1 <?xml version="1.0" encoding="iso-8859-1"?> 2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" 3 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 4 <html> 5 <head> 6 <!-- Copyright 1999,2000 Clark Cooper <coopercc (a] netheaven.com> 7 All rights reserved. 8 This is free software. You may distribute or modify according to 9 the terms of the MIT/X License --> 10 <title>Expat XML Parser</title> 11 <meta name="author" content="Clark Cooper, coopercc (a] netheaven.com" /> 12 <meta http-equiv="Content-Style-Type" content="text/css" /> 13 <link href="style.css" rel="stylesheet" type="text/css" /> 14 </head> 15 <body> 16 <table cellspacing="0" cellpadding="0" width="100%"> 17 <tr> 18 <td class="corner"><img src="expat.png" alt="(Expat logo)" /></td> 19 <td class="banner"><h1>The Expat XML Parser</h1></td> 20 </tr> 21 <tr> 22 <td class="releaseno">Release 2.0.1</td> 23 <td></td> 24 </tr> 25 </table> 26 <div class="content"> 27 28 <p>Expat is a library, written in C, for parsing XML documents. It's 29 the underlying XML parser for the open source Mozilla project, Perl's 30 <code>XML::Parser</code>, Python's <code>xml.parsers.expat</code>, and 31 other open-source XML parsers.</p> 32 33 <p>This library is the creation of James Clark, who's also given us 34 groff (an nroff look-alike), Jade (an implemention of ISO's DSSSL 35 stylesheet language for SGML), XP (a Java XML parser package), XT (a 36 Java XSL engine). James was also the technical lead on the XML 37 Working Group at W3C that produced the XML specification.</p> 38 39 <p>This is free software, licensed under the <a 40 href="../COPYING">MIT/X Consortium license</a>. You may download it 41 from <a href="http://www.libexpat.org/">the Expat home page</a>. 42 </p> 43 44 <p>The bulk of this document was originally commissioned as an article 45 by <a href="http://www.xml.com/">XML.com</a>. They graciously allowed 46 Clark Cooper to retain copyright and to distribute it with Expat. 47 This version has been substantially extended to include documentation 48 on features which have been added since the original article was 49 published, and additional information on using the original 50 interface.</p> 51 52 <hr /> 53 <h2>Table of Contents</h2> 54 <ul> 55 <li><a href="#overview">Overview</a></li> 56 <li><a href="#building">Building and Installing</a></li> 57 <li><a href="#using">Using Expat</a></li> 58 <li><a href="#reference">Reference</a> 59 <ul> 60 <li><a href="#creation">Parser Creation Functions</a> 61 <ul> 62 <li><a href="#XML_ParserCreate">XML_ParserCreate</a></li> 63 <li><a href="#XML_ParserCreateNS">XML_ParserCreateNS</a></li> 64 <li><a href="#XML_ParserCreate_MM">XML_ParserCreate_MM</a></li> 65 <li><a href="#XML_ExternalEntityParserCreate">XML_ExternalEntityParserCreate</a></li> 66 <li><a href="#XML_ParserFree">XML_ParserFree</a></li> 67 <li><a href="#XML_ParserReset">XML_ParserReset</a></li> 68 </ul> 69 </li> 70 <li><a href="#parsing">Parsing Functions</a> 71 <ul> 72 <li><a href="#XML_Parse">XML_Parse</a></li> 73 <li><a href="#XML_ParseBuffer">XML_ParseBuffer</a></li> 74 <li><a href="#XML_GetBuffer">XML_GetBuffer</a></li> 75 <li><a href="#XML_StopParser">XML_StopParser</a></li> 76 <li><a href="#XML_ResumeParser">XML_ResumeParser</a></li> 77 <li><a href="#XML_GetParsingStatus">XML_GetParsingStatus</a></li> 78 </ul> 79 </li> 80 <li><a href="#setting">Handler Setting Functions</a> 81 <ul> 82 <li><a href="#XML_SetStartElementHandler">XML_SetStartElementHandler</a></li> 83 <li><a href="#XML_SetEndElementHandler">XML_SetEndElementHandler</a></li> 84 <li><a href="#XML_SetElementHandler">XML_SetElementHandler</a></li> 85 <li><a href="#XML_SetCharacterDataHandler">XML_SetCharacterDataHandler</a></li> 86 <li><a href="#XML_SetProcessingInstructionHandler">XML_SetProcessingInstructionHandler</a></li> 87 <li><a href="#XML_SetCommentHandler">XML_SetCommentHandler</a></li> 88 <li><a href="#XML_SetStartCdataSectionHandler">XML_SetStartCdataSectionHandler</a></li> 89 <li><a href="#XML_SetEndCdataSectionHandler">XML_SetEndCdataSectionHandler</a></li> 90 <li><a href="#XML_SetCdataSectionHandler">XML_SetCdataSectionHandler</a></li> 91 <li><a href="#XML_SetDefaultHandler">XML_SetDefaultHandler</a></li> 92 <li><a href="#XML_SetDefaultHandlerExpand">XML_SetDefaultHandlerExpand</a></li> 93 <li><a href="#XML_SetExternalEntityRefHandler">XML_SetExternalEntityRefHandler</a></li> 94 <li><a href="#XML_SetExternalEntityRefHandlerArg">XML_SetExternalEntityRefHandlerArg</a></li> 95 <li><a href="#XML_SetSkippedEntityHandler">XML_SetSkippedEntityHandler</a></li> 96 <li><a href="#XML_SetUnknownEncodingHandler">XML_SetUnknownEncodingHandler</a></li> 97 <li><a href="#XML_SetStartNamespaceDeclHandler">XML_SetStartNamespaceDeclHandler</a></li> 98 <li><a href="#XML_SetEndNamespaceDeclHandler">XML_SetEndNamespaceDeclHandler</a></li> 99 <li><a href="#XML_SetNamespaceDeclHandler">XML_SetNamespaceDeclHandler</a></li> 100 <li><a href="#XML_SetXmlDeclHandler">XML_SetXmlDeclHandler</a></li> 101 <li><a href="#XML_SetStartDoctypeDeclHandler">XML_SetStartDoctypeDeclHandler</a></li> 102 <li><a href="#XML_SetEndDoctypeDeclHandler">XML_SetEndDoctypeDeclHandler</a></li> 103 <li><a href="#XML_SetDoctypeDeclHandler">XML_SetDoctypeDeclHandler</a></li> 104 <li><a href="#XML_SetElementDeclHandler">XML_SetElementDeclHandler</a></li> 105 <li><a href="#XML_SetAttlistDeclHandler">XML_SetAttlistDeclHandler</a></li> 106 <li><a href="#XML_SetEntityDeclHandler">XML_SetEntityDeclHandler</a></li> 107 <li><a href="#XML_SetUnparsedEntityDeclHandler">XML_SetUnparsedEntityDeclHandler</a></li> 108 <li><a href="#XML_SetNotationDeclHandler">XML_SetNotationDeclHandler</a></li> 109 <li><a href="#XML_SetNotStandaloneHandler">XML_SetNotStandaloneHandler</a></li> 110 </ul> 111 </li> 112 <li><a href="#position">Parse Position and Error Reporting Functions</a> 113 <ul> 114 <li><a href="#XML_GetErrorCode">XML_GetErrorCode</a></li> 115 <li><a href="#XML_ErrorString">XML_ErrorString</a></li> 116 <li><a href="#XML_GetCurrentByteIndex">XML_GetCurrentByteIndex</a></li> 117 <li><a href="#XML_GetCurrentLineNumber">XML_GetCurrentLineNumber</a></li> 118 <li><a href="#XML_GetCurrentColumnNumber">XML_GetCurrentColumnNumber</a></li> 119 <li><a href="#XML_GetCurrentByteCount">XML_GetCurrentByteCount</a></li> 120 <li><a href="#XML_GetInputContext">XML_GetInputContext</a></li> 121 </ul> 122 </li> 123 <li><a href="#miscellaneous">Miscellaneous Functions</a> 124 <ul> 125 <li><a href="#XML_SetUserData">XML_SetUserData</a></li> 126 <li><a href="#XML_GetUserData">XML_GetUserData</a></li> 127 <li><a href="#XML_UseParserAsHandlerArg">XML_UseParserAsHandlerArg</a></li> 128 <li><a href="#XML_SetBase">XML_SetBase</a></li> 129 <li><a href="#XML_GetBase">XML_GetBase</a></li> 130 <li><a href="#XML_GetSpecifiedAttributeCount">XML_GetSpecifiedAttributeCount</a></li> 131 <li><a href="#XML_GetIdAttributeIndex">XML_GetIdAttributeIndex</a></li> 132 <li><a href="#XML_SetEncoding">XML_SetEncoding</a></li> 133 <li><a href="#XML_SetParamEntityParsing">XML_SetParamEntityParsing</a></li> 134 <li><a href="#XML_UseForeignDTD">XML_UseForeignDTD</a></li> 135 <li><a href="#XML_SetReturnNSTriplet">XML_SetReturnNSTriplet</a></li> 136 <li><a href="#XML_DefaultCurrent">XML_DefaultCurrent</a></li> 137 <li><a href="#XML_ExpatVersion">XML_ExpatVersion</a></li> 138 <li><a href="#XML_ExpatVersionInfo">XML_ExpatVersionInfo</a></li> 139 <li><a href="#XML_GetFeatureList">XML_GetFeatureList</a></li> 140 <li><a href="#XML_FreeContentModel">XML_FreeContentModel</a></li> 141 <li><a href="#XML_MemMalloc">XML_MemMalloc</a></li> 142 <li><a href="#XML_MemRealloc">XML_MemRealloc</a></li> 143 <li><a href="#XML_MemFree">XML_MemFree</a></li> 144 </ul> 145 </li> 146 </ul> 147 </li> 148 </ul> 149 150 <hr /> 151 <h2><a name="overview">Overview</a></h2> 152 153 <p>Expat is a stream-oriented parser. You register callback (or 154 handler) functions with the parser and then start feeding it the 155 document. As the parser recognizes parts of the document, it will 156 call the appropriate handler for that part (if you've registered one.) 157 The document is fed to the parser in pieces, so you can start parsing 158 before you have all the document. This also allows you to parse really 159 huge documents that won't fit into memory.</p> 160 161 <p>Expat can be intimidating due to the many kinds of handlers and 162 options you can set. But you only need to learn four functions in 163 order to do 90% of what you'll want to do with it:</p> 164 165 <dl> 166 167 <dt><code><a href= "#XML_ParserCreate" 168 >XML_ParserCreate</a></code></dt> 169 <dd>Create a new parser object.</dd> 170 171 <dt><code><a href= "#XML_SetElementHandler" 172 >XML_SetElementHandler</a></code></dt> 173 <dd>Set handlers for start and end tags.</dd> 174 175 <dt><code><a href= "#XML_SetCharacterDataHandler" 176 >XML_SetCharacterDataHandler</a></code></dt> 177 <dd>Set handler for text.</dd> 178 179 <dt><code><a href= "#XML_Parse" 180 >XML_Parse</a></code></dt> 181 <dd>Pass a buffer full of document to the parser</dd> 182 </dl> 183 184 <p>These functions and others are described in the <a 185 href="#reference">reference</a> part of this document. The reference 186 section also describes in detail the parameters passed to the 187 different types of handlers.</p> 188 189 <p>Let's look at a very simple example program that only uses 3 of the 190 above functions (it doesn't need to set a character handler.) The 191 program <a href="../examples/outline.c">outline.c</a> prints an 192 element outline, indenting child elements to distinguish them from the 193 parent element that contains them. The start handler does all the 194 work. It prints two indenting spaces for every level of ancestor 195 elements, then it prints the element and attribute 196 information. Finally it increments the global <code>Depth</code> 197 variable.</p> 198 199 <pre class="eg"> 200 int Depth; 201 202 void XMLCALL 203 start(void *data, const char *el, const char **attr) { 204 int i; 205 206 for (i = 0; i < Depth; i++) 207 printf(" "); 208 209 printf("%s", el); 210 211 for (i = 0; attr[i]; i += 2) { 212 printf(" %s='%s'", attr[i], attr[i + 1]); 213 } 214 215 printf("\n"); 216 Depth++; 217 } /* End of start handler */ 218 </pre> 219 220 <p>The end tag simply does the bookkeeping work of decrementing 221 <code>Depth</code>.</p> 222 <pre class="eg"> 223 void XMLCALL 224 end(void *data, const char *el) { 225 Depth--; 226 } /* End of end handler */ 227 </pre> 228 229 <p>Note the <code>XMLCALL</code> annotation used for the callbacks. 230 This is used to ensure that the Expat and the callbacks are using the 231 same calling convention in case the compiler options used for Expat 232 itself and the client code are different. Expat tries not to care 233 what the default calling convention is, though it may require that it 234 be compiled with a default convention of "cdecl" on some platforms. 235 For code which uses Expat, however, the calling convention is 236 specified by the <code>XMLCALL</code> annotation on most platforms; 237 callbacks should be defined using this annotation.</p> 238 239 <p>The <code>XMLCALL</code> annotation was added in Expat 1.95.7, but 240 existing working Expat applications don't need to add it (since they 241 are already using the "cdecl" calling convention, or they wouldn't be 242 working). The annotation is only needed if the default calling 243 convention may be something other than "cdecl". To use the annotation 244 safely with older versions of Expat, you can conditionally define it 245 <em>after</em> including Expat's header file:</p> 246 247 <pre class="eg"> 248 #include <expat.h> 249 250 #ifndef XMLCALL 251 #if defined(_MSC_EXTENSIONS) && !defined(__BEOS__) && !defined(__CYGWIN__) 252 #define XMLCALL __cdecl 253 #elif defined(__GNUC__) 254 #define XMLCALL __attribute__((cdecl)) 255 #else 256 #define XMLCALL 257 #endif 258 #endif 259 </pre> 260 261 <p>After creating the parser, the main program just has the job of 262 shoveling the document to the parser so that it can do its work.</p> 263 264 <hr /> 265 <h2><a name="building">Building and Installing Expat</a></h2> 266 267 <p>The Expat distribution comes as a compressed (with GNU gzip) tar 268 file. You may download the latest version from <a href= 269 "http://sourceforge.net/projects/expat/" >Source Forge</a>. After 270 unpacking this, cd into the directory. Then follow either the Win32 271 directions or Unix directions below.</p> 272 273 <h3>Building under Win32</h3> 274 275 <p>If you're using the GNU compiler under cygwin, follow the Unix 276 directions in the next section. Otherwise if you have Microsoft's 277 Developer Studio installed, then from Windows Explorer double-click on 278 "expat.dsp" in the lib directory and build and install in the usual 279 manner.</p> 280 281 <p>Alternatively, you may download the Win32 binary package that 282 contains the "expat.h" include file and a pre-built DLL.</p> 283 284 <h3>Building under Unix (or GNU)</h3> 285 286 <p>First you'll need to run the configure shell script in order to 287 configure the Makefiles and headers for your system.</p> 288 289 <p>If you're happy with all the defaults that configure picks for you, 290 and you have permission on your system to install into /usr/local, you 291 can install Expat with this sequence of commands:</p> 292 293 <pre class="eg"> 294 ./configure 295 make 296 make install 297 </pre> 298 299 <p>There are some options that you can provide to this script, but the 300 only one we'll mention here is the <code>--prefix</code> option. You 301 can find out all the options available by running configure with just 302 the <code>--help</code> option.</p> 303 304 <p>By default, the configure script sets things up so that the library 305 gets installed in <code>/usr/local/lib</code> and the associated 306 header file in <code>/usr/local/include</code>. But if you were to 307 give the option, <code>--prefix=/home/me/mystuff</code>, then the 308 library and header would get installed in 309 <code>/home/me/mystuff/lib</code> and 310 <code>/home/me/mystuff/include</code> respectively.</p> 311 312 <h3>Configuring Expat Using the Pre-Processor</h3> 313 314 <p>Expat's feature set can be configured using a small number of 315 pre-processor definitions. The definition of this symbols does not 316 affect the set of entry points for Expat, only the behavior of the API 317 and the definition of character types in the case of 318 <code>XML_UNICODE_WCHAR_T</code>. The symbols are:</p> 319 320 <dl class="cpp-symbols"> 321 <dt>XML_DTD</dt> 322 <dd>Include support for using and reporting DTD-based content. If 323 this is defined, default attribute values from an external DTD subset 324 are reported and attribute value normalization occurs based on the 325 type of attributes defined in the external subset. Without 326 this, Expat has a smaller memory footprint and can be faster, but will 327 not load external entities or process conditional sections. This does 328 not affect the set of functions available in the API.</dd> 329 330 <dt>XML_NS</dt> 331 <dd>When defined, support for the <cite><a href= 332 "http://www.w3.org/TR/REC-xml-names/" >Namespaces in XML</a></cite> 333 specification is included.</dd> 334 335 <dt>XML_UNICODE</dt> 336 <dd>When defined, character data reported to the application is 337 encoded in UTF-16 using wide characters of the type 338 <code>XML_Char</code>. This is implied if 339 <code>XML_UNICODE_WCHAR_T</code> is defined.</dd> 340 341 <dt>XML_UNICODE_WCHAR_T</dt> 342 <dd>If defined, causes the <code>XML_Char</code> character type to be 343 defined using the <code>wchar_t</code> type; otherwise, <code>unsigned 344 short</code> is used. Defining this implies 345 <code>XML_UNICODE</code>.</dd> 346 347 <dt>XML_LARGE_SIZE</dt> 348 <dd>If defined, causes the <code>XML_Size</code> and <code>XML_Index</code> 349 integer types to be at least 64 bits in size. This is intended to support 350 processing of very large input streams, where the return values of 351 <code><a href="#XML_GetCurrentByteIndex" >XML_GetCurrentByteIndex</a></code>, 352 <code><a href="#XML_GetCurrentLineNumber" >XML_GetCurrentLineNumber</a></code> and 353 <code><a href="#XML_GetCurrentColumnNumber" >XML_GetCurrentColumnNumber</a></code> 354 could overflow. It may not be supported by all compilers, and is turned 355 off by default.</dd> 356 357 <dt>XML_CONTEXT_BYTES</dt> 358 <dd>The number of input bytes of markup context which the parser will 359 ensure are available for reporting via <code><a href= 360 "#XML_GetInputContext" >XML_GetInputContext</a></code>. This is 361 normally set to 1024, and must be set to a positive interger. If this 362 is not defined, the input context will not be available and <code><a 363 href= "#XML_GetInputContext" >XML_GetInputContext</a></code> will 364 always report NULL. Without this, Expat has a smaller memory 365 footprint and can be faster.</dd> 366 367 <dt>XML_STATIC</dt> 368 <dd>On Windows, this should be set if Expat is going to be linked 369 statically with the code that calls it; this is required to get all 370 the right MSVC magic annotations correct. This is ignored on other 371 platforms.</dd> 372 </dl> 373 374 <hr /> 375 <h2><a name="using">Using Expat</a></h2> 376 377 <h3>Compiling and Linking Against Expat</h3> 378 379 <p>Unless you installed Expat in a location not expected by your 380 compiler and linker, all you have to do to use Expat in your programs 381 is to include the Expat header (<code>#include <expat.h></code>) 382 in your files that make calls to it and to tell the linker that it 383 needs to link against the Expat library. On Unix systems, this would 384 usually be done with the <code>-lexpat</code> argument. Otherwise, 385 you'll need to tell the compiler where to look for the Expat header 386 and the linker where to find the Expat library. You may also need to 387 take steps to tell the operating system where to find this library at 388 run time.</p> 389 390 <p>On a Unix-based system, here's what a Makefile might look like when 391 Expat is installed in a standard location:</p> 392 393 <pre class="eg"> 394 CC=cc 395 LDFLAGS= 396 LIBS= -lexpat 397 xmlapp: xmlapp.o 398 $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS) 399 </pre> 400 401 <p>If you installed Expat in, say, <code>/home/me/mystuff</code>, then 402 the Makefile would look like this:</p> 403 404 <pre class="eg"> 405 CC=cc 406 CFLAGS= -I/home/me/mystuff/include 407 LDFLAGS= 408 LIBS= -L/home/me/mystuff/lib -lexpat 409 xmlapp: xmlapp.o 410 $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS) 411 </pre> 412 413 <p>You'd also have to set the environment variable 414 <code>LD_LIBRARY_PATH</code> to <code>/home/me/mystuff/lib</code> (or 415 to <code>${LD_LIBRARY_PATH}:/home/me/mystuff/lib</code> if 416 LD_LIBRARY_PATH already has some directories in it) in order to run 417 your application.</p> 418 419 <h3>Expat Basics</h3> 420 421 <p>As we saw in the example in the overview, the first step in parsing 422 an XML document with Expat is to create a parser object. There are <a 423 href="#creation">three functions</a> in the Expat API for creating a 424 parser object. However, only two of these (<code><a href= 425 "#XML_ParserCreate" >XML_ParserCreate</a></code> and <code><a href= 426 "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>) can be used for 427 constructing a parser for a top-level document. The object returned 428 by these functions is an opaque pointer (i.e. "expat.h" declares it as 429 void *) to data with further internal structure. In order to free the 430 memory associated with this object you must call <code><a href= 431 "#XML_ParserFree" >XML_ParserFree</a></code>. Note that if you have 432 provided any <a href="#userdata">user data</a> that gets stored in the 433 parser, then your application is responsible for freeing it prior to 434 calling <code>XML_ParserFree</code>.</p> 435 436 <p>The objects returned by the parser creation functions are good for 437 parsing only one XML document or external parsed entity. If your 438 application needs to parse many XML documents, then it needs to create 439 a parser object for each one. The best way to deal with this is to 440 create a higher level object that contains all the default 441 initialization you want for your parser objects.</p> 442 443 <p>Walking through a document hierarchy with a stream oriented parser 444 will require a good stack mechanism in order to keep track of current 445 context. For instance, to answer the simple question, "What element 446 does this text belong to?" requires a stack, since the parser may have 447 descended into other elements that are children of the current one and 448 has encountered this text on the way out.</p> 449 450 <p>The things you're likely to want to keep on a stack are the 451 currently opened element and it's attributes. You push this 452 information onto the stack in the start handler and you pop it off in 453 the end handler.</p> 454 455 <p>For some tasks, it is sufficient to just keep information on what 456 the depth of the stack is (or would be if you had one.) The outline 457 program shown above presents one example. Another such task would be 458 skipping over a complete element. When you see the start tag for the 459 element you want to skip, you set a skip flag and record the depth at 460 which the element started. When the end tag handler encounters the 461 same depth, the skipped element has ended and the flag may be 462 cleared. If you follow the convention that the root element starts at 463 1, then you can use the same variable for skip flag and skip 464 depth.</p> 465 466 <pre class="eg"> 467 void 468 init_info(Parseinfo *info) { 469 info->skip = 0; 470 info->depth = 1; 471 /* Other initializations here */ 472 } /* End of init_info */ 473 474 void XMLCALL 475 rawstart(void *data, const char *el, const char **attr) { 476 Parseinfo *inf = (Parseinfo *) data; 477 478 if (! inf->skip) { 479 if (should_skip(inf, el, attr)) { 480 inf->skip = inf->depth; 481 } 482 else 483 start(inf, el, attr); /* This does rest of start handling */ 484 } 485 486 inf->depth++; 487 } /* End of rawstart */ 488 489 void XMLCALL 490 rawend(void *data, const char *el) { 491 Parseinfo *inf = (Parseinfo *) data; 492 493 inf->depth--; 494 495 if (! inf->skip) 496 end(inf, el); /* This does rest of end handling */ 497 498 if (inf->skip == inf->depth) 499 inf->skip = 0; 500 } /* End rawend */ 501 </pre> 502 503 <p>Notice in the above example the difference in how depth is 504 manipulated in the start and end handlers. The end tag handler should 505 be the mirror image of the start tag handler. This is necessary to 506 properly model containment. Since, in the start tag handler, we 507 incremented depth <em>after</em> the main body of start tag code, then 508 in the end handler, we need to manipulate it <em>before</em> the main 509 body. If we'd decided to increment it first thing in the start 510 handler, then we'd have had to decrement it last thing in the end 511 handler.</p> 512 513 <h3 id="userdata">Communicating between handlers</h3> 514 515 <p>In order to be able to pass information between different handlers 516 without using globals, you'll need to define a data structure to hold 517 the shared variables. You can then tell Expat (with the <code><a href= 518 "#XML_SetUserData" >XML_SetUserData</a></code> function) to pass a 519 pointer to this structure to the handlers. This is the first 520 argument received by most handlers. In the <a href="#reference" 521 >reference section</a>, an argument to a callback function is named 522 <code>userData</code> and have type <code>void *</code> if the user 523 data is passed; it will have the type <code>XML_Parser</code> if the 524 parser itself is passed. When the parser is passed, the user data may 525 be retrieved using <code><a href="#XML_GetUserData" 526 >XML_GetUserData</a></code>.</p> 527 528 <p>One common case where multiple calls to a single handler may need 529 to communicate using an application data structure is the case when 530 content passed to the character data handler (set by <code><a href= 531 "#XML_SetCharacterDataHandler" 532 >XML_SetCharacterDataHandler</a></code>) needs to be accumulated. A 533 common first-time mistake with any of the event-oriented interfaces to 534 an XML parser is to expect all the text contained in an element to be 535 reported by a single call to the character data handler. Expat, like 536 many other XML parsers, reports such data as a sequence of calls; 537 there's no way to know when the end of the sequence is reached until a 538 different callback is made. A buffer referenced by the user data 539 structure proves both an effective and convenient place to accumulate 540 character data.</p> 541 542 <!-- XXX example needed here --> 543 544 545 <h3>XML Version</h3> 546 547 <p>Expat is an XML 1.0 parser, and as such never complains based on 548 the value of the <code>version</code> pseudo-attribute in the XML 549 declaration, if present.</p> 550 551 <p>If an application needs to check the version number (to support 552 alternate processing), it should use the <code><a href= 553 "#XML_SetXmlDeclHandler" >XML_SetXmlDeclHandler</a></code> function to 554 set a handler that uses the information in the XML declaration to 555 determine what to do. This example shows how to check that only a 556 version number of <code>"1.0"</code> is accepted:</p> 557 558 <pre class="eg"> 559 static int wrong_version; 560 static XML_Parser parser; 561 562 static void XMLCALL 563 xmldecl_handler(void *userData, 564 const XML_Char *version, 565 const XML_Char *encoding, 566 int standalone) 567 { 568 static const XML_Char Version_1_0[] = {'1', '.', '0', 0}; 569 570 int i; 571 572 for (i = 0; i < (sizeof(Version_1_0) / sizeof(Version_1_0[0])); ++i) { 573 if (version[i] != Version_1_0[i]) { 574 wrong_version = 1; 575 /* also clear all other handlers: */ 576 XML_SetCharacterDataHandler(parser, NULL); 577 ... 578 return; 579 } 580 } 581 ... 582 } 583 </pre> 584 585 <h3>Namespace Processing</h3> 586 587 <p>When the parser is created using the <code><a href= 588 "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>, function, Expat 589 performs namespace processing. Under namespace processing, Expat 590 consumes <code>xmlns</code> and <code>xmlns:...</code> attributes, 591 which declare namespaces for the scope of the element in which they 592 occur. This means that your start handler will not see these 593 attributes. Your application can still be informed of these 594 declarations by setting namespace declaration handlers with <a href= 595 "#XML_SetNamespaceDeclHandler" 596 ><code>XML_SetNamespaceDeclHandler</code></a>.</p> 597 598 <p>Element type and attribute names that belong to a given namespace 599 are passed to the appropriate handler in expanded form. By default 600 this expanded form is a concatenation of the namespace URI, the 601 separator character (which is the 2nd argument to <code><a href= 602 "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>), and the local 603 name (i.e. the part after the colon). Names with undeclared prefixes 604 are not well-formed when namespace processing is enabled, and will 605 trigger an error. Unprefixed attribute names are never expanded, 606 and unprefixed element names are only expanded when they are in the 607 scope of a default namespace.</p> 608 609 <p>However if <code><a href= "#XML_SetReturnNSTriplet" 610 >XML_SetReturnNSTriplet</a></code> has been called with a non-zero 611 <code>do_nst</code> parameter, then the expanded form for names with 612 an explicit prefix is a concatenation of: URI, separator, local name, 613 separator, prefix.</p> 614 615 <p>You can set handlers for the start of a namespace declaration and 616 for the end of a scope of a declaration with the <code><a href= 617 "#XML_SetNamespaceDeclHandler" >XML_SetNamespaceDeclHandler</a></code> 618 function. The StartNamespaceDeclHandler is called prior to the start 619 tag handler and the EndNamespaceDeclHandler is called after the 620 corresponding end tag that ends the namespace's scope. The namespace 621 start handler gets passed the prefix and URI for the namespace. For a 622 default namespace declaration (xmlns='...'), the prefix will be null. 623 The URI will be null for the case where the default namespace is being 624 unset. The namespace end handler just gets the prefix for the closing 625 scope.</p> 626 627 <p>These handlers are called for each declaration. So if, for 628 instance, a start tag had three namespace declarations, then the 629 StartNamespaceDeclHandler would be called three times before the start 630 tag handler is called, once for each declaration.</p> 631 632 <h3>Character Encodings</h3> 633 634 <p>While XML is based on Unicode, and every XML processor is required 635 to recognized UTF-8 and UTF-16 (1 and 2 byte encodings of Unicode), 636 other encodings may be declared in XML documents or entities. For the 637 main document, an XML declaration may contain an encoding 638 declaration:</p> 639 <pre> 640 <?xml version="1.0" encoding="ISO-8859-2"?> 641 </pre> 642 643 <p>External parsed entities may begin with a text declaration, which 644 looks like an XML declaration with just an encoding declaration:</p> 645 <pre> 646 <?xml encoding="Big5"?> 647 </pre> 648 649 <p>With Expat, you may also specify an encoding at the time of 650 creating a parser. This is useful when the encoding information may 651 come from a source outside the document itself (like a higher level 652 protocol.)</p> 653 654 <p><a name="builtin_encodings"></a>There are four built-in encodings 655 in Expat:</p> 656 <ul> 657 <li>UTF-8</li> 658 <li>UTF-16</li> 659 <li>ISO-8859-1</li> 660 <li>US-ASCII</li> 661 </ul> 662 663 <p>Anything else discovered in an encoding declaration or in the 664 protocol encoding specified in the parser constructor, triggers a call 665 to the <code>UnknownEncodingHandler</code>. This handler gets passed 666 the encoding name and a pointer to an <code>XML_Encoding</code> data 667 structure. Your handler must fill in this structure and return 668 <code>XML_STATUS_OK</code> if it knows how to deal with the 669 encoding. Otherwise the handler should return 670 <code>XML_STATUS_ERROR</code>. The handler also gets passed a pointer 671 to an optional application data structure that you may indicate when 672 you set the handler.</p> 673 674 <p>Expat places restrictions on character encodings that it can 675 support by filling in the <code>XML_Encoding</code> structure. 676 include file:</p> 677 <ol> 678 <li>Every ASCII character that can appear in a well-formed XML document 679 must be represented by a single byte, and that byte must correspond to 680 it's ASCII encoding (except for the characters $@\^'{}~)</li> 681 <li>Characters must be encoded in 4 bytes or less.</li> 682 <li>All characters encoded must have Unicode scalar values less than or 683 equal to 65535 (0xFFFF)<em>This does not apply to the built-in support 684 for UTF-16 and UTF-8</em></li> 685 <li>No character may be encoded by more that one distinct sequence of 686 bytes</li> 687 </ol> 688 689 <p><code>XML_Encoding</code> contains an array of integers that 690 correspond to the 1st byte of an encoding sequence. If the value in 691 the array for a byte is zero or positive, then the byte is a single 692 byte encoding that encodes the Unicode scalar value contained in the 693 array. A -1 in this array indicates a malformed byte. If the value is 694 -2, -3, or -4, then the byte is the beginning of a 2, 3, or 4 byte 695 sequence respectively. Multi-byte sequences are sent to the convert 696 function pointed at in the <code>XML_Encoding</code> structure. This 697 function should return the Unicode scalar value for the sequence or -1 698 if the sequence is malformed.</p> 699 700 <p>One pitfall that novice Expat users are likely to fall into is that 701 although Expat may accept input in various encodings, the strings that 702 it passes to the handlers are always encoded in UTF-8 or UTF-16 703 (depending on how Expat was compiled). Your application is responsible 704 for any translation of these strings into other encodings.</p> 705 706 <h3>Handling External Entity References</h3> 707 708 <p>Expat does not read or parse external entities directly. Note that 709 any external DTD is a special case of an external entity. If you've 710 set no <code>ExternalEntityRefHandler</code>, then external entity 711 references are silently ignored. Otherwise, it calls your handler with 712 the information needed to read and parse the external entity.</p> 713 714 <p>Your handler isn't actually responsible for parsing the entity, but 715 it is responsible for creating a subsidiary parser with <code><a href= 716 "#XML_ExternalEntityParserCreate" 717 >XML_ExternalEntityParserCreate</a></code> that will do the job. This 718 returns an instance of <code>XML_Parser</code> that has handlers and 719 other data structures initialized from the parent parser. You may then 720 use <code><a href= "#XML_Parse" >XML_Parse</a></code> or <code><a 721 href= "#XML_ParseBuffer">XML_ParseBuffer</a></code> calls against this 722 parser. Since external entities my refer to other external entities, 723 your handler should be prepared to be called recursively.</p> 724 725 <h3>Parsing DTDs</h3> 726 727 <p>In order to parse parameter entities, before starting the parse, 728 you must call <code><a href= "#XML_SetParamEntityParsing" 729 >XML_SetParamEntityParsing</a></code> with one of the following 730 arguments:</p> 731 <dl> 732 <dt><code>XML_PARAM_ENTITY_PARSING_NEVER</code></dt> 733 <dd>Don't parse parameter entities or the external subset</dd> 734 <dt><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></dt> 735 <dd>Parse parameter entites and the external subset unless 736 <code>standalone</code> was set to "yes" in the XML declaration.</dd> 737 <dt><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></dt> 738 <dd>Always parse parameter entities and the external subset</dd> 739 </dl> 740 741 <p>In order to read an external DTD, you also have to set an external 742 entity reference handler as described above.</p> 743 744 <h3 id="stop-resume">Temporarily Stopping Parsing</h3> 745 746 <p>Expat 1.95.8 introduces a new feature: its now possible to stop 747 parsing temporarily from within a handler function, even if more data 748 has already been passed into the parser. Applications for this 749 include</p> 750 751 <ul> 752 <li>Supporting the <a href= "http://www.w3.org/TR/xinclude/" 753 >XInclude</a> specification.</li> 754 755 <li>Delaying further processing until additional information is 756 available from some other source.</li> 757 758 <li>Adjusting processor load as task priorities shift within an 759 application.</li> 760 761 <li>Stopping parsing completely (simply free or reset the parser 762 instead of resuming in the outer parsing loop). This can be useful 763 if a application-domain error is found in the XML being parsed or if 764 the result of the parse is determined not to be useful after 765 all.</li> 766 </ul> 767 768 <p>To take advantage of this feature, the main parsing loop of an 769 application needs to support this specifically. It cannot be 770 supported with a parsing loop compatible with Expat 1.95.7 or 771 earlier (though existing loops will continue to work without 772 supporting the stop/resume feature).</p> 773 774 <p>An application that uses this feature for a single parser will have 775 the rough structure (in pseudo-code):</p> 776 777 <pre class="pseudocode"> 778 fd = open_input() 779 p = create_parser() 780 781 if parse_xml(p, fd) { 782 /* suspended */ 783 784 int suspended = 1; 785 786 while (suspended) { 787 do_something_else() 788 if ready_to_resume() { 789 suspended = continue_parsing(p, fd); 790 } 791 } 792 } 793 </pre> 794 795 <p>An application that may resume any of several parsers based on 796 input (either from the XML being parsed or some other source) will 797 certainly have more interesting control structures.</p> 798 799 <p>This C function could be used for the <code>parse_xml</code> 800 function mentioned in the pseudo-code above:</p> 801 802 <pre class="eg"> 803 #define BUFF_SIZE 10240 804 805 /* Parse a document from the open file descriptor 'fd' until the parse 806 is complete (the document has been completely parsed, or there's 807 been an error), or the parse is stopped. Return non-zero when 808 the parse is merely suspended. 809 */ 810 int 811 parse_xml(XML_Parser p, int fd) 812 { 813 for (;;) { 814 int last_chunk; 815 int bytes_read; 816 enum XML_Status status; 817 818 void *buff = XML_GetBuffer(p, BUFF_SIZE); 819 if (buff == NULL) { 820 /* handle error... */ 821 return 0; 822 } 823 bytes_read = read(fd, buff, BUFF_SIZE); 824 if (bytes_read < 0) { 825 /* handle error... */ 826 return 0; 827 } 828 status = XML_ParseBuffer(p, bytes_read, bytes_read == 0); 829 switch (status) { 830 case XML_STATUS_ERROR: 831 /* handle error... */ 832 return 0; 833 case XML_STATUS_SUSPENDED: 834 return 1; 835 } 836 if (bytes_read == 0) 837 return 0; 838 } 839 } 840 </pre> 841 842 <p>The corresponding <code>continue_parsing</code> function is 843 somewhat simpler, since it only need deal with the return code from 844 <code><a href= "#XML_ResumeParser">XML_ResumeParser</a></code>; it can 845 delegate the input handling to the <code>parse_xml</code> 846 function:</p> 847 848 <pre class="eg"> 849 /* Continue parsing a document which had been suspended. The 'p' and 850 'fd' arguments are the same as passed to parse_xml(). Return 851 non-zero when the parse is suspended. 852 */ 853 int 854 continue_parsing(XML_Parser p, int fd) 855 { 856 enum XML_Status status = XML_ResumeParser(p); 857 switch (status) { 858 case XML_STATUS_ERROR: 859 /* handle error... */ 860 return 0; 861 case XML_ERROR_NOT_SUSPENDED: 862 /* handle error... */ 863 return 0;. 864 case XML_STATUS_SUSPENDED: 865 return 1; 866 } 867 return parse_xml(p, fd); 868 } 869 </pre> 870 871 <p>Now that we've seen what a mess the top-level parsing loop can 872 become, what have we gained? Very simply, we can now use the <code><a 873 href= "#XML_StopParser" >XML_StopParser</a></code> function to stop 874 parsing, without having to go to great lengths to avoid additional 875 processing that we're expecting to ignore. As a bonus, we get to stop 876 parsing <em>temporarily</em>, and come back to it when we're 877 ready.</p> 878 879 <p>To stop parsing from a handler function, use the <code><a href= 880 "#XML_StopParser" >XML_StopParser</a></code> function. This function 881 takes two arguments; the parser being stopped and a flag indicating 882 whether the parse can be resumed in the future.</p> 883 884 <!-- XXX really need more here --> 885 886 887 <hr /> 888 <!-- ================================================================ --> 889 890 <h2><a name="reference">Expat Reference</a></h2> 891 892 <h3><a name="creation">Parser Creation</a></h3> 893 894 <pre class="fcndec" id="XML_ParserCreate"> 895 XML_Parser XMLCALL 896 XML_ParserCreate(const XML_Char *encoding); 897 </pre> 898 <div class="fcndef"> 899 Construct a new parser. If encoding is non-null, it specifies a 900 character encoding to use for the document. This overrides the document 901 encoding declaration. There are four built-in encodings: 902 <ul> 903 <li>US-ASCII</li> 904 <li>UTF-8</li> 905 <li>UTF-16</li> 906 <li>ISO-8859-1</li> 907 </ul> 908 Any other value will invoke a call to the UnknownEncodingHandler. 909 </div> 910 911 <pre class="fcndec" id="XML_ParserCreateNS"> 912 XML_Parser XMLCALL 913 XML_ParserCreateNS(const XML_Char *encoding, 914 XML_Char sep); 915 </pre> 916 <div class="fcndef"> 917 Constructs a new parser that has namespace processing in effect. Namespace 918 expanded element names and attribute names are returned as a concatenation 919 of the namespace URI, <em>sep</em>, and the local part of the name. This 920 means that you should pick a character for <em>sep</em> that can't be 921 part of a legal URI. There is a special case when <em>sep</em> is the null 922 character <code>'\0'</code>: the namespace URI and the local part will be 923 concatenated without any separator - this is intended to support RDF processors. 924 It is a programming error to use the null separator with 925 <a href= "#XML_SetReturnNSTriplet">namespace triplets</a>.</div> 926 927 <pre class="fcndec" id="XML_ParserCreate_MM"> 928 XML_Parser XMLCALL 929 XML_ParserCreate_MM(const XML_Char *encoding, 930 const XML_Memory_Handling_Suite *ms, 931 const XML_Char *sep); 932 </pre> 933 <pre class="signature"> 934 typedef struct { 935 void *(XMLCALL *malloc_fcn)(size_t size); 936 void *(XMLCALL *realloc_fcn)(void *ptr, size_t size); 937 void (XMLCALL *free_fcn)(void *ptr); 938 } XML_Memory_Handling_Suite; 939 </pre> 940 <div class="fcndef"> 941 <p>Construct a new parser using the suite of memory handling functions 942 specified in <code>ms</code>. If <code>ms</code> is NULL, then use the 943 standard set of memory management functions. If <code>sep</code> is 944 non NULL, then namespace processing is enabled in the created parser 945 and the character pointed at by sep is used as the separator between 946 the namespace URI and the local part of the name.</p> 947 </div> 948 949 <pre class="fcndec" id="XML_ExternalEntityParserCreate"> 950 XML_Parser XMLCALL 951 XML_ExternalEntityParserCreate(XML_Parser p, 952 const XML_Char *context, 953 const XML_Char *encoding); 954 </pre> 955 <div class="fcndef"> 956 Construct a new <code>XML_Parser</code> object for parsing an external 957 general entity. Context is the context argument passed in a call to a 958 ExternalEntityRefHandler. Other state information such as handlers, 959 user data, namespace processing is inherited from the parser passed as 960 the 1st argument. So you shouldn't need to call any of the behavior 961 changing functions on this parser (unless you want it to act 962 differently than the parent parser). 963 </div> 964 965 <pre class="fcndec" id="XML_ParserFree"> 966 void XMLCALL 967 XML_ParserFree(XML_Parser p); 968 </pre> 969 <div class="fcndef"> 970 Free memory used by the parser. Your application is responsible for 971 freeing any memory associated with <a href="#userdata">user data</a>. 972 </div> 973 974 <pre class="fcndec" id="XML_ParserReset"> 975 XML_Bool XMLCALL 976 XML_ParserReset(XML_Parser p, 977 const XML_Char *encoding); 978 </pre> 979 <div class="fcndef"> 980 Clean up the memory structures maintained by the parser so that it may 981 be used again. After this has been called, <code>parser</code> is 982 ready to start parsing a new document. All handlers are cleared from 983 the parser, except for the unknownEncodingHandler. The parser's external 984 state is re-initialized except for the values of ns and ns_triplets. 985 This function may not be used on a parser created using <code><a href= 986 "#XML_ExternalEntityParserCreate" >XML_ExternalEntityParserCreate</a 987 ></code>; it will return <code>XML_FALSE</code> in that case. Returns 988 <code>XML_TRUE</code> on success. Your application is responsible for 989 dealing with any memory associated with <a href="#userdata">user data</a>. 990 </div> 991 992 <h3><a name="parsing">Parsing</a></h3> 993 994 <p>To state the obvious: the three parsing functions <code><a href= 995 "#XML_Parse" >XML_Parse</a></code>, <code><a href= "#XML_ParseBuffer"> 996 XML_ParseBuffer</a></code> and <code><a href= "#XML_GetBuffer"> 997 XML_GetBuffer</a></code> must not be called from within a handler 998 unless they operate on a separate parser instance, that is, one that 999 did not call the handler. For example, it is OK to call the parsing 1000 functions from within an <code>XML_ExternalEntityRefHandler</code>, 1001 if they apply to the parser created by 1002 <code><a href= "#XML_ExternalEntityParserCreate" 1003 >XML_ExternalEntityParserCreate</a></code>.</p> 1004 1005 <p>Note: the <code>len</code> argument passed to these functions 1006 should be considerably less than the maximum value for an integer, 1007 as it could create an integer overflow situation if the added 1008 lengths of a buffer and the unprocessed portion of the previous buffer 1009 exceed the maximum integer value. Input data at the end of a buffer 1010 will remain unprocessed if it is part of an XML token for which the 1011 end is not part of that buffer.</p> 1012 1013 <pre class="fcndec" id="XML_Parse"> 1014 enum XML_Status XMLCALL 1015 XML_Parse(XML_Parser p, 1016 const char *s, 1017 int len, 1018 int isFinal); 1019 </pre> 1020 <pre class="signature"> 1021 enum XML_Status { 1022 XML_STATUS_ERROR = 0, 1023 XML_STATUS_OK = 1 1024 }; 1025 </pre> 1026 <div class="fcndef"> 1027 Parse some more of the document. The string <code>s</code> is a buffer 1028 containing part (or perhaps all) of the document. The number of bytes of s 1029 that are part of the document is indicated by <code>len</code>. This means 1030 that <code>s</code> doesn't have to be null terminated. It also means that 1031 if <code>len</code> is larger than the number of bytes in the block of 1032 memory that <code>s</code> points at, then a memory fault is likely. The 1033 <code>isFinal</code> parameter informs the parser that this is the last 1034 piece of the document. Frequently, the last piece is empty (i.e. 1035 <code>len</code> is zero.) 1036 If a parse error occurred, it returns <code>XML_STATUS_ERROR</code>. 1037 Otherwise it returns <code>XML_STATUS_OK</code> value. 1038 </div> 1039 1040 <pre class="fcndec" id="XML_ParseBuffer"> 1041 enum XML_Status XMLCALL 1042 XML_ParseBuffer(XML_Parser p, 1043 int len, 1044 int isFinal); 1045 </pre> 1046 <div class="fcndef"> 1047 This is just like <code><a href= "#XML_Parse" >XML_Parse</a></code>, 1048 except in this case Expat provides the buffer. By obtaining the 1049 buffer from Expat with the <code><a href= "#XML_GetBuffer" 1050 >XML_GetBuffer</a></code> function, the application can avoid double 1051 copying of the input. 1052 </div> 1053 1054 <pre class="fcndec" id="XML_GetBuffer"> 1055 void * XMLCALL 1056 XML_GetBuffer(XML_Parser p, 1057 int len); 1058 </pre> 1059 <div class="fcndef"> 1060 Obtain a buffer of size <code>len</code> to read a piece of the document 1061 into. A NULL value is returned if Expat can't allocate enough memory for 1062 this buffer. This has to be called prior to every call to 1063 <code><a href= "#XML_ParseBuffer" >XML_ParseBuffer</a></code>. A 1064 typical use would look like this: 1065 1066 <pre class="eg"> 1067 for (;;) { 1068 int bytes_read; 1069 void *buff = XML_GetBuffer(p, BUFF_SIZE); 1070 if (buff == NULL) { 1071 /* handle error */ 1072 } 1073 1074 bytes_read = read(docfd, buff, BUFF_SIZE); 1075 if (bytes_read < 0) { 1076 /* handle error */ 1077 } 1078 1079 if (! XML_ParseBuffer(p, bytes_read, bytes_read == 0)) { 1080 /* handle parse error */ 1081 } 1082 1083 if (bytes_read == 0) 1084 break; 1085 } 1086 </pre> 1087 </div> 1088 1089 <pre class="fcndec" id="XML_StopParser"> 1090 enum XML_Status XMLCALL 1091 XML_StopParser(XML_Parser p, 1092 XML_Bool resumable); 1093 </pre> 1094 <div class="fcndef"> 1095 1096 <p>Stops parsing, causing <code><a href= "#XML_Parse" 1097 >XML_Parse</a></code> or <code><a href= "#XML_ParseBuffer" 1098 >XML_ParseBuffer</a></code> to return. Must be called from within a 1099 call-back handler, except when aborting (when <code>resumable</code> 1100 is <code>XML_FALSE</code>) an already suspended parser. Some 1101 call-backs may still follow because they would otherwise get 1102 lost, including 1103 <ul> 1104 <li> the end element handler for empty elements when stopped in the 1105 start element handler,</li> 1106 <li> the end namespace declaration handler when stopped in the end 1107 element handler,</li> 1108 <li> the character data handler when stopped in the character data handler 1109 while making multiple call-backs on a contiguous chunk of characters,</li> 1110 </ul> 1111 and possibly others.</p> 1112 1113 <p>This can be called from most handlers, including DTD related 1114 call-backs, except when parsing an external parameter entity and 1115 <code>resumable</code> is <code>XML_TRUE</code>. Returns 1116 <code>XML_STATUS_OK</code> when successful, 1117 <code>XML_STATUS_ERROR</code> otherwise. The possible error codes 1118 are:</p> 1119 <dl> 1120 <dt><code>XML_ERROR_SUSPENDED</code></dt> 1121 <dd>when suspending an already suspended parser.</dd> 1122 <dt><code>XML_ERROR_FINISHED</code></dt> 1123 <dd>when the parser has already finished.</dd> 1124 <dt><code>XML_ERROR_SUSPEND_PE</code></dt> 1125 <dd>when suspending while parsing an external PE.</dd> 1126 </dl> 1127 1128 <p>Since the stop/resume feature requires application support in the 1129 outer parsing loop, it is an error to call this function for a parser 1130 not being handled appropriately; see <a href= "#stop-resume" 1131 >Temporarily Stopping Parsing</a> for more information.</p> 1132 1133 <p>When <code>resumable</code> is <code>XML_TRUE</code> then parsing 1134 is <em>suspended</em>, that is, <code><a href= "#XML_Parse" 1135 >XML_Parse</a></code> and <code><a href= "#XML_ParseBuffer" 1136 >XML_ParseBuffer</a></code> return <code>XML_STATUS_SUSPENDED</code>. 1137 Otherwise, parsing is <em>aborted</em>, that is, <code><a href= 1138 "#XML_Parse" >XML_Parse</a></code> and <code><a href= 1139 "#XML_ParseBuffer" >XML_ParseBuffer</a></code> return 1140 <code>XML_STATUS_ERROR</code> with error code 1141 <code>XML_ERROR_ABORTED</code>.</p> 1142 1143 <p><strong>Note:</strong> 1144 This will be applied to the current parser instance only, that is, if 1145 there is a parent parser then it will continue parsing when the 1146 external entity reference handler returns. It is up to the 1147 implementation of that handler to call <code><a href= 1148 "#XML_StopParser" >XML_StopParser</a></code> on the parent parser 1149 (recursively), if one wants to stop parsing altogether.</p> 1150 1151 <p>When suspended, parsing can be resumed by calling <code><a href= 1152 "#XML_ResumeParser" >XML_ResumeParser</a></code>.</p> 1153 1154 <p>New in Expat 1.95.8.</p> 1155 </div> 1156 1157 <pre class="fcndec" id="XML_ResumeParser"> 1158 enum XML_Status XMLCALL 1159 XML_ResumeParser(XML_Parser p); 1160 </pre> 1161 <div class="fcndef"> 1162 <p>Resumes parsing after it has been suspended with <code><a href= 1163 "#XML_StopParser" >XML_StopParser</a></code>. Must not be called from 1164 within a handler call-back. Returns same status codes as <code><a 1165 href= "#XML_Parse">XML_Parse</a></code> or <code><a href= 1166 "#XML_ParseBuffer" >XML_ParseBuffer</a></code>. An additional error 1167 code, <code>XML_ERROR_NOT_SUSPENDED</code>, will be returned if the 1168 parser was not currently suspended.</p> 1169 1170 <p><strong>Note:</strong> 1171 This must be called on the most deeply nested child parser instance 1172 first, and on its parent parser only after the child parser has 1173 finished, to be applied recursively until the document entity's parser 1174 is restarted. That is, the parent parser will not resume by itself 1175 and it is up to the application to call <code><a href= 1176 "#XML_ResumeParser" >XML_ResumeParser</a></code> on it at the 1177 appropriate moment.</p> 1178 1179 <p>New in Expat 1.95.8.</p> 1180 </div> 1181 1182 <pre class="fcndec" id="XML_GetParsingStatus"> 1183 void XMLCALL 1184 XML_GetParsingStatus(XML_Parser p, 1185 XML_ParsingStatus *status); 1186 </pre> 1187 <pre class="signature"> 1188 enum XML_Parsing { 1189 XML_INITIALIZED, 1190 XML_PARSING, 1191 XML_FINISHED, 1192 XML_SUSPENDED 1193 }; 1194 1195 typedef struct { 1196 enum XML_Parsing parsing; 1197 XML_Bool finalBuffer; 1198 } XML_ParsingStatus; 1199 </pre> 1200 <div class="fcndef"> 1201 <p>Returns status of parser with respect to being initialized, 1202 parsing, finished, or suspended, and whether the final buffer is being 1203 processed. The <code>status</code> parameter <em>must not</em> be 1204 NULL.</p> 1205 1206 <p>New in Expat 1.95.8.</p> 1207 </div> 1208 1209 1210 <h3><a name="setting">Handler Setting</a></h3> 1211 1212 <p>Although handlers are typically set prior to parsing and left alone, an 1213 application may choose to set or change the handler for a parsing event 1214 while the parse is in progress. For instance, your application may choose 1215 to ignore all text not descended from a <code>para</code> element. One 1216 way it could do this is to set the character handler when a para start tag 1217 is seen, and unset it for the corresponding end tag.</p> 1218 1219 <p>A handler may be <em>unset</em> by providing a NULL pointer to the 1220 appropriate handler setter. None of the handler setting functions have 1221 a return value.</p> 1222 1223 <p>Your handlers will be receiving strings in arrays of type 1224 <code>XML_Char</code>. This type is conditionally defined in expat.h as 1225 either <code>char</code>, <code>wchar_t</code> or <code>unsigned short</code>. 1226 The former implies UTF-8 encoding, the latter two imply UTF-16 encoding. 1227 Note that you'll receive them in this form independent of the original 1228 encoding of the document.</p> 1229 1230 <div class="handler"> 1231 <pre class="setter" id="XML_SetStartElementHandler"> 1232 void XMLCALL 1233 XML_SetStartElementHandler(XML_Parser p, 1234 XML_StartElementHandler start); 1235 </pre> 1236 <pre class="signature"> 1237 typedef void 1238 (XMLCALL *XML_StartElementHandler)(void *userData, 1239 const XML_Char *name, 1240 const XML_Char **atts); 1241 </pre> 1242 <p>Set handler for start (and empty) tags. Attributes are passed to the start 1243 handler as a pointer to a vector of char pointers. Each attribute seen in 1244 a start (or empty) tag occupies 2 consecutive places in this vector: the 1245 attribute name followed by the attribute value. These pairs are terminated 1246 by a null pointer.</p> 1247 <p>Note that an empty tag generates a call to both start and end handlers 1248 (in that order).</p> 1249 </div> 1250 1251 <div class="handler"> 1252 <pre class="setter" id="XML_SetEndElementHandler"> 1253 void XMLCALL 1254 XML_SetEndElementHandler(XML_Parser p, 1255 XML_EndElementHandler); 1256 </pre> 1257 <pre class="signature"> 1258 typedef void 1259 (XMLCALL *XML_EndElementHandler)(void *userData, 1260 const XML_Char *name); 1261 </pre> 1262 <p>Set handler for end (and empty) tags. As noted above, an empty tag 1263 generates a call to both start and end handlers.</p> 1264 </div> 1265 1266 <div class="handler"> 1267 <pre class="setter" id="XML_SetElementHandler"> 1268 void XMLCALL 1269 XML_SetElementHandler(XML_Parser p, 1270 XML_StartElementHandler start, 1271 XML_EndElementHandler end); 1272 </pre> 1273 <p>Set handlers for start and end tags with one call.</p> 1274 </div> 1275 1276 <div class="handler"> 1277 <pre class="setter" id="XML_SetCharacterDataHandler"> 1278 void XMLCALL 1279 XML_SetCharacterDataHandler(XML_Parser p, 1280 XML_CharacterDataHandler charhndl) 1281 </pre> 1282 <pre class="signature"> 1283 typedef void 1284 (XMLCALL *XML_CharacterDataHandler)(void *userData, 1285 const XML_Char *s, 1286 int len); 1287 </pre> 1288 <p>Set a text handler. The string your handler receives 1289 is <em>NOT nul-terminated</em>. You have to use the length argument 1290 to deal with the end of the string. A single block of contiguous text 1291 free of markup may still result in a sequence of calls to this handler. 1292 In other words, if you're searching for a pattern in the text, it may 1293 be split across calls to this handler. Note: Setting this handler to NULL 1294 may <em>NOT immediately</em> terminate call-backs if the parser is currently 1295 processing such a single block of contiguous markup-free text, as the parser 1296 will continue calling back until the end of the block is reached.</p> 1297 </div> 1298 1299 <div class="handler"> 1300 <pre class="setter" id="XML_SetProcessingInstructionHandler"> 1301 void XMLCALL 1302 XML_SetProcessingInstructionHandler(XML_Parser p, 1303 XML_ProcessingInstructionHandler proc) 1304 </pre> 1305 <pre class="signature"> 1306 typedef void 1307 (XMLCALL *XML_ProcessingInstructionHandler)(void *userData, 1308 const XML_Char *target, 1309 const XML_Char *data); 1310 1311 </pre> 1312 <p>Set a handler for processing instructions. The target is the first word 1313 in the processing instruction. The data is the rest of the characters in 1314 it after skipping all whitespace after the initial word.</p> 1315 </div> 1316 1317 <div class="handler"> 1318 <pre class="setter" id="XML_SetCommentHandler"> 1319 void XMLCALL 1320 XML_SetCommentHandler(XML_Parser p, 1321 XML_CommentHandler cmnt) 1322 </pre> 1323 <pre class="signature"> 1324 typedef void 1325 (XMLCALL *XML_CommentHandler)(void *userData, 1326 const XML_Char *data); 1327 </pre> 1328 <p>Set a handler for comments. The data is all text inside the comment 1329 delimiters.</p> 1330 </div> 1331 1332 <div class="handler"> 1333 <pre class="setter" id="XML_SetStartCdataSectionHandler"> 1334 void XMLCALL 1335 XML_SetStartCdataSectionHandler(XML_Parser p, 1336 XML_StartCdataSectionHandler start); 1337 </pre> 1338 <pre class="signature"> 1339 typedef void 1340 (XMLCALL *XML_StartCdataSectionHandler)(void *userData); 1341 </pre> 1342 <p>Set a handler that gets called at the beginning of a CDATA section.</p> 1343 </div> 1344 1345 <div class="handler"> 1346 <pre class="setter" id="XML_SetEndCdataSectionHandler"> 1347 void XMLCALL 1348 XML_SetEndCdataSectionHandler(XML_Parser p, 1349 XML_EndCdataSectionHandler end); 1350 </pre> 1351 <pre class="signature"> 1352 typedef void 1353 (XMLCALL *XML_EndCdataSectionHandler)(void *userData); 1354 </pre> 1355 <p>Set a handler that gets called at the end of a CDATA section.</p> 1356 </div> 1357 1358 <div class="handler"> 1359 <pre class="setter" id="XML_SetCdataSectionHandler"> 1360 void XMLCALL 1361 XML_SetCdataSectionHandler(XML_Parser p, 1362 XML_StartCdataSectionHandler start, 1363 XML_EndCdataSectionHandler end) 1364 </pre> 1365 <p>Sets both CDATA section handlers with one call.</p> 1366 </div> 1367 1368 <div class="handler"> 1369 <pre class="setter" id="XML_SetDefaultHandler"> 1370 void XMLCALL 1371 XML_SetDefaultHandler(XML_Parser p, 1372 XML_DefaultHandler hndl) 1373 </pre> 1374 <pre class="signature"> 1375 typedef void 1376 (XMLCALL *XML_DefaultHandler)(void *userData, 1377 const XML_Char *s, 1378 int len); 1379 </pre> 1380 1381 <p>Sets a handler for any characters in the document which wouldn't 1382 otherwise be handled. This includes both data for which no handlers 1383 can be set (like some kinds of DTD declarations) and data which could 1384 be reported but which currently has no handler set. The characters 1385 are passed exactly as they were present in the XML document except 1386 that they will be encoded in UTF-8 or UTF-16. Line boundaries are not 1387 normalized. Note that a byte order mark character is not passed to the 1388 default handler. There are no guarantees about how characters are 1389 divided between calls to the default handler: for example, a comment 1390 might be split between multiple calls. Setting the handler with 1391 this call has the side effect of turning off expansion of references 1392 to internally defined general entities. Instead these references are 1393 passed to the default handler.</p> 1394 1395 <p>See also <code><a 1396 href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p> 1397 </div> 1398 1399 <div class="handler"> 1400 <pre class="setter" id="XML_SetDefaultHandlerExpand"> 1401 void XMLCALL 1402 XML_SetDefaultHandlerExpand(XML_Parser p, 1403 XML_DefaultHandler hndl) 1404 </pre> 1405 <pre class="signature"> 1406 typedef void 1407 (XMLCALL *XML_DefaultHandler)(void *userData, 1408 const XML_Char *s, 1409 int len); 1410 </pre> 1411 <p>This sets a default handler, but doesn't inhibit the expansion of 1412 internal entity references. The entity reference will not be passed 1413 to the default handler.</p> 1414 1415 <p>See also <code><a 1416 href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p> 1417 </div> 1418 1419 <div class="handler"> 1420 <pre class="setter" id="XML_SetExternalEntityRefHandler"> 1421 void XMLCALL 1422 XML_SetExternalEntityRefHandler(XML_Parser p, 1423 XML_ExternalEntityRefHandler hndl) 1424 </pre> 1425 <pre class="signature"> 1426 typedef int 1427 (XMLCALL *XML_ExternalEntityRefHandler)(XML_Parser p, 1428 const XML_Char *context, 1429 const XML_Char *base, 1430 const XML_Char *systemId, 1431 const XML_Char *publicId); 1432 </pre> 1433 <p>Set an external entity reference handler. This handler is also 1434 called for processing an external DTD subset if parameter entity parsing 1435 is in effect. (See <a href="#XML_SetParamEntityParsing"> 1436 <code>XML_SetParamEntityParsing</code></a>.)</p> 1437 1438 <p>The <code>context</code> parameter specifies the parsing context in 1439 the format expected by the <code>context</code> argument to <code><a 1440 href="#XML_ExternalEntityParserCreate" 1441 >XML_ExternalEntityParserCreate</a></code>. <code>code</code> is 1442 valid only until the handler returns, so if the referenced entity is 1443 to be parsed later, it must be copied. <code>context</code> is NULL 1444 only when the entity is a parameter entity, which is how one can 1445 differentiate between general and parameter entities.</p> 1446 1447 <p>The <code>base</code> parameter is the base to use for relative 1448 system identifiers. It is set by <code><a 1449 href="#XML_SetBase">XML_SetBase</a></code> and may be NULL. The 1450 <code>publicId</code> parameter is the public id given in the entity 1451 declaration and may be NULL. <code>systemId</code> is the system 1452 identifier specified in the entity declaration and is never NULL.</p> 1453 1454 <p>There are a couple of ways in which this handler differs from 1455 others. First, this handler returns a status indicator (an 1456 integer). <code>XML_STATUS_OK</code> should be returned for successful 1457 handling of the external entity reference. Returning 1458 <code>XML_STATUS_ERROR</code> indicates failure, and causes the 1459 calling parser to return an 1460 <code>XML_ERROR_EXTERNAL_ENTITY_HANDLING</code> error.</p> 1461 1462 <p>Second, instead of having the user data as its first argument, it 1463 receives the parser that encountered the entity reference. This, along 1464 with the context parameter, may be used as arguments to a call to 1465 <code><a href= "#XML_ExternalEntityParserCreate" 1466 >XML_ExternalEntityParserCreate</a></code>. Using the returned 1467 parser, the body of the external entity can be recursively parsed.</p> 1468 1469 <p>Since this handler may be called recursively, it should not be saving 1470 information into global or static variables.</p> 1471 </div> 1472 1473 <pre class="fcndec" id="XML_SetExternalEntityRefHandlerArg"> 1474 void XMLCALL 1475 XML_SetExternalEntityRefHandlerArg(XML_Parser p, 1476 void *arg) 1477 </pre> 1478 <div class="fcndef"> 1479 <p>Set the argument passed to the ExternalEntityRefHandler. If 1480 <code>arg</code> is not NULL, it is the new value passed to the 1481 handler set using <code><a href="#XML_SetExternalEntityRefHandler" 1482 >XML_SetExternalEntityRefHandler</a></code>; if <code>arg</code> is 1483 NULL, the argument passed to the handler function will be the parser 1484 object itself.</p> 1485 1486 <p><strong>Note:</strong> 1487 The type of <code>arg</code> and the type of the first argument to the 1488 ExternalEntityRefHandler do not match. This function takes a 1489 <code>void *</code> to be passed to the handler, while the handler 1490 accepts an <code>XML_Parser</code>. This is a historical accident, 1491 but will not be corrected before Expat 2.0 (at the earliest) to avoid 1492 causing compiler warnings for code that's known to work with this 1493 API. It is the responsibility of the application code to know the 1494 actual type of the argument passed to the handler and to manage it 1495 properly.</p> 1496 </div> 1497 1498 <div class="handler"> 1499 <pre class="setter" id="XML_SetSkippedEntityHandler"> 1500 void XMLCALL 1501 XML_SetSkippedEntityHandler(XML_Parser p, 1502 XML_SkippedEntityHandler handler) 1503 </pre> 1504 <pre class="signature"> 1505 typedef void 1506 (XMLCALL *XML_SkippedEntityHandler)(void *userData, 1507 const XML_Char *entityName, 1508 int is_parameter_entity); 1509 </pre> 1510 <p>Set a skipped entity handler. This is called in two situations:</p> 1511 <ol> 1512 <li>An entity reference is encountered for which no declaration 1513 has been read <em>and</em> this is not an error.</li> 1514 <li>An internal entity reference is read, but not expanded, because 1515 <a href="#XML_SetDefaultHandler"><code>XML_SetDefaultHandler</code></a> 1516 has been called.</li> 1517 </ol> 1518 <p>The <code>is_parameter_entity</code> argument will be non-zero for 1519 a parameter entity and zero for a general entity.</p> <p>Note: skipped 1520 parameter entities in declarations and skipped general entities in 1521 attribute values cannot be reported, because the event would be out of 1522 sync with the reporting of the declarations or attribute values</p> 1523 </div> 1524 1525 <div class="handler"> 1526 <pre class="setter" id="XML_SetUnknownEncodingHandler"> 1527 void XMLCALL 1528 XML_SetUnknownEncodingHandler(XML_Parser p, 1529 XML_UnknownEncodingHandler enchandler, 1530 void *encodingHandlerData) 1531 </pre> 1532 <pre class="signature"> 1533 typedef int 1534 (XMLCALL *XML_UnknownEncodingHandler)(void *encodingHandlerData, 1535 const XML_Char *name, 1536 XML_Encoding *info); 1537 1538 typedef struct { 1539 int map[256]; 1540 void *data; 1541 int (XMLCALL *convert)(void *data, const char *s); 1542 void (XMLCALL *release)(void *data); 1543 } XML_Encoding; 1544 </pre> 1545 <p>Set a handler to deal with encodings other than the <a 1546 href="#builtin_encodings">built in set</a>. This should be done before 1547 <code><a href= "#XML_Parse" >XML_Parse</a></code> or <code><a href= 1548 "#XML_ParseBuffer" >XML_ParseBuffer</a></code> have been called on the 1549 given parser.</p> <p>If the handler knows how to deal with an encoding 1550 with the given name, it should fill in the <code>info</code> data 1551 structure and return <code>XML_STATUS_OK</code>. Otherwise it 1552 should return <code>XML_STATUS_ERROR</code>. The handler will be called 1553 at most once per parsed (external) entity. The optional application 1554 data pointer <code>encodingHandlerData</code> will be passed back to 1555 the handler.</p> 1556 1557 <p>The map array contains information for every possible possible leading 1558 byte in a byte sequence. If the corresponding value is >= 0, then it's 1559 a single byte sequence and the byte encodes that Unicode value. If the 1560 value is -1, then that byte is invalid as the initial byte in a sequence. 1561 If the value is -n, where n is an integer > 1, then n is the number of 1562 bytes in the sequence and the actual conversion is accomplished by a 1563 call to the function pointed at by convert. This function may return -1 1564 if the sequence itself is invalid. The convert pointer may be null if 1565 there are only single byte codes. The data parameter passed to the convert 1566 function is the data pointer from <code>XML_Encoding</code>. The 1567 string s is <em>NOT</em> nul-terminated and points at the sequence of 1568 bytes to be converted.</p> 1569 1570 <p>The function pointed at by <code>release</code> is called by the 1571 parser when it is finished with the encoding. It may be NULL.</p> 1572 </div> 1573 1574 <div class="handler"> 1575 <pre class="setter" id="XML_SetStartNamespaceDeclHandler"> 1576 void XMLCALL 1577 XML_SetStartNamespaceDeclHandler(XML_Parser p, 1578 XML_StartNamespaceDeclHandler start); 1579 </pre> 1580 <pre class="signature"> 1581 typedef void 1582 (XMLCALL *XML_StartNamespaceDeclHandler)(void *userData, 1583 const XML_Char *prefix, 1584 const XML_Char *uri); 1585 </pre> 1586 <p>Set a handler to be called when a namespace is declared. Namespace 1587 declarations occur inside start tags. But the namespace declaration start 1588 handler is called before the start tag handler for each namespace declared 1589 in that start tag.</p> 1590 </div> 1591 1592 <div class="handler"> 1593 <pre class="setter" id="XML_SetEndNamespaceDeclHandler"> 1594 void XMLCALL 1595 XML_SetEndNamespaceDeclHandler(XML_Parser p, 1596 XML_EndNamespaceDeclHandler end); 1597 </pre> 1598 <pre class="signature"> 1599 typedef void 1600 (XMLCALL *XML_EndNamespaceDeclHandler)(void *userData, 1601 const XML_Char *prefix); 1602 </pre> 1603 <p>Set a handler to be called when leaving the scope of a namespace 1604 declaration. This will be called, for each namespace declaration, 1605 after the handler for the end tag of the element in which the 1606 namespace was declared.</p> 1607 </div> 1608 1609 <div class="handler"> 1610 <pre class="setter" id="XML_SetNamespaceDeclHandler"> 1611 void XMLCALL 1612 XML_SetNamespaceDeclHandler(XML_Parser p, 1613 XML_StartNamespaceDeclHandler start, 1614 XML_EndNamespaceDeclHandler end) 1615 </pre> 1616 <p>Sets both namespace declaration handlers with a single call.</p> 1617 </div> 1618 1619 <div class="handler"> 1620 <pre class="setter" id="XML_SetXmlDeclHandler"> 1621 void XMLCALL 1622 XML_SetXmlDeclHandler(XML_Parser p, 1623 XML_XmlDeclHandler xmldecl); 1624 </pre> 1625 <pre class="signature"> 1626 typedef void 1627 (XMLCALL *XML_XmlDeclHandler)(void *userData, 1628 const XML_Char *version, 1629 const XML_Char *encoding, 1630 int standalone); 1631 </pre> 1632 <p>Sets a handler that is called for XML declarations and also for 1633 text declarations discovered in external entities. The way to 1634 distinguish is that the <code>version</code> parameter will be NULL 1635 for text declarations. The <code>encoding</code> parameter may be NULL 1636 for an XML declaration. The <code>standalone</code> argument will 1637 contain -1, 0, or 1 indicating respectively that there was no 1638 standalone parameter in the declaration, that it was given as no, or 1639 that it was given as yes.</p> 1640 </div> 1641 1642 <div class="handler"> 1643 <pre class="setter" id="XML_SetStartDoctypeDeclHandler"> 1644 void XMLCALL 1645 XML_SetStartDoctypeDeclHandler(XML_Parser p, 1646 XML_StartDoctypeDeclHandler start); 1647 </pre> 1648 <pre class="signature"> 1649 typedef void 1650 (XMLCALL *XML_StartDoctypeDeclHandler)(void *userData, 1651 const XML_Char *doctypeName, 1652 const XML_Char *sysid, 1653 const XML_Char *pubid, 1654 int has_internal_subset); 1655 </pre> 1656 <p>Set a handler that is called at the start of a DOCTYPE declaration, 1657 before any external or internal subset is parsed. Both <code>sysid</code> 1658 and <code>pubid</code> may be NULL. The <code>has_internal_subset</code> 1659 will be non-zero if the DOCTYPE declaration has an internal subset.</p> 1660 </div> 1661 1662 <div class="handler"> 1663 <pre class="setter" id="XML_SetEndDoctypeDeclHandler"> 1664 void XMLCALL 1665 XML_SetEndDoctypeDeclHandler(XML_Parser p, 1666 XML_EndDoctypeDeclHandler end); 1667 </pre> 1668 <pre class="signature"> 1669 typedef void 1670 (XMLCALL *XML_EndDoctypeDeclHandler)(void *userData); 1671 </pre> 1672 <p>Set a handler that is called at the end of a DOCTYPE declaration, 1673 after parsing any external subset.</p> 1674 </div> 1675 1676 <div class="handler"> 1677 <pre class="setter" id="XML_SetDoctypeDeclHandler"> 1678 void XMLCALL 1679 XML_SetDoctypeDeclHandler(XML_Parser p, 1680 XML_StartDoctypeDeclHandler start, 1681 XML_EndDoctypeDeclHandler end); 1682 </pre> 1683 <p>Set both doctype handlers with one call.</p> 1684 </div> 1685 1686 <div class="handler"> 1687 <pre class="setter" id="XML_SetElementDeclHandler"> 1688 void XMLCALL 1689 XML_SetElementDeclHandler(XML_Parser p, 1690 XML_ElementDeclHandler eldecl); 1691 </pre> 1692 <pre class="signature"> 1693 typedef void 1694 (XMLCALL *XML_ElementDeclHandler)(void *userData, 1695 const XML_Char *name, 1696 XML_Content *model); 1697 </pre> 1698 <pre class="signature"> 1699 enum XML_Content_Type { 1700 XML_CTYPE_EMPTY = 1, 1701 XML_CTYPE_ANY, 1702 XML_CTYPE_MIXED, 1703 XML_CTYPE_NAME, 1704 XML_CTYPE_CHOICE, 1705 XML_CTYPE_SEQ 1706 }; 1707 1708 enum XML_Content_Quant { 1709 XML_CQUANT_NONE, 1710 XML_CQUANT_OPT, 1711 XML_CQUANT_REP, 1712 XML_CQUANT_PLUS 1713 }; 1714 1715 typedef struct XML_cp XML_Content; 1716 1717 struct XML_cp { 1718 enum XML_Content_Type type; 1719 enum XML_Content_Quant quant; 1720 const XML_Char * name; 1721 unsigned int numchildren; 1722 XML_Content * children; 1723 }; 1724 </pre> 1725 <p>Sets a handler for element declarations in a DTD. The handler gets 1726 called with the name of the element in the declaration and a pointer 1727 to a structure that contains the element model. It is the 1728 application's responsibility to free this data structure using 1729 <code><a href="#XML_FreeContentModel" 1730 >XML_FreeContentModel</a></code>.</p> 1731 1732 <p>The <code>model</code> argument is the root of a tree of 1733 <code>XML_Content</code> nodes. If <code>type</code> equals 1734 <code>XML_CTYPE_EMPTY</code> or <code>XML_CTYPE_ANY</code>, then 1735 <code>quant</code> will be <code>XML_CQUANT_NONE</code>, and the other 1736 fields will be zero or NULL. If <code>type</code> is 1737 <code>XML_CTYPE_MIXED</code>, then <code>quant</code> will be 1738 <code>XML_CQUANT_NONE</code> or <code>XML_CQUANT_REP</code> and 1739 <code>numchildren</code> will contain the number of elements that are 1740 allowed to be mixed in and <code>children</code> points to an array of 1741 <code>XML_Content</code> structures that will all have type 1742 XML_CTYPE_NAME with no quantification. Only the root node can be type 1743 <code>XML_CTYPE_EMPTY</code>, <code>XML_CTYPE_ANY</code>, or 1744 <code>XML_CTYPE_MIXED</code>.</p> 1745 1746 <p>For type <code>XML_CTYPE_NAME</code>, the <code>name</code> field 1747 points to the name and the <code>numchildren</code> and 1748 <code>children</code> fields will be zero and NULL. The 1749 <code>quant</code> field will indicate any quantifiers placed on the 1750 name.</p> 1751 1752 <p>Types <code>XML_CTYPE_CHOICE</code> and <code>XML_CTYPE_SEQ</code> 1753 indicate a choice or sequence respectively. The 1754 <code>numchildren</code> field indicates how many nodes in the choice 1755 or sequence and <code>children</code> points to the nodes.</p> 1756 </div> 1757 1758 <div class="handler"> 1759 <pre class="setter" id="XML_SetAttlistDeclHandler"> 1760 void XMLCALL 1761 XML_SetAttlistDeclHandler(XML_Parser p, 1762 XML_AttlistDeclHandler attdecl); 1763 </pre> 1764 <pre class="signature"> 1765 typedef void 1766 (XMLCALL *XML_AttlistDeclHandler)(void *userData, 1767 const XML_Char *elname, 1768 const XML_Char *attname, 1769 const XML_Char *att_type, 1770 const XML_Char *dflt, 1771 int isrequired); 1772 </pre> 1773 <p>Set a handler for attlist declarations in the DTD. This handler is 1774 called for <em>each</em> attribute. So a single attlist declaration 1775 with multiple attributes declared will generate multiple calls to this 1776 handler. The <code>elname</code> parameter returns the name of the 1777 element for which the attribute is being declared. The attribute name 1778 is in the <code>attname</code> parameter. The attribute type is in the 1779 <code>att_type</code> parameter. It is the string representing the 1780 type in the declaration with whitespace removed.</p> 1781 1782 <p>The <code>dflt</code> parameter holds the default value. It will be 1783 NULL in the case of "#IMPLIED" or "#REQUIRED" attributes. You can 1784 distinguish these two cases by checking the <code>isrequired</code> 1785 parameter, which will be true in the case of "#REQUIRED" attributes. 1786 Attributes which are "#FIXED" will have also have a true 1787 <code>isrequired</code>, but they will have the non-NULL fixed value 1788 in the <code>dflt</code> parameter.</p> 1789 </div> 1790 1791 <div class="handler"> 1792 <pre class="setter" id="XML_SetEntityDeclHandler"> 1793 void XMLCALL 1794 XML_SetEntityDeclHandler(XML_Parser p, 1795 XML_EntityDeclHandler handler); 1796 </pre> 1797 <pre class="signature"> 1798 typedef void 1799 (XMLCALL *XML_EntityDeclHandler)(void *userData, 1800 const XML_Char *entityName, 1801 int is_parameter_entity, 1802 const XML_Char *value, 1803 int value_length, 1804 const XML_Char *base, 1805 const XML_Char *systemId, 1806 const XML_Char *publicId, 1807 const XML_Char *notationName); 1808 </pre> 1809 <p>Sets a handler that will be called for all entity declarations. 1810 The <code>is_parameter_entity</code> argument will be non-zero in the 1811 case of parameter entities and zero otherwise.</p> 1812 1813 <p>For internal entities (<code><!ENTITY foo "bar"></code>), 1814 <code>value</code> will be non-NULL and <code>systemId</code>, 1815 <code>publicId</code>, and <code>notationName</code> will all be NULL. 1816 The value string is <em>not</em> NULL terminated; the length is 1817 provided in the <code>value_length</code> parameter. Do not use 1818 <code>value_length</code> to test for internal entities, since it is 1819 legal to have zero-length values. Instead check for whether or not 1820 <code>value</code> is NULL.</p> <p>The <code>notationName</code> 1821 argument will have a non-NULL value only for unparsed entity 1822 declarations.</p> 1823 </div> 1824 1825 <div class="handler"> 1826 <pre class="setter" id="XML_SetUnparsedEntityDeclHandler"> 1827 void XMLCALL 1828 XML_SetUnparsedEntityDeclHandler(XML_Parser p, 1829 XML_UnparsedEntityDeclHandler h) 1830 </pre> 1831 <pre class="signature"> 1832 typedef void 1833 (XMLCALL *XML_UnparsedEntityDeclHandler)(void *userData, 1834 const XML_Char *entityName, 1835 const XML_Char *base, 1836 const XML_Char *systemId, 1837 const XML_Char *publicId, 1838 const XML_Char *notationName); 1839 </pre> 1840 <p>Set a handler that receives declarations of unparsed entities. These 1841 are entity declarations that have a notation (NDATA) field:</p> 1842 1843 <div id="eg"><pre> 1844 <!ENTITY logo SYSTEM "images/logo.gif" NDATA gif> 1845 </pre></div> 1846 <p>This handler is obsolete and is provided for backwards 1847 compatibility. Use instead <a href= "#XML_SetEntityDeclHandler" 1848 >XML_SetEntityDeclHandler</a>.</p> 1849 </div> 1850 1851 <div class="handler"> 1852 <pre class="setter" id="XML_SetNotationDeclHandler"> 1853 void XMLCALL 1854 XML_SetNotationDeclHandler(XML_Parser p, 1855 XML_NotationDeclHandler h) 1856 </pre> 1857 <pre class="signature"> 1858 typedef void 1859 (XMLCALL *XML_NotationDeclHandler)(void *userData, 1860 const XML_Char *notationName, 1861 const XML_Char *base, 1862 const XML_Char *systemId, 1863 const XML_Char *publicId); 1864 </pre> 1865 <p>Set a handler that receives notation declarations.</p> 1866 </div> 1867 1868 <div class="handler"> 1869 <pre class="setter" id="XML_SetNotStandaloneHandler"> 1870 void XMLCALL 1871 XML_SetNotStandaloneHandler(XML_Parser p, 1872 XML_NotStandaloneHandler h) 1873 </pre> 1874 <pre class="signature"> 1875 typedef int 1876 (XMLCALL *XML_NotStandaloneHandler)(void *userData); 1877 </pre> 1878 <p>Set a handler that is called if the document is not "standalone". 1879 This happens when there is an external subset or a reference to a 1880 parameter entity, but does not have standalone set to "yes" in an XML 1881 declaration. If this handler returns <code>XML_STATUS_ERROR</code>, 1882 then the parser will throw an <code>XML_ERROR_NOT_STANDALONE</code> 1883 error.</p> 1884 </div> 1885 1886 <h3><a name="position">Parse position and error reporting functions</a></h3> 1887 1888 <p>These are the functions you'll want to call when the parse 1889 functions return <code>XML_STATUS_ERROR</code> (a parse error has 1890 occurred), although the position reporting functions are useful outside 1891 of errors. The position reported is the byte position (in the original 1892 document or entity encoding) of the first of the sequence of 1893 characters that generated the current event (or the error that caused 1894 the parse functions to return <code>XML_STATUS_ERROR</code>.) The 1895 exceptions are callbacks trigged by declarations in the document 1896 prologue, in which case they exact position reported is somewhere in the 1897 relevant markup, but not necessarily as meaningful as for other 1898 events.</p> 1899 1900 <p>The position reporting functions are accurate only outside of the 1901 DTD. In other words, they usually return bogus information when 1902 called from within a DTD declaration handler.</p> 1903 1904 <pre class="fcndec" id="XML_GetErrorCode"> 1905 enum XML_Error XMLCALL 1906 XML_GetErrorCode(XML_Parser p); 1907 </pre> 1908 <div class="fcndef"> 1909 Return what type of error has occurred. 1910 </div> 1911 1912 <pre class="fcndec" id="XML_ErrorString"> 1913 const XML_LChar * XMLCALL 1914 XML_ErrorString(enum XML_Error code); 1915 </pre> 1916 <div class="fcndef"> 1917 Return a string describing the error corresponding to code. 1918 The code should be one of the enums that can be returned from 1919 <code><a href= "#XML_GetErrorCode" >XML_GetErrorCode</a></code>. 1920 </div> 1921 1922 <pre class="fcndec" id="XML_GetCurrentByteIndex"> 1923 XML_Index XMLCALL 1924 XML_GetCurrentByteIndex(XML_Parser p); 1925 </pre> 1926 <div class="fcndef"> 1927 Return the byte offset of the position. This always corresponds to 1928 the values returned by <code><a href= "#XML_GetCurrentLineNumber" 1929 >XML_GetCurrentLineNumber</a></code> and <code><a href= 1930 "#XML_GetCurrentColumnNumber" >XML_GetCurrentColumnNumber</a></code>. 1931 </div> 1932 1933 <pre class="fcndec" id="XML_GetCurrentLineNumber"> 1934 XML_Size XMLCALL 1935 XML_GetCurrentLineNumber(XML_Parser p); 1936 </pre> 1937 <div class="fcndef"> 1938 Return the line number of the position. The first line is reported as 1939 <code>1</code>. 1940 </div> 1941 1942 <pre class="fcndec" id="XML_GetCurrentColumnNumber"> 1943 XML_Size XMLCALL 1944 XML_GetCurrentColumnNumber(XML_Parser p); 1945 </pre> 1946 <div class="fcndef"> 1947 Return the offset, from the beginning of the current line, of 1948 the position. 1949 </div> 1950 1951 <pre class="fcndec" id="XML_GetCurrentByteCount"> 1952 int XMLCALL 1953 XML_GetCurrentByteCount(XML_Parser p); 1954 </pre> 1955 <div class="fcndef"> 1956 Return the number of bytes in the current event. Returns 1957 <code>0</code> if the event is inside a reference to an internal 1958 entity and for the end-tag event for empty element tags (the later can 1959 be used to distinguish empty-element tags from empty elements using 1960 separate start and end tags). 1961 </div> 1962 1963 <pre class="fcndec" id="XML_GetInputContext"> 1964 const char * XMLCALL 1965 XML_GetInputContext(XML_Parser p, 1966 int *offset, 1967 int *size); 1968 </pre> 1969 <div class="fcndef"> 1970 1971 <p>Returns the parser's input buffer, sets the integer pointed at by 1972 <code>offset</code> to the offset within this buffer of the current 1973 parse position, and set the integer pointed at by <code>size</code> to 1974 the size of the returned buffer.</p> 1975 1976 <p>This should only be called from within a handler during an active 1977 parse and the returned buffer should only be referred to from within 1978 the handler that made the call. This input buffer contains the 1979 untranslated bytes of the input.</p> 1980 1981 <p>Only a limited amount of context is kept, so if the event 1982 triggering a call spans over a very large amount of input, the actual 1983 parse position may be before the beginning of the buffer.</p> 1984 1985 <p>If <code>XML_CONTEXT_BYTES</code> is not defined, this will always 1986 return NULL.</p> 1987 </div> 1988 1989 <h3><a name="miscellaneous">Miscellaneous functions</a></h3> 1990 1991 <p>The functions in this section either obtain state information from 1992 the parser or can be used to dynamicly set parser options.</p> 1993 1994 <pre class="fcndec" id="XML_SetUserData"> 1995 void XMLCALL 1996 XML_SetUserData(XML_Parser p, 1997 void *userData); 1998 </pre> 1999 <div class="fcndef"> 2000 This sets the user data pointer that gets passed to handlers. It 2001 overwrites any previous value for this pointer. Note that the 2002 application is responsible for freeing the memory associated with 2003 <code>userData</code> when it is finished with the parser. So if you 2004 call this when there's already a pointer there, and you haven't freed 2005 the memory associated with it, then you've probably just leaked 2006 memory. 2007 </div> 2008 2009 <pre class="fcndec" id="XML_GetUserData"> 2010 void * XMLCALL 2011 XML_GetUserData(XML_Parser p); 2012 </pre> 2013 <div class="fcndef"> 2014 This returns the user data pointer that gets passed to handlers. 2015 It is actually implemented as a macro. 2016 </div> 2017 2018 <pre class="fcndec" id="XML_UseParserAsHandlerArg"> 2019 void XMLCALL 2020 XML_UseParserAsHandlerArg(XML_Parser p); 2021 </pre> 2022 <div class="fcndef"> 2023 After this is called, handlers receive the parser in their 2024 <code>userData</code> arguments. The user data can still be obtained 2025 using the <code><a href= "#XML_GetUserData" 2026 >XML_GetUserData</a></code> function. 2027 </div> 2028 2029 <pre class="fcndec" id="XML_SetBase"> 2030 enum XML_Status XMLCALL 2031 XML_SetBase(XML_Parser p, 2032 const XML_Char *base); 2033 </pre> 2034 <div class="fcndef"> 2035 Set the base to be used for resolving relative URIs in system 2036 identifiers. The return value is <code>XML_STATUS_ERROR</code> if 2037 there's no memory to store base, otherwise it's 2038 <code>XML_STATUS_OK</code>. 2039 </div> 2040 2041 <pre class="fcndec" id="XML_GetBase"> 2042 const XML_Char * XMLCALL 2043 XML_GetBase(XML_Parser p); 2044 </pre> 2045 <div class="fcndef"> 2046 Return the base for resolving relative URIs. 2047 </div> 2048 2049 <pre class="fcndec" id="XML_GetSpecifiedAttributeCount"> 2050 int XMLCALL 2051 XML_GetSpecifiedAttributeCount(XML_Parser p); 2052 </pre> 2053 <div class="fcndef"> 2054 When attributes are reported to the start handler in the atts vector, 2055 attributes that were explicitly set in the element occur before any 2056 attributes that receive their value from default information in an 2057 ATTLIST declaration. This function returns the number of attributes 2058 that were explicitly set times two, thus giving the offset in the 2059 <code>atts</code> array passed to the start tag handler of the first 2060 attribute set due to defaults. It supplies information for the last 2061 call to a start handler. If called inside a start handler, then that 2062 means the current call. 2063 </div> 2064 2065 <pre class="fcndec" id="XML_GetIdAttributeIndex"> 2066 int XMLCALL 2067 XML_GetIdAttributeIndex(XML_Parser p); 2068 </pre> 2069 <div class="fcndef"> 2070 Returns the index of the ID attribute passed in the atts array in the 2071 last call to <code><a href= "#XML_StartElementHandler" 2072 >XML_StartElementHandler</a></code>, or -1 if there is no ID 2073 attribute. If called inside a start handler, then that means the 2074 current call. 2075 </div> 2076 2077 <pre class="fcndec" id="XML_SetEncoding"> 2078 enum XML_Status XMLCALL 2079 XML_SetEncoding(XML_Parser p, 2080 const XML_Char *encoding); 2081 </pre> 2082 <div class="fcndef"> 2083 Set the encoding to be used by the parser. It is equivalent to 2084 passing a non-null encoding argument to the parser creation functions. 2085 It must not be called after <code><a href= "#XML_Parse" 2086 >XML_Parse</a></code> or <code><a href= "#XML_ParseBuffer" 2087 >XML_ParseBuffer</a></code> have been called on the given parser. 2088 Returns <code>XML_STATUS_OK</code> on success or 2089 <code>XML_STATUS_ERROR</code> on error. 2090 </div> 2091 2092 <pre class="fcndec" id="XML_SetParamEntityParsing"> 2093 int XMLCALL 2094 XML_SetParamEntityParsing(XML_Parser p, 2095 enum XML_ParamEntityParsing code); 2096 </pre> 2097 <div class="fcndef"> 2098 This enables parsing of parameter entities, including the external 2099 parameter entity that is the external DTD subset, according to 2100 <code>code</code>. 2101 The choices for <code>code</code> are: 2102 <ul> 2103 <li><code>XML_PARAM_ENTITY_PARSING_NEVER</code></li> 2104 <li><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></li> 2105 <li><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></li> 2106 </ul> 2107 </div> 2108 2109 <pre class="fcndec" id="XML_UseForeignDTD"> 2110 enum XML_Error XMLCALL 2111 XML_UseForeignDTD(XML_Parser parser, XML_Bool useDTD); 2112 </pre> 2113 <div class="fcndef"> 2114 <p>This function allows an application to provide an external subset 2115 for the document type declaration for documents which do not specify 2116 an external subset of their own. For documents which specify an 2117 external subset in their DOCTYPE declaration, the application-provided 2118 subset will be ignored. If the document does not contain a DOCTYPE 2119 declaration at all and <code>useDTD</code> is true, the 2120 application-provided subset will be parsed, but the 2121 <code>startDoctypeDeclHandler</code> and 2122 <code>endDoctypeDeclHandler</code> functions, if set, will not be 2123 called. The setting of parameter entity parsing, controlled using 2124 <code><a href= "#XML_SetParamEntityParsing" 2125 >XML_SetParamEntityParsing</a></code>, will be honored.</p> 2126 2127 <p>The application-provided external subset is read by calling the 2128 external entity reference handler set via <code><a href= 2129 "#XML_SetExternalEntityRefHandler" 2130 >XML_SetExternalEntityRefHandler</a></code> with both 2131 <code>publicId</code> and <code>systemId</code> set to NULL.</p> 2132 2133 <p>If this function is called after parsing has begun, it returns 2134 <code>XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING</code> and ignores 2135 <code>useDTD</code>. If called when Expat has been compiled without 2136 DTD support, it returns 2137 <code>XML_ERROR_FEATURE_REQUIRES_XML_DTD</code>. Otherwise, it 2138 returns <code>XML_ERROR_NONE</code>.</p> 2139 2140 <p><b>Note:</b> For the purpose of checking WFC: Entity Declared, passing 2141 <code>useDTD == XML_TRUE</code> will make the parser behave as if 2142 the document had a DTD with an external subset. This holds true even if 2143 the external entity reference handler returns without action.</p> 2144 </div> 2145 2146 <pre class="fcndec" id="XML_SetReturnNSTriplet"> 2147 void XMLCALL 2148 XML_SetReturnNSTriplet(XML_Parser parser, 2149 int do_nst); 2150 </pre> 2151 <div class="fcndef"> 2152 <p> 2153 This function only has an effect when using a parser created with 2154 <code><a href= "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>, 2155 i.e. when namespace processing is in effect. The <code>do_nst</code> 2156 sets whether or not prefixes are returned with names qualified with a 2157 namespace prefix. If this function is called with <code>do_nst</code> 2158 non-zero, then afterwards namespace qualified names (that is qualified 2159 with a prefix as opposed to belonging to a default namespace) are 2160 returned as a triplet with the three parts separated by the namespace 2161 separator specified when the parser was created. The order of 2162 returned parts is URI, local name, and prefix.</p> <p>If 2163 <code>do_nst</code> is zero, then namespaces are reported in the 2164 default manner, URI then local_name separated by the namespace 2165 separator.</p> 2166 </div> 2167 2168 <pre class="fcndec" id="XML_DefaultCurrent"> 2169 void XMLCALL 2170 XML_DefaultCurrent(XML_Parser parser); 2171 </pre> 2172 <div class="fcndef"> 2173 This can be called within a handler for a start element, end element, 2174 processing instruction or character data. It causes the corresponding 2175 markup to be passed to the default handler set by <code><a 2176 href="#XML_SetDefaultHandler" >XML_SetDefaultHandler</a></code> or 2177 <code><a href="#XML_SetDefaultHandlerExpand" 2178 >XML_SetDefaultHandlerExpand</a></code>. It does nothing if there is 2179 not a default handler. 2180 </div> 2181 2182 <pre class="fcndec" id="XML_ExpatVersion"> 2183 XML_LChar * XMLCALL 2184 XML_ExpatVersion(); 2185 </pre> 2186 <div class="fcndef"> 2187 Return the library version as a string (e.g. <code>"expat_1.95.1"</code>). 2188 </div> 2189 2190 <pre class="fcndec" id="XML_ExpatVersionInfo"> 2191 struct XML_Expat_Version XMLCALL 2192 XML_ExpatVersionInfo(); 2193 </pre> 2194 <pre class="signature"> 2195 typedef struct { 2196 int major; 2197 int minor; 2198 int micro; 2199 } XML_Expat_Version; 2200 </pre> 2201 <div class="fcndef"> 2202 Return the library version information as a structure. 2203 Some macros are also defined that support compile-time tests of the 2204 library version: 2205 <ul> 2206 <li><code>XML_MAJOR_VERSION</code></li> 2207 <li><code>XML_MINOR_VERSION</code></li> 2208 <li><code>XML_MICRO_VERSION</code></li> 2209 </ul> 2210 Testing these constants is currently the best way to determine if 2211 particular parts of the Expat API are available. 2212 </div> 2213 2214 <pre class="fcndec" id="XML_GetFeatureList"> 2215 const XML_Feature * XMLCALL 2216 XML_GetFeatureList(); 2217 </pre> 2218 <pre class="signature"> 2219 enum XML_FeatureEnum { 2220 XML_FEATURE_END = 0, 2221 XML_FEATURE_UNICODE, 2222 XML_FEATURE_UNICODE_WCHAR_T, 2223 XML_FEATURE_DTD, 2224 XML_FEATURE_CONTEXT_BYTES, 2225 XML_FEATURE_MIN_SIZE, 2226 XML_FEATURE_SIZEOF_XML_CHAR, 2227 XML_FEATURE_SIZEOF_XML_LCHAR, 2228 XML_FEATURE_NS, 2229 XML_FEATURE_LARGE_SIZE 2230 }; 2231 2232 typedef struct { 2233 enum XML_FeatureEnum feature; 2234 XML_LChar *name; 2235 long int value; 2236 } XML_Feature; 2237 </pre> 2238 <div class="fcndef"> 2239 <p>Returns a list of "feature" records, providing details on how 2240 Expat was configured at compile time. Most applications should not 2241 need to worry about this, but this information is otherwise not 2242 available from Expat. This function allows code that does need to 2243 check these features to do so at runtime.</p> 2244 2245 <p>The return value is an array of <code>XML_Feature</code>, 2246 terminated by a record with a <code>feature</code> of 2247 <code>XML_FEATURE_END</code> and <code>name</code> of NULL, 2248 identifying the feature-test macros Expat was compiled with. Since an 2249 application that requires this kind of information needs to determine 2250 the type of character the <code>name</code> points to, records for the 2251 <code>XML_FEATURE_SIZEOF_XML_CHAR</code> and 2252 <code>XML_FEATURE_SIZEOF_XML_LCHAR</code> will be located at the 2253 beginning of the list, followed by <code>XML_FEATURE_UNICODE</code> 2254 and <code>XML_FEATURE_UNICODE_WCHAR_T</code>, if they are present at 2255 all.</p> 2256 2257 <p>Some features have an associated value. If there isn't an 2258 associated value, the <code>value</code> field is set to 0. At this 2259 time, the following features have been defined to have values:</p> 2260 2261 <dl> 2262 <dt><code>XML_FEATURE_SIZEOF_XML_CHAR</code></dt> 2263 <dd>The number of bytes occupied by one <code>XML_Char</code> 2264 character.</dd> 2265 <dt><code>XML_FEATURE_SIZEOF_XML_LCHAR</code></dt> 2266 <dd>The number of bytes occupied by one <code>XML_LChar</code> 2267 character.</dd> 2268 <dt><code>XML_FEATURE_CONTEXT_BYTES</code></dt> 2269 <dd>The maximum number of characters of context which can be 2270 reported by <code><a href= "#XML_GetInputContext" 2271 >XML_GetInputContext</a></code>.</dd> 2272 </dl> 2273 </div> 2274 2275 <pre class="fcndec" id="XML_FreeContentModel"> 2276 void XMLCALL 2277 XML_FreeContentModel(XML_Parser parser, XML_Content *model); 2278 </pre> 2279 <div class="fcndef"> 2280 Function to deallocate the <code>model</code> argument passed to the 2281 <code>XML_ElementDeclHandler</code> callback set using <code><a 2282 href="#XML_SetElementDeclHandler" >XML_ElementDeclHandler</a></code>. 2283 This function should not be used for any other purpose. 2284 </div> 2285 2286 <p>The following functions allow external code to share the memory 2287 allocator an <code>XML_Parser</code> has been configured to use. This 2288 is especially useful for third-party libraries that interact with a 2289 parser object created by application code, or heavily layered 2290 applications. This can be essential when using dynamically loaded 2291 libraries which use different C standard libraries (this can happen on 2292 Windows, at least).</p> 2293 2294 <pre class="fcndec" id="XML_MemMalloc"> 2295 void * XMLCALL 2296 XML_MemMalloc(XML_Parser parser, size_t size); 2297 </pre> 2298 <div class="fcndef"> 2299 Allocate <code>size</code> bytes of memory using the allocator the 2300 <code>parser</code> object has been configured to use. Returns a 2301 pointer to the memory or NULL on failure. Memory allocated in this 2302 way must be freed using <code><a href="#XML_MemFree" 2303 >XML_MemFree</a></code>. 2304 </div> 2305 2306 <pre class="fcndec" id="XML_MemRealloc"> 2307 void * XMLCALL 2308 XML_MemRealloc(XML_Parser parser, void *ptr, size_t size); 2309 </pre> 2310 <div class="fcndef"> 2311 Allocate <code>size</code> bytes of memory using the allocator the 2312 <code>parser</code> object has been configured to use. 2313 <code>ptr</code> must point to a block of memory allocated by <code><a 2314 href="#XML_MemMalloc" >XML_MemMalloc</a></code> or 2315 <code>XML_MemRealloc</code>, or be NULL. This function tries to 2316 expand the block pointed to by <code>ptr</code> if possible. Returns 2317 a pointer to the memory or NULL on failure. On success, the original 2318 block has either been expanded or freed. On failure, the original 2319 block has not been freed; the caller is responsible for freeing the 2320 original block. Memory allocated in this way must be freed using 2321 <code><a href="#XML_MemFree" 2322 >XML_MemFree</a></code>. 2323 </div> 2324 2325 <pre class="fcndec" id="XML_MemFree"> 2326 void XMLCALL 2327 XML_MemFree(XML_Parser parser, void *ptr); 2328 </pre> 2329 <div class="fcndef"> 2330 Free a block of memory pointed to by <code>ptr</code>. The block must 2331 have been allocated by <code><a href="#XML_MemMalloc" 2332 >XML_MemMalloc</a></code> or <code>XML_MemRealloc</code>, or be NULL. 2333 </div> 2334 2335 <hr /> 2336 <p><a href="http://validator.w3.org/check/referer"><img 2337 src="valid-xhtml10.png" alt="Valid XHTML 1.0!" 2338 height="31" width="88" class="noborder" /></a></p> 2339 </div> 2340 </body> 2341 </html> 2342
