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 #if MOONLIGHT
  75                         is_ascii_single = encoding is UTF8Encoding;
  76 #else
  77                         is_ascii_single = encoding is UTF8Encoding || encoding.IsSingleByte;
  78 #endif
  79                 }
  80
  81                 void CheckState ()
  82                 {
  83                         switch (state) {
  84                         case WriteState.Closed:
  85                         case WriteState.Error:
  86                                 throw new InvalidOperationException (String.Format ("This XmlDictionaryReader is already at '{0}' state", state));
  87                         }
  88                 }
  89
  90                 // copied from System.Silverlight JavaScriptSerializer.
  91                 static string EscapeStringLiteral (string input)
  92                 {
  93                         StringBuilder sb = null;
  94                         int i = 0, start = 0;
  95                         for (; i < input.Length; i++) {
  96                                 switch (input [i]) {
  97                                 case '"':
  98                                         AppendBuffer (ref sb, input, start, i, @"\""");
  99                                         break;
 100                                 case '\\':
 101                                         AppendBuffer (ref sb, input, start, i, @"\\");
 102                                         break;
 103                                 case '/':
 104                                         AppendBuffer (ref sb, input, start, i, @"\/");
 105                                         break;
 106                                 case '\x8':
 107                                         AppendBuffer (ref sb, input, start, i, @"\b");
 108                                         break;
 109                                 case '\f':
 110                                         AppendBuffer (ref sb, input, start, i, @"\f");
 111                                         break;
 112                                 case '\n':
 113                                         AppendBuffer (ref sb, input, start, i, /*@"\n"*/@"\u000a");
 114                                         break;
 115                                 case '\r':
 116                                         AppendBuffer (ref sb, input, start, i, /*@"\r"*/@"\u000d");
 117                                         break;
 118                                 case '\t':
 119                                         AppendBuffer (ref sb, input, start, i, /*@"\t"*/@"\u0009");
 120                                         break;
 121                                 default:
 122                                         continue;
 123                                 }
 124                                 start = i + 1;
 125                         }
 126                         string remaining = input.Substring (start, i - start);
 127                         if (sb != null)
 128                                 return sb.Append (remaining).ToString ();
 129                         else
 130                                 return remaining;
 131                 }
 132
 133                 static void AppendBuffer (ref StringBuilder sb, string input, int start, int i, string append)
 134                 {
 135                         if (sb == null)
 136                                 sb = new StringBuilder ();
 137                         if (i != start)
 138                                 sb.Append (input, start, i - start);
 139                         sb.Append (append);
 140                 }
 141
 142                 public override WriteState WriteState {
 143                         get { return state; }
 144                 }
 145
 146                 public override void Close ()
 147                 {
 148                         // close all open elements
 149                         while (element_kinds.Count > 0)
 150                                 WriteEndElement ();
 151
 152                         if (close_output)
 153                                 output.Close ();
 154                         else
 155                                 output.Flush ();
 156
 157                         state = WriteState.Closed;
 158                 }
 159
 160                 public override void Flush ()
 161                 {
 162                         output.Flush ();
 163                 }
 164
 165                 public override void WriteStartElement (string prefix, string localName, string ns)
 166                 {
 167                         CheckState ();
 168
 169                         if (localName == null)
 170                                 throw new ArgumentNullException ("localName");
 171                         else if (localName.Length == 0)
 172                                 throw new ArgumentException ("Empty string is not a valid localName in this XmlDictionaryWriter");
 173
 174                         if (!String.IsNullOrEmpty (ns))
 175                                 throw new ArgumentException ("Non-empty namespace URI is not allowed in this XmlDictionaryWriter");
 176                         if (!String.IsNullOrEmpty (prefix))
 177                                 throw new ArgumentException ("Non-empty prefix is not allowed in this XmlDictionaryWriter");
 178
 179                         if (state == WriteState.Attribute)
 180                                 WriteEndAttribute ();
 181                         if (state == WriteState.Element)
 182                                 CloseStartElement ();
 183
 184                         else if (state != WriteState.Start && element_kinds.Count == 0)
 185                                 throw new XmlException ("This XmlDictionaryWriter does not support multiple top-level elements");
 186
 187                         if (element_kinds.Count == 0) {
 188                                 if (localName != "root")
 189                                         throw new XmlException ("Only 'root' is allowed for the name of the top-level element");
 190                         } else {
 191                                 switch (element_kinds.Peek ()) {
 192                                 case ElementType.Array:
 193                                         if (localName != "item")
 194                                                 throw new XmlException ("Only 'item' is allowed as a content element of an array");
 195                                         break;
 196                                 case ElementType.String:
 197                                         throw new XmlException ("Mixed content is not allowed in this XmlDictionaryWriter");
 198                                 case ElementType.Null:
 199                                         throw new XmlException ("Current type is null and writing element inside null is not allowed");
 200                                 case ElementType.None:
 201                                         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");
 202                                 }
 203
 204                                 if (first_content_flags.Peek ()) {
 205                                         first_content_flags.Pop ();
 206                                         first_content_flags.Push (false);
 207                                 }
 208                                 else
 209                                         OutputAsciiChar (',');
 210
 211                                 if (element_kinds.Peek () != ElementType.Array) {
 212                                         OutputAsciiChar ('"');
 213                                         OutputString (localName);
 214                                         OutputAsciiChar ('\"');
 215                                         OutputAsciiChar (':');
 216                                 }
 217                         }
 218
 219                         element_kinds.Push (ElementType.None); // undetermined yet
 220
 221                         state = WriteState.Element;
 222                 }
 223
 224                 public override void WriteEndElement ()
 225                 {
 226                         CheckState ();
 227
 228                         if (state == WriteState.Attribute)
 229                                 throw new XmlException ("Cannot end element when an attribute is being written");
 230                         if (state == WriteState.Element)
 231                                 CloseStartElement ();
 232
 233                         if (element_kinds.Count == 0)
 234                                 throw new XmlException ("There is no open element to close");
 235                         switch (element_kinds.Pop ()) {
 236                         case ElementType.String:
 237                                 if (!is_null) {
 238                                         if (no_string_yet)
 239                                                 OutputAsciiChar ('"');
 240                                         OutputAsciiChar ('"');
 241                                 }
 242                                 no_string_yet = true;
 243                                 is_null = false;
 244                                 break;
 245                         case ElementType.Array:
 246                                 OutputAsciiChar (']');
 247                                 break;
 248                         case ElementType.Object:
 249                                 OutputAsciiChar ('}');
 250                                 break;
 251                         }
 252
 253                         // not sure if it is correct though ...
 254                         state = WriteState.Content;
 255                         first_content_flags.Pop ();
 256                 }
 257
 258                 public override void WriteFullEndElement ()
 259                 {
 260                         WriteEndElement (); // no such difference in JSON.
 261                 }
 262
 263                 public override void WriteStartAttribute (string prefix, string localName, string ns)
 264                 {
 265                         CheckState ();
 266
 267                         if (state != WriteState.Element)
 268                                 throw new XmlException ("Cannot write attribute as this XmlDictionaryWriter is not at element state");
 269
 270                         if (!String.IsNullOrEmpty (ns))
 271                                 throw new ArgumentException ("Non-empty namespace URI is not allowed in this XmlDictionaryWriter");
 272                         if (!String.IsNullOrEmpty (prefix))
 273                                 throw new ArgumentException ("Non-empty prefix is not allowed in this XmlDictionaryWriter");
 274
 275                         if (localName != "type" && localName != "__type")
 276                                 throw new ArgumentException ("Only 'type' and '__type' are allowed as an attribute name in this XmlDictionaryWriter");
 277
 278                         if (state != WriteState.Element)
 279                                 throw new InvalidOperationException (String.Format ("Attribute cannot be written in {0} mode", state));
 280
 281                         attr_name = localName;
 282                         state = WriteState.Attribute;
 283                 }
 284
 285                 public override void WriteEndAttribute ()
 286                 {
 287                         CheckState ();
 288
 289                         if (state != WriteState.Attribute)
 290                                 throw new XmlException ("Cannot close attribute, as this XmlDictionaryWriter is not at attribute state");
 291
 292                         if (attr_name == "type") {
 293                                 switch (attr_value) {
 294                                 case "object":
 295                                         element_kinds.Pop ();
 296                                         element_kinds.Push (ElementType.Object);
 297                                         OutputAsciiChar ('{');
 298                                         break;
 299                                 case "array":
 300                                         element_kinds.Pop ();
 301                                         element_kinds.Push (ElementType.Array);
 302                                         OutputAsciiChar ('[');
 303                                         break;
 304                                 case "number":
 305                                         element_kinds.Pop ();
 306                                         element_kinds.Push (ElementType.Number);
 307                                         break;
 308                                 case "boolean":
 309                                         element_kinds.Pop ();
 310                                         element_kinds.Push (ElementType.Boolean);
 311                                         break;
 312                                 case "string":
 313                                         element_kinds.Pop ();
 314                                         element_kinds.Push (ElementType.String);
 315                                         break;
 316                                 case "null":
 317                                         element_kinds.Pop ();
 318                                         element_kinds.Push (ElementType.Null);
 319                                         OutputString ("null");
 320                                         break;
 321                                 default:
 322                                         throw new XmlException (String.Format ("Unexpected type attribute value '{0}'", attr_value));
 323                                 }
 324                         }
 325                         else
 326                                 runtime_type = attr_value;
 327
 328                         state = WriteState.Element;
 329                         attr_value = null;
 330                 }
 331
 332                 void CloseStartElement ()
 333                 {
 334                         if (element_kinds.Peek () == ElementType.None) {
 335                                 element_kinds.Pop ();
 336                                 element_kinds.Push (ElementType.String);
 337                                 no_string_yet = true;
 338                                 is_null = false;
 339                         }
 340
 341                         first_content_flags.Push (true);
 342
 343                         if (runtime_type != null) {
 344                                 OutputString ("\"__type\":\"");
 345                                 OutputString (runtime_type);
 346                                 OutputAsciiChar ('\"');
 347                                 runtime_type = null;
 348                                 first_content_flags.Pop ();
 349                                 first_content_flags.Push (false);
 350                         }
 351                 }
 352
 353                 public override void WriteString (string text)
 354                 {
 355                         CheckState ();
 356
 357                         if (state == WriteState.Start)
 358                                 throw new InvalidOperationException ("Top-level content string is not allowed in this XmlDictionaryWriter");
 359
 360                         if (state == WriteState.Element) {
 361                                 CloseStartElement ();
 362                                 state = WriteState.Content;
 363                         }
 364
 365                         if (state == WriteState.Attribute)
 366                                 attr_value += text;
 367                         else if (text == null) {
 368                                 no_string_yet = false;
 369                                 is_null = true;
 370                                 if (element_kinds.Peek () != ElementType.Null)
 371                                         OutputString ("null");
 372                         } else {
 373                                 switch (element_kinds.Peek ()) {
 374                                 case ElementType.String:
 375                                         if (no_string_yet) {
 376                                                 OutputAsciiChar ('"');
 377                                                 no_string_yet = false;
 378                                         }
 379                                         break;
 380                                 case ElementType.Number:
 381                                         // .NET is buggy here, it just outputs raw string, which results in invalid JSON format.
 382                                         bool isString = false;
 383                                         switch (text) {
 384                                         case "INF":
 385                                         case "-INF":
 386                                         case "NaN":
 387                                                 isString = true;
 388                                                 break;
 389                                         }
 390                                         if (isString) {
 391                                                 element_kinds.Pop ();
 392                                                 element_kinds.Push (ElementType.String);
 393                                                 goto case ElementType.String;
 394                                         }
 395                                         break;
 396                                 case ElementType.Boolean:
 397                                         break;
 398                                 default:
 399                                         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 ()));
 400                                 }
 401
 402                                 OutputString (EscapeStringLiteral (text));
 403                         }
 404                 }
 405
 406                 #region mostly-ignored operations
 407
 408                 public override string LookupPrefix (string ns)
 409                 {
 410                         // Since there is no way to declare namespaces in
 411                         // this writer, it always returns fixed results.
 412                         if (ns == null)
 413                                 throw new ArgumentNullException ("ns");
 414                         else if (ns.Length == 0)
 415                                 return String.Empty;
 416                         else if (ns == "http://www.w3.org/2000/xmlns/")
 417                                 return "xmlns";
 418                         else if (ns == "http://www.w3.org/XML/1998/namespace")
 419                                 return "xml";
 420                         return null;
 421                 }
 422
 423                 public override void WriteStartDocument ()
 424                 {
 425                         CheckState ();
 426                 }
 427
 428                 public override void WriteStartDocument (bool standalone)
 429                 {
 430                         CheckState ();
 431                 }
 432
 433                 public override void WriteEndDocument ()
 434                 {
 435                         CheckState ();
 436                 }
 437
 438                 #endregion
 439
 440                 #region unsupported operations
 441
 442                 public override void WriteDocType (string name, string pubid, string sysid, string intSubset)
 443                 {
 444                         CheckState ();
 445
 446                         throw new NotSupportedException ("This XmlDictionaryWriter does not support writing doctype declaration");
 447                 }
 448
 449                 public override void WriteComment (string text)
 450                 {
 451                         CheckState ();
 452
 453                         throw new NotSupportedException ("This XmlDictionaryWriter does not support writing comment");
 454                 }
 455
 456                 public override void WriteEntityRef (string text)
 457                 {
 458                         CheckState ();
 459
 460                         throw new NotSupportedException ("This XmlDictionaryWriter does not support writing entity reference");
 461                 }
 462
 463                 public override void WriteProcessingInstruction (string target, string data)
 464                 {
 465                         CheckState ();
 466
 467                         if (String.Compare (target, "xml", StringComparison.OrdinalIgnoreCase) != 0)
 468                                 throw new ArgumentException ("This XmlDictionaryWriter does not support writing processing instruction");
 469                 }
 470
 471                 #endregion
 472
 473                 #region WriteString() variants
 474
 475                 public override void WriteRaw (string text)
 476                 {
 477 #if MOONLIGHT
 478                         OutputString (text);
 479 #else
 480                         WriteString (text);
 481 #endif
 482                 }
 483
 484                 public override void WriteRaw (char [] chars, int start, int length)
 485                 {
 486                         WriteChars (chars, start, length);
 487                 }
 488
 489                 public override void WriteCData (string text)
 490                 {
 491                         WriteString (text);
 492                 }
 493
 494                 public override void WriteCharEntity (char entity)
 495                 {
 496                         WriteString (entity.ToString ());
 497                 }
 498
 499                 public override void WriteChars (char [] chars, int start, int length)
 500                 {
 501                         WriteString (new string (chars, start, length));
 502                 }
 503
 504                 public override void WriteSurrogateCharEntity (char high, char low)
 505                 {
 506                         WriteChars (new char [] {high, low}, 0, 2);
 507                 }
 508
 509                 public override void WriteBase64 (byte [] bytes, int start, int length)
 510                 {
 511                         WriteString (Convert.ToBase64String (bytes, start, length));
 512                 }
 513
 514                 public override void WriteWhitespace (string text)
 515                 {
 516                         if (text == null)
 517                                 throw new ArgumentNullException ("text");
 518                         for (int i = 0; i < text.Length; i++) {
 519                                 if (text [i] != ' ') {
 520                                         for (int j = i; j < text.Length; j++) {
 521                                                 switch (text [j]) {
 522                                                 case '\t':
 523                                                 case ' ':
 524                                                 case '\n':
 525                                                 case '\r':
 526                                                         continue;
 527                                                 default:
 528                                                         throw new ArgumentException (String.Format ("WriteWhitespace() does not accept non-whitespace character '{0}'", text [j]));
 529                                                 }
 530                                         }
 531                                         break;
 532                                 }
 533                         }
 534                         WriteString (text);
 535                 }
 536
 537                 char [] char_buf = new char [1];
 538                 void OutputAsciiChar (char c)
 539                 {
 540                         if (is_ascii_single)
 541                                 output.WriteByte ((byte) c);
 542                         else {
 543                                 char_buf [0] = c;
 544                                 int size = encoding.GetBytes (char_buf, 0, 1, encbuf, 0);
 545                                 output.Write (encbuf, 0, size);
 546                         }
 547                 }
 548
 549                 void OutputString (string s)
 550                 {
 551                         int size = encoding.GetByteCount (s);
 552                         if (encbuf.Length < size)
 553                                 encbuf = new byte [size];
 554                         size = encoding.GetBytes (s, 0, s.Length, encbuf, 0);
 555                         output.Write (encbuf, 0, size);
 556                 }
 557
 558                 #endregion
 559         }
 560 }