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@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@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 29the underlying XML parser for the open source Mozilla project, Perl's 30<code>XML::Parser</code>, Python's <code>xml.parsers.expat</code>, and 31other open-source XML parsers.</p> 32 33<p>This library is the creation of James Clark, who's also given us 34groff (an nroff look-alike), Jade (an implemention of ISO's DSSSL 35stylesheet language for SGML), XP (a Java XML parser package), XT (a 36Java XSL engine). James was also the technical lead on the XML 37Working Group at W3C that produced the XML specification.</p> 38 39<p>This is free software, licensed under the <a 40href="../COPYING">MIT/X Consortium license</a>. You may download it 41from <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 45by <a href="http://www.xml.com/">XML.com</a>. They graciously allowed 46Clark Cooper to retain copyright and to distribute it with Expat. 47This version has been substantially extended to include documentation 48on features which have been added since the original article was 49published, and additional information on using the original 50interface.</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_GetAttributeInfo">XML_GetAttributeInfo</a></li> 133 <li><a href="#XML_SetEncoding">XML_SetEncoding</a></li> 134 <li><a href="#XML_SetParamEntityParsing">XML_SetParamEntityParsing</a></li> 135 <li><a href="#XML_SetHashSalt">XML_SetHashSalt</a></li> 136 <li><a href="#XML_UseForeignDTD">XML_UseForeignDTD</a></li> 137 <li><a href="#XML_SetReturnNSTriplet">XML_SetReturnNSTriplet</a></li> 138 <li><a href="#XML_DefaultCurrent">XML_DefaultCurrent</a></li> 139 <li><a href="#XML_ExpatVersion">XML_ExpatVersion</a></li> 140 <li><a href="#XML_ExpatVersionInfo">XML_ExpatVersionInfo</a></li> 141 <li><a href="#XML_GetFeatureList">XML_GetFeatureList</a></li> 142 <li><a href="#XML_FreeContentModel">XML_FreeContentModel</a></li> 143 <li><a href="#XML_MemMalloc">XML_MemMalloc</a></li> 144 <li><a href="#XML_MemRealloc">XML_MemRealloc</a></li> 145 <li><a href="#XML_MemFree">XML_MemFree</a></li> 146 </ul> 147 </li> 148 </ul> 149 </li> 150</ul> 151 152<hr /> 153<h2><a name="overview">Overview</a></h2> 154 155<p>Expat is a stream-oriented parser. You register callback (or 156handler) functions with the parser and then start feeding it the 157document. As the parser recognizes parts of the document, it will 158call the appropriate handler for that part (if you've registered one.) 159The document is fed to the parser in pieces, so you can start parsing 160before you have all the document. This also allows you to parse really 161huge documents that won't fit into memory.</p> 162 163<p>Expat can be intimidating due to the many kinds of handlers and 164options you can set. But you only need to learn four functions in 165order to do 90% of what you'll want to do with it:</p> 166 167<dl> 168 169<dt><code><a href= "#XML_ParserCreate" 170 >XML_ParserCreate</a></code></dt> 171 <dd>Create a new parser object.</dd> 172 173<dt><code><a href= "#XML_SetElementHandler" 174 >XML_SetElementHandler</a></code></dt> 175 <dd>Set handlers for start and end tags.</dd> 176 177<dt><code><a href= "#XML_SetCharacterDataHandler" 178 >XML_SetCharacterDataHandler</a></code></dt> 179 <dd>Set handler for text.</dd> 180 181<dt><code><a href= "#XML_Parse" 182 >XML_Parse</a></code></dt> 183 <dd>Pass a buffer full of document to the parser</dd> 184</dl> 185 186<p>These functions and others are described in the <a 187href="#reference">reference</a> part of this document. The reference 188section also describes in detail the parameters passed to the 189different types of handlers.</p> 190 191<p>Let's look at a very simple example program that only uses 3 of the 192above functions (it doesn't need to set a character handler.) The 193program <a href="../examples/outline.c">outline.c</a> prints an 194element outline, indenting child elements to distinguish them from the 195parent element that contains them. The start handler does all the 196work. It prints two indenting spaces for every level of ancestor 197elements, then it prints the element and attribute 198information. Finally it increments the global <code>Depth</code> 199variable.</p> 200 201<pre class="eg"> 202int Depth; 203 204void XMLCALL 205start(void *data, const char *el, const char **attr) { 206 int i; 207 208 for (i = 0; i < Depth; i++) 209 printf(" "); 210 211 printf("%s", el); 212 213 for (i = 0; attr[i]; i += 2) { 214 printf(" %s='%s'", attr[i], attr[i + 1]); 215 } 216 217 printf("\n"); 218 Depth++; 219} /* End of start handler */ 220</pre> 221 222<p>The end tag simply does the bookkeeping work of decrementing 223<code>Depth</code>.</p> 224<pre class="eg"> 225void XMLCALL 226end(void *data, const char *el) { 227 Depth--; 228} /* End of end handler */ 229</pre> 230 231<p>Note the <code>XMLCALL</code> annotation used for the callbacks. 232This is used to ensure that the Expat and the callbacks are using the 233same calling convention in case the compiler options used for Expat 234itself and the client code are different. Expat tries not to care 235what the default calling convention is, though it may require that it 236be compiled with a default convention of "cdecl" on some platforms. 237For code which uses Expat, however, the calling convention is 238specified by the <code>XMLCALL</code> annotation on most platforms; 239callbacks should be defined using this annotation.</p> 240 241<p>The <code>XMLCALL</code> annotation was added in Expat 1.95.7, but 242existing working Expat applications don't need to add it (since they 243are already using the "cdecl" calling convention, or they wouldn't be 244working). The annotation is only needed if the default calling 245convention may be something other than "cdecl". To use the annotation 246safely with older versions of Expat, you can conditionally define it 247<em>after</em> including Expat's header file:</p> 248 249<pre class="eg"> 250#include <expat.h> 251 252#ifndef XMLCALL 253#if defined(_MSC_EXTENSIONS) && !defined(__BEOS__) && !defined(__CYGWIN__) 254#define XMLCALL __cdecl 255#elif defined(__GNUC__) 256#define XMLCALL __attribute__((cdecl)) 257#else 258#define XMLCALL 259#endif 260#endif 261</pre> 262 263<p>After creating the parser, the main program just has the job of 264shoveling the document to the parser so that it can do its work.</p> 265 266<hr /> 267<h2><a name="building">Building and Installing Expat</a></h2> 268 269<p>The Expat distribution comes as a compressed (with GNU gzip) tar 270file. You may download the latest version from <a href= 271"http://sourceforge.net/projects/expat/" >Source Forge</a>. After 272unpacking this, cd into the directory. Then follow either the Win32 273directions or Unix directions below.</p> 274 275<h3>Building under Win32</h3> 276 277<p>If you're using the GNU compiler under cygwin, follow the Unix 278directions in the next section. Otherwise if you have Microsoft's 279Developer Studio installed, then from Windows Explorer double-click on 280"expat.dsp" in the lib directory and build and install in the usual 281manner.</p> 282 283<p>Alternatively, you may download the Win32 binary package that 284contains the "expat.h" include file and a pre-built DLL.</p> 285 286<h3>Building under Unix (or GNU)</h3> 287 288<p>First you'll need to run the configure shell script in order to 289configure the Makefiles and headers for your system.</p> 290 291<p>If you're happy with all the defaults that configure picks for you, 292and you have permission on your system to install into /usr/local, you 293can install Expat with this sequence of commands:</p> 294 295<pre class="eg"> 296./configure 297make 298make install 299</pre> 300 301<p>There are some options that you can provide to this script, but the 302only one we'll mention here is the <code>--prefix</code> option. You 303can find out all the options available by running configure with just 304the <code>--help</code> option.</p> 305 306<p>By default, the configure script sets things up so that the library 307gets installed in <code>/usr/local/lib</code> and the associated 308header file in <code>/usr/local/include</code>. But if you were to 309give the option, <code>--prefix=/home/me/mystuff</code>, then the 310library and header would get installed in 311<code>/home/me/mystuff/lib</code> and 312<code>/home/me/mystuff/include</code> respectively.</p> 313 314<h3>Configuring Expat Using the Pre-Processor</h3> 315 316<p>Expat's feature set can be configured using a small number of 317pre-processor definitions. The definition of this symbols does not 318affect the set of entry points for Expat, only the behavior of the API 319and the definition of character types in the case of 320<code>XML_UNICODE_WCHAR_T</code>. The symbols are:</p> 321 322<dl class="cpp-symbols"> 323<dt>XML_DTD</dt> 324<dd>Include support for using and reporting DTD-based content. If 325this is defined, default attribute values from an external DTD subset 326are reported and attribute value normalization occurs based on the 327type of attributes defined in the external subset. Without 328this, Expat has a smaller memory footprint and can be faster, but will 329not load external entities or process conditional sections. This does 330not affect the set of functions available in the API.</dd> 331 332<dt>XML_NS</dt> 333<dd>When defined, support for the <cite><a href= 334"http://www.w3.org/TR/REC-xml-names/" >Namespaces in XML</a></cite> 335specification is included.</dd> 336 337<dt>XML_UNICODE</dt> 338<dd>When defined, character data reported to the application is 339encoded in UTF-16 using wide characters of the type 340<code>XML_Char</code>. This is implied if 341<code>XML_UNICODE_WCHAR_T</code> is defined.</dd> 342 343<dt>XML_UNICODE_WCHAR_T</dt> 344<dd>If defined, causes the <code>XML_Char</code> character type to be 345defined using the <code>wchar_t</code> type; otherwise, <code>unsigned 346short</code> is used. Defining this implies 347<code>XML_UNICODE</code>.</dd> 348 349<dt>XML_LARGE_SIZE</dt> 350<dd>If defined, causes the <code>XML_Size</code> and <code>XML_Index</code> 351integer types to be at least 64 bits in size. This is intended to support 352processing of very large input streams, where the return values of 353<code><a href="#XML_GetCurrentByteIndex" >XML_GetCurrentByteIndex</a></code>, 354<code><a href="#XML_GetCurrentLineNumber" >XML_GetCurrentLineNumber</a></code> and 355<code><a href="#XML_GetCurrentColumnNumber" >XML_GetCurrentColumnNumber</a></code> 356could overflow. It may not be supported by all compilers, and is turned 357off by default.</dd> 358 359<dt>XML_CONTEXT_BYTES</dt> 360<dd>The number of input bytes of markup context which the parser will 361ensure are available for reporting via <code><a href= 362"#XML_GetInputContext" >XML_GetInputContext</a></code>. This is 363normally set to 1024, and must be set to a positive interger. If this 364is not defined, the input context will not be available and <code><a 365href= "#XML_GetInputContext" >XML_GetInputContext</a></code> will 366always report NULL. Without this, Expat has a smaller memory 367footprint and can be faster.</dd> 368 369<dt>XML_STATIC</dt> 370<dd>On Windows, this should be set if Expat is going to be linked 371statically with the code that calls it; this is required to get all 372the right MSVC magic annotations correct. This is ignored on other 373platforms.</dd> 374 375<dt>XML_ATTR_INFO</dt> 376<dd>If defined, makes the the additional function <code><a href= 377"#XML_GetAttributeInfo" >XML_GetAttributeInfo</a></code> available 378for reporting attribute byte offsets.</dd> 379</dl> 380 381<hr /> 382<h2><a name="using">Using Expat</a></h2> 383 384<h3>Compiling and Linking Against Expat</h3> 385 386<p>Unless you installed Expat in a location not expected by your 387compiler and linker, all you have to do to use Expat in your programs 388is to include the Expat header (<code>#include <expat.h></code>) 389in your files that make calls to it and to tell the linker that it 390needs to link against the Expat library. On Unix systems, this would 391usually be done with the <code>-lexpat</code> argument. Otherwise, 392you'll need to tell the compiler where to look for the Expat header 393and the linker where to find the Expat library. You may also need to 394take steps to tell the operating system where to find this library at 395run time.</p> 396 397<p>On a Unix-based system, here's what a Makefile might look like when 398Expat is installed in a standard location:</p> 399 400<pre class="eg"> 401CC=cc 402LDFLAGS= 403LIBS= -lexpat 404xmlapp: xmlapp.o 405 $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS) 406</pre> 407 408<p>If you installed Expat in, say, <code>/home/me/mystuff</code>, then 409the Makefile would look like this:</p> 410 411<pre class="eg"> 412CC=cc 413CFLAGS= -I/home/me/mystuff/include 414LDFLAGS= 415LIBS= -L/home/me/mystuff/lib -lexpat 416xmlapp: xmlapp.o 417 $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS) 418</pre> 419 420<p>You'd also have to set the environment variable 421<code>LD_LIBRARY_PATH</code> to <code>/home/me/mystuff/lib</code> (or 422to <code>${LD_LIBRARY_PATH}:/home/me/mystuff/lib</code> if 423LD_LIBRARY_PATH already has some directories in it) in order to run 424your application.</p> 425 426<h3>Expat Basics</h3> 427 428<p>As we saw in the example in the overview, the first step in parsing 429an XML document with Expat is to create a parser object. There are <a 430href="#creation">three functions</a> in the Expat API for creating a 431parser object. However, only two of these (<code><a href= 432"#XML_ParserCreate" >XML_ParserCreate</a></code> and <code><a href= 433"#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>) can be used for 434constructing a parser for a top-level document. The object returned 435by these functions is an opaque pointer (i.e. "expat.h" declares it as 436void *) to data with further internal structure. In order to free the 437memory associated with this object you must call <code><a href= 438"#XML_ParserFree" >XML_ParserFree</a></code>. Note that if you have 439provided any <a href="#userdata">user data</a> that gets stored in the 440parser, then your application is responsible for freeing it prior to 441calling <code>XML_ParserFree</code>.</p> 442 443<p>The objects returned by the parser creation functions are good for 444parsing only one XML document or external parsed entity. If your 445application needs to parse many XML documents, then it needs to create 446a parser object for each one. The best way to deal with this is to 447create a higher level object that contains all the default 448initialization you want for your parser objects.</p> 449 450<p>Walking through a document hierarchy with a stream oriented parser 451will require a good stack mechanism in order to keep track of current 452context. For instance, to answer the simple question, "What element 453does this text belong to?" requires a stack, since the parser may have 454descended into other elements that are children of the current one and 455has encountered this text on the way out.</p> 456 457<p>The things you're likely to want to keep on a stack are the 458currently opened element and it's attributes. You push this 459information onto the stack in the start handler and you pop it off in 460the end handler.</p> 461 462<p>For some tasks, it is sufficient to just keep information on what 463the depth of the stack is (or would be if you had one.) The outline 464program shown above presents one example. Another such task would be 465skipping over a complete element. When you see the start tag for the 466element you want to skip, you set a skip flag and record the depth at 467which the element started. When the end tag handler encounters the 468same depth, the skipped element has ended and the flag may be 469cleared. If you follow the convention that the root element starts at 4701, then you can use the same variable for skip flag and skip 471depth.</p> 472 473<pre class="eg"> 474void 475init_info(Parseinfo *info) { 476 info->skip = 0; 477 info->depth = 1; 478 /* Other initializations here */ 479} /* End of init_info */ 480 481void XMLCALL 482rawstart(void *data, const char *el, const char **attr) { 483 Parseinfo *inf = (Parseinfo *) data; 484 485 if (! inf->skip) { 486 if (should_skip(inf, el, attr)) { 487 inf->skip = inf->depth; 488 } 489 else 490 start(inf, el, attr); /* This does rest of start handling */ 491 } 492 493 inf->depth++; 494} /* End of rawstart */ 495 496void XMLCALL 497rawend(void *data, const char *el) { 498 Parseinfo *inf = (Parseinfo *) data; 499 500 inf->depth--; 501 502 if (! inf->skip) 503 end(inf, el); /* This does rest of end handling */ 504 505 if (inf->skip == inf->depth) 506 inf->skip = 0; 507} /* End rawend */ 508</pre> 509 510<p>Notice in the above example the difference in how depth is 511manipulated in the start and end handlers. The end tag handler should 512be the mirror image of the start tag handler. This is necessary to 513properly model containment. Since, in the start tag handler, we 514incremented depth <em>after</em> the main body of start tag code, then 515in the end handler, we need to manipulate it <em>before</em> the main 516body. If we'd decided to increment it first thing in the start 517handler, then we'd have had to decrement it last thing in the end 518handler.</p> 519 520<h3 id="userdata">Communicating between handlers</h3> 521 522<p>In order to be able to pass information between different handlers 523without using globals, you'll need to define a data structure to hold 524the shared variables. You can then tell Expat (with the <code><a href= 525"#XML_SetUserData" >XML_SetUserData</a></code> function) to pass a 526pointer to this structure to the handlers. This is the first 527argument received by most handlers. In the <a href="#reference" 528>reference section</a>, an argument to a callback function is named 529<code>userData</code> and have type <code>void *</code> if the user 530data is passed; it will have the type <code>XML_Parser</code> if the 531parser itself is passed. When the parser is passed, the user data may 532be retrieved using <code><a href="#XML_GetUserData" 533>XML_GetUserData</a></code>.</p> 534 535<p>One common case where multiple calls to a single handler may need 536to communicate using an application data structure is the case when 537content passed to the character data handler (set by <code><a href= 538"#XML_SetCharacterDataHandler" 539>XML_SetCharacterDataHandler</a></code>) needs to be accumulated. A 540common first-time mistake with any of the event-oriented interfaces to 541an XML parser is to expect all the text contained in an element to be 542reported by a single call to the character data handler. Expat, like 543many other XML parsers, reports such data as a sequence of calls; 544there's no way to know when the end of the sequence is reached until a 545different callback is made. A buffer referenced by the user data 546structure proves both an effective and convenient place to accumulate 547character data.</p> 548 549<!-- XXX example needed here --> 550 551 552<h3>XML Version</h3> 553 554<p>Expat is an XML 1.0 parser, and as such never complains based on 555the value of the <code>version</code> pseudo-attribute in the XML 556declaration, if present.</p> 557 558<p>If an application needs to check the version number (to support 559alternate processing), it should use the <code><a href= 560"#XML_SetXmlDeclHandler" >XML_SetXmlDeclHandler</a></code> function to 561set a handler that uses the information in the XML declaration to 562determine what to do. This example shows how to check that only a 563version number of <code>"1.0"</code> is accepted:</p> 564 565<pre class="eg"> 566static int wrong_version; 567static XML_Parser parser; 568 569static void XMLCALL 570xmldecl_handler(void *userData, 571 const XML_Char *version, 572 const XML_Char *encoding, 573 int standalone) 574{ 575 static const XML_Char Version_1_0[] = {'1', '.', '0', 0}; 576 577 int i; 578 579 for (i = 0; i < (sizeof(Version_1_0) / sizeof(Version_1_0[0])); ++i) { 580 if (version[i] != Version_1_0[i]) { 581 wrong_version = 1; 582 /* also clear all other handlers: */ 583 XML_SetCharacterDataHandler(parser, NULL); 584 ... 585 return; 586 } 587 } 588 ... 589} 590</pre> 591 592<h3>Namespace Processing</h3> 593 594<p>When the parser is created using the <code><a href= 595"#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>, function, Expat 596performs namespace processing. Under namespace processing, Expat 597consumes <code>xmlns</code> and <code>xmlns:...</code> attributes, 598which declare namespaces for the scope of the element in which they 599occur. This means that your start handler will not see these 600attributes. Your application can still be informed of these 601declarations by setting namespace declaration handlers with <a href= 602"#XML_SetNamespaceDeclHandler" 603><code>XML_SetNamespaceDeclHandler</code></a>.</p> 604 605<p>Element type and attribute names that belong to a given namespace 606are passed to the appropriate handler in expanded form. By default 607this expanded form is a concatenation of the namespace URI, the 608separator character (which is the 2nd argument to <code><a href= 609"#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>), and the local 610name (i.e. the part after the colon). Names with undeclared prefixes 611are not well-formed when namespace processing is enabled, and will 612trigger an error. Unprefixed attribute names are never expanded, 613and unprefixed element names are only expanded when they are in the 614scope of a default namespace.</p> 615 616<p>However if <code><a href= "#XML_SetReturnNSTriplet" 617>XML_SetReturnNSTriplet</a></code> has been called with a non-zero 618<code>do_nst</code> parameter, then the expanded form for names with 619an explicit prefix is a concatenation of: URI, separator, local name, 620separator, prefix.</p> 621 622<p>You can set handlers for the start of a namespace declaration and 623for the end of a scope of a declaration with the <code><a href= 624"#XML_SetNamespaceDeclHandler" >XML_SetNamespaceDeclHandler</a></code> 625function. The StartNamespaceDeclHandler is called prior to the start 626tag handler and the EndNamespaceDeclHandler is called after the 627corresponding end tag that ends the namespace's scope. The namespace 628start handler gets passed the prefix and URI for the namespace. For a 629default namespace declaration (xmlns='...'), the prefix will be null. 630The URI will be null for the case where the default namespace is being 631unset. The namespace end handler just gets the prefix for the closing 632scope.</p> 633 634<p>These handlers are called for each declaration. So if, for 635instance, a start tag had three namespace declarations, then the 636StartNamespaceDeclHandler would be called three times before the start 637tag handler is called, once for each declaration.</p> 638 639<h3>Character Encodings</h3> 640 641<p>While XML is based on Unicode, and every XML processor is required 642to recognized UTF-8 and UTF-16 (1 and 2 byte encodings of Unicode), 643other encodings may be declared in XML documents or entities. For the 644main document, an XML declaration may contain an encoding 645declaration:</p> 646<pre> 647<?xml version="1.0" encoding="ISO-8859-2"?> 648</pre> 649 650<p>External parsed entities may begin with a text declaration, which 651looks like an XML declaration with just an encoding declaration:</p> 652<pre> 653<?xml encoding="Big5"?> 654</pre> 655 656<p>With Expat, you may also specify an encoding at the time of 657creating a parser. This is useful when the encoding information may 658come from a source outside the document itself (like a higher level 659protocol.)</p> 660 661<p><a name="builtin_encodings"></a>There are four built-in encodings 662in Expat:</p> 663<ul> 664<li>UTF-8</li> 665<li>UTF-16</li> 666<li>ISO-8859-1</li> 667<li>US-ASCII</li> 668</ul> 669 670<p>Anything else discovered in an encoding declaration or in the 671protocol encoding specified in the parser constructor, triggers a call 672to the <code>UnknownEncodingHandler</code>. This handler gets passed 673the encoding name and a pointer to an <code>XML_Encoding</code> data 674structure. Your handler must fill in this structure and return 675<code>XML_STATUS_OK</code> if it knows how to deal with the 676encoding. Otherwise the handler should return 677<code>XML_STATUS_ERROR</code>. The handler also gets passed a pointer 678to an optional application data structure that you may indicate when 679you set the handler.</p> 680 681<p>Expat places restrictions on character encodings that it can 682support by filling in the <code>XML_Encoding</code> structure. 683include file:</p> 684<ol> 685<li>Every ASCII character that can appear in a well-formed XML document 686must be represented by a single byte, and that byte must correspond to 687it's ASCII encoding (except for the characters $@\^'{}~)</li> 688<li>Characters must be encoded in 4 bytes or less.</li> 689<li>All characters encoded must have Unicode scalar values less than or 690equal to 65535 (0xFFFF)<em>This does not apply to the built-in support 691for UTF-16 and UTF-8</em></li> 692<li>No character may be encoded by more that one distinct sequence of 693bytes</li> 694</ol> 695 696<p><code>XML_Encoding</code> contains an array of integers that 697correspond to the 1st byte of an encoding sequence. If the value in 698the array for a byte is zero or positive, then the byte is a single 699byte encoding that encodes the Unicode scalar value contained in the 700array. A -1 in this array indicates a malformed byte. If the value is 701-2, -3, or -4, then the byte is the beginning of a 2, 3, or 4 byte 702sequence respectively. Multi-byte sequences are sent to the convert 703function pointed at in the <code>XML_Encoding</code> structure. This 704function should return the Unicode scalar value for the sequence or -1 705if the sequence is malformed.</p> 706 707<p>One pitfall that novice Expat users are likely to fall into is that 708although Expat may accept input in various encodings, the strings that 709it passes to the handlers are always encoded in UTF-8 or UTF-16 710(depending on how Expat was compiled). Your application is responsible 711for any translation of these strings into other encodings.</p> 712 713<h3>Handling External Entity References</h3> 714 715<p>Expat does not read or parse external entities directly. Note that 716any external DTD is a special case of an external entity. If you've 717set no <code>ExternalEntityRefHandler</code>, then external entity 718references are silently ignored. Otherwise, it calls your handler with 719the information needed to read and parse the external entity.</p> 720 721<p>Your handler isn't actually responsible for parsing the entity, but 722it is responsible for creating a subsidiary parser with <code><a href= 723"#XML_ExternalEntityParserCreate" 724>XML_ExternalEntityParserCreate</a></code> that will do the job. This 725returns an instance of <code>XML_Parser</code> that has handlers and 726other data structures initialized from the parent parser. You may then 727use <code><a href= "#XML_Parse" >XML_Parse</a></code> or <code><a 728href= "#XML_ParseBuffer">XML_ParseBuffer</a></code> calls against this 729parser. Since external entities my refer to other external entities, 730your handler should be prepared to be called recursively.</p> 731 732<h3>Parsing DTDs</h3> 733 734<p>In order to parse parameter entities, before starting the parse, 735you must call <code><a href= "#XML_SetParamEntityParsing" 736>XML_SetParamEntityParsing</a></code> with one of the following 737arguments:</p> 738<dl> 739<dt><code>XML_PARAM_ENTITY_PARSING_NEVER</code></dt> 740<dd>Don't parse parameter entities or the external subset</dd> 741<dt><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></dt> 742<dd>Parse parameter entites and the external subset unless 743<code>standalone</code> was set to "yes" in the XML declaration.</dd> 744<dt><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></dt> 745<dd>Always parse parameter entities and the external subset</dd> 746</dl> 747 748<p>In order to read an external DTD, you also have to set an external 749entity reference handler as described above.</p> 750 751<h3 id="stop-resume">Temporarily Stopping Parsing</h3> 752 753<p>Expat 1.95.8 introduces a new feature: its now possible to stop 754parsing temporarily from within a handler function, even if more data 755has already been passed into the parser. Applications for this 756include</p> 757 758<ul> 759 <li>Supporting the <a href= "http://www.w3.org/TR/xinclude/" 760 >XInclude</a> specification.</li> 761 762 <li>Delaying further processing until additional information is 763 available from some other source.</li> 764 765 <li>Adjusting processor load as task priorities shift within an 766 application.</li> 767 768 <li>Stopping parsing completely (simply free or reset the parser 769 instead of resuming in the outer parsing loop). This can be useful 770 if a application-domain error is found in the XML being parsed or if 771 the result of the parse is determined not to be useful after 772 all.</li> 773</ul> 774 775<p>To take advantage of this feature, the main parsing loop of an 776application needs to support this specifically. It cannot be 777supported with a parsing loop compatible with Expat 1.95.7 or 778earlier (though existing loops will continue to work without 779supporting the stop/resume feature).</p> 780 781<p>An application that uses this feature for a single parser will have 782the rough structure (in pseudo-code):</p> 783 784<pre class="pseudocode"> 785fd = open_input() 786p = create_parser() 787 788if parse_xml(p, fd) { 789 /* suspended */ 790 791 int suspended = 1; 792 793 while (suspended) { 794 do_something_else() 795 if ready_to_resume() { 796 suspended = continue_parsing(p, fd); 797 } 798 } 799} 800</pre> 801 802<p>An application that may resume any of several parsers based on 803input (either from the XML being parsed or some other source) will 804certainly have more interesting control structures.</p> 805 806<p>This C function could be used for the <code>parse_xml</code> 807function mentioned in the pseudo-code above:</p> 808 809<pre class="eg"> 810#define BUFF_SIZE 10240 811 812/* Parse a document from the open file descriptor 'fd' until the parse 813 is complete (the document has been completely parsed, or there's 814 been an error), or the parse is stopped. Return non-zero when 815 the parse is merely suspended. 816*/ 817int 818parse_xml(XML_Parser p, int fd) 819{ 820 for (;;) { 821 int last_chunk; 822 int bytes_read; 823 enum XML_Status status; 824 825 void *buff = XML_GetBuffer(p, BUFF_SIZE); 826 if (buff == NULL) { 827 /* handle error... */ 828 return 0; 829 } 830 bytes_read = read(fd, buff, BUFF_SIZE); 831 if (bytes_read < 0) { 832 /* handle error... */ 833 return 0; 834 } 835 status = XML_ParseBuffer(p, bytes_read, bytes_read == 0); 836 switch (status) { 837 case XML_STATUS_ERROR: 838 /* handle error... */ 839 return 0; 840 case XML_STATUS_SUSPENDED: 841 return 1; 842 } 843 if (bytes_read == 0) 844 return 0; 845 } 846} 847</pre> 848 849<p>The corresponding <code>continue_parsing</code> function is 850somewhat simpler, since it only need deal with the return code from 851<code><a href= "#XML_ResumeParser">XML_ResumeParser</a></code>; it can 852delegate the input handling to the <code>parse_xml</code> 853function:</p> 854 855<pre class="eg"> 856/* Continue parsing a document which had been suspended. The 'p' and 857 'fd' arguments are the same as passed to parse_xml(). Return 858 non-zero when the parse is suspended. 859*/ 860int 861continue_parsing(XML_Parser p, int fd) 862{ 863 enum XML_Status status = XML_ResumeParser(p); 864 switch (status) { 865 case XML_STATUS_ERROR: 866 /* handle error... */ 867 return 0; 868 case XML_ERROR_NOT_SUSPENDED: 869 /* handle error... */ 870 return 0;. 871 case XML_STATUS_SUSPENDED: 872 return 1; 873 } 874 return parse_xml(p, fd); 875} 876</pre> 877 878<p>Now that we've seen what a mess the top-level parsing loop can 879become, what have we gained? Very simply, we can now use the <code><a 880href= "#XML_StopParser" >XML_StopParser</a></code> function to stop 881parsing, without having to go to great lengths to avoid additional 882processing that we're expecting to ignore. As a bonus, we get to stop 883parsing <em>temporarily</em>, and come back to it when we're 884ready.</p> 885 886<p>To stop parsing from a handler function, use the <code><a href= 887"#XML_StopParser" >XML_StopParser</a></code> function. This function 888takes two arguments; the parser being stopped and a flag indicating 889whether the parse can be resumed in the future.</p> 890 891<!-- XXX really need more here --> 892 893 894<hr /> 895<!-- ================================================================ --> 896 897<h2><a name="reference">Expat Reference</a></h2> 898 899<h3><a name="creation">Parser Creation</a></h3> 900 901<pre class="fcndec" id="XML_ParserCreate"> 902XML_Parser XMLCALL 903XML_ParserCreate(const XML_Char *encoding); 904</pre> 905<div class="fcndef"> 906Construct a new parser. If encoding is non-null, it specifies a 907character encoding to use for the document. This overrides the document 908encoding declaration. There are four built-in encodings: 909<ul> 910<li>US-ASCII</li> 911<li>UTF-8</li> 912<li>UTF-16</li> 913<li>ISO-8859-1</li> 914</ul> 915Any other value will invoke a call to the UnknownEncodingHandler. 916</div> 917 918<pre class="fcndec" id="XML_ParserCreateNS"> 919XML_Parser XMLCALL 920XML_ParserCreateNS(const XML_Char *encoding, 921 XML_Char sep); 922</pre> 923<div class="fcndef"> 924Constructs a new parser that has namespace processing in effect. Namespace 925expanded element names and attribute names are returned as a concatenation 926of the namespace URI, <em>sep</em>, and the local part of the name. This 927means that you should pick a character for <em>sep</em> that can't be part 928of an URI. Since Expat does not check namespace URIs for conformance, the 929only safe choice for a namespace separator is a character that is illegal 930in XML. For instance, <code>'\xFF'</code> is not legal in UTF-8, and 931<code>'\xFFFF'</code> is not legal in UTF-16. There is a special case when 932<em>sep</em> is the null character <code>'\0'</code>: the namespace URI and 933the local part will be concatenated without any separator - this is intended 934to support RDF processors. It is a programming error to use the null separator 935with <a href= "#XML_SetReturnNSTriplet">namespace triplets</a>.</div> 936 937<pre class="fcndec" id="XML_ParserCreate_MM"> 938XML_Parser XMLCALL 939XML_ParserCreate_MM(const XML_Char *encoding, 940 const XML_Memory_Handling_Suite *ms, 941 const XML_Char *sep); 942</pre> 943<pre class="signature"> 944typedef struct { 945 void *(XMLCALL *malloc_fcn)(size_t size); 946 void *(XMLCALL *realloc_fcn)(void *ptr, size_t size); 947 void (XMLCALL *free_fcn)(void *ptr); 948} XML_Memory_Handling_Suite; 949</pre> 950<div class="fcndef"> 951<p>Construct a new parser using the suite of memory handling functions 952specified in <code>ms</code>. If <code>ms</code> is NULL, then use the 953standard set of memory management functions. If <code>sep</code> is 954non NULL, then namespace processing is enabled in the created parser 955and the character pointed at by sep is used as the separator between 956the namespace URI and the local part of the name.</p> 957</div> 958 959<pre class="fcndec" id="XML_ExternalEntityParserCreate"> 960XML_Parser XMLCALL 961XML_ExternalEntityParserCreate(XML_Parser p, 962 const XML_Char *context, 963 const XML_Char *encoding); 964</pre> 965<div class="fcndef"> 966Construct a new <code>XML_Parser</code> object for parsing an external 967general entity. Context is the context argument passed in a call to a 968ExternalEntityRefHandler. Other state information such as handlers, 969user data, namespace processing is inherited from the parser passed as 970the 1st argument. So you shouldn't need to call any of the behavior 971changing functions on this parser (unless you want it to act 972differently than the parent parser). 973</div> 974 975<pre class="fcndec" id="XML_ParserFree"> 976void XMLCALL 977XML_ParserFree(XML_Parser p); 978</pre> 979<div class="fcndef"> 980Free memory used by the parser. Your application is responsible for 981freeing any memory associated with <a href="#userdata">user data</a>. 982</div> 983 984<pre class="fcndec" id="XML_ParserReset"> 985XML_Bool XMLCALL 986XML_ParserReset(XML_Parser p, 987 const XML_Char *encoding); 988</pre> 989<div class="fcndef"> 990Clean up the memory structures maintained by the parser so that it may 991be used again. After this has been called, <code>parser</code> is 992ready to start parsing a new document. All handlers are cleared from 993the parser, except for the unknownEncodingHandler. The parser's external 994state is re-initialized except for the values of ns and ns_triplets. 995This function may not be used on a parser created using <code><a href= 996"#XML_ExternalEntityParserCreate" >XML_ExternalEntityParserCreate</a 997></code>; it will return <code>XML_FALSE</code> in that case. Returns 998<code>XML_TRUE</code> on success. Your application is responsible for 999dealing with any memory associated with <a href="#userdata">user data</a>. 1000</div> 1001 1002<h3><a name="parsing">Parsing</a></h3> 1003 1004<p>To state the obvious: the three parsing functions <code><a href= 1005"#XML_Parse" >XML_Parse</a></code>, <code><a href= "#XML_ParseBuffer"> 1006XML_ParseBuffer</a></code> and <code><a href= "#XML_GetBuffer"> 1007XML_GetBuffer</a></code> must not be called from within a handler 1008unless they operate on a separate parser instance, that is, one that 1009did not call the handler. For example, it is OK to call the parsing 1010functions from within an <code>XML_ExternalEntityRefHandler</code>, 1011if they apply to the parser created by 1012<code><a href= "#XML_ExternalEntityParserCreate" 1013>XML_ExternalEntityParserCreate</a></code>.</p> 1014 1015<p>Note: the <code>len</code> argument passed to these functions 1016should be considerably less than the maximum value for an integer, 1017as it could create an integer overflow situation if the added 1018lengths of a buffer and the unprocessed portion of the previous buffer 1019exceed the maximum integer value. Input data at the end of a buffer 1020will remain unprocessed if it is part of an XML token for which the 1021end is not part of that buffer.</p> 1022 1023<pre class="fcndec" id="XML_Parse"> 1024enum XML_Status XMLCALL 1025XML_Parse(XML_Parser p, 1026 const char *s, 1027 int len, 1028 int isFinal); 1029</pre> 1030<pre class="signature"> 1031enum XML_Status { 1032 XML_STATUS_ERROR = 0, 1033 XML_STATUS_OK = 1 1034}; 1035</pre> 1036<div class="fcndef"> 1037Parse some more of the document. The string <code>s</code> is a buffer 1038containing part (or perhaps all) of the document. The number of bytes of s 1039that are part of the document is indicated by <code>len</code>. This means 1040that <code>s</code> doesn't have to be null terminated. It also means that 1041if <code>len</code> is larger than the number of bytes in the block of 1042memory that <code>s</code> points at, then a memory fault is likely. The 1043<code>isFinal</code> parameter informs the parser that this is the last 1044piece of the document. Frequently, the last piece is empty (i.e. 1045<code>len</code> is zero.) 1046If a parse error occurred, it returns <code>XML_STATUS_ERROR</code>. 1047Otherwise it returns <code>XML_STATUS_OK</code> value. 1048</div> 1049 1050<pre class="fcndec" id="XML_ParseBuffer"> 1051enum XML_Status XMLCALL 1052XML_ParseBuffer(XML_Parser p, 1053 int len, 1054 int isFinal); 1055</pre> 1056<div class="fcndef"> 1057This is just like <code><a href= "#XML_Parse" >XML_Parse</a></code>, 1058except in this case Expat provides the buffer. By obtaining the 1059buffer from Expat with the <code><a href= "#XML_GetBuffer" 1060>XML_GetBuffer</a></code> function, the application can avoid double 1061copying of the input. 1062</div> 1063 1064<pre class="fcndec" id="XML_GetBuffer"> 1065void * XMLCALL 1066XML_GetBuffer(XML_Parser p, 1067 int len); 1068</pre> 1069<div class="fcndef"> 1070Obtain a buffer of size <code>len</code> to read a piece of the document 1071into. A NULL value is returned if Expat can't allocate enough memory for 1072this buffer. This has to be called prior to every call to 1073<code><a href= "#XML_ParseBuffer" >XML_ParseBuffer</a></code>. A 1074typical use would look like this: 1075 1076<pre class="eg"> 1077for (;;) { 1078 int bytes_read; 1079 void *buff = XML_GetBuffer(p, BUFF_SIZE); 1080 if (buff == NULL) { 1081 /* handle error */ 1082 } 1083 1084 bytes_read = read(docfd, buff, BUFF_SIZE); 1085 if (bytes_read < 0) { 1086 /* handle error */ 1087 } 1088 1089 if (! XML_ParseBuffer(p, bytes_read, bytes_read == 0)) { 1090 /* handle parse error */ 1091 } 1092 1093 if (bytes_read == 0) 1094 break; 1095} 1096</pre> 1097</div> 1098 1099<pre class="fcndec" id="XML_StopParser"> 1100enum XML_Status XMLCALL 1101XML_StopParser(XML_Parser p, 1102 XML_Bool resumable); 1103</pre> 1104<div class="fcndef"> 1105 1106<p>Stops parsing, causing <code><a href= "#XML_Parse" 1107>XML_Parse</a></code> or <code><a href= "#XML_ParseBuffer" 1108>XML_ParseBuffer</a></code> to return. Must be called from within a 1109call-back handler, except when aborting (when <code>resumable</code> 1110is <code>XML_FALSE</code>) an already suspended parser. Some 1111call-backs may still follow because they would otherwise get 1112lost, including 1113<ul> 1114 <li> the end element handler for empty elements when stopped in the 1115 start element handler,</li> 1116 <li> the end namespace declaration handler when stopped in the end 1117 element handler,</li> 1118 <li> the character data handler when stopped in the character data handler 1119 while making multiple call-backs on a contiguous chunk of characters,</li> 1120</ul> 1121and possibly others.</p> 1122 1123<p>This can be called from most handlers, including DTD related 1124call-backs, except when parsing an external parameter entity and 1125<code>resumable</code> is <code>XML_TRUE</code>. Returns 1126<code>XML_STATUS_OK</code> when successful, 1127<code>XML_STATUS_ERROR</code> otherwise. The possible error codes 1128are:</p> 1129<dl> 1130 <dt><code>XML_ERROR_SUSPENDED</code></dt> 1131 <dd>when suspending an already suspended parser.</dd> 1132 <dt><code>XML_ERROR_FINISHED</code></dt> 1133 <dd>when the parser has already finished.</dd> 1134 <dt><code>XML_ERROR_SUSPEND_PE</code></dt> 1135 <dd>when suspending while parsing an external PE.</dd> 1136</dl> 1137 1138<p>Since the stop/resume feature requires application support in the 1139outer parsing loop, it is an error to call this function for a parser 1140not being handled appropriately; see <a href= "#stop-resume" 1141>Temporarily Stopping Parsing</a> for more information.</p> 1142 1143<p>When <code>resumable</code> is <code>XML_TRUE</code> then parsing 1144is <em>suspended</em>, that is, <code><a href= "#XML_Parse" 1145>XML_Parse</a></code> and <code><a href= "#XML_ParseBuffer" 1146>XML_ParseBuffer</a></code> return <code>XML_STATUS_SUSPENDED</code>. 1147Otherwise, parsing is <em>aborted</em>, that is, <code><a href= 1148"#XML_Parse" >XML_Parse</a></code> and <code><a href= 1149"#XML_ParseBuffer" >XML_ParseBuffer</a></code> return 1150<code>XML_STATUS_ERROR</code> with error code 1151<code>XML_ERROR_ABORTED</code>.</p> 1152 1153<p><strong>Note:</strong> 1154This will be applied to the current parser instance only, that is, if 1155there is a parent parser then it will continue parsing when the 1156external entity reference handler returns. It is up to the 1157implementation of that handler to call <code><a href= 1158"#XML_StopParser" >XML_StopParser</a></code> on the parent parser 1159(recursively), if one wants to stop parsing altogether.</p> 1160 1161<p>When suspended, parsing can be resumed by calling <code><a href= 1162"#XML_ResumeParser" >XML_ResumeParser</a></code>.</p> 1163 1164<p>New in Expat 1.95.8.</p> 1165</div> 1166 1167<pre class="fcndec" id="XML_ResumeParser"> 1168enum XML_Status XMLCALL 1169XML_ResumeParser(XML_Parser p); 1170</pre> 1171<div class="fcndef"> 1172<p>Resumes parsing after it has been suspended with <code><a href= 1173"#XML_StopParser" >XML_StopParser</a></code>. Must not be called from 1174within a handler call-back. Returns same status codes as <code><a 1175href= "#XML_Parse">XML_Parse</a></code> or <code><a href= 1176"#XML_ParseBuffer" >XML_ParseBuffer</a></code>. An additional error 1177code, <code>XML_ERROR_NOT_SUSPENDED</code>, will be returned if the 1178parser was not currently suspended.</p> 1179 1180<p><strong>Note:</strong> 1181This must be called on the most deeply nested child parser instance 1182first, and on its parent parser only after the child parser has 1183finished, to be applied recursively until the document entity's parser 1184is restarted. That is, the parent parser will not resume by itself 1185and it is up to the application to call <code><a href= 1186"#XML_ResumeParser" >XML_ResumeParser</a></code> on it at the 1187appropriate moment.</p> 1188 1189<p>New in Expat 1.95.8.</p> 1190</div> 1191 1192<pre class="fcndec" id="XML_GetParsingStatus"> 1193void XMLCALL 1194XML_GetParsingStatus(XML_Parser p, 1195 XML_ParsingStatus *status); 1196</pre> 1197<pre class="signature"> 1198enum XML_Parsing { 1199 XML_INITIALIZED, 1200 XML_PARSING, 1201 XML_FINISHED, 1202 XML_SUSPENDED 1203}; 1204 1205typedef struct { 1206 enum XML_Parsing parsing; 1207 XML_Bool finalBuffer; 1208} XML_ParsingStatus; 1209</pre> 1210<div class="fcndef"> 1211<p>Returns status of parser with respect to being initialized, 1212parsing, finished, or suspended, and whether the final buffer is being 1213processed. The <code>status</code> parameter <em>must not</em> be 1214NULL.</p> 1215 1216<p>New in Expat 1.95.8.</p> 1217</div> 1218 1219 1220<h3><a name="setting">Handler Setting</a></h3> 1221 1222<p>Although handlers are typically set prior to parsing and left alone, an 1223application may choose to set or change the handler for a parsing event 1224while the parse is in progress. For instance, your application may choose 1225to ignore all text not descended from a <code>para</code> element. One 1226way it could do this is to set the character handler when a para start tag 1227is seen, and unset it for the corresponding end tag.</p> 1228 1229<p>A handler may be <em>unset</em> by providing a NULL pointer to the 1230appropriate handler setter. None of the handler setting functions have 1231a return value.</p> 1232 1233<p>Your handlers will be receiving strings in arrays of type 1234<code>XML_Char</code>. This type is conditionally defined in expat.h as 1235either <code>char</code>, <code>wchar_t</code> or <code>unsigned short</code>. 1236The former implies UTF-8 encoding, the latter two imply UTF-16 encoding. 1237Note that you'll receive them in this form independent of the original 1238encoding of the document.</p> 1239 1240<div class="handler"> 1241<pre class="setter" id="XML_SetStartElementHandler"> 1242void XMLCALL 1243XML_SetStartElementHandler(XML_Parser p, 1244 XML_StartElementHandler start); 1245</pre> 1246<pre class="signature"> 1247typedef void 1248(XMLCALL *XML_StartElementHandler)(void *userData, 1249 const XML_Char *name, 1250 const XML_Char **atts); 1251</pre> 1252<p>Set handler for start (and empty) tags. Attributes are passed to the start 1253handler as a pointer to a vector of char pointers. Each attribute seen in 1254a start (or empty) tag occupies 2 consecutive places in this vector: the 1255attribute name followed by the attribute value. These pairs are terminated 1256by a null pointer.</p> 1257<p>Note that an empty tag generates a call to both start and end handlers 1258(in that order).</p> 1259</div> 1260 1261<div class="handler"> 1262<pre class="setter" id="XML_SetEndElementHandler"> 1263void XMLCALL 1264XML_SetEndElementHandler(XML_Parser p, 1265 XML_EndElementHandler); 1266</pre> 1267<pre class="signature"> 1268typedef void 1269(XMLCALL *XML_EndElementHandler)(void *userData, 1270 const XML_Char *name); 1271</pre> 1272<p>Set handler for end (and empty) tags. As noted above, an empty tag 1273generates a call to both start and end handlers.</p> 1274</div> 1275 1276<div class="handler"> 1277<pre class="setter" id="XML_SetElementHandler"> 1278void XMLCALL 1279XML_SetElementHandler(XML_Parser p, 1280 XML_StartElementHandler start, 1281 XML_EndElementHandler end); 1282</pre> 1283<p>Set handlers for start and end tags with one call.</p> 1284</div> 1285 1286<div class="handler"> 1287<pre class="setter" id="XML_SetCharacterDataHandler"> 1288void XMLCALL 1289XML_SetCharacterDataHandler(XML_Parser p, 1290 XML_CharacterDataHandler charhndl) 1291</pre> 1292<pre class="signature"> 1293typedef void 1294(XMLCALL *XML_CharacterDataHandler)(void *userData, 1295 const XML_Char *s, 1296 int len); 1297</pre> 1298<p>Set a text handler. The string your handler receives 1299is <em>NOT nul-terminated</em>. You have to use the length argument 1300to deal with the end of the string. A single block of contiguous text 1301free of markup may still result in a sequence of calls to this handler. 1302In other words, if you're searching for a pattern in the text, it may 1303be split across calls to this handler. Note: Setting this handler to NULL 1304may <em>NOT immediately</em> terminate call-backs if the parser is currently 1305processing such a single block of contiguous markup-free text, as the parser 1306will continue calling back until the end of the block is reached.</p> 1307</div> 1308 1309<div class="handler"> 1310<pre class="setter" id="XML_SetProcessingInstructionHandler"> 1311void XMLCALL 1312XML_SetProcessingInstructionHandler(XML_Parser p, 1313 XML_ProcessingInstructionHandler proc) 1314</pre> 1315<pre class="signature"> 1316typedef void 1317(XMLCALL *XML_ProcessingInstructionHandler)(void *userData, 1318 const XML_Char *target, 1319 const XML_Char *data); 1320 1321</pre> 1322<p>Set a handler for processing instructions. The target is the first word 1323in the processing instruction. The data is the rest of the characters in 1324it after skipping all whitespace after the initial word.</p> 1325</div> 1326 1327<div class="handler"> 1328<pre class="setter" id="XML_SetCommentHandler"> 1329void XMLCALL 1330XML_SetCommentHandler(XML_Parser p, 1331 XML_CommentHandler cmnt) 1332</pre> 1333<pre class="signature"> 1334typedef void 1335(XMLCALL *XML_CommentHandler)(void *userData, 1336 const XML_Char *data); 1337</pre> 1338<p>Set a handler for comments. The data is all text inside the comment 1339delimiters.</p> 1340</div> 1341 1342<div class="handler"> 1343<pre class="setter" id="XML_SetStartCdataSectionHandler"> 1344void XMLCALL 1345XML_SetStartCdataSectionHandler(XML_Parser p, 1346 XML_StartCdataSectionHandler start); 1347</pre> 1348<pre class="signature"> 1349typedef void 1350(XMLCALL *XML_StartCdataSectionHandler)(void *userData); 1351</pre> 1352<p>Set a handler that gets called at the beginning of a CDATA section.</p> 1353</div> 1354 1355<div class="handler"> 1356<pre class="setter" id="XML_SetEndCdataSectionHandler"> 1357void XMLCALL 1358XML_SetEndCdataSectionHandler(XML_Parser p, 1359 XML_EndCdataSectionHandler end); 1360</pre> 1361<pre class="signature"> 1362typedef void 1363(XMLCALL *XML_EndCdataSectionHandler)(void *userData); 1364</pre> 1365<p>Set a handler that gets called at the end of a CDATA section.</p> 1366</div> 1367 1368<div class="handler"> 1369<pre class="setter" id="XML_SetCdataSectionHandler"> 1370void XMLCALL 1371XML_SetCdataSectionHandler(XML_Parser p, 1372 XML_StartCdataSectionHandler start, 1373 XML_EndCdataSectionHandler end) 1374</pre> 1375<p>Sets both CDATA section handlers with one call.</p> 1376</div> 1377 1378<div class="handler"> 1379<pre class="setter" id="XML_SetDefaultHandler"> 1380void XMLCALL 1381XML_SetDefaultHandler(XML_Parser p, 1382 XML_DefaultHandler hndl) 1383</pre> 1384<pre class="signature"> 1385typedef void 1386(XMLCALL *XML_DefaultHandler)(void *userData, 1387 const XML_Char *s, 1388 int len); 1389</pre> 1390 1391<p>Sets a handler for any characters in the document which wouldn't 1392otherwise be handled. This includes both data for which no handlers 1393can be set (like some kinds of DTD declarations) and data which could 1394be reported but which currently has no handler set. The characters 1395are passed exactly as they were present in the XML document except 1396that they will be encoded in UTF-8 or UTF-16. Line boundaries are not 1397normalized. Note that a byte order mark character is not passed to the 1398default handler. There are no guarantees about how characters are 1399divided between calls to the default handler: for example, a comment 1400might be split between multiple calls. Setting the handler with 1401this call has the side effect of turning off expansion of references 1402to internally defined general entities. Instead these references are 1403passed to the default handler.</p> 1404 1405<p>See also <code><a 1406href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p> 1407</div> 1408 1409<div class="handler"> 1410<pre class="setter" id="XML_SetDefaultHandlerExpand"> 1411void XMLCALL 1412XML_SetDefaultHandlerExpand(XML_Parser p, 1413 XML_DefaultHandler hndl) 1414</pre> 1415<pre class="signature"> 1416typedef void 1417(XMLCALL *XML_DefaultHandler)(void *userData, 1418 const XML_Char *s, 1419 int len); 1420</pre> 1421<p>This sets a default handler, but doesn't inhibit the expansion of 1422internal entity references. The entity reference will not be passed 1423to the default handler.</p> 1424 1425<p>See also <code><a 1426href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p> 1427</div> 1428 1429<div class="handler"> 1430<pre class="setter" id="XML_SetExternalEntityRefHandler"> 1431void XMLCALL 1432XML_SetExternalEntityRefHandler(XML_Parser p, 1433 XML_ExternalEntityRefHandler hndl) 1434</pre> 1435<pre class="signature"> 1436typedef int 1437(XMLCALL *XML_ExternalEntityRefHandler)(XML_Parser p, 1438 const XML_Char *context, 1439 const XML_Char *base, 1440 const XML_Char *systemId, 1441 const XML_Char *publicId); 1442</pre> 1443<p>Set an external entity reference handler. This handler is also 1444called for processing an external DTD subset if parameter entity parsing 1445is in effect. (See <a href="#XML_SetParamEntityParsing"> 1446<code>XML_SetParamEntityParsing</code></a>.)</p> 1447 1448<p>The <code>context</code> parameter specifies the parsing context in 1449the format expected by the <code>context</code> argument to <code><a 1450href="#XML_ExternalEntityParserCreate" 1451>XML_ExternalEntityParserCreate</a></code>. <code>code</code> is 1452valid only until the handler returns, so if the referenced entity is 1453to be parsed later, it must be copied. <code>context</code> is NULL 1454only when the entity is a parameter entity, which is how one can 1455differentiate between general and parameter entities.</p> 1456 1457<p>The <code>base</code> parameter is the base to use for relative 1458system identifiers. It is set by <code><a 1459href="#XML_SetBase">XML_SetBase</a></code> and may be NULL. The 1460<code>publicId</code> parameter is the public id given in the entity 1461declaration and may be NULL. <code>systemId</code> is the system 1462identifier specified in the entity declaration and is never NULL.</p> 1463 1464<p>There are a couple of ways in which this handler differs from 1465others. First, this handler returns a status indicator (an 1466integer). <code>XML_STATUS_OK</code> should be returned for successful 1467handling of the external entity reference. Returning 1468<code>XML_STATUS_ERROR</code> indicates failure, and causes the 1469calling parser to return an 1470<code>XML_ERROR_EXTERNAL_ENTITY_HANDLING</code> error.</p> 1471 1472<p>Second, instead of having the user data as its first argument, it 1473receives the parser that encountered the entity reference. This, along 1474with the context parameter, may be used as arguments to a call to 1475<code><a href= "#XML_ExternalEntityParserCreate" 1476>XML_ExternalEntityParserCreate</a></code>. Using the returned 1477parser, the body of the external entity can be recursively parsed.</p> 1478 1479<p>Since this handler may be called recursively, it should not be saving 1480information into global or static variables.</p> 1481</div> 1482 1483<pre class="fcndec" id="XML_SetExternalEntityRefHandlerArg"> 1484void XMLCALL 1485XML_SetExternalEntityRefHandlerArg(XML_Parser p, 1486 void *arg) 1487</pre> 1488<div class="fcndef"> 1489<p>Set the argument passed to the ExternalEntityRefHandler. If 1490<code>arg</code> is not NULL, it is the new value passed to the 1491handler set using <code><a href="#XML_SetExternalEntityRefHandler" 1492>XML_SetExternalEntityRefHandler</a></code>; if <code>arg</code> is 1493NULL, the argument passed to the handler function will be the parser 1494object itself.</p> 1495 1496<p><strong>Note:</strong> 1497The type of <code>arg</code> and the type of the first argument to the 1498ExternalEntityRefHandler do not match. This function takes a 1499<code>void *</code> to be passed to the handler, while the handler 1500accepts an <code>XML_Parser</code>. This is a historical accident, 1501but will not be corrected before Expat 2.0 (at the earliest) to avoid 1502causing compiler warnings for code that's known to work with this 1503API. It is the responsibility of the application code to know the 1504actual type of the argument passed to the handler and to manage it 1505properly.</p> 1506</div> 1507 1508<div class="handler"> 1509<pre class="setter" id="XML_SetSkippedEntityHandler"> 1510void XMLCALL 1511XML_SetSkippedEntityHandler(XML_Parser p, 1512 XML_SkippedEntityHandler handler) 1513</pre> 1514<pre class="signature"> 1515typedef void 1516(XMLCALL *XML_SkippedEntityHandler)(void *userData, 1517 const XML_Char *entityName, 1518 int is_parameter_entity); 1519</pre> 1520<p>Set a skipped entity handler. This is called in two situations:</p> 1521<ol> 1522 <li>An entity reference is encountered for which no declaration 1523 has been read <em>and</em> this is not an error.</li> 1524 <li>An internal entity reference is read, but not expanded, because 1525 <a href="#XML_SetDefaultHandler"><code>XML_SetDefaultHandler</code></a> 1526 has been called.</li> 1527</ol> 1528<p>The <code>is_parameter_entity</code> argument will be non-zero for 1529a parameter entity and zero for a general entity.</p> <p>Note: skipped 1530parameter entities in declarations and skipped general entities in 1531attribute values cannot be reported, because the event would be out of 1532sync with the reporting of the declarations or attribute values</p> 1533</div> 1534 1535<div class="handler"> 1536<pre class="setter" id="XML_SetUnknownEncodingHandler"> 1537void XMLCALL 1538XML_SetUnknownEncodingHandler(XML_Parser p, 1539 XML_UnknownEncodingHandler enchandler, 1540 void *encodingHandlerData) 1541</pre> 1542<pre class="signature"> 1543typedef int 1544(XMLCALL *XML_UnknownEncodingHandler)(void *encodingHandlerData, 1545 const XML_Char *name, 1546 XML_Encoding *info); 1547 1548typedef struct { 1549 int map[256]; 1550 void *data; 1551 int (XMLCALL *convert)(void *data, const char *s); 1552 void (XMLCALL *release)(void *data); 1553} XML_Encoding; 1554</pre> 1555<p>Set a handler to deal with encodings other than the <a 1556href="#builtin_encodings">built in set</a>. This should be done before 1557<code><a href= "#XML_Parse" >XML_Parse</a></code> or <code><a href= 1558"#XML_ParseBuffer" >XML_ParseBuffer</a></code> have been called on the 1559given parser.</p> <p>If the handler knows how to deal with an encoding 1560with the given name, it should fill in the <code>info</code> data 1561structure and return <code>XML_STATUS_OK</code>. Otherwise it 1562should return <code>XML_STATUS_ERROR</code>. The handler will be called 1563at most once per parsed (external) entity. The optional application 1564data pointer <code>encodingHandlerData</code> will be passed back to 1565the handler.</p> 1566 1567<p>The map array contains information for every possible possible leading 1568byte in a byte sequence. If the corresponding value is >= 0, then it's 1569a single byte sequence and the byte encodes that Unicode value. If the 1570value is -1, then that byte is invalid as the initial byte in a sequence. 1571If the value is -n, where n is an integer > 1, then n is the number of 1572bytes in the sequence and the actual conversion is accomplished by a 1573call to the function pointed at by convert. This function may return -1 1574if the sequence itself is invalid. The convert pointer may be null if 1575there are only single byte codes. The data parameter passed to the convert 1576function is the data pointer from <code>XML_Encoding</code>. The 1577string s is <em>NOT</em> nul-terminated and points at the sequence of 1578bytes to be converted.</p> 1579 1580<p>The function pointed at by <code>release</code> is called by the 1581parser when it is finished with the encoding. It may be NULL.</p> 1582</div> 1583 1584<div class="handler"> 1585<pre class="setter" id="XML_SetStartNamespaceDeclHandler"> 1586void XMLCALL 1587XML_SetStartNamespaceDeclHandler(XML_Parser p, 1588 XML_StartNamespaceDeclHandler start); 1589</pre> 1590<pre class="signature"> 1591typedef void 1592(XMLCALL *XML_StartNamespaceDeclHandler)(void *userData, 1593 const XML_Char *prefix, 1594 const XML_Char *uri); 1595</pre> 1596<p>Set a handler to be called when a namespace is declared. Namespace 1597declarations occur inside start tags. But the namespace declaration start 1598handler is called before the start tag handler for each namespace declared 1599in that start tag.</p> 1600</div> 1601 1602<div class="handler"> 1603<pre class="setter" id="XML_SetEndNamespaceDeclHandler"> 1604void XMLCALL 1605XML_SetEndNamespaceDeclHandler(XML_Parser p, 1606 XML_EndNamespaceDeclHandler end); 1607</pre> 1608<pre class="signature"> 1609typedef void 1610(XMLCALL *XML_EndNamespaceDeclHandler)(void *userData, 1611 const XML_Char *prefix); 1612</pre> 1613<p>Set a handler to be called when leaving the scope of a namespace 1614declaration. This will be called, for each namespace declaration, 1615after the handler for the end tag of the element in which the 1616namespace was declared.</p> 1617</div> 1618 1619<div class="handler"> 1620<pre class="setter" id="XML_SetNamespaceDeclHandler"> 1621void XMLCALL 1622XML_SetNamespaceDeclHandler(XML_Parser p, 1623 XML_StartNamespaceDeclHandler start, 1624 XML_EndNamespaceDeclHandler end) 1625</pre> 1626<p>Sets both namespace declaration handlers with a single call.</p> 1627</div> 1628 1629<div class="handler"> 1630<pre class="setter" id="XML_SetXmlDeclHandler"> 1631void XMLCALL 1632XML_SetXmlDeclHandler(XML_Parser p, 1633 XML_XmlDeclHandler xmldecl); 1634</pre> 1635<pre class="signature"> 1636typedef void 1637(XMLCALL *XML_XmlDeclHandler)(void *userData, 1638 const XML_Char *version, 1639 const XML_Char *encoding, 1640 int standalone); 1641</pre> 1642<p>Sets a handler that is called for XML declarations and also for 1643text declarations discovered in external entities. The way to 1644distinguish is that the <code>version</code> parameter will be NULL 1645for text declarations. The <code>encoding</code> parameter may be NULL 1646for an XML declaration. The <code>standalone</code> argument will 1647contain -1, 0, or 1 indicating respectively that there was no 1648standalone parameter in the declaration, that it was given as no, or 1649that it was given as yes.</p> 1650</div> 1651 1652<div class="handler"> 1653<pre class="setter" id="XML_SetStartDoctypeDeclHandler"> 1654void XMLCALL 1655XML_SetStartDoctypeDeclHandler(XML_Parser p, 1656 XML_StartDoctypeDeclHandler start); 1657</pre> 1658<pre class="signature"> 1659typedef void 1660(XMLCALL *XML_StartDoctypeDeclHandler)(void *userData, 1661 const XML_Char *doctypeName, 1662 const XML_Char *sysid, 1663 const XML_Char *pubid, 1664 int has_internal_subset); 1665</pre> 1666<p>Set a handler that is called at the start of a DOCTYPE declaration, 1667before any external or internal subset is parsed. Both <code>sysid</code> 1668and <code>pubid</code> may be NULL. The <code>has_internal_subset</code> 1669will be non-zero if the DOCTYPE declaration has an internal subset.</p> 1670</div> 1671 1672<div class="handler"> 1673<pre class="setter" id="XML_SetEndDoctypeDeclHandler"> 1674void XMLCALL 1675XML_SetEndDoctypeDeclHandler(XML_Parser p, 1676 XML_EndDoctypeDeclHandler end); 1677</pre> 1678<pre class="signature"> 1679typedef void 1680(XMLCALL *XML_EndDoctypeDeclHandler)(void *userData); 1681</pre> 1682<p>Set a handler that is called at the end of a DOCTYPE declaration, 1683after parsing any external subset.</p> 1684</div> 1685 1686<div class="handler"> 1687<pre class="setter" id="XML_SetDoctypeDeclHandler"> 1688void XMLCALL 1689XML_SetDoctypeDeclHandler(XML_Parser p, 1690 XML_StartDoctypeDeclHandler start, 1691 XML_EndDoctypeDeclHandler end); 1692</pre> 1693<p>Set both doctype handlers with one call.</p> 1694</div> 1695 1696<div class="handler"> 1697<pre class="setter" id="XML_SetElementDeclHandler"> 1698void XMLCALL 1699XML_SetElementDeclHandler(XML_Parser p, 1700 XML_ElementDeclHandler eldecl); 1701</pre> 1702<pre class="signature"> 1703typedef void 1704(XMLCALL *XML_ElementDeclHandler)(void *userData, 1705 const XML_Char *name, 1706 XML_Content *model); 1707</pre> 1708<pre class="signature"> 1709enum XML_Content_Type { 1710 XML_CTYPE_EMPTY = 1, 1711 XML_CTYPE_ANY, 1712 XML_CTYPE_MIXED, 1713 XML_CTYPE_NAME, 1714 XML_CTYPE_CHOICE, 1715 XML_CTYPE_SEQ 1716}; 1717 1718enum XML_Content_Quant { 1719 XML_CQUANT_NONE, 1720 XML_CQUANT_OPT, 1721 XML_CQUANT_REP, 1722 XML_CQUANT_PLUS 1723}; 1724 1725typedef struct XML_cp XML_Content; 1726 1727struct XML_cp { 1728 enum XML_Content_Type type; 1729 enum XML_Content_Quant quant; 1730 const XML_Char * name; 1731 unsigned int numchildren; 1732 XML_Content * children; 1733}; 1734</pre> 1735<p>Sets a handler for element declarations in a DTD. The handler gets 1736called with the name of the element in the declaration and a pointer 1737to a structure that contains the element model. It is the 1738application's responsibility to free this data structure using 1739<code><a href="#XML_FreeContentModel" 1740>XML_FreeContentModel</a></code>.</p> 1741 1742<p>The <code>model</code> argument is the root of a tree of 1743<code>XML_Content</code> nodes. If <code>type</code> equals 1744<code>XML_CTYPE_EMPTY</code> or <code>XML_CTYPE_ANY</code>, then 1745<code>quant</code> will be <code>XML_CQUANT_NONE</code>, and the other 1746fields will be zero or NULL. If <code>type</code> is 1747<code>XML_CTYPE_MIXED</code>, then <code>quant</code> will be 1748<code>XML_CQUANT_NONE</code> or <code>XML_CQUANT_REP</code> and 1749<code>numchildren</code> will contain the number of elements that are 1750allowed to be mixed in and <code>children</code> points to an array of 1751<code>XML_Content</code> structures that will all have type 1752XML_CTYPE_NAME with no quantification. Only the root node can be type 1753<code>XML_CTYPE_EMPTY</code>, <code>XML_CTYPE_ANY</code>, or 1754<code>XML_CTYPE_MIXED</code>.</p> 1755 1756<p>For type <code>XML_CTYPE_NAME</code>, the <code>name</code> field 1757points to the name and the <code>numchildren</code> and 1758<code>children</code> fields will be zero and NULL. The 1759<code>quant</code> field will indicate any quantifiers placed on the 1760name.</p> 1761 1762<p>Types <code>XML_CTYPE_CHOICE</code> and <code>XML_CTYPE_SEQ</code> 1763indicate a choice or sequence respectively. The 1764<code>numchildren</code> field indicates how many nodes in the choice 1765or sequence and <code>children</code> points to the nodes.</p> 1766</div> 1767 1768<div class="handler"> 1769<pre class="setter" id="XML_SetAttlistDeclHandler"> 1770void XMLCALL 1771XML_SetAttlistDeclHandler(XML_Parser p, 1772 XML_AttlistDeclHandler attdecl); 1773</pre> 1774<pre class="signature"> 1775typedef void 1776(XMLCALL *XML_AttlistDeclHandler)(void *userData, 1777 const XML_Char *elname, 1778 const XML_Char *attname, 1779 const XML_Char *att_type, 1780 const XML_Char *dflt, 1781 int isrequired); 1782</pre> 1783<p>Set a handler for attlist declarations in the DTD. This handler is 1784called for <em>each</em> attribute. So a single attlist declaration 1785with multiple attributes declared will generate multiple calls to this 1786handler. The <code>elname</code> parameter returns the name of the 1787element for which the attribute is being declared. The attribute name 1788is in the <code>attname</code> parameter. The attribute type is in the 1789<code>att_type</code> parameter. It is the string representing the 1790type in the declaration with whitespace removed.</p> 1791 1792<p>The <code>dflt</code> parameter holds the default value. It will be 1793NULL in the case of "#IMPLIED" or "#REQUIRED" attributes. You can 1794distinguish these two cases by checking the <code>isrequired</code> 1795parameter, which will be true in the case of "#REQUIRED" attributes. 1796Attributes which are "#FIXED" will have also have a true 1797<code>isrequired</code>, but they will have the non-NULL fixed value 1798in the <code>dflt</code> parameter.</p> 1799</div> 1800 1801<div class="handler"> 1802<pre class="setter" id="XML_SetEntityDeclHandler"> 1803void XMLCALL 1804XML_SetEntityDeclHandler(XML_Parser p, 1805 XML_EntityDeclHandler handler); 1806</pre> 1807<pre class="signature"> 1808typedef void 1809(XMLCALL *XML_EntityDeclHandler)(void *userData, 1810 const XML_Char *entityName, 1811 int is_parameter_entity, 1812 const XML_Char *value, 1813 int value_length, 1814 const XML_Char *base, 1815 const XML_Char *systemId, 1816 const XML_Char *publicId, 1817 const XML_Char *notationName); 1818</pre> 1819<p>Sets a handler that will be called for all entity declarations. 1820The <code>is_parameter_entity</code> argument will be non-zero in the 1821case of parameter entities and zero otherwise.</p> 1822 1823<p>For internal entities (<code><!ENTITY foo "bar"></code>), 1824<code>value</code> will be non-NULL and <code>systemId</code>, 1825<code>publicId</code>, and <code>notationName</code> will all be NULL. 1826The value string is <em>not</em> NULL terminated; the length is 1827provided in the <code>value_length</code> parameter. Do not use 1828<code>value_length</code> to test for internal entities, since it is 1829legal to have zero-length values. Instead check for whether or not 1830<code>value</code> is NULL.</p> <p>The <code>notationName</code> 1831argument will have a non-NULL value only for unparsed entity 1832declarations.</p> 1833</div> 1834 1835<div class="handler"> 1836<pre class="setter" id="XML_SetUnparsedEntityDeclHandler"> 1837void XMLCALL 1838XML_SetUnparsedEntityDeclHandler(XML_Parser p, 1839 XML_UnparsedEntityDeclHandler h) 1840</pre> 1841<pre class="signature"> 1842typedef void 1843(XMLCALL *XML_UnparsedEntityDeclHandler)(void *userData, 1844 const XML_Char *entityName, 1845 const XML_Char *base, 1846 const XML_Char *systemId, 1847 const XML_Char *publicId, 1848 const XML_Char *notationName); 1849</pre> 1850<p>Set a handler that receives declarations of unparsed entities. These 1851are entity declarations that have a notation (NDATA) field:</p> 1852 1853<div id="eg"><pre> 1854<!ENTITY logo SYSTEM "images/logo.gif" NDATA gif> 1855</pre></div> 1856<p>This handler is obsolete and is provided for backwards 1857compatibility. Use instead <a href= "#XML_SetEntityDeclHandler" 1858>XML_SetEntityDeclHandler</a>.</p> 1859</div> 1860 1861<div class="handler"> 1862<pre class="setter" id="XML_SetNotationDeclHandler"> 1863void XMLCALL 1864XML_SetNotationDeclHandler(XML_Parser p, 1865 XML_NotationDeclHandler h) 1866</pre> 1867<pre class="signature"> 1868typedef void 1869(XMLCALL *XML_NotationDeclHandler)(void *userData, 1870 const XML_Char *notationName, 1871 const XML_Char *base, 1872 const XML_Char *systemId, 1873 const XML_Char *publicId); 1874</pre> 1875<p>Set a handler that receives notation declarations.</p> 1876</div> 1877 1878<div class="handler"> 1879<pre class="setter" id="XML_SetNotStandaloneHandler"> 1880void XMLCALL 1881XML_SetNotStandaloneHandler(XML_Parser p, 1882 XML_NotStandaloneHandler h) 1883</pre> 1884<pre class="signature"> 1885typedef int 1886(XMLCALL *XML_NotStandaloneHandler)(void *userData); 1887</pre> 1888<p>Set a handler that is called if the document is not "standalone". 1889This happens when there is an external subset or a reference to a 1890parameter entity, but does not have standalone set to "yes" in an XML 1891declaration. If this handler returns <code>XML_STATUS_ERROR</code>, 1892then the parser will throw an <code>XML_ERROR_NOT_STANDALONE</code> 1893error.</p> 1894</div> 1895 1896<h3><a name="position">Parse position and error reporting functions</a></h3> 1897 1898<p>These are the functions you'll want to call when the parse 1899functions return <code>XML_STATUS_ERROR</code> (a parse error has 1900occurred), although the position reporting functions are useful outside 1901of errors. The position reported is the byte position (in the original 1902document or entity encoding) of the first of the sequence of 1903characters that generated the current event (or the error that caused 1904the parse functions to return <code>XML_STATUS_ERROR</code>.) The 1905exceptions are callbacks trigged by declarations in the document 1906prologue, in which case they exact position reported is somewhere in the 1907relevant markup, but not necessarily as meaningful as for other 1908events.</p> 1909 1910<p>The position reporting functions are accurate only outside of the 1911DTD. In other words, they usually return bogus information when 1912called from within a DTD declaration handler.</p> 1913 1914<pre class="fcndec" id="XML_GetErrorCode"> 1915enum XML_Error XMLCALL 1916XML_GetErrorCode(XML_Parser p); 1917</pre> 1918<div class="fcndef"> 1919Return what type of error has occurred. 1920</div> 1921 1922<pre class="fcndec" id="XML_ErrorString"> 1923const XML_LChar * XMLCALL 1924XML_ErrorString(enum XML_Error code); 1925</pre> 1926<div class="fcndef"> 1927Return a string describing the error corresponding to code. 1928The code should be one of the enums that can be returned from 1929<code><a href= "#XML_GetErrorCode" >XML_GetErrorCode</a></code>. 1930</div> 1931 1932<pre class="fcndec" id="XML_GetCurrentByteIndex"> 1933XML_Index XMLCALL 1934XML_GetCurrentByteIndex(XML_Parser p); 1935</pre> 1936<div class="fcndef"> 1937Return the byte offset of the position. This always corresponds to 1938the values returned by <code><a href= "#XML_GetCurrentLineNumber" 1939>XML_GetCurrentLineNumber</a></code> and <code><a href= 1940"#XML_GetCurrentColumnNumber" >XML_GetCurrentColumnNumber</a></code>. 1941</div> 1942 1943<pre class="fcndec" id="XML_GetCurrentLineNumber"> 1944XML_Size XMLCALL 1945XML_GetCurrentLineNumber(XML_Parser p); 1946</pre> 1947<div class="fcndef"> 1948Return the line number of the position. The first line is reported as 1949<code>1</code>. 1950</div> 1951 1952<pre class="fcndec" id="XML_GetCurrentColumnNumber"> 1953XML_Size XMLCALL 1954XML_GetCurrentColumnNumber(XML_Parser p); 1955</pre> 1956<div class="fcndef"> 1957Return the offset, from the beginning of the current line, of 1958the position. 1959</div> 1960 1961<pre class="fcndec" id="XML_GetCurrentByteCount"> 1962int XMLCALL 1963XML_GetCurrentByteCount(XML_Parser p); 1964</pre> 1965<div class="fcndef"> 1966Return the number of bytes in the current event. Returns 1967<code>0</code> if the event is inside a reference to an internal 1968entity and for the end-tag event for empty element tags (the later can 1969be used to distinguish empty-element tags from empty elements using 1970separate start and end tags). 1971</div> 1972 1973<pre class="fcndec" id="XML_GetInputContext"> 1974const char * XMLCALL 1975XML_GetInputContext(XML_Parser p, 1976 int *offset, 1977 int *size); 1978</pre> 1979<div class="fcndef"> 1980 1981<p>Returns the parser's input buffer, sets the integer pointed at by 1982<code>offset</code> to the offset within this buffer of the current 1983parse position, and set the integer pointed at by <code>size</code> to 1984the size of the returned buffer.</p> 1985 1986<p>This should only be called from within a handler during an active 1987parse and the returned buffer should only be referred to from within 1988the handler that made the call. This input buffer contains the 1989untranslated bytes of the input.</p> 1990 1991<p>Only a limited amount of context is kept, so if the event 1992triggering a call spans over a very large amount of input, the actual 1993parse position may be before the beginning of the buffer.</p> 1994 1995<p>If <code>XML_CONTEXT_BYTES</code> is not defined, this will always 1996return NULL.</p> 1997</div> 1998 1999<h3><a name="miscellaneous">Miscellaneous functions</a></h3> 2000 2001<p>The functions in this section either obtain state information from 2002the parser or can be used to dynamicly set parser options.</p> 2003 2004<pre class="fcndec" id="XML_SetUserData"> 2005void XMLCALL 2006XML_SetUserData(XML_Parser p, 2007 void *userData); 2008</pre> 2009<div class="fcndef"> 2010This sets the user data pointer that gets passed to handlers. It 2011overwrites any previous value for this pointer. Note that the 2012application is responsible for freeing the memory associated with 2013<code>userData</code> when it is finished with the parser. So if you 2014call this when there's already a pointer there, and you haven't freed 2015the memory associated with it, then you've probably just leaked 2016memory. 2017</div> 2018 2019<pre class="fcndec" id="XML_GetUserData"> 2020void * XMLCALL 2021XML_GetUserData(XML_Parser p); 2022</pre> 2023<div class="fcndef"> 2024This returns the user data pointer that gets passed to handlers. 2025It is actually implemented as a macro. 2026</div> 2027 2028<pre class="fcndec" id="XML_UseParserAsHandlerArg"> 2029void XMLCALL 2030XML_UseParserAsHandlerArg(XML_Parser p); 2031</pre> 2032<div class="fcndef"> 2033After this is called, handlers receive the parser in their 2034<code>userData</code> arguments. The user data can still be obtained 2035using the <code><a href= "#XML_GetUserData" 2036>XML_GetUserData</a></code> function. 2037</div> 2038 2039<pre class="fcndec" id="XML_SetBase"> 2040enum XML_Status XMLCALL 2041XML_SetBase(XML_Parser p, 2042 const XML_Char *base); 2043</pre> 2044<div class="fcndef"> 2045Set the base to be used for resolving relative URIs in system 2046identifiers. The return value is <code>XML_STATUS_ERROR</code> if 2047there's no memory to store base, otherwise it's 2048<code>XML_STATUS_OK</code>. 2049</div> 2050 2051<pre class="fcndec" id="XML_GetBase"> 2052const XML_Char * XMLCALL 2053XML_GetBase(XML_Parser p); 2054</pre> 2055<div class="fcndef"> 2056Return the base for resolving relative URIs. 2057</div> 2058 2059<pre class="fcndec" id="XML_GetSpecifiedAttributeCount"> 2060int XMLCALL 2061XML_GetSpecifiedAttributeCount(XML_Parser p); 2062</pre> 2063<div class="fcndef"> 2064When attributes are reported to the start handler in the atts vector, 2065attributes that were explicitly set in the element occur before any 2066attributes that receive their value from default information in an 2067ATTLIST declaration. This function returns the number of attributes 2068that were explicitly set times two, thus giving the offset in the 2069<code>atts</code> array passed to the start tag handler of the first 2070attribute set due to defaults. It supplies information for the last 2071call to a start handler. If called inside a start handler, then that 2072means the current call. 2073</div> 2074 2075<pre class="fcndec" id="XML_GetIdAttributeIndex"> 2076int XMLCALL 2077XML_GetIdAttributeIndex(XML_Parser p); 2078</pre> 2079<div class="fcndef"> 2080Returns the index of the ID attribute passed in the atts array in the 2081last call to <code><a href= "#XML_StartElementHandler" 2082>XML_StartElementHandler</a></code>, or -1 if there is no ID 2083attribute. If called inside a start handler, then that means the 2084current call. 2085</div> 2086 2087<pre class="fcndec" id="XML_GetAttributeInfo"> 2088const XML_AttrInfo * XMLCALL 2089XML_GetAttributeInfo(XML_Parser parser); 2090</pre> 2091<pre class="signature"> 2092typedef struct { 2093 XML_Index nameStart; /* Offset to beginning of the attribute name. */ 2094 XML_Index nameEnd; /* Offset after the attribute name's last byte. */ 2095 XML_Index valueStart; /* Offset to beginning of the attribute value. */ 2096 XML_Index valueEnd; /* Offset after the attribute value's last byte. */ 2097} XML_AttrInfo; 2098</pre> 2099<div class="fcndef"> 2100Returns an array of <code>XML_AttrInfo</code> structures for the 2101attribute/value pairs passed in the last call to the 2102<code>XML_StartElementHandler</code> that were specified 2103in the start-tag rather than defaulted. Each attribute/value pair counts 2104as 1; thus the number of entries in the array is 2105<code>XML_GetSpecifiedAttributeCount(parser) / 2</code>. 2106</div> 2107 2108<pre class="fcndec" id="XML_SetEncoding"> 2109enum XML_Status XMLCALL 2110XML_SetEncoding(XML_Parser p, 2111 const XML_Char *encoding); 2112</pre> 2113<div class="fcndef"> 2114Set the encoding to be used by the parser. It is equivalent to 2115passing a non-null encoding argument to the parser creation functions. 2116It must not be called after <code><a href= "#XML_Parse" 2117>XML_Parse</a></code> or <code><a href= "#XML_ParseBuffer" 2118>XML_ParseBuffer</a></code> have been called on the given parser. 2119Returns <code>XML_STATUS_OK</code> on success or 2120<code>XML_STATUS_ERROR</code> on error. 2121</div> 2122 2123<pre class="fcndec" id="XML_SetParamEntityParsing"> 2124int XMLCALL 2125XML_SetParamEntityParsing(XML_Parser p, 2126 enum XML_ParamEntityParsing code); 2127</pre> 2128<div class="fcndef"> 2129This enables parsing of parameter entities, including the external 2130parameter entity that is the external DTD subset, according to 2131<code>code</code>. 2132The choices for <code>code</code> are: 2133<ul> 2134<li><code>XML_PARAM_ENTITY_PARSING_NEVER</code></li> 2135<li><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></li> 2136<li><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></li> 2137</ul> 2138<b>Note:</b> If <code>XML_SetParamEntityParsing</code> is called after 2139<code>XML_Parse</code> or <code>XML_ParseBuffer</code>, then it has 2140no effect and will always return 0. 2141</div> 2142 2143<pre class="fcndec" id="XML_SetHashSalt"> 2144int XMLCALL 2145XML_SetHashSalt(XML_Parser p, 2146 unsigned long hash_salt); 2147</pre> 2148<div class="fcndef"> 2149Sets the hash salt to use for internal hash calculations. 2150Helps in preventing DoS attacks based on predicting hash 2151function behavior. In order to have an effect this must be called 2152before parsing has started. Returns 1 if successful, 0 when called 2153after <code>XML_Parse</code> or <code>XML_ParseBuffer</code>. 2154<p><b>Note:</b>This call is optional, as the parser will auto-generate 2155a new random salt value if no value has been set at the start of parsing. 2156<p><b>Note:</b>One should not call <code>XML_SetHashSalt</code> with a 2157hash salt value of 0, as this value is used as sentinel value to indicate 2158that <code>XML_SetHashSalt</code> has <b>not</b> been called. Consequently 2159such a call will have no effect, even if it returns 1.</p> 2160</div> 2161 2162<pre class="fcndec" id="XML_UseForeignDTD"> 2163enum XML_Error XMLCALL 2164XML_UseForeignDTD(XML_Parser parser, XML_Bool useDTD); 2165</pre> 2166<div class="fcndef"> 2167<p>This function allows an application to provide an external subset 2168for the document type declaration for documents which do not specify 2169an external subset of their own. For documents which specify an 2170external subset in their DOCTYPE declaration, the application-provided 2171subset will be ignored. If the document does not contain a DOCTYPE 2172declaration at all and <code>useDTD</code> is true, the 2173application-provided subset will be parsed, but the 2174<code>startDoctypeDeclHandler</code> and 2175<code>endDoctypeDeclHandler</code> functions, if set, will not be 2176called. The setting of parameter entity parsing, controlled using 2177<code><a href= "#XML_SetParamEntityParsing" 2178>XML_SetParamEntityParsing</a></code>, will be honored.</p> 2179 2180<p>The application-provided external subset is read by calling the 2181external entity reference handler set via <code><a href= 2182"#XML_SetExternalEntityRefHandler" 2183>XML_SetExternalEntityRefHandler</a></code> with both 2184<code>publicId</code> and <code>systemId</code> set to NULL.</p> 2185 2186<p>If this function is called after parsing has begun, it returns 2187<code>XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING</code> and ignores 2188<code>useDTD</code>. If called when Expat has been compiled without 2189DTD support, it returns 2190<code>XML_ERROR_FEATURE_REQUIRES_XML_DTD</code>. Otherwise, it 2191returns <code>XML_ERROR_NONE</code>.</p> 2192 2193<p><b>Note:</b> For the purpose of checking WFC: Entity Declared, passing 2194<code>useDTD == XML_TRUE</code> will make the parser behave as if 2195the document had a DTD with an external subset. This holds true even if 2196the external entity reference handler returns without action.</p> 2197</div> 2198 2199<pre class="fcndec" id="XML_SetReturnNSTriplet"> 2200void XMLCALL 2201XML_SetReturnNSTriplet(XML_Parser parser, 2202 int do_nst); 2203</pre> 2204<div class="fcndef"> 2205<p> 2206This function only has an effect when using a parser created with 2207<code><a href= "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>, 2208i.e. when namespace processing is in effect. The <code>do_nst</code> 2209sets whether or not prefixes are returned with names qualified with a 2210namespace prefix. If this function is called with <code>do_nst</code> 2211non-zero, then afterwards namespace qualified names (that is qualified 2212with a prefix as opposed to belonging to a default namespace) are 2213returned as a triplet with the three parts separated by the namespace 2214separator specified when the parser was created. The order of 2215returned parts is URI, local name, and prefix.</p> <p>If 2216<code>do_nst</code> is zero, then namespaces are reported in the 2217default manner, URI then local_name separated by the namespace 2218separator.</p> 2219</div> 2220 2221<pre class="fcndec" id="XML_DefaultCurrent"> 2222void XMLCALL 2223XML_DefaultCurrent(XML_Parser parser); 2224</pre> 2225<div class="fcndef"> 2226This can be called within a handler for a start element, end element, 2227processing instruction or character data. It causes the corresponding 2228markup to be passed to the default handler set by <code><a 2229href="#XML_SetDefaultHandler" >XML_SetDefaultHandler</a></code> or 2230<code><a href="#XML_SetDefaultHandlerExpand" 2231>XML_SetDefaultHandlerExpand</a></code>. It does nothing if there is 2232not a default handler. 2233</div> 2234 2235<pre class="fcndec" id="XML_ExpatVersion"> 2236XML_LChar * XMLCALL 2237XML_ExpatVersion(); 2238</pre> 2239<div class="fcndef"> 2240Return the library version as a string (e.g. <code>"expat_1.95.1"</code>). 2241</div> 2242 2243<pre class="fcndec" id="XML_ExpatVersionInfo"> 2244struct XML_Expat_Version XMLCALL 2245XML_ExpatVersionInfo(); 2246</pre> 2247<pre class="signature"> 2248typedef struct { 2249 int major; 2250 int minor; 2251 int micro; 2252} XML_Expat_Version; 2253</pre> 2254<div class="fcndef"> 2255Return the library version information as a structure. 2256Some macros are also defined that support compile-time tests of the 2257library version: 2258<ul> 2259<li><code>XML_MAJOR_VERSION</code></li> 2260<li><code>XML_MINOR_VERSION</code></li> 2261<li><code>XML_MICRO_VERSION</code></li> 2262</ul> 2263Testing these constants is currently the best way to determine if 2264particular parts of the Expat API are available. 2265</div> 2266 2267<pre class="fcndec" id="XML_GetFeatureList"> 2268const XML_Feature * XMLCALL 2269XML_GetFeatureList(); 2270</pre> 2271<pre class="signature"> 2272enum XML_FeatureEnum { 2273 XML_FEATURE_END = 0, 2274 XML_FEATURE_UNICODE, 2275 XML_FEATURE_UNICODE_WCHAR_T, 2276 XML_FEATURE_DTD, 2277 XML_FEATURE_CONTEXT_BYTES, 2278 XML_FEATURE_MIN_SIZE, 2279 XML_FEATURE_SIZEOF_XML_CHAR, 2280 XML_FEATURE_SIZEOF_XML_LCHAR, 2281 XML_FEATURE_NS, 2282 XML_FEATURE_LARGE_SIZE 2283}; 2284 2285typedef struct { 2286 enum XML_FeatureEnum feature; 2287 XML_LChar *name; 2288 long int value; 2289} XML_Feature; 2290</pre> 2291<div class="fcndef"> 2292<p>Returns a list of "feature" records, providing details on how 2293Expat was configured at compile time. Most applications should not 2294need to worry about this, but this information is otherwise not 2295available from Expat. This function allows code that does need to 2296check these features to do so at runtime.</p> 2297 2298<p>The return value is an array of <code>XML_Feature</code>, 2299terminated by a record with a <code>feature</code> of 2300<code>XML_FEATURE_END</code> and <code>name</code> of NULL, 2301identifying the feature-test macros Expat was compiled with. Since an 2302application that requires this kind of information needs to determine 2303the type of character the <code>name</code> points to, records for the 2304<code>XML_FEATURE_SIZEOF_XML_CHAR</code> and 2305<code>XML_FEATURE_SIZEOF_XML_LCHAR</code> will be located at the 2306beginning of the list, followed by <code>XML_FEATURE_UNICODE</code> 2307and <code>XML_FEATURE_UNICODE_WCHAR_T</code>, if they are present at 2308all.</p> 2309 2310<p>Some features have an associated value. If there isn't an 2311associated value, the <code>value</code> field is set to 0. At this 2312time, the following features have been defined to have values:</p> 2313 2314<dl> 2315 <dt><code>XML_FEATURE_SIZEOF_XML_CHAR</code></dt> 2316 <dd>The number of bytes occupied by one <code>XML_Char</code> 2317 character.</dd> 2318 <dt><code>XML_FEATURE_SIZEOF_XML_LCHAR</code></dt> 2319 <dd>The number of bytes occupied by one <code>XML_LChar</code> 2320 character.</dd> 2321 <dt><code>XML_FEATURE_CONTEXT_BYTES</code></dt> 2322 <dd>The maximum number of characters of context which can be 2323 reported by <code><a href= "#XML_GetInputContext" 2324 >XML_GetInputContext</a></code>.</dd> 2325</dl> 2326</div> 2327 2328<pre class="fcndec" id="XML_FreeContentModel"> 2329void XMLCALL 2330XML_FreeContentModel(XML_Parser parser, XML_Content *model); 2331</pre> 2332<div class="fcndef"> 2333Function to deallocate the <code>model</code> argument passed to the 2334<code>XML_ElementDeclHandler</code> callback set using <code><a 2335href="#XML_SetElementDeclHandler" >XML_ElementDeclHandler</a></code>. 2336This function should not be used for any other purpose. 2337</div> 2338 2339<p>The following functions allow external code to share the memory 2340allocator an <code>XML_Parser</code> has been configured to use. This 2341is especially useful for third-party libraries that interact with a 2342parser object created by application code, or heavily layered 2343applications. This can be essential when using dynamically loaded 2344libraries which use different C standard libraries (this can happen on 2345Windows, at least).</p> 2346 2347<pre class="fcndec" id="XML_MemMalloc"> 2348void * XMLCALL 2349XML_MemMalloc(XML_Parser parser, size_t size); 2350</pre> 2351<div class="fcndef"> 2352Allocate <code>size</code> bytes of memory using the allocator the 2353<code>parser</code> object has been configured to use. Returns a 2354pointer to the memory or NULL on failure. Memory allocated in this 2355way must be freed using <code><a href="#XML_MemFree" 2356>XML_MemFree</a></code>. 2357</div> 2358 2359<pre class="fcndec" id="XML_MemRealloc"> 2360void * XMLCALL 2361XML_MemRealloc(XML_Parser parser, void *ptr, size_t size); 2362</pre> 2363<div class="fcndef"> 2364Allocate <code>size</code> bytes of memory using the allocator the 2365<code>parser</code> object has been configured to use. 2366<code>ptr</code> must point to a block of memory allocated by <code><a 2367href="#XML_MemMalloc" >XML_MemMalloc</a></code> or 2368<code>XML_MemRealloc</code>, or be NULL. This function tries to 2369expand the block pointed to by <code>ptr</code> if possible. Returns 2370a pointer to the memory or NULL on failure. On success, the original 2371block has either been expanded or freed. On failure, the original 2372block has not been freed; the caller is responsible for freeing the 2373original block. Memory allocated in this way must be freed using 2374<code><a href="#XML_MemFree" 2375>XML_MemFree</a></code>. 2376</div> 2377 2378<pre class="fcndec" id="XML_MemFree"> 2379void XMLCALL 2380XML_MemFree(XML_Parser parser, void *ptr); 2381</pre> 2382<div class="fcndef"> 2383Free a block of memory pointed to by <code>ptr</code>. The block must 2384have been allocated by <code><a href="#XML_MemMalloc" 2385>XML_MemMalloc</a></code> or <code>XML_MemRealloc</code>, or be NULL. 2386</div> 2387 2388<hr /> 2389<p><a href="http://validator.w3.org/check/referer"><img 2390 src="valid-xhtml10.png" alt="Valid XHTML 1.0!" 2391 height="31" width="88" class="noborder" /></a></p> 2392</div> 2393</body> 2394</html> 2395
