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1 /* |
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2 * Copyright 2006 Sun Microsystems, Inc. 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. Sun designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
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22 * CA 95054 USA or visit www.sun.com if you need additional information or |
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23 * have any questions. |
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24 */ |
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25 |
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26 package com.sun.codemodel.internal.util; |
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27 |
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28 import java.nio.CharBuffer; |
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29 import java.nio.charset.CoderResult; |
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30 |
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31 |
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32 /** |
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33 * Utility class for dealing with surrogates. |
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34 * |
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35 * @author Mark Reinhold |
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36 */ |
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37 |
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38 class Surrogate { |
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39 |
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40 private Surrogate() { } |
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41 |
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42 // UTF-16 surrogate-character ranges |
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43 // |
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44 public static final char MIN_HIGH = '\uD800'; |
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45 public static final char MAX_HIGH = '\uDBFF'; |
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46 public static final char MIN_LOW = '\uDC00'; |
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47 public static final char MAX_LOW = '\uDFFF'; |
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48 public static final char MIN = MIN_HIGH; |
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49 public static final char MAX = MAX_LOW; |
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50 |
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51 // Range of UCS-4 values that need surrogates in UTF-16 |
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52 // |
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53 public static final int UCS4_MIN = 0x10000; |
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54 public static final int UCS4_MAX = (1 << 20) + UCS4_MIN - 1; |
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55 |
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56 /** |
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57 * Tells whether or not the given UTF-16 value is a high surrogate. |
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58 */ |
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59 public static boolean isHigh(int c) { |
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60 return (MIN_HIGH <= c) && (c <= MAX_HIGH); |
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61 } |
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62 |
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63 /** |
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64 * Tells whether or not the given UTF-16 value is a low surrogate. |
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65 */ |
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66 public static boolean isLow(int c) { |
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67 return (MIN_LOW <= c) && (c <= MAX_LOW); |
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68 } |
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69 |
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70 /** |
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71 * Tells whether or not the given UTF-16 value is a surrogate character, |
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72 */ |
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73 public static boolean is(int c) { |
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74 return (MIN <= c) && (c <= MAX); |
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75 } |
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76 |
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77 /** |
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78 * Tells whether or not the given UCS-4 character must be represented as a |
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79 * surrogate pair in UTF-16. |
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80 */ |
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81 public static boolean neededFor(int uc) { |
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82 return (uc >= UCS4_MIN) && (uc <= UCS4_MAX); |
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83 } |
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84 |
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85 /** |
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86 * Returns the high UTF-16 surrogate for the given UCS-4 character. |
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87 */ |
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88 public static char high(int uc) { |
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89 return (char)(0xd800 | (((uc - UCS4_MIN) >> 10) & 0x3ff)); |
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90 } |
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91 |
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92 /** |
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93 * Returns the low UTF-16 surrogate for the given UCS-4 character. |
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94 */ |
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95 public static char low(int uc) { |
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96 return (char)(0xdc00 | ((uc - UCS4_MIN) & 0x3ff)); |
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97 } |
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98 |
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99 /** |
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100 * Converts the given surrogate pair into a 32-bit UCS-4 character. |
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101 */ |
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102 public static int toUCS4(char c, char d) { |
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103 return (((c & 0x3ff) << 10) | (d & 0x3ff)) + 0x10000; |
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104 } |
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105 |
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106 /** |
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107 * Surrogate parsing support. Charset implementations may use instances of |
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108 * this class to handle the details of parsing UTF-16 surrogate pairs. |
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109 */ |
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110 public static class Parser { |
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111 |
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112 public Parser() { } |
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113 |
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114 private int character; // UCS-4 |
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115 private CoderResult error = CoderResult.UNDERFLOW; |
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116 private boolean isPair; |
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117 |
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118 /** |
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119 * Returns the UCS-4 character previously parsed. |
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120 */ |
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121 public int character() { |
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122 return character; |
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123 } |
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124 |
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125 /** |
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126 * Tells whether or not the previously-parsed UCS-4 character was |
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127 * originally represented by a surrogate pair. |
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128 */ |
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129 public boolean isPair() { |
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130 return isPair; |
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131 } |
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132 |
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133 /** |
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134 * Returns the number of UTF-16 characters consumed by the previous |
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135 * parse. |
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136 */ |
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137 public int increment() { |
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138 return isPair ? 2 : 1; |
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139 } |
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140 |
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141 /** |
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142 * If the previous parse operation detected an error, return the object |
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143 * describing that error. |
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144 */ |
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145 public CoderResult error() { |
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146 return error; |
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147 } |
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148 |
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149 /** |
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150 * Returns an unmappable-input result object, with the appropriate |
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151 * input length, for the previously-parsed character. |
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152 */ |
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153 public CoderResult unmappableResult() { |
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154 return CoderResult.unmappableForLength(isPair ? 2 : 1); |
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155 } |
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156 |
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157 /** |
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158 * Parses a UCS-4 character from the given source buffer, handling |
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159 * surrogates. |
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160 * |
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161 * @param c The first character |
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162 * @param in The source buffer, from which one more character |
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163 * will be consumed if c is a high surrogate |
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164 * |
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165 * @return Either a parsed UCS-4 character, in which case the isPair() |
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166 * and increment() methods will return meaningful values, or |
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167 * -1, in which case error() will return a descriptive result |
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168 * object |
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169 */ |
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170 public int parse(char c, CharBuffer in) { |
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171 if (isHigh(c)) { |
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172 if (!in.hasRemaining()) { |
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173 error = CoderResult.UNDERFLOW; |
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174 return -1; |
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175 } |
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176 char d = in.get(); |
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177 if (isLow(d)) { |
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178 character = toUCS4(c, d); |
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179 isPair = true; |
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180 error = null; |
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181 return character; |
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182 } |
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183 error = CoderResult.malformedForLength(1); |
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184 return -1; |
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185 } |
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186 if (isLow(c)) { |
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187 error = CoderResult.malformedForLength(1); |
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188 return -1; |
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189 } |
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190 character = c; |
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191 isPair = false; |
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192 error = null; |
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193 return character; |
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194 } |
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195 |
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196 /** |
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197 * Parses a UCS-4 character from the given source buffer, handling |
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198 * surrogates. |
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199 * |
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200 * @param c The first character |
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201 * @param ia The input array, from which one more character |
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202 * will be consumed if c is a high surrogate |
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203 * @param ip The input index |
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204 * @param il The input limit |
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205 * |
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206 * @return Either a parsed UCS-4 character, in which case the isPair() |
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207 * and increment() methods will return meaningful values, or |
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208 * -1, in which case error() will return a descriptive result |
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209 * object |
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210 */ |
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211 public int parse(char c, char[] ia, int ip, int il) { |
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212 if (isHigh(c)) { |
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213 if (il - ip < 2) { |
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214 error = CoderResult.UNDERFLOW; |
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215 return -1; |
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216 } |
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217 char d = ia[ip + 1]; |
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218 if (isLow(d)) { |
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219 character = toUCS4(c, d); |
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220 isPair = true; |
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221 error = null; |
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222 return character; |
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223 } |
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224 error = CoderResult.malformedForLength(1); |
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225 return -1; |
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226 } |
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227 if (isLow(c)) { |
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228 error = CoderResult.malformedForLength(1); |
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229 return -1; |
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230 } |
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231 character = c; |
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232 isPair = false; |
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233 error = null; |
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234 return character; |
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235 } |
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236 |
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237 } |
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238 |
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239 /** |
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240 * Surrogate generation support. Charset implementations may use instances |
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241 * of this class to handle the details of generating UTF-16 surrogate |
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242 * pairs. |
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243 */ |
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244 public static class Generator { |
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245 |
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246 public Generator() { } |
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247 |
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248 private CoderResult error = CoderResult.OVERFLOW; |
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249 |
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250 /** |
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251 * If the previous generation operation detected an error, return the |
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252 * object describing that error. |
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253 */ |
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254 public CoderResult error() { |
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255 return error; |
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256 } |
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257 |
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258 /** |
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259 * Generates one or two UTF-16 characters to represent the given UCS-4 |
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260 * character. |
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261 * |
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262 * @param uc The UCS-4 character |
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263 * @param len The number of input bytes from which the UCS-4 value |
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264 * was constructed (used when creating result objects) |
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265 * @param dst The destination buffer, to which one or two UTF-16 |
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266 * characters will be written |
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267 * |
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268 * @return Either a positive count of the number of UTF-16 characters |
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269 * written to the destination buffer, or -1, in which case |
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270 * error() will return a descriptive result object |
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271 */ |
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272 public int generate(int uc, int len, CharBuffer dst) { |
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273 if (uc <= 0xffff) { |
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274 if (is(uc)) { |
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275 error = CoderResult.malformedForLength(len); |
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276 return -1; |
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277 } |
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278 if (dst.remaining() < 1) { |
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279 error = CoderResult.OVERFLOW; |
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280 return -1; |
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281 } |
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282 dst.put((char)uc); |
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283 error = null; |
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284 return 1; |
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285 } |
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286 if (uc < UCS4_MIN) { |
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287 error = CoderResult.malformedForLength(len); |
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288 return -1; |
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289 } |
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290 if (uc <= UCS4_MAX) { |
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291 if (dst.remaining() < 2) { |
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292 error = CoderResult.OVERFLOW; |
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293 return -1; |
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294 } |
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295 dst.put(high(uc)); |
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296 dst.put(low(uc)); |
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297 error = null; |
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298 return 2; |
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299 } |
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300 error = CoderResult.unmappableForLength(len); |
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301 return -1; |
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302 } |
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303 |
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304 /** |
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305 * Generates one or two UTF-16 characters to represent the given UCS-4 |
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306 * character. |
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307 * |
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308 * @param uc The UCS-4 character |
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309 * @param len The number of input bytes from which the UCS-4 value |
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310 * was constructed (used when creating result objects) |
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311 * @param da The destination array, to which one or two UTF-16 |
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312 * characters will be written |
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313 * @param dp The destination position |
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314 * @param dl The destination limit |
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315 * |
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316 * @return Either a positive count of the number of UTF-16 characters |
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317 * written to the destination buffer, or -1, in which case |
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318 * error() will return a descriptive result object |
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319 */ |
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320 public int generate(int uc, int len, char[] da, int dp, int dl) { |
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321 if (uc <= 0xffff) { |
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322 if (is(uc)) { |
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323 error = CoderResult.malformedForLength(len); |
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324 return -1; |
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325 } |
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326 if (dl - dp < 1) { |
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327 error = CoderResult.OVERFLOW; |
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328 return -1; |
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329 } |
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330 da[dp] = (char)uc; |
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331 error = null; |
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332 return 1; |
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333 } |
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334 if (uc < UCS4_MIN) { |
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335 error = CoderResult.malformedForLength(len); |
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336 return -1; |
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337 } |
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338 if (uc <= UCS4_MAX) { |
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339 if (dl - dp < 2) { |
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340 error = CoderResult.OVERFLOW; |
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341 return -1; |
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342 } |
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343 da[dp] = high(uc); |
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344 da[dp + 1] = low(uc); |
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345 error = null; |
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346 return 2; |
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347 } |
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348 error = CoderResult.unmappableForLength(len); |
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349 return -1; |
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350 } |
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351 |
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352 } |
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353 |
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354 } |