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1 /* |
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2 * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Oracle designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Oracle in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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22 * or visit www.oracle.com if you need additional information or have any |
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23 * questions. |
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24 */ |
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25 package jdk.internal.net.http.hpack; |
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26 |
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27 import java.io.IOException; |
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28 import java.nio.ByteBuffer; |
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29 |
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30 import static java.lang.String.format; |
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31 |
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32 /** |
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33 * Huffman coding table. |
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34 * |
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35 * <p> Instances of this class are safe for use by multiple threads. |
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36 * |
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37 * @since 9 |
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38 */ |
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39 public final class Huffman { |
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40 |
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41 // TODO: check if reset is done in both reader and writer |
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42 |
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43 static final class Reader { |
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44 |
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45 private Node curr; // position in the trie |
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46 private int len; // length of the path from the root to 'curr' |
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47 private int p; // byte probe |
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48 |
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49 { |
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50 reset(); |
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51 } |
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52 |
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53 public void read(ByteBuffer source, |
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54 Appendable destination, |
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55 boolean isLast) throws IOException { |
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56 read(source, destination, true, isLast); |
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57 } |
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58 |
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59 // Takes 'isLast' rather than returns whether the reading is done or |
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60 // not, for more informative exceptions. |
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61 void read(ByteBuffer source, |
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62 Appendable destination, |
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63 boolean reportEOS, /* reportEOS is exposed for tests */ |
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64 boolean isLast) throws IOException { |
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65 Node c = curr; |
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66 int l = len; |
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67 /* |
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68 Since ByteBuffer is itself stateful, its position is |
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69 remembered here NOT as a part of Reader's state, |
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70 but to set it back in the case of a failure |
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71 */ |
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72 int pos = source.position(); |
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73 |
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74 while (source.hasRemaining()) { |
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75 int d = source.get(); |
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76 for (; p != 0; p >>= 1) { |
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77 c = c.getChild(p & d); |
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78 l++; |
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79 if (c.isLeaf()) { |
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80 if (reportEOS && c.isEOSPath) { |
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81 throw new IOException("Encountered EOS"); |
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82 } |
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83 char ch; |
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84 try { |
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85 ch = c.getChar(); |
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86 } catch (IllegalStateException e) { |
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87 source.position(pos); // do we need this? |
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88 throw new IOException(e); |
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89 } |
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90 try { |
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91 destination.append(ch); |
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92 } catch (IOException e) { |
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93 source.position(pos); // do we need this? |
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94 throw e; |
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95 } |
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96 c = INSTANCE.root; |
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97 l = 0; |
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98 } |
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99 curr = c; |
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100 len = l; |
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101 } |
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102 resetProbe(); |
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103 pos++; |
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104 } |
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105 if (!isLast) { |
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106 return; // it's too early to jump to any conclusions, let's wait |
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107 } |
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108 if (c.isLeaf()) { |
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109 return; // it's perfectly ok, no extra padding bits |
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110 } |
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111 if (c.isEOSPath && len <= 7) { |
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112 return; // it's ok, some extra padding bits |
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113 } |
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114 if (c.isEOSPath) { |
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115 throw new IOException( |
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116 "Padding is too long (len=" + len + ") " + |
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117 "or unexpected end of data"); |
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118 } |
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119 throw new IOException( |
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120 "Not a EOS prefix padding or unexpected end of data"); |
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121 } |
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122 |
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123 public void reset() { |
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124 curr = INSTANCE.root; |
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125 len = 0; |
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126 resetProbe(); |
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127 } |
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128 |
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129 private void resetProbe() { |
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130 p = 0x80; |
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131 } |
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132 } |
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133 |
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134 static final class Writer { |
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135 |
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136 private int pos; // position in 'source' |
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137 private int avail = 8; // number of least significant bits available in 'curr' |
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138 private int curr; // next byte to put to the destination |
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139 private int rem; // number of least significant bits in 'code' yet to be processed |
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140 private int code; // current code being written |
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141 |
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142 private CharSequence source; |
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143 private int end; |
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144 |
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145 public Writer from(CharSequence input, int start, int end) { |
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146 if (start < 0 || end < 0 || end > input.length() || start > end) { |
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147 throw new IndexOutOfBoundsException( |
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148 String.format("input.length()=%s, start=%s, end=%s", |
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149 input.length(), start, end)); |
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150 } |
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151 pos = start; |
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152 this.end = end; |
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153 this.source = input; |
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154 return this; |
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155 } |
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156 |
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157 public boolean write(ByteBuffer destination) { |
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158 for (; pos < end; pos++) { |
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159 if (rem == 0) { |
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160 Code desc = INSTANCE.codeOf(source.charAt(pos)); |
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161 rem = desc.length; |
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162 code = desc.code; |
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163 } |
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164 while (rem > 0) { |
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165 if (rem < avail) { |
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166 curr |= (code << (avail - rem)); |
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167 avail -= rem; |
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168 rem = 0; |
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169 } else { |
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170 int c = (curr | (code >>> (rem - avail))); |
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171 if (destination.hasRemaining()) { |
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172 destination.put((byte) c); |
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173 } else { |
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174 return false; |
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175 } |
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176 curr = c; |
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177 code <<= (32 - rem + avail); // throw written bits off the cliff (is this Sparta?) |
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178 code >>>= (32 - rem + avail); // return to the position |
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179 rem -= avail; |
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180 curr = 0; |
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181 avail = 8; |
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182 } |
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183 } |
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184 } |
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185 |
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186 if (avail < 8) { // have to pad |
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187 if (destination.hasRemaining()) { |
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188 destination.put((byte) (curr | (INSTANCE.EOS.code >>> (INSTANCE.EOS.length - avail)))); |
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189 avail = 8; |
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190 } else { |
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191 return false; |
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192 } |
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193 } |
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194 |
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195 return true; |
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196 } |
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197 |
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198 public Writer reset() { |
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199 source = null; |
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200 end = -1; |
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201 pos = -1; |
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202 avail = 8; |
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203 curr = 0; |
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204 code = 0; |
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205 return this; |
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206 } |
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207 } |
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208 |
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209 /** |
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210 * Shared instance. |
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211 */ |
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212 public static final Huffman INSTANCE = new Huffman(); |
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213 |
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214 private final Code EOS = new Code(0x3fffffff, 30); |
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215 private final Code[] codes = new Code[257]; |
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216 private final Node root = new Node() { |
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217 @Override |
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218 public String toString() { return "root"; } |
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219 }; |
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220 |
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221 // TODO: consider builder and immutable trie |
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222 private Huffman() { |
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223 // @formatter:off |
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224 addChar(0, 0x1ff8, 13); |
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225 addChar(1, 0x7fffd8, 23); |
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226 addChar(2, 0xfffffe2, 28); |
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227 addChar(3, 0xfffffe3, 28); |
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228 addChar(4, 0xfffffe4, 28); |
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229 addChar(5, 0xfffffe5, 28); |
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230 addChar(6, 0xfffffe6, 28); |
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231 addChar(7, 0xfffffe7, 28); |
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232 addChar(8, 0xfffffe8, 28); |
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233 addChar(9, 0xffffea, 24); |
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234 addChar(10, 0x3ffffffc, 30); |
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235 addChar(11, 0xfffffe9, 28); |
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236 addChar(12, 0xfffffea, 28); |
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237 addChar(13, 0x3ffffffd, 30); |
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238 addChar(14, 0xfffffeb, 28); |
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239 addChar(15, 0xfffffec, 28); |
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240 addChar(16, 0xfffffed, 28); |
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241 addChar(17, 0xfffffee, 28); |
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242 addChar(18, 0xfffffef, 28); |
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243 addChar(19, 0xffffff0, 28); |
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244 addChar(20, 0xffffff1, 28); |
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245 addChar(21, 0xffffff2, 28); |
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246 addChar(22, 0x3ffffffe, 30); |
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247 addChar(23, 0xffffff3, 28); |
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248 addChar(24, 0xffffff4, 28); |
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249 addChar(25, 0xffffff5, 28); |
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250 addChar(26, 0xffffff6, 28); |
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251 addChar(27, 0xffffff7, 28); |
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252 addChar(28, 0xffffff8, 28); |
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253 addChar(29, 0xffffff9, 28); |
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254 addChar(30, 0xffffffa, 28); |
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255 addChar(31, 0xffffffb, 28); |
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256 addChar(32, 0x14, 6); |
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257 addChar(33, 0x3f8, 10); |
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258 addChar(34, 0x3f9, 10); |
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259 addChar(35, 0xffa, 12); |
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260 addChar(36, 0x1ff9, 13); |
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261 addChar(37, 0x15, 6); |
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262 addChar(38, 0xf8, 8); |
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263 addChar(39, 0x7fa, 11); |
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264 addChar(40, 0x3fa, 10); |
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265 addChar(41, 0x3fb, 10); |
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266 addChar(42, 0xf9, 8); |
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267 addChar(43, 0x7fb, 11); |
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268 addChar(44, 0xfa, 8); |
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269 addChar(45, 0x16, 6); |
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270 addChar(46, 0x17, 6); |
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271 addChar(47, 0x18, 6); |
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272 addChar(48, 0x0, 5); |
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273 addChar(49, 0x1, 5); |
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274 addChar(50, 0x2, 5); |
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275 addChar(51, 0x19, 6); |
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276 addChar(52, 0x1a, 6); |
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277 addChar(53, 0x1b, 6); |
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278 addChar(54, 0x1c, 6); |
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279 addChar(55, 0x1d, 6); |
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280 addChar(56, 0x1e, 6); |
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281 addChar(57, 0x1f, 6); |
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282 addChar(58, 0x5c, 7); |
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283 addChar(59, 0xfb, 8); |
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284 addChar(60, 0x7ffc, 15); |
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285 addChar(61, 0x20, 6); |
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286 addChar(62, 0xffb, 12); |
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287 addChar(63, 0x3fc, 10); |
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288 addChar(64, 0x1ffa, 13); |
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289 addChar(65, 0x21, 6); |
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290 addChar(66, 0x5d, 7); |
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291 addChar(67, 0x5e, 7); |
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292 addChar(68, 0x5f, 7); |
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293 addChar(69, 0x60, 7); |
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294 addChar(70, 0x61, 7); |
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295 addChar(71, 0x62, 7); |
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296 addChar(72, 0x63, 7); |
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297 addChar(73, 0x64, 7); |
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298 addChar(74, 0x65, 7); |
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299 addChar(75, 0x66, 7); |
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300 addChar(76, 0x67, 7); |
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301 addChar(77, 0x68, 7); |
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302 addChar(78, 0x69, 7); |
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303 addChar(79, 0x6a, 7); |
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304 addChar(80, 0x6b, 7); |
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305 addChar(81, 0x6c, 7); |
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306 addChar(82, 0x6d, 7); |
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307 addChar(83, 0x6e, 7); |
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308 addChar(84, 0x6f, 7); |
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309 addChar(85, 0x70, 7); |
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310 addChar(86, 0x71, 7); |
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311 addChar(87, 0x72, 7); |
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312 addChar(88, 0xfc, 8); |
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313 addChar(89, 0x73, 7); |
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314 addChar(90, 0xfd, 8); |
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315 addChar(91, 0x1ffb, 13); |
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316 addChar(92, 0x7fff0, 19); |
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317 addChar(93, 0x1ffc, 13); |
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318 addChar(94, 0x3ffc, 14); |
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319 addChar(95, 0x22, 6); |
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320 addChar(96, 0x7ffd, 15); |
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321 addChar(97, 0x3, 5); |
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322 addChar(98, 0x23, 6); |
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323 addChar(99, 0x4, 5); |
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324 addChar(100, 0x24, 6); |
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325 addChar(101, 0x5, 5); |
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326 addChar(102, 0x25, 6); |
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327 addChar(103, 0x26, 6); |
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328 addChar(104, 0x27, 6); |
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329 addChar(105, 0x6, 5); |
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330 addChar(106, 0x74, 7); |
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331 addChar(107, 0x75, 7); |
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332 addChar(108, 0x28, 6); |
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333 addChar(109, 0x29, 6); |
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334 addChar(110, 0x2a, 6); |
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335 addChar(111, 0x7, 5); |
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336 addChar(112, 0x2b, 6); |
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337 addChar(113, 0x76, 7); |
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338 addChar(114, 0x2c, 6); |
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339 addChar(115, 0x8, 5); |
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340 addChar(116, 0x9, 5); |
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341 addChar(117, 0x2d, 6); |
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342 addChar(118, 0x77, 7); |
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343 addChar(119, 0x78, 7); |
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344 addChar(120, 0x79, 7); |
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345 addChar(121, 0x7a, 7); |
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346 addChar(122, 0x7b, 7); |
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347 addChar(123, 0x7ffe, 15); |
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348 addChar(124, 0x7fc, 11); |
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349 addChar(125, 0x3ffd, 14); |
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350 addChar(126, 0x1ffd, 13); |
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351 addChar(127, 0xffffffc, 28); |
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352 addChar(128, 0xfffe6, 20); |
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353 addChar(129, 0x3fffd2, 22); |
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354 addChar(130, 0xfffe7, 20); |
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355 addChar(131, 0xfffe8, 20); |
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356 addChar(132, 0x3fffd3, 22); |
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357 addChar(133, 0x3fffd4, 22); |
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358 addChar(134, 0x3fffd5, 22); |
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359 addChar(135, 0x7fffd9, 23); |
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360 addChar(136, 0x3fffd6, 22); |
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361 addChar(137, 0x7fffda, 23); |
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362 addChar(138, 0x7fffdb, 23); |
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363 addChar(139, 0x7fffdc, 23); |
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364 addChar(140, 0x7fffdd, 23); |
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365 addChar(141, 0x7fffde, 23); |
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366 addChar(142, 0xffffeb, 24); |
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367 addChar(143, 0x7fffdf, 23); |
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368 addChar(144, 0xffffec, 24); |
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369 addChar(145, 0xffffed, 24); |
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370 addChar(146, 0x3fffd7, 22); |
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371 addChar(147, 0x7fffe0, 23); |
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372 addChar(148, 0xffffee, 24); |
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373 addChar(149, 0x7fffe1, 23); |
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374 addChar(150, 0x7fffe2, 23); |
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375 addChar(151, 0x7fffe3, 23); |
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376 addChar(152, 0x7fffe4, 23); |
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377 addChar(153, 0x1fffdc, 21); |
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378 addChar(154, 0x3fffd8, 22); |
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379 addChar(155, 0x7fffe5, 23); |
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380 addChar(156, 0x3fffd9, 22); |
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381 addChar(157, 0x7fffe6, 23); |
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382 addChar(158, 0x7fffe7, 23); |
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383 addChar(159, 0xffffef, 24); |
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384 addChar(160, 0x3fffda, 22); |
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385 addChar(161, 0x1fffdd, 21); |
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386 addChar(162, 0xfffe9, 20); |
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387 addChar(163, 0x3fffdb, 22); |
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388 addChar(164, 0x3fffdc, 22); |
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389 addChar(165, 0x7fffe8, 23); |
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390 addChar(166, 0x7fffe9, 23); |
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391 addChar(167, 0x1fffde, 21); |
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392 addChar(168, 0x7fffea, 23); |
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393 addChar(169, 0x3fffdd, 22); |
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394 addChar(170, 0x3fffde, 22); |
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395 addChar(171, 0xfffff0, 24); |
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396 addChar(172, 0x1fffdf, 21); |
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397 addChar(173, 0x3fffdf, 22); |
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398 addChar(174, 0x7fffeb, 23); |
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399 addChar(175, 0x7fffec, 23); |
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400 addChar(176, 0x1fffe0, 21); |
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401 addChar(177, 0x1fffe1, 21); |
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402 addChar(178, 0x3fffe0, 22); |
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403 addChar(179, 0x1fffe2, 21); |
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404 addChar(180, 0x7fffed, 23); |
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405 addChar(181, 0x3fffe1, 22); |
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406 addChar(182, 0x7fffee, 23); |
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407 addChar(183, 0x7fffef, 23); |
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408 addChar(184, 0xfffea, 20); |
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409 addChar(185, 0x3fffe2, 22); |
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410 addChar(186, 0x3fffe3, 22); |
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411 addChar(187, 0x3fffe4, 22); |
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412 addChar(188, 0x7ffff0, 23); |
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413 addChar(189, 0x3fffe5, 22); |
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414 addChar(190, 0x3fffe6, 22); |
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415 addChar(191, 0x7ffff1, 23); |
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416 addChar(192, 0x3ffffe0, 26); |
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417 addChar(193, 0x3ffffe1, 26); |
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418 addChar(194, 0xfffeb, 20); |
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419 addChar(195, 0x7fff1, 19); |
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420 addChar(196, 0x3fffe7, 22); |
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421 addChar(197, 0x7ffff2, 23); |
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422 addChar(198, 0x3fffe8, 22); |
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423 addChar(199, 0x1ffffec, 25); |
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424 addChar(200, 0x3ffffe2, 26); |
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425 addChar(201, 0x3ffffe3, 26); |
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426 addChar(202, 0x3ffffe4, 26); |
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427 addChar(203, 0x7ffffde, 27); |
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428 addChar(204, 0x7ffffdf, 27); |
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429 addChar(205, 0x3ffffe5, 26); |
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430 addChar(206, 0xfffff1, 24); |
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431 addChar(207, 0x1ffffed, 25); |
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432 addChar(208, 0x7fff2, 19); |
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433 addChar(209, 0x1fffe3, 21); |
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434 addChar(210, 0x3ffffe6, 26); |
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435 addChar(211, 0x7ffffe0, 27); |
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436 addChar(212, 0x7ffffe1, 27); |
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437 addChar(213, 0x3ffffe7, 26); |
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438 addChar(214, 0x7ffffe2, 27); |
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439 addChar(215, 0xfffff2, 24); |
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440 addChar(216, 0x1fffe4, 21); |
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441 addChar(217, 0x1fffe5, 21); |
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442 addChar(218, 0x3ffffe8, 26); |
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443 addChar(219, 0x3ffffe9, 26); |
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444 addChar(220, 0xffffffd, 28); |
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445 addChar(221, 0x7ffffe3, 27); |
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446 addChar(222, 0x7ffffe4, 27); |
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447 addChar(223, 0x7ffffe5, 27); |
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448 addChar(224, 0xfffec, 20); |
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449 addChar(225, 0xfffff3, 24); |
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450 addChar(226, 0xfffed, 20); |
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451 addChar(227, 0x1fffe6, 21); |
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452 addChar(228, 0x3fffe9, 22); |
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453 addChar(229, 0x1fffe7, 21); |
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454 addChar(230, 0x1fffe8, 21); |
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455 addChar(231, 0x7ffff3, 23); |
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456 addChar(232, 0x3fffea, 22); |
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457 addChar(233, 0x3fffeb, 22); |
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458 addChar(234, 0x1ffffee, 25); |
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459 addChar(235, 0x1ffffef, 25); |
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460 addChar(236, 0xfffff4, 24); |
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461 addChar(237, 0xfffff5, 24); |
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462 addChar(238, 0x3ffffea, 26); |
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463 addChar(239, 0x7ffff4, 23); |
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464 addChar(240, 0x3ffffeb, 26); |
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465 addChar(241, 0x7ffffe6, 27); |
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466 addChar(242, 0x3ffffec, 26); |
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467 addChar(243, 0x3ffffed, 26); |
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468 addChar(244, 0x7ffffe7, 27); |
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469 addChar(245, 0x7ffffe8, 27); |
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470 addChar(246, 0x7ffffe9, 27); |
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471 addChar(247, 0x7ffffea, 27); |
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472 addChar(248, 0x7ffffeb, 27); |
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473 addChar(249, 0xffffffe, 28); |
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474 addChar(250, 0x7ffffec, 27); |
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475 addChar(251, 0x7ffffed, 27); |
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476 addChar(252, 0x7ffffee, 27); |
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477 addChar(253, 0x7ffffef, 27); |
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478 addChar(254, 0x7fffff0, 27); |
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479 addChar(255, 0x3ffffee, 26); |
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480 addEOS (256, EOS.code, EOS.length); |
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481 // @formatter:on |
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482 } |
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483 |
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484 |
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485 /** |
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486 * Calculates the number of bytes required to represent the given {@code |
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487 * CharSequence} with the Huffman coding. |
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488 * |
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489 * @param value |
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490 * characters |
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491 * |
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492 * @return number of bytes |
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493 * |
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494 * @throws NullPointerException |
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495 * if the value is null |
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496 */ |
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497 public int lengthOf(CharSequence value) { |
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498 return lengthOf(value, 0, value.length()); |
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499 } |
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500 |
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501 /** |
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502 * Calculates the number of bytes required to represent a subsequence of the |
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503 * given {@code CharSequence} with the Huffman coding. |
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504 * |
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505 * @param value |
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506 * characters |
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507 * @param start |
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508 * the start index, inclusive |
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509 * @param end |
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510 * the end index, exclusive |
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511 * |
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512 * @return number of bytes |
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513 * |
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514 * @throws NullPointerException |
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515 * if the value is null |
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516 * @throws IndexOutOfBoundsException |
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517 * if any invocation of {@code value.charAt(i)}, where |
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518 * {@code start <= i < end} would throw an IndexOutOfBoundsException |
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519 */ |
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520 public int lengthOf(CharSequence value, int start, int end) { |
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521 int len = 0; |
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522 for (int i = start; i < end; i++) { |
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523 char c = value.charAt(i); |
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524 len += INSTANCE.codeOf(c).length; |
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525 } |
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526 // Integer division with ceiling, assumption: |
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527 assert (len / 8 + (len % 8 != 0 ? 1 : 0)) == (len + 7) / 8 : len; |
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528 return (len + 7) / 8; |
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529 } |
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530 |
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531 private void addChar(int c, int code, int bitLength) { |
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532 addLeaf(c, code, bitLength, false); |
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533 codes[c] = new Code(code, bitLength); |
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534 } |
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535 |
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536 private void addEOS(int c, int code, int bitLength) { |
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537 addLeaf(c, code, bitLength, true); |
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538 codes[c] = new Code(code, bitLength); |
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539 } |
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540 |
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541 private void addLeaf(int c, int code, int bitLength, boolean isEOS) { |
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542 if (bitLength < 1) { |
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543 throw new IllegalArgumentException("bitLength < 1"); |
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544 } |
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545 Node curr = root; |
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546 for (int p = 1 << bitLength - 1; p != 0 && !curr.isLeaf(); p = p >> 1) { |
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547 curr.isEOSPath |= isEOS; // If it's already true, it can't become false |
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548 curr = curr.addChildIfAbsent(p & code); |
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549 } |
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550 curr.isEOSPath |= isEOS; // The last one needs to have this property as well |
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551 if (curr.isLeaf()) { |
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552 throw new IllegalStateException("Specified code is already taken"); |
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553 } |
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554 curr.setChar((char) c); |
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555 } |
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556 |
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557 private Code codeOf(char c) { |
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558 if (c > 255) { |
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559 throw new IllegalArgumentException("char=" + ((int) c)); |
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560 } |
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561 return codes[c]; |
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562 } |
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563 |
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564 // |
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565 // For debugging/testing purposes |
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566 // |
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567 Node getRoot() { |
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568 return root; |
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569 } |
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570 |
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571 // |
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572 // Guarantees: |
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573 // |
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574 // if (isLeaf() == true) => getChar() is a legal call |
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575 // if (isLeaf() == false) => getChild(i) is a legal call (though it can |
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576 // return null) |
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577 // |
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578 static class Node { |
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579 |
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580 Node left; |
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581 Node right; |
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582 boolean isEOSPath; |
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583 |
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584 boolean charIsSet; |
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585 char c; |
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586 |
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587 Node getChild(int selector) { |
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588 if (isLeaf()) { |
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589 throw new IllegalStateException("This is a leaf node"); |
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590 } |
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591 Node result = selector == 0 ? left : right; |
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592 if (result == null) { |
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593 throw new IllegalStateException(format( |
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594 "Node doesn't have a child (selector=%s)", selector)); |
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595 } |
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596 return result; |
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597 } |
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598 |
|
599 boolean isLeaf() { |
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600 return charIsSet; |
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601 } |
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602 |
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603 char getChar() { |
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604 if (!isLeaf()) { |
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605 throw new IllegalStateException("This node is not a leaf node"); |
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606 } |
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607 return c; |
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608 } |
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609 |
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610 void setChar(char c) { |
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611 if (charIsSet) { |
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612 throw new IllegalStateException( |
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613 "This node has been taken already"); |
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614 } |
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615 if (left != null || right != null) { |
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616 throw new IllegalStateException("The node cannot be made " |
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617 + "a leaf as it's already has a child"); |
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618 } |
|
619 this.c = c; |
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620 charIsSet = true; |
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621 } |
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622 |
|
623 Node addChildIfAbsent(int i) { |
|
624 if (charIsSet) { |
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625 throw new IllegalStateException("The node cannot have a child " |
|
626 + "as it's already a leaf node"); |
|
627 } |
|
628 Node child; |
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629 if (i == 0) { |
|
630 if ((child = left) == null) { |
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631 child = left = new Node(); |
|
632 } |
|
633 } else { |
|
634 if ((child = right) == null) { |
|
635 child = right = new Node(); |
|
636 } |
|
637 } |
|
638 return child; |
|
639 } |
|
640 |
|
641 @Override |
|
642 public String toString() { |
|
643 if (isLeaf()) { |
|
644 if (isEOSPath) { |
|
645 return "EOS"; |
|
646 } else { |
|
647 return format("char: (%3s) '%s'", (int) c, c); |
|
648 } |
|
649 } |
|
650 return "/\\"; |
|
651 } |
|
652 } |
|
653 |
|
654 // TODO: value-based class? |
|
655 // FIXME: can we re-use Node instead of this class? |
|
656 private static final class Code { |
|
657 |
|
658 final int code; |
|
659 final int length; |
|
660 |
|
661 private Code(int code, int length) { |
|
662 this.code = code; |
|
663 this.length = length; |
|
664 } |
|
665 |
|
666 public int getCode() { |
|
667 return code; |
|
668 } |
|
669 |
|
670 public int getLength() { |
|
671 return length; |
|
672 } |
|
673 |
|
674 @Override |
|
675 public String toString() { |
|
676 long p = 1 << length; |
|
677 return Long.toBinaryString(code + p).substring(1) |
|
678 + ", length=" + length; |
|
679 } |
|
680 } |
|
681 } |