Most "ReplaceAt" commonly methods seen online fail when replace a character at a specific position in a Unicode string.
Unicode String Replace At Issue
Lets examine Unicode string "πΆπ₯Γ©-"
πΆ Unicode Character 'MULTIPLE MUSICAL NOTES' (U+1F3B6) - 4-byte Unicode character
π₯ Fire Emoji U+1F525 - 4-byte Unicode character
Γ© Latin Small Letter e with Acute U+00E9 - 2-byte Unicode character
- Unicode Character 'HYPHEN-MINUS' (U+002D) - 2-byte Unicode character
π Smiling Face with Smiling Eyes Emoji U+1F60A - 4-byte Unicode character (replacement)
πΆπ₯Γ©- is length of 6, but there are ONLY 4 characters! Why not len=4?
πΆπ₯ are double byte UNICODE characters (> \u10000) of width or len 2 each
πΆπ₯Γ©- below will replace space after lasting character '-' (position 4) with a sub using most common techniques seen online
This is due to the fact that Unicode code points outside of the Basic Multilingual Plane (BMP) > U+FFFF, are are represented in UTF-16 using 4 byte surrogate pairs, rather than using 2 bytes.
Specifically, the High Surrogate (U+D800–U+DBFF) and Low Surrogate (U+DC00–U+DFFF) codes are reserved for encoding non-BMP characters in UTF-16 by using a pair of 16-bit codes: one High Surrogate and one Low Surrogate. A single surrogate code point will never be assigned a character.
To correctly count the number of characters in a string that may contain code points higher than U+FFFF, you can use the StringInfo class (from System.Globalization).
Below is an large enumeration of common ReplaceAt implementations available on internet. They all fail, except for one that using StringInfo. .
UnicocodeReplaceAt method replaces a character in a string at specific zero-based index and handles null char '\0' properly, by removing if from resultant string.
Output
Unicode String Replace At Issue
Lets examine Unicode string "πΆπ₯Γ©-"
πΆ Unicode Character 'MULTIPLE MUSICAL NOTES' (U+1F3B6) - 4-byte Unicode character
π₯ Fire Emoji U+1F525 - 4-byte Unicode character
Γ© Latin Small Letter e with Acute U+00E9 - 2-byte Unicode character
- Unicode Character 'HYPHEN-MINUS' (U+002D) - 2-byte Unicode character
π Smiling Face with Smiling Eyes Emoji U+1F60A - 4-byte Unicode character (replacement)
πΆπ₯Γ©- is length of 6, but there are ONLY 4 characters! Why not len=4?
πΆπ₯ are double byte UNICODE characters (> \u10000) of width or len 2 each
πΆπ₯Γ©- below will replace space after lasting character '-' (position 4) with a sub using most common techniques seen online
This is due to the fact that Unicode code points outside of the Basic Multilingual Plane (BMP) > U+FFFF, are are represented in UTF-16 using 4 byte surrogate pairs, rather than using 2 bytes.
Specifically, the High Surrogate (U+D800–U+DBFF) and Low Surrogate (U+DC00–U+DFFF) codes are reserved for encoding non-BMP characters in UTF-16 by using a pair of 16-bit codes: one High Surrogate and one Low Surrogate. A single surrogate code point will never be assigned a character.
To correctly count the number of characters in a string that may contain code points higher than U+FFFF, you can use the StringInfo class (from System.Globalization).
Below is an large enumeration of common ReplaceAt implementations available on internet. They all fail, except for one that using StringInfo. .
UnicocodeReplaceAt method replaces a character in a string at specific zero-based index and handles null char '\0' properly, by removing if from resultant string.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 | using System.Linq; using System.Diagnostics; using System; using System.Text; using System.Globalization; //Created for //http://metadataconsulting.blogspot.com/2019/03/A-Unicode-ReplaceAt-string-extension-method-handles-Unicode-string-properly.html public static class Program { const char cEMPTY = '\0'; static readonly string EMPTY = cEMPTY.ToString(); public static string UnicodeReplaceAtFastest(this string s, int idx, string replace) { // This StringBuilder holds the output results. StringBuilder sb = new StringBuilder(); // Use the ParseCombiningCharacters method to // get the index of each real character in the string. Int32[] textElemIndex = StringInfo.ParseCombiningCharacters(s); if (string.IsNullOrEmpty(s)) return s; if (idx < 1) return s; string newstring = string.Empty; if (textElemIndex.Length == 1) { return replace; } else if (idx < textElemIndex.Length) { idx = idx - 1; return s.Remove(textElemIndex[idx], textElemIndex[idx + 1] - textElemIndex[idx]).Insert(textElemIndex[idx], replace.ToString()); } else if (idx == textElemIndex.Length) { idx = idx - 1; return s.Remove(textElemIndex[idx], s.Length - textElemIndex[idx]).Insert(textElemIndex[idx], replace.ToString()); } else return s; } public static string UnicodeReplaceAtFast(this string s, int idx, string replace) { // This StringBuilder holds the output results. StringBuilder sb = new StringBuilder(); // Use the enumerator returned from GetTextElementEnumerator // method to examine each real character. TextElementEnumerator charEnum = StringInfo.GetTextElementEnumerator(s); if (string.IsNullOrEmpty(s)) return s; if (idx < 1) return s; //string newstring = string.Empty; //if (textElemIndex.Length == 1) //{ // return replace; //} //else if (idx <= textElemIndex.Length) //{ idx = idx - 1; while (charEnum.MoveNext()) { if (charEnum.ElementIndex != idx) sb.Append(charEnum.GetTextElement()); else sb.Append(replace); // i++; } return sb.ToString(); //} //else // return s; } public static string UnicodeReplaceAt(this string str, int offset, char replaceChar) { int count = 1; //number of characters to remove at location offset string replaceBy = replaceChar.ToString(); return new StringInfo(str).ReplaceByPosition(replaceBy, offset, count).String; } public static StringInfo ReplaceByPosition(this StringInfo str, string replaceBy, int offset, int count) { if (replaceBy != EMPTY) return str.RemoveByTextElements(offset, count).InsertByTextElements(offset, replaceBy); else if (!string.IsNullOrEmpty(replaceBy)) return str.RemoveByTextElements(offset, count).InsertByTextElements(offset, replaceBy); else return str.RemoveByTextElements(offset, count); } public static StringInfo RemoveByTextElements(this StringInfo str, int offset, int count) { //Tue 20-Aug-19 11:32am metadataconsulting.ca - replaceat index > string.len return orginal string if (offset > str.LengthInTextElements) return str; return new StringInfo(string.Concat( str.SubstringByTextElements(0, offset), offset + count < str.LengthInTextElements ? str.SubstringByTextElements(offset + count, str.LengthInTextElements - count - offset) : string.Empty )); } public static StringInfo InsertByTextElements(this StringInfo str, int offset, string insertStr) { //Tue 20-Aug-19 11:32am metadataconsulting.ca - replaceat index > string.len return orginal string if (offset > str.LengthInTextElements) return str; if (string.IsNullOrEmpty(str.String)) return new StringInfo(insertStr); return new StringInfo(string.Concat( str.SubstringByTextElements(0, offset), insertStr, str.LengthInTextElements - offset > 0 ? str.SubstringByTextElements(offset, str.LengthInTextElements - offset) : "" )); } public static string SubsituteStringStringBuilder(this string s, int idx, char replaceChar) { if (string.IsNullOrEmpty(s) || idx >= s.Length || idx < 0) return s; return new StringBuilder(s).Remove(idx, 1).Insert(idx, replaceChar.ToString()).ToString(); } public static string ReplaceAtSubstring(this string s, int idx, char replaceChar) { if (string.IsNullOrEmpty(s) || idx >= s.Length || idx < 0) return s; return s.Substring(0, idx) + replaceChar.ToString() + s.Substring(idx + replaceChar.ToString().Length, s.Length - (idx + replaceChar.ToString().Length)); } public static string ReplaceAtStringManipulation(this string s, int idx, char replaceChar) { if (string.IsNullOrEmpty(s) || idx >= s.Length || idx < 0) return s; return s.Remove(idx, 1).Insert(idx, replaceChar.ToString()); } public static string ReplaceAtLinq(this string value, int index, char newchar) { if (value.Length <= index) return value; else return string.Concat(value.Select((c, i) => i == index ? newchar : c)); } public static string ReplaceAtCharArray(this string input, uint index, char newChar) { if (string.IsNullOrEmpty(input) || index >= input.Length) return input; char[] chars = input.ToCharArray(); chars[index] = newChar; return new string(chars); } public static void Main() { //In .NET 4.5 and later also UTF-16 is supported //Console.OutputEncoding = System.Text.Encoding.Unicode; //Γ© Latin Small Letter e with Acute U+00E9 - single byte Unicode character //π Smiling Face with Smiling Eyes Emoji U+1F60A - double byte Unicode character //πΆ Multiple Musical Notes Emoji U+1F3B6 - - double byte Unicode character //π₯ Fire Emoji U+1F525 -- double byte Unicode character Console.WriteLine("Unicode String Replace At Issue"); Console.WriteLine("Lets examine string \"πΆπ₯Γ©-\""); Console.WriteLine("πΆπ₯Γ©- is length of " + "πΆπ₯Γ©-".Length + ", but there are ONLY 4 characters! Why not len=4?"); Console.WriteLine("πΆπ₯ are double byte UNICODE characters (> \\u10000) of width or len 2 each "); Console.WriteLine("πΆπ₯Γ©- below will replace space after lasting character '-' (position 4) with a sub using most common techniques seen online"); Console.WriteLine(); Stopwatch sw = new Stopwatch(); sw.Start(); Console.WriteLine("πΆπ₯Γ©- using ReplaceAtCharArray".ReplaceAtCharArray(4, 'X')); sw.Stop(); Console.WriteLine("in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Restart(); Console.WriteLine("πΆπ₯Γ©- using ReplaceAtLinq".ReplaceAtLinq(4, 'Y')); sw.Stop(); Console.WriteLine("in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Restart(); Console.WriteLine("πΆπ₯Γ©- using ReplaceAtStringManipulation".ReplaceAtStringManipulation(4, 'Z')); sw.Stop(); Console.WriteLine("in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Restart(); Console.WriteLine("πΆπ₯Γ©- using ReplaceAtSubstring".ReplaceAtSubstring(4, 'A')); sw.Stop(); Console.WriteLine("in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Restart(); Console.WriteLine("πΆπ₯Γ©- using SubsituteStringStringBuilder".SubsituteStringStringBuilder(4, 'W')); sw.Stop(); Console.WriteLine("in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Restart(); Console.WriteLine("πΆπ₯Γ©- using UnicodeReplaceAt".UnicodeReplaceAt(4, '4')); sw.Stop(); Console.WriteLine("in {0} ticks.", sw.ElapsedTicks.ToString("N0")); Console.WriteLine(); Console.WriteLine("UnicodeReplaceAt replaces properly at position 4 in zero based index string"); Console.WriteLine(); sw.Restart(); Console.Write("πΆπ₯Γ©- using UnicodeReplaceAt(0, '0')".UnicodeReplaceAt(0, '0')); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Restart(); Console.Write("πΆπ₯Γ©- using UnicodeReplaceAt(1, '1')".UnicodeReplaceAt(1, '1')); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Restart(); Console.Write("πΆπ₯Γ©- using UnicodeReplaceAt(2, '2')".UnicodeReplaceAt(2, '2')); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Restart(); Console.Write("πΆπ₯Γ©- using UnicodeReplaceAt(3, '3')".UnicodeReplaceAt(3, '3')); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Restart(); Console.Write("πΆπ₯Γ©- using UnicodeReplaceAt(4, '4')".UnicodeReplaceAt(4, '4')); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); Console.Write("πΆπ₯Γ©-".UnicodeReplaceAt(5, '5')+" using UnicodeReplaceAt(5, '5') - this is beyond end of string, so return orginal string"); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); Console.WriteLine(); Console.WriteLine(); Console.WriteLine(" FAST testing."); Console.WriteLine(); Console.WriteLine(); sw.Reset(); sw.Start(); Console.Write("πΆπ₯Γ©-a\u0304\u0308bc\u0327".UnicodeReplaceAtFast(5, "π") + " using UnicodeReplaceAtFast(5, 'π') - cool but still O(100) more :("); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Reset(); sw.Start(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); Console.Write("a\u0304".UnicodeReplaceAtFast(1, "π") + " using UnicodeReplaceAtFast(1, 'π') - bounds check - 1 char"); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Reset(); sw.Start(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); Console.Write("a\u0304".UnicodeReplaceAtFast(0, "π") + " using UnicodeReplaceAtFast(0, 'π') - bounds check - wrong index"); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); Console.WriteLine(); Console.WriteLine(); Console.WriteLine(" FASTEST testing."); Console.WriteLine(); Console.WriteLine(); sw.Reset(); sw.Start(); Console.Write("πΆπ₯Γ©-a\u0304\u0308bc\u0327".UnicodeReplaceAtFastest(5, "π") + " using UnicodeReplaceAtFastest(5, 'π') - cool but still O(100) more than string.Replace :("); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Reset(); sw.Start(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); Console.Write("a\u0304".UnicodeReplaceAtFastest(1, "π") + " using UnicodeReplaceAtFastest(1, 'π') - bounds check - 1 char"); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Reset(); sw.Start(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); Console.Write("a\u0304".UnicodeReplaceAtFastest(0, "π") + " using UnicodeReplaceAtFastest(0, 'π') - bounds check - 0 index"); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Reset(); sw.Start(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); Console.Write("a\u0304".UnicodeReplaceAtFastest(5, "π") + " using UnicodeReplaceAtFastest(5, 'π') - bounds check - after end index"); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Reset(); sw.Start(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); Console.Write("πΆπ₯Γ©-a\u0304\u0308bc\u0327".UnicodeReplaceAtFastest(6, "π") + " using UnicodeReplaceAtFastest(6, 'π') - bounds check - after end index"); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Reset(); sw.Start(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); Console.Write("πΆπ₯Γ©-a\u0304\u0308bc\u0327".UnicodeReplaceAtFastest(7, "π") + " using UnicodeReplaceAtFastest(7, 'π') - bounds check - after end index"); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); sw.Reset(); sw.Start(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); Console.Write("πΆπ₯Γ©-a\u0304\u0308bc\u0327".UnicodeReplaceAtFastest(8, "π") + " using UnicodeReplaceAtFastest(8, 'π') - bounds check - after end index"); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); Console.WriteLine(); Console.WriteLine("String.Replace works, but replaces all characters, not at specific location as above functions"); Console.WriteLine(); sw.Reset(); sw.Start(); Console.Write("πΆπ₯Γ©- using String.Replace".Replace("π₯", "+") + "('π₯', '+')"); sw.Stop(); Console.WriteLine(" in {0} ticks.", sw.ElapsedTicks.ToString("N0")); } } |
Output
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 | Unicode String Replace At Issue Lets examine string "πΆπ₯Γ©-" πΆπ₯Γ©- is length of 6, but there are ONLY 4 characters! Why not len=4? πΆπ₯ are double byte UNICODE characters (> \u10000) of width or len 2 each πΆπ₯Γ©- below will replace space after lasting character '-' (position 4) with a sub using most common techniques seen online πΆπ₯X- using ReplaceAtCharArray in 2,089 ticks. πΆπ₯Y- using ReplaceAtLinq in 3,724 ticks. πΆπ₯Z- using ReplaceAtStringManipulation in 1,411 ticks. πΆπ₯A- using ReplaceAtSubstring in 1,768 ticks. πΆπ₯W- using SubsituteStringStringBuilder in 1,701 ticks. πΆπ₯Γ©-4using UnicodeReplaceAt in 5,811 ticks. UnicodeReplaceAt replaces properly at position 4 in zero based index string 0π₯Γ©- using UnicodeReplaceAt(0, '0') in 31 ticks. πΆ1Γ©- using UnicodeReplaceAt(1, '1') in 24 ticks. πΆπ₯2- using UnicodeReplaceAt(2, '2') in 23 ticks. πΆπ₯Γ©3 using UnicodeReplaceAt(3, '3') in 76 ticks. πΆπ₯Γ©-4using UnicodeReplaceAt(4, '4') in 22 ticks. πΆπ₯Γ©- using UnicodeReplaceAt(5, '5') - this is beyond end of string, so return orginal string in 22 ticks. FAST testing. πΆπ₯π-ā̈bç using UnicodeReplaceAtFast(5, 'π') - cool but still O(100) more :( in 2,014 ticks. in 3 ticks. π using UnicodeReplaceAtFast(1, 'π') - bounds check - 1 char in 23 ticks. in 3 ticks. ā using UnicodeReplaceAtFast(0, 'π') - bounds check - wrong index in 19 ticks. FASTEST testing. πΆπ₯Γ©-πbç using UnicodeReplaceAtFastest(5, 'π') - cool but still O(100) more than string.Replace :( in 2,155 ticks. in 2 ticks. π using UnicodeReplaceAtFastest(1, 'π') - bounds check - 1 char in 23 ticks. in 3 ticks. ā using UnicodeReplaceAtFastest(0, 'π') - bounds check - 0 index in 21 ticks. in 3 ticks. π using UnicodeReplaceAtFastest(5, 'π') - bounds check - after end index in 63 ticks. String.Replace works, but replaces all characters, not at specific location as above functions πΆ+Γ©- using String.Replace('π₯', '+') in 15 ticks. |
No comments:
Post a Comment