See https://github.com/google/guava/issues/3542
checkPositionIndexes(off, off + len, buf.length);
int i = off;
for (; i < off + len; i++) {
int b = read();
if (b == -1) {
int read = i - off;
return read == 0 ? -1 : read;
}
buf[i] = (byte) b;
}
return i - off;
}
@Override
public void close() throws IOException {
reader.close();
}
};
}
@Override
public BaseEncoding omitPadding() {
return (paddingChar == null) ? this : newInstance(alphabet, null);
}
@Override
public BaseEncoding withPadChar(char padChar) {
if (8 % alphabet.bitsPerChar == 0
|| (paddingChar != null && paddingChar.charValue() == padChar)) {
return this;
} else {
return newInstance(alphabet, padChar);
}
}
@Override
public BaseEncoding withSeparator(String separator, int afterEveryChars) {
for (int i = 0; i < separator.length(); i++) {
checkArgument(
!alphabet.matches(separator.charAt(i)),
"Separator (%s) cannot contain alphabet characters",
separator);
}
if (paddingChar != null) {
checkArgument(
separator.indexOf(paddingChar.charValue()) < 0,
"Separator (%s) cannot contain padding character",
separator);
}
return new SeparatedBaseEncoding(this, separator, afterEveryChars);
}
@LazyInit @CheckForNull private transient BaseEncoding upperCase;
@LazyInit @CheckForNull private transient BaseEncoding lowerCase;
@Override
public BaseEncoding upperCase() {
BaseEncoding result = upperCase;
if (result == null) {
Alphabet upper = alphabet.upperCase();
result = upperCase = (upper == alphabet) ? this : newInstance(upper, paddingChar);
}
return result;
}
@Override
public BaseEncoding lowerCase() {
BaseEncoding result = lowerCase;
if (result == null) {
Alphabet lower = alphabet.lowerCase();
result = lowerCase = (lower == alphabet) ? this : newInstance(lower, paddingChar);
}
return result;
}
BaseEncoding newInstance(Alphabet alphabet, @CheckForNull Character paddingChar) {
return new StandardBaseEncoding(alphabet, paddingChar);
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder("BaseEncoding.");
builder.append(alphabet.toString());
if (8 % alphabet.bitsPerChar != 0) {
if (paddingChar == null) {
builder.append(".omitPadding()");
} else {
builder.append(".withPadChar('").append(paddingChar).append("')");
}
}
return builder.toString();
}
@Override
public boolean equals(@CheckForNull Object other) {
if (other instanceof StandardBaseEncoding) {
StandardBaseEncoding that = (StandardBaseEncoding) other;
return this.alphabet.equals(that.alphabet)
&& Objects.equal(this.paddingChar, that.paddingChar);
}
return false;
}
@Override
public int hashCode() {
return alphabet.hashCode() ^ Objects.hashCode(paddingChar);
}
}
static final class Base16Encoding extends StandardBaseEncoding {
final char[] encoding = new char[512];
Base16Encoding(String name, String alphabetChars) {
this(new Alphabet(name, alphabetChars.toCharArray()));
}
private Base16Encoding(Alphabet alphabet) {
super(alphabet, null);
checkArgument(alphabet.chars.length == 16);
for (int i = 0; i < 256; ++i) {
encoding[i] = alphabet.encode(i >>> 4);
encoding[i | 0x100] = alphabet.encode(i & 0xF);
}
}
@Override
void encodeTo(Appendable target, byte[] bytes, int off, int len) throws IOException {
checkNotNull(target);
checkPositionIndexes(off, off + len, bytes.length);
for (int i = 0; i < len; ++i) {
int b = bytes[off + i] & 0xFF;
target.append(encoding[b]);
target.append(encoding[b | 0x100]);
}
}
@Override
int decodeTo(byte[] target, CharSequence chars) throws DecodingException {
checkNotNull(target);
if (chars.length() % 2 == 1) {
throw new DecodingException("Invalid input length " + chars.length());
}
int bytesWritten = 0;
for (int i = 0; i < chars.length(); i += 2) {
int decoded = alphabet.decode(chars.charAt(i)) << 4 | alphabet.decode(chars.charAt(i + 1));
target[bytesWritten++] = (byte) decoded;
}
return bytesWritten;
}
@Override
BaseEncoding newInstance(Alphabet alphabet, @CheckForNull Character paddingChar) {
return new Base16Encoding(alphabet);
}
}
static final class Base64Encoding extends StandardBaseEncoding {
Base64Encoding(String name, String alphabetChars, @CheckForNull Character paddingChar) {
this(new Alphabet(name, alphabetChars.toCharArray()), paddingChar);
}
private Base64Encoding(Alphabet alphabet, @CheckForNull Character paddingChar) {
super(alphabet, paddingChar);
checkArgument(alphabet.chars.length == 64);
}
@Override
void encodeTo(Appendable target, byte[] bytes, int off, int len) throws IOException {
checkNotNull(target);
checkPositionIndexes(off, off + len, bytes.length);
int i = off;
for (int remaining = len; remaining >= 3; remaining -= 3) {
int chunk = (bytes[i++] & 0xFF) << 16 | (bytes[i++] & 0xFF) << 8 | bytes[i++] & 0xFF;
target.append(alphabet.encode(chunk >>> 18));
target.append(alphabet.encode((chunk >>> 12) & 0x3F));
target.append(alphabet.encode((chunk >>> 6) & 0x3F));
target.append(alphabet.encode(chunk & 0x3F));
}
if (i < off + len) {
encodeChunkTo(target, bytes, i, off + len - i);
}
}
@Override
int decodeTo(byte[] target, CharSequence chars) throws DecodingException {
checkNotNull(target);
chars = trimTrailingPadding(chars);
if (!alphabet.isValidPaddingStartPosition(chars.length())) {
throw new DecodingException("Invalid input length " + chars.length());
}
int bytesWritten = 0;
for (int i = 0; i < chars.length(); ) {
int chunk = alphabet.decode(chars.charAt(i++)) << 18;
chunk |= alphabet.decode(chars.charAt(i++)) << 12;
target[bytesWritten++] = (byte) (chunk >>> 16);
if (i < chars.length()) {
chunk |= alphabet.decode(chars.charAt(i++)) << 6;
target[bytesWritten++] = (byte) ((chunk >>> 8) & 0xFF);
if (i < chars.length()) {
chunk |= alphabet.decode(chars.charAt(i++));
target[bytesWritten++] = (byte) (chunk & 0xFF);
}
}
}
return bytesWritten;
}
@Override
BaseEncoding newInstance(Alphabet alphabet, @CheckForNull Character paddingChar) {
return new Base64Encoding(alphabet, paddingChar);
}
}
@GwtIncompatible
static Reader ignoringReader(final Reader delegate, final String toIgnore) {
checkNotNull(delegate);
checkNotNull(toIgnore);
return new Reader() {
@Override
public int read() throws IOException {
int readChar;
do {
readChar = delegate.read();
} while (readChar != -1 && toIgnore.indexOf((char) readChar) >= 0);
return readChar;
}
@Override
public int read(char[] cbuf, int off, int len) throws IOException {
throw new UnsupportedOperationException();
}
@Override
public void close() throws IOException {
delegate.close();
}
};
}
static Appendable separatingAppendable(
final Appendable delegate, final String separator, final int afterEveryChars) {
checkNotNull(delegate);
checkNotNull(separator);
checkArgument(afterEveryChars > 0);
return new Appendable() {
int charsUntilSeparator = afterEveryChars;
@Override
public Appendable append(char c) throws IOException {
if (charsUntilSeparator == 0) {
delegate.append(separator);
charsUntilSeparator = afterEveryChars;
}
delegate.append(c);
charsUntilSeparator--;
return this;
}
@Override
public Appendable append(@CheckForNull CharSequence chars, int off, int len) {
throw new UnsupportedOperationException();
}
@Override
public Appendable append(@CheckForNull CharSequence chars) {
throw new UnsupportedOperationException();
}
};
}
@GwtIncompatible // Writer
static Writer separatingWriter(
final Writer delegate, final String separator, final int afterEveryChars) {
final Appendable separatingAppendable =
separatingAppendable(delegate, separator, afterEveryChars);
return new Writer() {
@Override
public void write(int c) throws IOException {
separatingAppendable.append((char) c);
}
@Override
public void write(char[] chars, int off, int len) throws IOException {
throw new UnsupportedOperationException();
}
@Override
public void flush() throws IOException {
delegate.flush();
}
@Override
public void close() throws IOException {
delegate.close();
}
};
}
static final class SeparatedBaseEncoding extends BaseEncoding {
private final BaseEncoding delegate;
private final String separator;
private final int afterEveryChars;
SeparatedBaseEncoding(BaseEncoding delegate, String separator, int afterEveryChars) {
this.delegate = checkNotNull(delegate);
this.separator = checkNotNull(separator);
this.afterEveryChars = afterEveryChars;
checkArgument(
afterEveryChars > 0, "Cannot add a separator after every %s chars", afterEveryChars);
}
@Override
CharSequence trimTrailingPadding(CharSequence chars) {
return delegate.trimTrailingPadding(chars);
}
@Override
int maxEncodedSize(int bytes) {
int unseparatedSize = delegate.maxEncodedSize(bytes);
return unseparatedSize
+ separator.length() * divide(Math.max(0, unseparatedSize - 1), afterEveryChars, FLOOR);
}
@GwtIncompatible // Writer,OutputStream
@Override
public OutputStream encodingStream(final Writer output) {
return delegate.encodingStream(separatingWriter(output, separator, afterEveryChars));
}
@Override
void encodeTo(Appendable target, byte[] bytes, int off, int len) throws IOException {
delegate.encodeTo(separatingAppendable(target, separator, afterEveryChars), bytes, off, len);
}
@Override
int maxDecodedSize(int chars) {
return delegate.maxDecodedSize(chars);
}
@Override
public boolean canDecode(CharSequence chars) {
StringBuilder builder = new StringBuilder();
for (int i = 0; i < chars.length(); i++) {
char c = chars.charAt(i);
if (separator.indexOf(c) < 0) {
builder.append(c);
}
}
return delegate.canDecode(builder);
}
@Override
int decodeTo(byte[] target, CharSequence chars) throws DecodingException {
StringBuilder stripped = new StringBuilder(chars.length());
for (int i = 0; i < chars.length(); i++) {
char c = chars.charAt(i);
if (separator.indexOf(c) < 0) {
stripped.append(c);
}
}
return delegate.decodeTo(target, stripped);
}
@Override
@GwtIncompatible // Reader,InputStream
public InputStream decodingStream(final Reader reader) {
return delegate.decodingStream(ignoringReader(reader, separator));
}
@Override
public BaseEncoding omitPadding() {
return delegate.omitPadding().withSeparator(separator, afterEveryChars);
}
@Override
public BaseEncoding withPadChar(char padChar) {
return delegate.withPadChar(padChar).withSeparator(separator, afterEveryChars);
}
@Override
public BaseEncoding withSeparator(String separator, int afterEveryChars) {
throw new UnsupportedOperationException("Already have a separator");
}
@Override
public BaseEncoding upperCase() {
return delegate.upperCase().withSeparator(separator, afterEveryChars);
}
@Override
public BaseEncoding lowerCase() {
return delegate.lowerCase().withSeparator(separator, afterEveryChars);
}
@Override
public String toString() {
return delegate + ".withSeparator(\"" + separator + "\", " + afterEveryChars + ")";
}
}
}