mcs/class/System.ServiceModel.Web/System.Runtime.Serialization.Json/JsonWriter.cs

   1 //
   2 // JsonWriter.cs
   3 //
   4 // Author:
   5 //      Atsushi Enomoto  <atsushi@ximian.com>
   6 //
   7 // Copyright (C) 2007 Novell, Inc (http://www.novell.com)
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28 using System;
  29 using System.Collections.Generic;
  30 using System.Globalization;
  31 using System.IO;
  32 using System.Text;
  33 using System.Xml;
  34
  35 namespace System.Runtime.Serialization.Json
  36 {
  37         class JsonWriter : XmlDictionaryWriter, IXmlJsonWriterInitializer
  38         {
  39                 enum ElementType
  40                 {
  41                         None,
  42                         Null,
  43                         Object,
  44                         Array,
  45                         String,
  46                         Number,
  47                         Boolean,
  48                 }
  49
  50                 Stream output;
  51                 bool close_output;
  52                 WriteState state;
  53                 Stack<ElementType> element_kinds = new Stack<ElementType> ();
  54                 Stack<bool> first_content_flags = new Stack<bool> ();
  55                 string attr_name, attr_value, runtime_type;
  56                 Encoding encoding;
  57                 byte [] encbuf = new byte [1024];
  58                 bool no_string_yet = true, is_null, is_ascii_single;
  59
  60                 public JsonWriter (Stream stream, Encoding encoding, bool closeOutput)
  61                 {
  62                         SetOutput (stream, encoding, closeOutput);
  63                 }
  64
  65                 public void SetOutput (Stream stream, Encoding encoding, bool ownsStream)
  66                 {
  67                         if (stream == null)
  68                                 throw new ArgumentNullException ("stream");
  69                         if (encoding == null)
  70                                 throw new ArgumentNullException ("encoding");
  71                         output = stream;
  72                         this.encoding = encoding;
  73                         close_output = ownsStream;
  74                         is_ascii_single = encoding is UTF8Encoding || encoding.IsSingleByte;
  75                 }
  76
  77                 void CheckState ()
  78                 {
  79                         switch (state) {
  80                         case WriteState.Closed:
  81                         case WriteState.Error:
  82                                 throw new InvalidOperationException (String.Format ("This XmlDictionaryReader is already at '{0}' state", state));
  83                         }
  84                 }
  85
  86                 // copied from System.Silverlight JavaScriptSerializer.
  87                 static string EscapeStringLiteral (string input)
  88                 {
  89                         StringBuilder sb = null;
  90                         int i = 0, start = 0;
  91                         for (; i < input.Length; i++) {
  92                                 switch (input [i]) {
  93                                 case '"':
  94                                         AppendBuffer (ref sb, input, start, i, @"\""");
  95                                         break;
  96                                 case '\\':
  97                                         AppendBuffer (ref sb, input, start, i, @"\\");
  98                                         break;
  99                                 case '/':
 100                                         AppendBuffer (ref sb, input, start, i, @"\/");
 101                                         break;
 102                                 case '\x8':
 103                                         AppendBuffer (ref sb, input, start, i, @"\b");
 104                                         break;
 105                                 case '\f':
 106                                         AppendBuffer (ref sb, input, start, i, @"\f");
 107                                         break;
 108                                 case '\n':
 109                                         AppendBuffer (ref sb, input, start, i, /*@"\n"*/@"\u000a");
 110                                         break;
 111                                 case '\r':
 112                                         AppendBuffer (ref sb, input, start, i, /*@"\r"*/@"\u000d");
 113                                         break;
 114                                 case '\t':
 115                                         AppendBuffer (ref sb, input, start, i, /*@"\t"*/@"\u0009");
 116                                         break;
 117                                 default:
 118                                         continue;
 119                                 }
 120                                 start = i + 1;
 121                         }
 122                         string remaining = input.Substring (start, i - start);
 123                         if (sb != null)
 124                                 return sb.Append (remaining).ToString ();
 125                         else
 126                                 return remaining;
 127                 }
 128
 129                 static void AppendBuffer (ref StringBuilder sb, string input, int start, int i, string append)
 130                 {
 131                         if (sb == null)
 132                                 sb = new StringBuilder ();
 133                         if (i != start)
 134                                 sb.Append (input, start, i - start);
 135                         sb.Append (append);
 136                 }
 137
 138                 public override WriteState WriteState {
 139                         get { return state; }
 140                 }
 141
 142                 public override void Close ()
 143                 {
 144                         // close all open elements
 145                         while (element_kinds.Count > 0)
 146                                 WriteEndElement ();
 147
 148                         if (close_output)
 149                                 output.Close ();
 150                         else
 151                                 output.Flush ();
 152
 153                         state = WriteState.Closed;
 154                 }
 155
 156                 public override void Flush ()
 157                 {
 158                         output.Flush ();
 159                 }
 160
 161                 public override void WriteStartElement (string prefix, string localName, string ns)
 162                 {
 163                         CheckState ();
 164
 165                         if (localName == null)
 166                                 throw new ArgumentNullException ("localName");
 167                         else if (localName.Length == 0)
 168                                 throw new ArgumentException ("Empty string is not a valid localName in this XmlDictionaryWriter");
 169
 170                         if (!String.IsNullOrEmpty (ns))
 171                                 throw new ArgumentException ("Non-empty namespace URI is not allowed in this XmlDictionaryWriter");
 172                         if (!String.IsNullOrEmpty (prefix))
 173                                 throw new ArgumentException ("Non-empty prefix is not allowed in this XmlDictionaryWriter");
 174
 175                         if (state == WriteState.Attribute)
 176                                 WriteEndAttribute ();
 177                         if (state == WriteState.Element)
 178                                 CloseStartElement ();
 179
 180                         else if (state != WriteState.Start && element_kinds.Count == 0)
 181                                 throw new XmlException ("This XmlDictionaryWriter does not support multiple top-level elements");
 182
 183                         if (element_kinds.Count == 0) {
 184                                 if (localName != "root")
 185                                         throw new XmlException ("Only 'root' is allowed for the name of the top-level element");
 186                         } else {
 187                                 switch (element_kinds.Peek ()) {
 188                                 case ElementType.Array:
 189                                         if (localName != "item")
 190                                                 throw new XmlException ("Only 'item' is allowed as a content element of an array");
 191                                         break;
 192                                 case ElementType.String:
 193                                         throw new XmlException ("Mixed content is not allowed in this XmlDictionaryWriter");
 194                                 case ElementType.Null:
 195                                         throw new XmlException ("Current type is null and writing element inside null is not allowed");
 196                                 case ElementType.None:
 197                                         throw new XmlException ("Before writing a child element, an element needs 'type' attribute to indicate whether the element is a JSON array or a JSON object in this XmlDictionaryWriter");
 198                                 }
 199
 200                                 if (first_content_flags.Peek ()) {
 201                                         first_content_flags.Pop ();
 202                                         first_content_flags.Push (false);
 203                                 }
 204                                 else
 205                                         OutputAsciiChar (',');
 206
 207                                 if (element_kinds.Peek () != ElementType.Array) {
 208                                         OutputAsciiChar ('"');
 209                                         OutputString (localName);
 210                                         OutputAsciiChar ('\"');
 211                                         OutputAsciiChar (':');
 212                                 }
 213                         }
 214
 215                         element_kinds.Push (ElementType.None); // undetermined yet
 216
 217                         state = WriteState.Element;
 218                 }
 219
 220                 public override void WriteEndElement ()
 221                 {
 222                         CheckState ();
 223
 224                         if (state == WriteState.Attribute)
 225                                 throw new XmlException ("Cannot end element when an attribute is being written");
 226                         if (state == WriteState.Element)
 227                                 CloseStartElement ();
 228
 229                         if (element_kinds.Count == 0)
 230                                 throw new XmlException ("There is no open element to close");
 231                         switch (element_kinds.Pop ()) {
 232                         case ElementType.String:
 233                                 if (!is_null) {
 234                                         if (no_string_yet)
 235                                                 OutputAsciiChar ('"');
 236                                         OutputAsciiChar ('"');
 237                                 }
 238                                 no_string_yet = true;
 239                                 is_null = false;
 240                                 break;
 241                         case ElementType.Array:
 242                                 OutputAsciiChar (']');
 243                                 break;
 244                         case ElementType.Object:
 245                                 OutputAsciiChar ('}');
 246                                 break;
 247                         }
 248
 249                         // not sure if it is correct though ...
 250                         state = WriteState.Content;
 251                         first_content_flags.Pop ();
 252                 }
 253
 254                 public override void WriteFullEndElement ()
 255                 {
 256                         WriteEndElement (); // no such difference in JSON.
 257                 }
 258
 259                 public override void WriteStartAttribute (string prefix, string localName, string ns)
 260                 {
 261                         CheckState ();
 262
 263                         if (state != WriteState.Element)
 264                                 throw new XmlException ("Cannot write attribute as this XmlDictionaryWriter is not at element state");
 265
 266                         if (!String.IsNullOrEmpty (ns))
 267                                 throw new ArgumentException ("Non-empty namespace URI is not allowed in this XmlDictionaryWriter");
 268                         if (!String.IsNullOrEmpty (prefix))
 269                                 throw new ArgumentException ("Non-empty prefix is not allowed in this XmlDictionaryWriter");
 270
 271                         if (localName != "type" && localName != "__type")
 272                                 throw new ArgumentException ("Only 'type' and '__type' are allowed as an attribute name in this XmlDictionaryWriter");
 273
 274                         if (state != WriteState.Element)
 275                                 throw new InvalidOperationException (String.Format ("Attribute cannot be written in {0} mode", state));
 276
 277                         attr_name = localName;
 278                         state = WriteState.Attribute;
 279                 }
 280
 281                 public override void WriteEndAttribute ()
 282                 {
 283                         CheckState ();
 284
 285                         if (state != WriteState.Attribute)
 286                                 throw new XmlException ("Cannot close attribute, as this XmlDictionaryWriter is not at attribute state");
 287
 288                         if (attr_name == "type") {
 289                                 switch (attr_value) {
 290                                 case "object":
 291                                         element_kinds.Pop ();
 292                                         element_kinds.Push (ElementType.Object);
 293                                         OutputAsciiChar ('{');
 294                                         break;
 295                                 case "array":
 296                                         element_kinds.Pop ();
 297                                         element_kinds.Push (ElementType.Array);
 298                                         OutputAsciiChar ('[');
 299                                         break;
 300                                 case "number":
 301                                         element_kinds.Pop ();
 302                                         element_kinds.Push (ElementType.Number);
 303                                         break;
 304                                 case "boolean":
 305                                         element_kinds.Pop ();
 306                                         element_kinds.Push (ElementType.Boolean);
 307                                         break;
 308                                 case "string":
 309                                         element_kinds.Pop ();
 310                                         element_kinds.Push (ElementType.String);
 311                                         break;
 312                                 case "null":
 313                                         element_kinds.Pop ();
 314                                         element_kinds.Push (ElementType.Null);
 315                                         OutputString ("null");
 316                                         break;
 317                                 default:
 318                                         throw new XmlException (String.Format ("Unexpected type attribute value '{0}'", attr_value));
 319                                 }
 320                         }
 321                         else
 322                                 runtime_type = attr_value;
 323
 324                         state = WriteState.Element;
 325                         attr_value = null;
 326                 }
 327
 328                 void CloseStartElement ()
 329                 {
 330                         if (element_kinds.Peek () == ElementType.None) {
 331                                 element_kinds.Pop ();
 332                                 element_kinds.Push (ElementType.String);
 333                                 no_string_yet = true;
 334                                 is_null = false;
 335                         }
 336
 337                         first_content_flags.Push (true);
 338
 339                         if (runtime_type != null) {
 340                                 OutputString ("\"__type\":\"");
 341                                 OutputString (runtime_type);
 342                                 OutputAsciiChar ('\"');
 343                                 runtime_type = null;
 344                                 first_content_flags.Pop ();
 345                                 first_content_flags.Push (false);
 346                         }
 347                 }
 348
 349                 public override void WriteString (string text)
 350                 {
 351                         CheckState ();
 352
 353                         if (state == WriteState.Start)
 354                                 throw new InvalidOperationException ("Top-level content string is not allowed in this XmlDictionaryWriter");
 355
 356                         if (state == WriteState.Element) {
 357                                 CloseStartElement ();
 358                                 state = WriteState.Content;
 359                         }
 360
 361                         if (state == WriteState.Attribute)
 362                                 attr_value += text;
 363                         else if (text == null) {
 364                                 no_string_yet = false;
 365                                 is_null = true;
 366                                 if (element_kinds.Peek () != ElementType.Null)
 367                                         OutputString ("null");
 368                         } else {
 369                                 switch (element_kinds.Peek ()) {
 370                                 case ElementType.String:
 371                                         if (no_string_yet) {
 372                                                 OutputAsciiChar ('"');
 373                                                 no_string_yet = false;
 374                                         }
 375                                         break;
 376                                 case ElementType.Number:
 377                                         // .NET is buggy here, it just outputs raw string, which results in invalid JSON format.
 378                                         bool isString = false;
 379                                         switch (text) {
 380                                         case "INF":
 381                                         case "-INF":
 382                                         case "NaN":
 383                                                 isString = true;
 384                                                 break;
 385                                         }
 386                                         if (isString) {
 387                                                 element_kinds.Pop ();
 388                                                 element_kinds.Push (ElementType.String);
 389                                                 goto case ElementType.String;
 390                                         }
 391                                         break;
 392                                 case ElementType.Boolean:
 393                                         break;
 394                                 default:
 395                                         throw new XmlException (String.Format ("Simple content string is allowed only for string, number and boolean types and not for {0} type", element_kinds.Peek ()));
 396                                 }
 397
 398                                 OutputString (EscapeStringLiteral (text));
 399                         }
 400                 }
 401
 402                 #region mostly-ignored operations
 403
 404                 public override string LookupPrefix (string ns)
 405                 {
 406                         // Since there is no way to declare namespaces in
 407                         // this writer, it always returns fixed results.
 408                         if (ns == null)
 409                                 throw new ArgumentNullException ("ns");
 410                         else if (ns.Length == 0)
 411                                 return String.Empty;
 412                         else if (ns == "http://www.w3.org/2000/xmlns/")
 413                                 return "xmlns";
 414                         else if (ns == "http://www.w3.org/XML/1998/namespace")
 415                                 return "xml";
 416                         return null;
 417                 }
 418
 419                 public override void WriteStartDocument ()
 420                 {
 421                         CheckState ();
 422                 }
 423
 424                 public override void WriteStartDocument (bool standalone)
 425                 {
 426                         CheckState ();
 427                 }
 428
 429                 public override void WriteEndDocument ()
 430                 {
 431                         CheckState ();
 432                 }
 433
 434                 #endregion
 435
 436                 #region unsupported operations
 437
 438                 public override void WriteDocType (string name, string pubid, string sysid, string intSubset)
 439                 {
 440                         CheckState ();
 441
 442                         throw new NotSupportedException ("This XmlDictionaryWriter does not support writing doctype declaration");
 443                 }
 444
 445                 public override void WriteComment (string text)
 446                 {
 447                         CheckState ();
 448
 449                         throw new NotSupportedException ("This XmlDictionaryWriter does not support writing comment");
 450                 }
 451
 452                 public override void WriteEntityRef (string text)
 453                 {
 454                         CheckState ();
 455
 456                         throw new NotSupportedException ("This XmlDictionaryWriter does not support writing entity reference");
 457                 }
 458
 459                 public override void WriteProcessingInstruction (string target, string data)
 460                 {
 461                         CheckState ();
 462
 463                         if (String.Compare (target, "xml", StringComparison.OrdinalIgnoreCase) != 0)
 464                                 throw new ArgumentException ("This XmlDictionaryWriter does not support writing processing instruction");
 465                 }
 466
 467                 #endregion
 468
 469                 #region WriteString() variants
 470
 471                 public override void WriteRaw (string text)
 472                 {
 473                         WriteString (text);
 474                 }
 475
 476                 public override void WriteRaw (char [] chars, int start, int length)
 477                 {
 478                         WriteChars (chars, start, length);
 479                 }
 480
 481                 public override void WriteCData (string text)
 482                 {
 483                         WriteString (text);
 484                 }
 485
 486                 public override void WriteCharEntity (char entity)
 487                 {
 488                         WriteString (entity.ToString ());
 489                 }
 490
 491                 public override void WriteChars (char [] chars, int start, int length)
 492                 {
 493                         WriteString (new string (chars, start, length));
 494                 }
 495
 496                 public override void WriteSurrogateCharEntity (char high, char low)
 497                 {
 498                         WriteChars (new char [] {high, low}, 0, 2);
 499                 }
 500
 501                 public override void WriteBase64 (byte [] bytes, int start, int length)
 502                 {
 503                         WriteString (Convert.ToBase64String (bytes, start, length));
 504                 }
 505
 506                 public override void WriteWhitespace (string text)
 507                 {
 508                         if (text == null)
 509                                 throw new ArgumentNullException ("text");
 510                         for (int i = 0; i < text.Length; i++) {
 511                                 if (text [i] != ' ') {
 512                                         for (int j = i; j < text.Length; j++) {
 513                                                 switch (text [j]) {
 514                                                 case '\t':
 515                                                 case ' ':
 516                                                 case '\n':
 517                                                 case '\r':
 518                                                         continue;
 519                                                 default:
 520                                                         throw new ArgumentException (String.Format ("WriteWhitespace() does not accept non-whitespace character '{0}'", text [j]));
 521                                                 }
 522                                         }
 523                                         break;
 524                                 }
 525                         }
 526                         WriteString (text);
 527                 }
 528
 529                 char [] char_buf = new char [1];
 530                 void OutputAsciiChar (char c)
 531                 {
 532                         if (is_ascii_single)
 533                                 output.WriteByte ((byte) c);
 534                         else {
 535                                 char_buf [0] = c;
 536                                 int size = encoding.GetBytes (char_buf, 0, 1, encbuf, 0);
 537                                 output.Write (encbuf, 0, size);
 538                         }
 539                 }
 540
 541                 void OutputString (string s)
 542                 {
 543                         int size = encoding.GetByteCount (s);
 544                         if (encbuf.Length < size)
 545                                 encbuf = new byte [size];
 546                         size = encoding.GetBytes (s, 0, s.Length, encbuf, 0);
 547                         output.Write (encbuf, 0, size);
 548                 }
 549
 550                 #endregion
 551         }
 552 }