/*
* Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.net.http.internal.hpack;
import java.io.IOException;
import java.nio.ByteBuffer;
import static java.lang.String.format;
/**
* Huffman coding table.
*
* <p> Instances of this class are safe for use by multiple threads.
*
* @since 9
*/
public final class Huffman {
// TODO: check if reset is done in both reader and writer
static final class Reader {
private Node curr; // position in the trie
private int len; // length of the path from the root to 'curr'
private int p; // byte probe
{
reset();
}
public void read(ByteBuffer source,
Appendable destination,
boolean isLast) throws IOException {
read(source, destination, true, isLast);
}
// Takes 'isLast' rather than returns whether the reading is done or
// not, for more informative exceptions.
void read(ByteBuffer source,
Appendable destination,
boolean reportEOS, /* reportEOS is exposed for tests */
boolean isLast) throws IOException {
Node c = curr;
int l = len;
/*
Since ByteBuffer is itself stateful, its position is
remembered here NOT as a part of Reader's state,
but to set it back in the case of a failure
*/
int pos = source.position();
while (source.hasRemaining()) {
int d = source.get();
for (; p != 0; p >>= 1) {
c = c.getChild(p & d);
l++;
if (c.isLeaf()) {
if (reportEOS && c.isEOSPath) {
throw new IOException("Encountered EOS");
}
char ch;
try {
ch = c.getChar();
} catch (IllegalStateException e) {
source.position(pos); // do we need this?
throw new IOException(e);
}
try {
destination.append(ch);
} catch (IOException e) {
source.position(pos); // do we need this?
throw e;
}
c = INSTANCE.root;
l = 0;
}
curr = c;
len = l;
}
resetProbe();
pos++;
}
if (!isLast) {
return; // it's too early to jump to any conclusions, let's wait
}
if (c.isLeaf()) {
return; // it's perfectly ok, no extra padding bits
}
if (c.isEOSPath && len <= 7) {
return; // it's ok, some extra padding bits
}
if (c.isEOSPath) {
throw new IOException(
"Padding is too long (len=" + len + ") " +
"or unexpected end of data");
}
throw new IOException(
"Not a EOS prefix padding or unexpected end of data");
}
public void reset() {
curr = INSTANCE.root;
len = 0;
resetProbe();
}
private void resetProbe() {
p = 0x80;
}
}
static final class Writer {
private int pos; // position in 'source'
private int avail = 8; // number of least significant bits available in 'curr'
private int curr; // next byte to put to the destination
private int rem; // number of least significant bits in 'code' yet to be processed
private int code; // current code being written
private CharSequence source;
private int end;
public Writer from(CharSequence input, int start, int end) {
if (start < 0 || end < 0 || end > input.length() || start > end) {
throw new IndexOutOfBoundsException(
String.format("input.length()=%s, start=%s, end=%s",
input.length(), start, end));
}
pos = start;
this.end = end;
this.source = input;
return this;
}
public boolean write(ByteBuffer destination) {
for (; pos < end; pos++) {
if (rem == 0) {
Code desc = INSTANCE.codeOf(source.charAt(pos));
rem = desc.length;
code = desc.code;
}
while (rem > 0) {
if (rem < avail) {
curr |= (code << (avail - rem));
avail -= rem;
rem = 0;
} else {
int c = (curr | (code >>> (rem - avail)));
if (destination.hasRemaining()) {
destination.put((byte) c);
} else {
return false;
}
curr = c;
code <<= (32 - rem + avail); // throw written bits off the cliff (is this Sparta?)
code >>>= (32 - rem + avail); // return to the position
rem -= avail;
curr = 0;
avail = 8;
}
}
}
if (avail < 8) { // have to pad
if (destination.hasRemaining()) {
destination.put((byte) (curr | (INSTANCE.EOS.code >>> (INSTANCE.EOS.length - avail))));
avail = 8;
} else {
return false;
}
}
return true;
}
public Writer reset() {
source = null;
end = -1;
pos = -1;
avail = 8;
curr = 0;
code = 0;
return this;
}
}
/**
* Shared instance.
*/
public static final Huffman INSTANCE = new Huffman();
private final Code EOS = new Code(0x3fffffff, 30);
private final Code[] codes = new Code[257];
private final Node root = new Node() {
@Override
public String toString() { return "root"; }
};
// TODO: consider builder and immutable trie
private Huffman() {
// @formatter:off
addChar(0, 0x1ff8, 13);
addChar(1, 0x7fffd8, 23);
addChar(2, 0xfffffe2, 28);
addChar(3, 0xfffffe3, 28);
addChar(4, 0xfffffe4, 28);
addChar(5, 0xfffffe5, 28);
addChar(6, 0xfffffe6, 28);
addChar(7, 0xfffffe7, 28);
addChar(8, 0xfffffe8, 28);
addChar(9, 0xffffea, 24);
addChar(10, 0x3ffffffc, 30);
addChar(11, 0xfffffe9, 28);
addChar(12, 0xfffffea, 28);
addChar(13, 0x3ffffffd, 30);
addChar(14, 0xfffffeb, 28);
addChar(15, 0xfffffec, 28);
addChar(16, 0xfffffed, 28);
addChar(17, 0xfffffee, 28);
addChar(18, 0xfffffef, 28);
addChar(19, 0xffffff0, 28);
addChar(20, 0xffffff1, 28);
addChar(21, 0xffffff2, 28);
addChar(22, 0x3ffffffe, 30);
addChar(23, 0xffffff3, 28);
addChar(24, 0xffffff4, 28);
addChar(25, 0xffffff5, 28);
addChar(26, 0xffffff6, 28);
addChar(27, 0xffffff7, 28);
addChar(28, 0xffffff8, 28);
addChar(29, 0xffffff9, 28);
addChar(30, 0xffffffa, 28);
addChar(31, 0xffffffb, 28);
addChar(32, 0x14, 6);
addChar(33, 0x3f8, 10);
addChar(34, 0x3f9, 10);
addChar(35, 0xffa, 12);
addChar(36, 0x1ff9, 13);
addChar(37, 0x15, 6);
addChar(38, 0xf8, 8);
addChar(39, 0x7fa, 11);
addChar(40, 0x3fa, 10);
addChar(41, 0x3fb, 10);
addChar(42, 0xf9, 8);
addChar(43, 0x7fb, 11);
addChar(44, 0xfa, 8);
addChar(45, 0x16, 6);
addChar(46, 0x17, 6);
addChar(47, 0x18, 6);
addChar(48, 0x0, 5);
addChar(49, 0x1, 5);
addChar(50, 0x2, 5);
addChar(51, 0x19, 6);
addChar(52, 0x1a, 6);
addChar(53, 0x1b, 6);
addChar(54, 0x1c, 6);
addChar(55, 0x1d, 6);
addChar(56, 0x1e, 6);
addChar(57, 0x1f, 6);
addChar(58, 0x5c, 7);
addChar(59, 0xfb, 8);
addChar(60, 0x7ffc, 15);
addChar(61, 0x20, 6);
addChar(62, 0xffb, 12);
addChar(63, 0x3fc, 10);
addChar(64, 0x1ffa, 13);
addChar(65, 0x21, 6);
addChar(66, 0x5d, 7);
addChar(67, 0x5e, 7);
addChar(68, 0x5f, 7);
addChar(69, 0x60, 7);
addChar(70, 0x61, 7);
addChar(71, 0x62, 7);
addChar(72, 0x63, 7);
addChar(73, 0x64, 7);
addChar(74, 0x65, 7);
addChar(75, 0x66, 7);
addChar(76, 0x67, 7);
addChar(77, 0x68, 7);
addChar(78, 0x69, 7);
addChar(79, 0x6a, 7);
addChar(80, 0x6b, 7);
addChar(81, 0x6c, 7);
addChar(82, 0x6d, 7);
addChar(83, 0x6e, 7);
addChar(84, 0x6f, 7);
addChar(85, 0x70, 7);
addChar(86, 0x71, 7);
addChar(87, 0x72, 7);
addChar(88, 0xfc, 8);
addChar(89, 0x73, 7);
addChar(90, 0xfd, 8);
addChar(91, 0x1ffb, 13);
addChar(92, 0x7fff0, 19);
addChar(93, 0x1ffc, 13);
addChar(94, 0x3ffc, 14);
addChar(95, 0x22, 6);
addChar(96, 0x7ffd, 15);
addChar(97, 0x3, 5);
addChar(98, 0x23, 6);
addChar(99, 0x4, 5);
addChar(100, 0x24, 6);
addChar(101, 0x5, 5);
addChar(102, 0x25, 6);
addChar(103, 0x26, 6);
addChar(104, 0x27, 6);
addChar(105, 0x6, 5);
addChar(106, 0x74, 7);
addChar(107, 0x75, 7);
addChar(108, 0x28, 6);
addChar(109, 0x29, 6);
addChar(110, 0x2a, 6);
addChar(111, 0x7, 5);
addChar(112, 0x2b, 6);
addChar(113, 0x76, 7);
addChar(114, 0x2c, 6);
addChar(115, 0x8, 5);
addChar(116, 0x9, 5);
addChar(117, 0x2d, 6);
addChar(118, 0x77, 7);
addChar(119, 0x78, 7);
addChar(120, 0x79, 7);
addChar(121, 0x7a, 7);
addChar(122, 0x7b, 7);
addChar(123, 0x7ffe, 15);
addChar(124, 0x7fc, 11);
addChar(125, 0x3ffd, 14);
addChar(126, 0x1ffd, 13);
addChar(127, 0xffffffc, 28);
addChar(128, 0xfffe6, 20);
addChar(129, 0x3fffd2, 22);
addChar(130, 0xfffe7, 20);
addChar(131, 0xfffe8, 20);
addChar(132, 0x3fffd3, 22);
addChar(133, 0x3fffd4, 22);
addChar(134, 0x3fffd5, 22);
addChar(135, 0x7fffd9, 23);
addChar(136, 0x3fffd6, 22);
addChar(137, 0x7fffda, 23);
addChar(138, 0x7fffdb, 23);
addChar(139, 0x7fffdc, 23);
addChar(140, 0x7fffdd, 23);
addChar(141, 0x7fffde, 23);
addChar(142, 0xffffeb, 24);
addChar(143, 0x7fffdf, 23);
addChar(144, 0xffffec, 24);
addChar(145, 0xffffed, 24);
addChar(146, 0x3fffd7, 22);
addChar(147, 0x7fffe0, 23);
addChar(148, 0xffffee, 24);
addChar(149, 0x7fffe1, 23);
addChar(150, 0x7fffe2, 23);
addChar(151, 0x7fffe3, 23);
addChar(152, 0x7fffe4, 23);
addChar(153, 0x1fffdc, 21);
addChar(154, 0x3fffd8, 22);
addChar(155, 0x7fffe5, 23);
addChar(156, 0x3fffd9, 22);
addChar(157, 0x7fffe6, 23);
addChar(158, 0x7fffe7, 23);
addChar(159, 0xffffef, 24);
addChar(160, 0x3fffda, 22);
addChar(161, 0x1fffdd, 21);
addChar(162, 0xfffe9, 20);
addChar(163, 0x3fffdb, 22);
addChar(164, 0x3fffdc, 22);
addChar(165, 0x7fffe8, 23);
addChar(166, 0x7fffe9, 23);
addChar(167, 0x1fffde, 21);
addChar(168, 0x7fffea, 23);
addChar(169, 0x3fffdd, 22);
addChar(170, 0x3fffde, 22);
addChar(171, 0xfffff0, 24);
addChar(172, 0x1fffdf, 21);
addChar(173, 0x3fffdf, 22);
addChar(174, 0x7fffeb, 23);
addChar(175, 0x7fffec, 23);
addChar(176, 0x1fffe0, 21);
addChar(177, 0x1fffe1, 21);
addChar(178, 0x3fffe0, 22);
addChar(179, 0x1fffe2, 21);
addChar(180, 0x7fffed, 23);
addChar(181, 0x3fffe1, 22);
addChar(182, 0x7fffee, 23);
addChar(183, 0x7fffef, 23);
addChar(184, 0xfffea, 20);
addChar(185, 0x3fffe2, 22);
addChar(186, 0x3fffe3, 22);
addChar(187, 0x3fffe4, 22);
addChar(188, 0x7ffff0, 23);
addChar(189, 0x3fffe5, 22);
addChar(190, 0x3fffe6, 22);
addChar(191, 0x7ffff1, 23);
addChar(192, 0x3ffffe0, 26);
addChar(193, 0x3ffffe1, 26);
addChar(194, 0xfffeb, 20);
addChar(195, 0x7fff1, 19);
addChar(196, 0x3fffe7, 22);
addChar(197, 0x7ffff2, 23);
addChar(198, 0x3fffe8, 22);
addChar(199, 0x1ffffec, 25);
addChar(200, 0x3ffffe2, 26);
addChar(201, 0x3ffffe3, 26);
addChar(202, 0x3ffffe4, 26);
addChar(203, 0x7ffffde, 27);
addChar(204, 0x7ffffdf, 27);
addChar(205, 0x3ffffe5, 26);
addChar(206, 0xfffff1, 24);
addChar(207, 0x1ffffed, 25);
addChar(208, 0x7fff2, 19);
addChar(209, 0x1fffe3, 21);
addChar(210, 0x3ffffe6, 26);
addChar(211, 0x7ffffe0, 27);
addChar(212, 0x7ffffe1, 27);
addChar(213, 0x3ffffe7, 26);
addChar(214, 0x7ffffe2, 27);
addChar(215, 0xfffff2, 24);
addChar(216, 0x1fffe4, 21);
addChar(217, 0x1fffe5, 21);
addChar(218, 0x3ffffe8, 26);
addChar(219, 0x3ffffe9, 26);
addChar(220, 0xffffffd, 28);
addChar(221, 0x7ffffe3, 27);
addChar(222, 0x7ffffe4, 27);
addChar(223, 0x7ffffe5, 27);
addChar(224, 0xfffec, 20);
addChar(225, 0xfffff3, 24);
addChar(226, 0xfffed, 20);
addChar(227, 0x1fffe6, 21);
addChar(228, 0x3fffe9, 22);
addChar(229, 0x1fffe7, 21);
addChar(230, 0x1fffe8, 21);
addChar(231, 0x7ffff3, 23);
addChar(232, 0x3fffea, 22);
addChar(233, 0x3fffeb, 22);
addChar(234, 0x1ffffee, 25);
addChar(235, 0x1ffffef, 25);
addChar(236, 0xfffff4, 24);
addChar(237, 0xfffff5, 24);
addChar(238, 0x3ffffea, 26);
addChar(239, 0x7ffff4, 23);
addChar(240, 0x3ffffeb, 26);
addChar(241, 0x7ffffe6, 27);
addChar(242, 0x3ffffec, 26);
addChar(243, 0x3ffffed, 26);
addChar(244, 0x7ffffe7, 27);
addChar(245, 0x7ffffe8, 27);
addChar(246, 0x7ffffe9, 27);
addChar(247, 0x7ffffea, 27);
addChar(248, 0x7ffffeb, 27);
addChar(249, 0xffffffe, 28);
addChar(250, 0x7ffffec, 27);
addChar(251, 0x7ffffed, 27);
addChar(252, 0x7ffffee, 27);
addChar(253, 0x7ffffef, 27);
addChar(254, 0x7fffff0, 27);
addChar(255, 0x3ffffee, 26);
addEOS (256, EOS.code, EOS.length);
// @formatter:on
}
/**
* Calculates the number of bytes required to represent the given {@code
* CharSequence} with the Huffman coding.
*
* @param value
* characters
*
* @return number of bytes
*
* @throws NullPointerException
* if the value is null
*/
public int lengthOf(CharSequence value) {
return lengthOf(value, 0, value.length());
}
/**
* Calculates the number of bytes required to represent a subsequence of the
* given {@code CharSequence} with the Huffman coding.
*
* @param value
* characters
* @param start
* the start index, inclusive
* @param end
* the end index, exclusive
*
* @return number of bytes
*
* @throws NullPointerException
* if the value is null
* @throws IndexOutOfBoundsException
* if any invocation of {@code value.charAt(i)}, where
* {@code start <= i < end} would throw an IndexOutOfBoundsException
*/
public int lengthOf(CharSequence value, int start, int end) {
int len = 0;
for (int i = start; i < end; i++) {
char c = value.charAt(i);
len += INSTANCE.codeOf(c).length;
}
// Integer division with ceiling, assumption:
assert (len / 8 + (len % 8 != 0 ? 1 : 0)) == (len + 7) / 8 : len;
return (len + 7) / 8;
}
private void addChar(int c, int code, int bitLength) {
addLeaf(c, code, bitLength, false);
codes[c] = new Code(code, bitLength);
}
private void addEOS(int c, int code, int bitLength) {
addLeaf(c, code, bitLength, true);
codes[c] = new Code(code, bitLength);
}
private void addLeaf(int c, int code, int bitLength, boolean isEOS) {
if (bitLength < 1) {
throw new IllegalArgumentException("bitLength < 1");
}
Node curr = root;
for (int p = 1 << bitLength - 1; p != 0 && !curr.isLeaf(); p = p >> 1) {
curr.isEOSPath |= isEOS; // If it's already true, it can't become false
curr = curr.addChildIfAbsent(p & code);
}
curr.isEOSPath |= isEOS; // The last one needs to have this property as well
if (curr.isLeaf()) {
throw new IllegalStateException("Specified code is already taken");
}
curr.setChar((char) c);
}
private Code codeOf(char c) {
if (c > 255) {
throw new IllegalArgumentException("char=" + ((int) c));
}
return codes[c];
}
//
// For debugging/testing purposes
//
Node getRoot() {
return root;
}
//
// Guarantees:
//
// if (isLeaf() == true) => getChar() is a legal call
// if (isLeaf() == false) => getChild(i) is a legal call (though it can
// return null)
//
static class Node {
Node left;
Node right;
boolean isEOSPath;
boolean charIsSet;
char c;
Node getChild(int selector) {
if (isLeaf()) {
throw new IllegalStateException("This is a leaf node");
}
Node result = selector == 0 ? left : right;
if (result == null) {
throw new IllegalStateException(format(
"Node doesn't have a child (selector=%s)", selector));
}
return result;
}
boolean isLeaf() {
return charIsSet;
}
char getChar() {
if (!isLeaf()) {
throw new IllegalStateException("This node is not a leaf node");
}
return c;
}
void setChar(char c) {
if (charIsSet) {
throw new IllegalStateException(
"This node has been taken already");
}
if (left != null || right != null) {
throw new IllegalStateException("The node cannot be made "
+ "a leaf as it's already has a child");
}
this.c = c;
charIsSet = true;
}
Node addChildIfAbsent(int i) {
if (charIsSet) {
throw new IllegalStateException("The node cannot have a child "
+ "as it's already a leaf node");
}
Node child;
if (i == 0) {
if ((child = left) == null) {
child = left = new Node();
}
} else {
if ((child = right) == null) {
child = right = new Node();
}
}
return child;
}
@Override
public String toString() {
if (isLeaf()) {
if (isEOSPath) {
return "EOS";
} else {
return format("char: (%3s) '%s'", (int) c, c);
}
}
return "/\\";
}
}
// TODO: value-based class?
// FIXME: can we re-use Node instead of this class?
private static final class Code {
final int code;
final int length;
private Code(int code, int length) {
this.code = code;
this.length = length;
}
public int getCode() {
return code;
}
public int getLength() {
return length;
}
@Override
public String toString() {
long p = 1 << length;
return Long.toBinaryString(code + p).substring(1)
+ ", length=" + length;
}
}
}