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 implementation 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, 280you can use CMake to generate a <code>.sln</code> file, e.g. 281<code> 282cmake -G"Visual Studio 15 2017" -DCMAKE_BUILD_TYPE=RelWithDebInfo . 283</code>, and build Expat using <code>msbuild /m expat.sln</code> after.</p> 284 285<p>Alternatively, you may download the Win32 binary package that 286contains the "expat.h" include file and a pre-built DLL.</p> 287 288<h3>Building under Unix (or GNU)</h3> 289 290<p>First you'll need to run the configure shell script in order to 291configure the Makefiles and headers for your system.</p> 292 293<p>If you're happy with all the defaults that configure picks for you, 294and you have permission on your system to install into /usr/local, you 295can install Expat with this sequence of commands:</p> 296 297<pre class="eg"> 298./configure 299make 300make install 301</pre> 302 303<p>There are some options that you can provide to this script, but the 304only one we'll mention here is the <code>--prefix</code> option. You 305can find out all the options available by running configure with just 306the <code>--help</code> option.</p> 307 308<p>By default, the configure script sets things up so that the library 309gets installed in <code>/usr/local/lib</code> and the associated 310header file in <code>/usr/local/include</code>. But if you were to 311give the option, <code>--prefix=/home/me/mystuff</code>, then the 312library and header would get installed in 313<code>/home/me/mystuff/lib</code> and 314<code>/home/me/mystuff/include</code> respectively.</p> 315 316<h3>Configuring Expat Using the Pre-Processor</h3> 317 318<p>Expat's feature set can be configured using a small number of 319pre-processor definitions. The definition of this symbols does not 320affect the set of entry points for Expat, only the behavior of the API 321and the definition of character types in the case of 322<code>XML_UNICODE_WCHAR_T</code>. The symbols are:</p> 323 324<dl class="cpp-symbols"> 325<dt>XML_DTD</dt> 326<dd>Include support for using and reporting DTD-based content. If 327this is defined, default attribute values from an external DTD subset 328are reported and attribute value normalization occurs based on the 329type of attributes defined in the external subset. Without 330this, Expat has a smaller memory footprint and can be faster, but will 331not load external entities or process conditional sections. This does 332not affect the set of functions available in the API.</dd> 333 334<dt>XML_NS</dt> 335<dd>When defined, support for the <cite><a href= 336"http://www.w3.org/TR/REC-xml-names/" >Namespaces in XML</a></cite> 337specification is included.</dd> 338 339<dt>XML_UNICODE</dt> 340<dd>When defined, character data reported to the application is 341encoded in UTF-16 using wide characters of the type 342<code>XML_Char</code>. This is implied if 343<code>XML_UNICODE_WCHAR_T</code> is defined.</dd> 344 345<dt>XML_UNICODE_WCHAR_T</dt> 346<dd>If defined, causes the <code>XML_Char</code> character type to be 347defined using the <code>wchar_t</code> type; otherwise, <code>unsigned 348short</code> is used. Defining this implies 349<code>XML_UNICODE</code>.</dd> 350 351<dt>XML_LARGE_SIZE</dt> 352<dd>If defined, causes the <code>XML_Size</code> and <code>XML_Index</code> 353integer types to be at least 64 bits in size. This is intended to support 354processing of very large input streams, where the return values of 355<code><a href="#XML_GetCurrentByteIndex" >XML_GetCurrentByteIndex</a></code>, 356<code><a href="#XML_GetCurrentLineNumber" >XML_GetCurrentLineNumber</a></code> and 357<code><a href="#XML_GetCurrentColumnNumber" >XML_GetCurrentColumnNumber</a></code> 358could overflow. It may not be supported by all compilers, and is turned 359off by default.</dd> 360 361<dt>XML_CONTEXT_BYTES</dt> 362<dd>The number of input bytes of markup context which the parser will 363ensure are available for reporting via <code><a href= 364"#XML_GetInputContext" >XML_GetInputContext</a></code>. This is 365normally set to 1024, and must be set to a positive integer. If this 366is not defined, the input context will not be available and <code><a 367href= "#XML_GetInputContext" >XML_GetInputContext</a></code> will 368always report NULL. Without this, Expat has a smaller memory 369footprint and can be faster.</dd> 370 371<dt>XML_STATIC</dt> 372<dd>On Windows, this should be set if Expat is going to be linked 373statically with the code that calls it; this is required to get all 374the right MSVC magic annotations correct. This is ignored on other 375platforms.</dd> 376 377<dt>XML_ATTR_INFO</dt> 378<dd>If defined, makes the additional function <code><a href= 379"#XML_GetAttributeInfo" >XML_GetAttributeInfo</a></code> available 380for reporting attribute byte offsets.</dd> 381</dl> 382 383<hr /> 384<h2><a name="using">Using Expat</a></h2> 385 386<h3>Compiling and Linking Against Expat</h3> 387 388<p>Unless you installed Expat in a location not expected by your 389compiler and linker, all you have to do to use Expat in your programs 390is to include the Expat header (<code>#include <expat.h></code>) 391in your files that make calls to it and to tell the linker that it 392needs to link against the Expat library. On Unix systems, this would 393usually be done with the <code>-lexpat</code> argument. Otherwise, 394you'll need to tell the compiler where to look for the Expat header 395and the linker where to find the Expat library. You may also need to 396take steps to tell the operating system where to find this library at 397run time.</p> 398 399<p>On a Unix-based system, here's what a Makefile might look like when 400Expat is installed in a standard location:</p> 401 402<pre class="eg"> 403CC=cc 404LDFLAGS= 405LIBS= -lexpat 406xmlapp: xmlapp.o 407 $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS) 408</pre> 409 410<p>If you installed Expat in, say, <code>/home/me/mystuff</code>, then 411the Makefile would look like this:</p> 412 413<pre class="eg"> 414CC=cc 415CFLAGS= -I/home/me/mystuff/include 416LDFLAGS= 417LIBS= -L/home/me/mystuff/lib -lexpat 418xmlapp: xmlapp.o 419 $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS) 420</pre> 421 422<p>You'd also have to set the environment variable 423<code>LD_LIBRARY_PATH</code> to <code>/home/me/mystuff/lib</code> (or 424to <code>${LD_LIBRARY_PATH}:/home/me/mystuff/lib</code> if 425LD_LIBRARY_PATH already has some directories in it) in order to run 426your application.</p> 427 428<h3>Expat Basics</h3> 429 430<p>As we saw in the example in the overview, the first step in parsing 431an XML document with Expat is to create a parser object. There are <a 432href="#creation">three functions</a> in the Expat API for creating a 433parser object. However, only two of these (<code><a href= 434"#XML_ParserCreate" >XML_ParserCreate</a></code> and <code><a href= 435"#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>) can be used for 436constructing a parser for a top-level document. The object returned 437by these functions is an opaque pointer (i.e. "expat.h" declares it as 438void *) to data with further internal structure. In order to free the 439memory associated with this object you must call <code><a href= 440"#XML_ParserFree" >XML_ParserFree</a></code>. Note that if you have 441provided any <a href="#userdata">user data</a> that gets stored in the 442parser, then your application is responsible for freeing it prior to 443calling <code>XML_ParserFree</code>.</p> 444 445<p>The objects returned by the parser creation functions are good for 446parsing only one XML document or external parsed entity. If your 447application needs to parse many XML documents, then it needs to create 448a parser object for each one. The best way to deal with this is to 449create a higher level object that contains all the default 450initialization you want for your parser objects.</p> 451 452<p>Walking through a document hierarchy with a stream oriented parser 453will require a good stack mechanism in order to keep track of current 454context. For instance, to answer the simple question, "What element 455does this text belong to?" requires a stack, since the parser may have 456descended into other elements that are children of the current one and 457has encountered this text on the way out.</p> 458 459<p>The things you're likely to want to keep on a stack are the 460currently opened element and it's attributes. You push this 461information onto the stack in the start handler and you pop it off in 462the end handler.</p> 463 464<p>For some tasks, it is sufficient to just keep information on what 465the depth of the stack is (or would be if you had one.) The outline 466program shown above presents one example. Another such task would be 467skipping over a complete element. When you see the start tag for the 468element you want to skip, you set a skip flag and record the depth at 469which the element started. When the end tag handler encounters the 470same depth, the skipped element has ended and the flag may be 471cleared. If you follow the convention that the root element starts at 4721, then you can use the same variable for skip flag and skip 473depth.</p> 474 475<pre class="eg"> 476void 477init_info(Parseinfo *info) { 478 info->skip = 0; 479 info->depth = 1; 480 /* Other initializations here */ 481} /* End of init_info */ 482 483void XMLCALL 484rawstart(void *data, const char *el, const char **attr) { 485 Parseinfo *inf = (Parseinfo *) data; 486 487 if (! inf->skip) { 488 if (should_skip(inf, el, attr)) { 489 inf->skip = inf->depth; 490 } 491 else 492 start(inf, el, attr); /* This does rest of start handling */ 493 } 494 495 inf->depth++; 496} /* End of rawstart */ 497 498void XMLCALL 499rawend(void *data, const char *el) { 500 Parseinfo *inf = (Parseinfo *) data; 501 502 inf->depth--; 503 504 if (! inf->skip) 505 end(inf, el); /* This does rest of end handling */ 506 507 if (inf->skip == inf->depth) 508 inf->skip = 0; 509} /* End rawend */ 510</pre> 511 512<p>Notice in the above example the difference in how depth is 513manipulated in the start and end handlers. The end tag handler should 514be the mirror image of the start tag handler. This is necessary to 515properly model containment. Since, in the start tag handler, we 516incremented depth <em>after</em> the main body of start tag code, then 517in the end handler, we need to manipulate it <em>before</em> the main 518body. If we'd decided to increment it first thing in the start 519handler, then we'd have had to decrement it last thing in the end 520handler.</p> 521 522<h3 id="userdata">Communicating between handlers</h3> 523 524<p>In order to be able to pass information between different handlers 525without using globals, you'll need to define a data structure to hold 526the shared variables. You can then tell Expat (with the <code><a href= 527"#XML_SetUserData" >XML_SetUserData</a></code> function) to pass a 528pointer to this structure to the handlers. This is the first 529argument received by most handlers. In the <a href="#reference" 530>reference section</a>, an argument to a callback function is named 531<code>userData</code> and have type <code>void *</code> if the user 532data is passed; it will have the type <code>XML_Parser</code> if the 533parser itself is passed. When the parser is passed, the user data may 534be retrieved using <code><a href="#XML_GetUserData" 535>XML_GetUserData</a></code>.</p> 536 537<p>One common case where multiple calls to a single handler may need 538to communicate using an application data structure is the case when 539content passed to the character data handler (set by <code><a href= 540"#XML_SetCharacterDataHandler" 541>XML_SetCharacterDataHandler</a></code>) needs to be accumulated. A 542common first-time mistake with any of the event-oriented interfaces to 543an XML parser is to expect all the text contained in an element to be 544reported by a single call to the character data handler. Expat, like 545many other XML parsers, reports such data as a sequence of calls; 546there's no way to know when the end of the sequence is reached until a 547different callback is made. A buffer referenced by the user data 548structure proves both an effective and convenient place to accumulate 549character data.</p> 550 551<!-- XXX example needed here --> 552 553 554<h3>XML Version</h3> 555 556<p>Expat is an XML 1.0 parser, and as such never complains based on 557the value of the <code>version</code> pseudo-attribute in the XML 558declaration, if present.</p> 559 560<p>If an application needs to check the version number (to support 561alternate processing), it should use the <code><a href= 562"#XML_SetXmlDeclHandler" >XML_SetXmlDeclHandler</a></code> function to 563set a handler that uses the information in the XML declaration to 564determine what to do. This example shows how to check that only a 565version number of <code>"1.0"</code> is accepted:</p> 566 567<pre class="eg"> 568static int wrong_version; 569static XML_Parser parser; 570 571static void XMLCALL 572xmldecl_handler(void *userData, 573 const XML_Char *version, 574 const XML_Char *encoding, 575 int standalone) 576{ 577 static const XML_Char Version_1_0[] = {'1', '.', '0', 0}; 578 579 int i; 580 581 for (i = 0; i < (sizeof(Version_1_0) / sizeof(Version_1_0[0])); ++i) { 582 if (version[i] != Version_1_0[i]) { 583 wrong_version = 1; 584 /* also clear all other handlers: */ 585 XML_SetCharacterDataHandler(parser, NULL); 586 ... 587 return; 588 } 589 } 590 ... 591} 592</pre> 593 594<h3>Namespace Processing</h3> 595 596<p>When the parser is created using the <code><a href= 597"#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>, function, Expat 598performs namespace processing. Under namespace processing, Expat 599consumes <code>xmlns</code> and <code>xmlns:...</code> attributes, 600which declare namespaces for the scope of the element in which they 601occur. This means that your start handler will not see these 602attributes. Your application can still be informed of these 603declarations by setting namespace declaration handlers with <a href= 604"#XML_SetNamespaceDeclHandler" 605><code>XML_SetNamespaceDeclHandler</code></a>.</p> 606 607<p>Element type and attribute names that belong to a given namespace 608are passed to the appropriate handler in expanded form. By default 609this expanded form is a concatenation of the namespace URI, the 610separator character (which is the 2nd argument to <code><a href= 611"#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>), and the local 612name (i.e. the part after the colon). Names with undeclared prefixes 613are not well-formed when namespace processing is enabled, and will 614trigger an error. Unprefixed attribute names are never expanded, 615and unprefixed element names are only expanded when they are in the 616scope of a default namespace.</p> 617 618<p>However if <code><a href= "#XML_SetReturnNSTriplet" 619>XML_SetReturnNSTriplet</a></code> has been called with a non-zero 620<code>do_nst</code> parameter, then the expanded form for names with 621an explicit prefix is a concatenation of: URI, separator, local name, 622separator, prefix.</p> 623 624<p>You can set handlers for the start of a namespace declaration and 625for the end of a scope of a declaration with the <code><a href= 626"#XML_SetNamespaceDeclHandler" >XML_SetNamespaceDeclHandler</a></code> 627function. The StartNamespaceDeclHandler is called prior to the start 628tag handler and the EndNamespaceDeclHandler is called after the 629corresponding end tag that ends the namespace's scope. The namespace 630start handler gets passed the prefix and URI for the namespace. For a 631default namespace declaration (xmlns='...'), the prefix will be null. 632The URI will be null for the case where the default namespace is being 633unset. The namespace end handler just gets the prefix for the closing 634scope.</p> 635 636<p>These handlers are called for each declaration. So if, for 637instance, a start tag had three namespace declarations, then the 638StartNamespaceDeclHandler would be called three times before the start 639tag handler is called, once for each declaration.</p> 640 641<h3>Character Encodings</h3> 642 643<p>While XML is based on Unicode, and every XML processor is required 644to recognized UTF-8 and UTF-16 (1 and 2 byte encodings of Unicode), 645other encodings may be declared in XML documents or entities. For the 646main document, an XML declaration may contain an encoding 647declaration:</p> 648<pre> 649<?xml version="1.0" encoding="ISO-8859-2"?> 650</pre> 651 652<p>External parsed entities may begin with a text declaration, which 653looks like an XML declaration with just an encoding declaration:</p> 654<pre> 655<?xml encoding="Big5"?> 656</pre> 657 658<p>With Expat, you may also specify an encoding at the time of 659creating a parser. This is useful when the encoding information may 660come from a source outside the document itself (like a higher level 661protocol.)</p> 662 663<p><a name="builtin_encodings"></a>There are four built-in encodings 664in Expat:</p> 665<ul> 666<li>UTF-8</li> 667<li>UTF-16</li> 668<li>ISO-8859-1</li> 669<li>US-ASCII</li> 670</ul> 671 672<p>Anything else discovered in an encoding declaration or in the 673protocol encoding specified in the parser constructor, triggers a call 674to the <code>UnknownEncodingHandler</code>. This handler gets passed 675the encoding name and a pointer to an <code>XML_Encoding</code> data 676structure. Your handler must fill in this structure and return 677<code>XML_STATUS_OK</code> if it knows how to deal with the 678encoding. Otherwise the handler should return 679<code>XML_STATUS_ERROR</code>. The handler also gets passed a pointer 680to an optional application data structure that you may indicate when 681you set the handler.</p> 682 683<p>Expat places restrictions on character encodings that it can 684support by filling in the <code>XML_Encoding</code> structure. 685include file:</p> 686<ol> 687<li>Every ASCII character that can appear in a well-formed XML document 688must be represented by a single byte, and that byte must correspond to 689it's ASCII encoding (except for the characters $@\^'{}~)</li> 690<li>Characters must be encoded in 4 bytes or less.</li> 691<li>All characters encoded must have Unicode scalar values less than or 692equal to 65535 (0xFFFF)<em>This does not apply to the built-in support 693for UTF-16 and UTF-8</em></li> 694<li>No character may be encoded by more that one distinct sequence of 695bytes</li> 696</ol> 697 698<p><code>XML_Encoding</code> contains an array of integers that 699correspond to the 1st byte of an encoding sequence. If the value in 700the array for a byte is zero or positive, then the byte is a single 701byte encoding that encodes the Unicode scalar value contained in the 702array. A -1 in this array indicates a malformed byte. If the value is 703-2, -3, or -4, then the byte is the beginning of a 2, 3, or 4 byte 704sequence respectively. Multi-byte sequences are sent to the convert 705function pointed at in the <code>XML_Encoding</code> structure. This 706function should return the Unicode scalar value for the sequence or -1 707if the sequence is malformed.</p> 708 709<p>One pitfall that novice Expat users are likely to fall into is that 710although Expat may accept input in various encodings, the strings that 711it passes to the handlers are always encoded in UTF-8 or UTF-16 712(depending on how Expat was compiled). Your application is responsible 713for any translation of these strings into other encodings.</p> 714 715<h3>Handling External Entity References</h3> 716 717<p>Expat does not read or parse external entities directly. Note that 718any external DTD is a special case of an external entity. If you've 719set no <code>ExternalEntityRefHandler</code>, then external entity 720references are silently ignored. Otherwise, it calls your handler with 721the information needed to read and parse the external entity.</p> 722 723<p>Your handler isn't actually responsible for parsing the entity, but 724it is responsible for creating a subsidiary parser with <code><a href= 725"#XML_ExternalEntityParserCreate" 726>XML_ExternalEntityParserCreate</a></code> that will do the job. This 727returns an instance of <code>XML_Parser</code> that has handlers and 728other data structures initialized from the parent parser. You may then 729use <code><a href= "#XML_Parse" >XML_Parse</a></code> or <code><a 730href= "#XML_ParseBuffer">XML_ParseBuffer</a></code> calls against this 731parser. Since external entities my refer to other external entities, 732your handler should be prepared to be called recursively.</p> 733 734<h3>Parsing DTDs</h3> 735 736<p>In order to parse parameter entities, before starting the parse, 737you must call <code><a href= "#XML_SetParamEntityParsing" 738>XML_SetParamEntityParsing</a></code> with one of the following 739arguments:</p> 740<dl> 741<dt><code>XML_PARAM_ENTITY_PARSING_NEVER</code></dt> 742<dd>Don't parse parameter entities or the external subset</dd> 743<dt><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></dt> 744<dd>Parse parameter entities and the external subset unless 745<code>standalone</code> was set to "yes" in the XML declaration.</dd> 746<dt><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></dt> 747<dd>Always parse parameter entities and the external subset</dd> 748</dl> 749 750<p>In order to read an external DTD, you also have to set an external 751entity reference handler as described above.</p> 752 753<h3 id="stop-resume">Temporarily Stopping Parsing</h3> 754 755<p>Expat 1.95.8 introduces a new feature: its now possible to stop 756parsing temporarily from within a handler function, even if more data 757has already been passed into the parser. Applications for this 758include</p> 759 760<ul> 761 <li>Supporting the <a href= "http://www.w3.org/TR/xinclude/" 762 >XInclude</a> specification.</li> 763 764 <li>Delaying further processing until additional information is 765 available from some other source.</li> 766 767 <li>Adjusting processor load as task priorities shift within an 768 application.</li> 769 770 <li>Stopping parsing completely (simply free or reset the parser 771 instead of resuming in the outer parsing loop). This can be useful 772 if an application-domain error is found in the XML being parsed or if 773 the result of the parse is determined not to be useful after 774 all.</li> 775</ul> 776 777<p>To take advantage of this feature, the main parsing loop of an 778application needs to support this specifically. It cannot be 779supported with a parsing loop compatible with Expat 1.95.7 or 780earlier (though existing loops will continue to work without 781supporting the stop/resume feature).</p> 782 783<p>An application that uses this feature for a single parser will have 784the rough structure (in pseudo-code):</p> 785 786<pre class="pseudocode"> 787fd = open_input() 788p = create_parser() 789 790if parse_xml(p, fd) { 791 /* suspended */ 792 793 int suspended = 1; 794 795 while (suspended) { 796 do_something_else() 797 if ready_to_resume() { 798 suspended = continue_parsing(p, fd); 799 } 800 } 801} 802</pre> 803 804<p>An application that may resume any of several parsers based on 805input (either from the XML being parsed or some other source) will 806certainly have more interesting control structures.</p> 807 808<p>This C function could be used for the <code>parse_xml</code> 809function mentioned in the pseudo-code above:</p> 810 811<pre class="eg"> 812#define BUFF_SIZE 10240 813 814/* Parse a document from the open file descriptor 'fd' until the parse 815 is complete (the document has been completely parsed, or there's 816 been an error), or the parse is stopped. Return non-zero when 817 the parse is merely suspended. 818*/ 819int 820parse_xml(XML_Parser p, int fd) 821{ 822 for (;;) { 823 int last_chunk; 824 int bytes_read; 825 enum XML_Status status; 826 827 void *buff = XML_GetBuffer(p, BUFF_SIZE); 828 if (buff == NULL) { 829 /* handle error... */ 830 return 0; 831 } 832 bytes_read = read(fd, buff, BUFF_SIZE); 833 if (bytes_read < 0) { 834 /* handle error... */ 835 return 0; 836 } 837 status = XML_ParseBuffer(p, bytes_read, bytes_read == 0); 838 switch (status) { 839 case XML_STATUS_ERROR: 840 /* handle error... */ 841 return 0; 842 case XML_STATUS_SUSPENDED: 843 return 1; 844 } 845 if (bytes_read == 0) 846 return 0; 847 } 848} 849</pre> 850 851<p>The corresponding <code>continue_parsing</code> function is 852somewhat simpler, since it only need deal with the return code from 853<code><a href= "#XML_ResumeParser">XML_ResumeParser</a></code>; it can 854delegate the input handling to the <code>parse_xml</code> 855function:</p> 856 857<pre class="eg"> 858/* Continue parsing a document which had been suspended. The 'p' and 859 'fd' arguments are the same as passed to parse_xml(). Return 860 non-zero when the parse is suspended. 861*/ 862int 863continue_parsing(XML_Parser p, int fd) 864{ 865 enum XML_Status status = XML_ResumeParser(p); 866 switch (status) { 867 case XML_STATUS_ERROR: 868 /* handle error... */ 869 return 0; 870 case XML_ERROR_NOT_SUSPENDED: 871 /* handle error... */ 872 return 0;. 873 case XML_STATUS_SUSPENDED: 874 return 1; 875 } 876 return parse_xml(p, fd); 877} 878</pre> 879 880<p>Now that we've seen what a mess the top-level parsing loop can 881become, what have we gained? Very simply, we can now use the <code><a 882href= "#XML_StopParser" >XML_StopParser</a></code> function to stop 883parsing, without having to go to great lengths to avoid additional 884processing that we're expecting to ignore. As a bonus, we get to stop 885parsing <em>temporarily</em>, and come back to it when we're 886ready.</p> 887 888<p>To stop parsing from a handler function, use the <code><a href= 889"#XML_StopParser" >XML_StopParser</a></code> function. This function 890takes two arguments; the parser being stopped and a flag indicating 891whether the parse can be resumed in the future.</p> 892 893<!-- XXX really need more here --> 894 895 896<hr /> 897<!-- ================================================================ --> 898 899<h2><a name="reference">Expat Reference</a></h2> 900 901<h3><a name="creation">Parser Creation</a></h3> 902 903<pre class="fcndec" id="XML_ParserCreate"> 904XML_Parser XMLCALL 905XML_ParserCreate(const XML_Char *encoding); 906</pre> 907<div class="fcndef"> 908Construct a new parser. If encoding is non-null, it specifies a 909character encoding to use for the document. This overrides the document 910encoding declaration. There are four built-in encodings: 911<ul> 912<li>US-ASCII</li> 913<li>UTF-8</li> 914<li>UTF-16</li> 915<li>ISO-8859-1</li> 916</ul> 917Any other value will invoke a call to the UnknownEncodingHandler. 918</div> 919 920<pre class="fcndec" id="XML_ParserCreateNS"> 921XML_Parser XMLCALL 922XML_ParserCreateNS(const XML_Char *encoding, 923 XML_Char sep); 924</pre> 925<div class="fcndef"> 926Constructs a new parser that has namespace processing in effect. Namespace 927expanded element names and attribute names are returned as a concatenation 928of the namespace URI, <em>sep</em>, and the local part of the name. This 929means that you should pick a character for <em>sep</em> that can't be part 930of an URI. Since Expat does not check namespace URIs for conformance, the 931only safe choice for a namespace separator is a character that is illegal 932in XML. For instance, <code>'\xFF'</code> is not legal in UTF-8, and 933<code>'\xFFFF'</code> is not legal in UTF-16. There is a special case when 934<em>sep</em> is the null character <code>'\0'</code>: the namespace URI and 935the local part will be concatenated without any separator - this is intended 936to support RDF processors. It is a programming error to use the null separator 937with <a href= "#XML_SetReturnNSTriplet">namespace triplets</a>.</div> 938 939<pre class="fcndec" id="XML_ParserCreate_MM"> 940XML_Parser XMLCALL 941XML_ParserCreate_MM(const XML_Char *encoding, 942 const XML_Memory_Handling_Suite *ms, 943 const XML_Char *sep); 944</pre> 945<pre class="signature"> 946typedef struct { 947 void *(XMLCALL *malloc_fcn)(size_t size); 948 void *(XMLCALL *realloc_fcn)(void *ptr, size_t size); 949 void (XMLCALL *free_fcn)(void *ptr); 950} XML_Memory_Handling_Suite; 951</pre> 952<div class="fcndef"> 953<p>Construct a new parser using the suite of memory handling functions 954specified in <code>ms</code>. If <code>ms</code> is NULL, then use the 955standard set of memory management functions. If <code>sep</code> is 956non NULL, then namespace processing is enabled in the created parser 957and the character pointed at by sep is used as the separator between 958the namespace URI and the local part of the name.</p> 959</div> 960 961<pre class="fcndec" id="XML_ExternalEntityParserCreate"> 962XML_Parser XMLCALL 963XML_ExternalEntityParserCreate(XML_Parser p, 964 const XML_Char *context, 965 const XML_Char *encoding); 966</pre> 967<div class="fcndef"> 968Construct a new <code>XML_Parser</code> object for parsing an external 969general entity. Context is the context argument passed in a call to a 970ExternalEntityRefHandler. Other state information such as handlers, 971user data, namespace processing is inherited from the parser passed as 972the 1st argument. So you shouldn't need to call any of the behavior 973changing functions on this parser (unless you want it to act 974differently than the parent parser). 975</div> 976 977<pre class="fcndec" id="XML_ParserFree"> 978void XMLCALL 979XML_ParserFree(XML_Parser p); 980</pre> 981<div class="fcndef"> 982Free memory used by the parser. Your application is responsible for 983freeing any memory associated with <a href="#userdata">user data</a>. 984</div> 985 986<pre class="fcndec" id="XML_ParserReset"> 987XML_Bool XMLCALL 988XML_ParserReset(XML_Parser p, 989 const XML_Char *encoding); 990</pre> 991<div class="fcndef"> 992Clean up the memory structures maintained by the parser so that it may 993be used again. After this has been called, <code>parser</code> is 994ready to start parsing a new document. All handlers are cleared from 995the parser, except for the unknownEncodingHandler. The parser's external 996state is re-initialized except for the values of ns and ns_triplets. 997This function may not be used on a parser created using <code><a href= 998"#XML_ExternalEntityParserCreate" >XML_ExternalEntityParserCreate</a 999></code>; it will return <code>XML_FALSE</code> in that case. Returns 1000<code>XML_TRUE</code> on success. Your application is responsible for 1001dealing with any memory associated with <a href="#userdata">user data</a>. 1002</div> 1003 1004<h3><a name="parsing">Parsing</a></h3> 1005 1006<p>To state the obvious: the three parsing functions <code><a href= 1007"#XML_Parse" >XML_Parse</a></code>, <code><a href= "#XML_ParseBuffer"> 1008XML_ParseBuffer</a></code> and <code><a href= "#XML_GetBuffer"> 1009XML_GetBuffer</a></code> must not be called from within a handler 1010unless they operate on a separate parser instance, that is, one that 1011did not call the handler. For example, it is OK to call the parsing 1012functions from within an <code>XML_ExternalEntityRefHandler</code>, 1013if they apply to the parser created by 1014<code><a href= "#XML_ExternalEntityParserCreate" 1015>XML_ExternalEntityParserCreate</a></code>.</p> 1016 1017<p>Note: the <code>len</code> argument passed to these functions 1018should be considerably less than the maximum value for an integer, 1019as it could create an integer overflow situation if the added 1020lengths of a buffer and the unprocessed portion of the previous buffer 1021exceed the maximum integer value. Input data at the end of a buffer 1022will remain unprocessed if it is part of an XML token for which the 1023end is not part of that buffer.</p> 1024 1025<pre class="fcndec" id="XML_Parse"> 1026enum XML_Status XMLCALL 1027XML_Parse(XML_Parser p, 1028 const char *s, 1029 int len, 1030 int isFinal); 1031</pre> 1032<pre class="signature"> 1033enum XML_Status { 1034 XML_STATUS_ERROR = 0, 1035 XML_STATUS_OK = 1 1036}; 1037</pre> 1038<div class="fcndef"> 1039Parse some more of the document. The string <code>s</code> is a buffer 1040containing part (or perhaps all) of the document. The number of bytes of s 1041that are part of the document is indicated by <code>len</code>. This means 1042that <code>s</code> doesn't have to be null terminated. It also means that 1043if <code>len</code> is larger than the number of bytes in the block of 1044memory that <code>s</code> points at, then a memory fault is likely. The 1045<code>isFinal</code> parameter informs the parser that this is the last 1046piece of the document. Frequently, the last piece is empty (i.e. 1047<code>len</code> is zero.) 1048If a parse error occurred, it returns <code>XML_STATUS_ERROR</code>. 1049Otherwise it returns <code>XML_STATUS_OK</code> value. 1050</div> 1051 1052<pre class="fcndec" id="XML_ParseBuffer"> 1053enum XML_Status XMLCALL 1054XML_ParseBuffer(XML_Parser p, 1055 int len, 1056 int isFinal); 1057</pre> 1058<div class="fcndef"> 1059This is just like <code><a href= "#XML_Parse" >XML_Parse</a></code>, 1060except in this case Expat provides the buffer. By obtaining the 1061buffer from Expat with the <code><a href= "#XML_GetBuffer" 1062>XML_GetBuffer</a></code> function, the application can avoid double 1063copying of the input. 1064</div> 1065 1066<pre class="fcndec" id="XML_GetBuffer"> 1067void * XMLCALL 1068XML_GetBuffer(XML_Parser p, 1069 int len); 1070</pre> 1071<div class="fcndef"> 1072Obtain a buffer of size <code>len</code> to read a piece of the document 1073into. A NULL value is returned if Expat can't allocate enough memory for 1074this buffer. This has to be called prior to every call to 1075<code><a href= "#XML_ParseBuffer" >XML_ParseBuffer</a></code>. A 1076typical use would look like this: 1077 1078<pre class="eg"> 1079for (;;) { 1080 int bytes_read; 1081 void *buff = XML_GetBuffer(p, BUFF_SIZE); 1082 if (buff == NULL) { 1083 /* handle error */ 1084 } 1085 1086 bytes_read = read(docfd, buff, BUFF_SIZE); 1087 if (bytes_read < 0) { 1088 /* handle error */ 1089 } 1090 1091 if (! XML_ParseBuffer(p, bytes_read, bytes_read == 0)) { 1092 /* handle parse error */ 1093 } 1094 1095 if (bytes_read == 0) 1096 break; 1097} 1098</pre> 1099</div> 1100 1101<pre class="fcndec" id="XML_StopParser"> 1102enum XML_Status XMLCALL 1103XML_StopParser(XML_Parser p, 1104 XML_Bool resumable); 1105</pre> 1106<div class="fcndef"> 1107 1108<p>Stops parsing, causing <code><a href= "#XML_Parse" 1109>XML_Parse</a></code> or <code><a href= "#XML_ParseBuffer" 1110>XML_ParseBuffer</a></code> to return. Must be called from within a 1111call-back handler, except when aborting (when <code>resumable</code> 1112is <code>XML_FALSE</code>) an already suspended parser. Some 1113call-backs may still follow because they would otherwise get 1114lost, including 1115<ul> 1116 <li> the end element handler for empty elements when stopped in the 1117 start element handler,</li> 1118 <li> the end namespace declaration handler when stopped in the end 1119 element handler,</li> 1120 <li> the character data handler when stopped in the character data handler 1121 while making multiple call-backs on a contiguous chunk of characters,</li> 1122</ul> 1123and possibly others.</p> 1124 1125<p>This can be called from most handlers, including DTD related 1126call-backs, except when parsing an external parameter entity and 1127<code>resumable</code> is <code>XML_TRUE</code>. Returns 1128<code>XML_STATUS_OK</code> when successful, 1129<code>XML_STATUS_ERROR</code> otherwise. The possible error codes 1130are:</p> 1131<dl> 1132 <dt><code>XML_ERROR_SUSPENDED</code></dt> 1133 <dd>when suspending an already suspended parser.</dd> 1134 <dt><code>XML_ERROR_FINISHED</code></dt> 1135 <dd>when the parser has already finished.</dd> 1136 <dt><code>XML_ERROR_SUSPEND_PE</code></dt> 1137 <dd>when suspending while parsing an external PE.</dd> 1138</dl> 1139 1140<p>Since the stop/resume feature requires application support in the 1141outer parsing loop, it is an error to call this function for a parser 1142not being handled appropriately; see <a href= "#stop-resume" 1143>Temporarily Stopping Parsing</a> for more information.</p> 1144 1145<p>When <code>resumable</code> is <code>XML_TRUE</code> then parsing 1146is <em>suspended</em>, that is, <code><a href= "#XML_Parse" 1147>XML_Parse</a></code> and <code><a href= "#XML_ParseBuffer" 1148>XML_ParseBuffer</a></code> return <code>XML_STATUS_SUSPENDED</code>. 1149Otherwise, parsing is <em>aborted</em>, that is, <code><a href= 1150"#XML_Parse" >XML_Parse</a></code> and <code><a href= 1151"#XML_ParseBuffer" >XML_ParseBuffer</a></code> return 1152<code>XML_STATUS_ERROR</code> with error code 1153<code>XML_ERROR_ABORTED</code>.</p> 1154 1155<p><strong>Note:</strong> 1156This will be applied to the current parser instance only, that is, if 1157there is a parent parser then it will continue parsing when the 1158external entity reference handler returns. It is up to the 1159implementation of that handler to call <code><a href= 1160"#XML_StopParser" >XML_StopParser</a></code> on the parent parser 1161(recursively), if one wants to stop parsing altogether.</p> 1162 1163<p>When suspended, parsing can be resumed by calling <code><a href= 1164"#XML_ResumeParser" >XML_ResumeParser</a></code>.</p> 1165 1166<p>New in Expat 1.95.8.</p> 1167</div> 1168 1169<pre class="fcndec" id="XML_ResumeParser"> 1170enum XML_Status XMLCALL 1171XML_ResumeParser(XML_Parser p); 1172</pre> 1173<div class="fcndef"> 1174<p>Resumes parsing after it has been suspended with <code><a href= 1175"#XML_StopParser" >XML_StopParser</a></code>. Must not be called from 1176within a handler call-back. Returns same status codes as <code><a 1177href= "#XML_Parse">XML_Parse</a></code> or <code><a href= 1178"#XML_ParseBuffer" >XML_ParseBuffer</a></code>. An additional error 1179code, <code>XML_ERROR_NOT_SUSPENDED</code>, will be returned if the 1180parser was not currently suspended.</p> 1181 1182<p><strong>Note:</strong> 1183This must be called on the most deeply nested child parser instance 1184first, and on its parent parser only after the child parser has 1185finished, to be applied recursively until the document entity's parser 1186is restarted. That is, the parent parser will not resume by itself 1187and it is up to the application to call <code><a href= 1188"#XML_ResumeParser" >XML_ResumeParser</a></code> on it at the 1189appropriate moment.</p> 1190 1191<p>New in Expat 1.95.8.</p> 1192</div> 1193 1194<pre class="fcndec" id="XML_GetParsingStatus"> 1195void XMLCALL 1196XML_GetParsingStatus(XML_Parser p, 1197 XML_ParsingStatus *status); 1198</pre> 1199<pre class="signature"> 1200enum XML_Parsing { 1201 XML_INITIALIZED, 1202 XML_PARSING, 1203 XML_FINISHED, 1204 XML_SUSPENDED 1205}; 1206 1207typedef struct { 1208 enum XML_Parsing parsing; 1209 XML_Bool finalBuffer; 1210} XML_ParsingStatus; 1211</pre> 1212<div class="fcndef"> 1213<p>Returns status of parser with respect to being initialized, 1214parsing, finished, or suspended, and whether the final buffer is being 1215processed. The <code>status</code> parameter <em>must not</em> be 1216NULL.</p> 1217 1218<p>New in Expat 1.95.8.</p> 1219</div> 1220 1221 1222<h3><a name="setting">Handler Setting</a></h3> 1223 1224<p>Although handlers are typically set prior to parsing and left alone, an 1225application may choose to set or change the handler for a parsing event 1226while the parse is in progress. For instance, your application may choose 1227to ignore all text not descended from a <code>para</code> element. One 1228way it could do this is to set the character handler when a para start tag 1229is seen, and unset it for the corresponding end tag.</p> 1230 1231<p>A handler may be <em>unset</em> by providing a NULL pointer to the 1232appropriate handler setter. None of the handler setting functions have 1233a return value.</p> 1234 1235<p>Your handlers will be receiving strings in arrays of type 1236<code>XML_Char</code>. This type is conditionally defined in expat.h as 1237either <code>char</code>, <code>wchar_t</code> or <code>unsigned short</code>. 1238The former implies UTF-8 encoding, the latter two imply UTF-16 encoding. 1239Note that you'll receive them in this form independent of the original 1240encoding of the document.</p> 1241 1242<div class="handler"> 1243<pre class="setter" id="XML_SetStartElementHandler"> 1244void XMLCALL 1245XML_SetStartElementHandler(XML_Parser p, 1246 XML_StartElementHandler start); 1247</pre> 1248<pre class="signature"> 1249typedef void 1250(XMLCALL *XML_StartElementHandler)(void *userData, 1251 const XML_Char *name, 1252 const XML_Char **atts); 1253</pre> 1254<p>Set handler for start (and empty) tags. Attributes are passed to the start 1255handler as a pointer to a vector of char pointers. Each attribute seen in 1256a start (or empty) tag occupies 2 consecutive places in this vector: the 1257attribute name followed by the attribute value. These pairs are terminated 1258by a null pointer.</p> 1259<p>Note that an empty tag generates a call to both start and end handlers 1260(in that order).</p> 1261</div> 1262 1263<div class="handler"> 1264<pre class="setter" id="XML_SetEndElementHandler"> 1265void XMLCALL 1266XML_SetEndElementHandler(XML_Parser p, 1267 XML_EndElementHandler); 1268</pre> 1269<pre class="signature"> 1270typedef void 1271(XMLCALL *XML_EndElementHandler)(void *userData, 1272 const XML_Char *name); 1273</pre> 1274<p>Set handler for end (and empty) tags. As noted above, an empty tag 1275generates a call to both start and end handlers.</p> 1276</div> 1277 1278<div class="handler"> 1279<pre class="setter" id="XML_SetElementHandler"> 1280void XMLCALL 1281XML_SetElementHandler(XML_Parser p, 1282 XML_StartElementHandler start, 1283 XML_EndElementHandler end); 1284</pre> 1285<p>Set handlers for start and end tags with one call.</p> 1286</div> 1287 1288<div class="handler"> 1289<pre class="setter" id="XML_SetCharacterDataHandler"> 1290void XMLCALL 1291XML_SetCharacterDataHandler(XML_Parser p, 1292 XML_CharacterDataHandler charhndl) 1293</pre> 1294<pre class="signature"> 1295typedef void 1296(XMLCALL *XML_CharacterDataHandler)(void *userData, 1297 const XML_Char *s, 1298 int len); 1299</pre> 1300<p>Set a text handler. The string your handler receives 1301is <em>NOT nul-terminated</em>. You have to use the length argument 1302to deal with the end of the string. A single block of contiguous text 1303free of markup may still result in a sequence of calls to this handler. 1304In other words, if you're searching for a pattern in the text, it may 1305be split across calls to this handler. Note: Setting this handler to NULL 1306may <em>NOT immediately</em> terminate call-backs if the parser is currently 1307processing such a single block of contiguous markup-free text, as the parser 1308will continue calling back until the end of the block is reached.</p> 1309</div> 1310 1311<div class="handler"> 1312<pre class="setter" id="XML_SetProcessingInstructionHandler"> 1313void XMLCALL 1314XML_SetProcessingInstructionHandler(XML_Parser p, 1315 XML_ProcessingInstructionHandler proc) 1316</pre> 1317<pre class="signature"> 1318typedef void 1319(XMLCALL *XML_ProcessingInstructionHandler)(void *userData, 1320 const XML_Char *target, 1321 const XML_Char *data); 1322 1323</pre> 1324<p>Set a handler for processing instructions. The target is the first word 1325in the processing instruction. The data is the rest of the characters in 1326it after skipping all whitespace after the initial word.</p> 1327</div> 1328 1329<div class="handler"> 1330<pre class="setter" id="XML_SetCommentHandler"> 1331void XMLCALL 1332XML_SetCommentHandler(XML_Parser p, 1333 XML_CommentHandler cmnt) 1334</pre> 1335<pre class="signature"> 1336typedef void 1337(XMLCALL *XML_CommentHandler)(void *userData, 1338 const XML_Char *data); 1339</pre> 1340<p>Set a handler for comments. The data is all text inside the comment 1341delimiters.</p> 1342</div> 1343 1344<div class="handler"> 1345<pre class="setter" id="XML_SetStartCdataSectionHandler"> 1346void XMLCALL 1347XML_SetStartCdataSectionHandler(XML_Parser p, 1348 XML_StartCdataSectionHandler start); 1349</pre> 1350<pre class="signature"> 1351typedef void 1352(XMLCALL *XML_StartCdataSectionHandler)(void *userData); 1353</pre> 1354<p>Set a handler that gets called at the beginning of a CDATA section.</p> 1355</div> 1356 1357<div class="handler"> 1358<pre class="setter" id="XML_SetEndCdataSectionHandler"> 1359void XMLCALL 1360XML_SetEndCdataSectionHandler(XML_Parser p, 1361 XML_EndCdataSectionHandler end); 1362</pre> 1363<pre class="signature"> 1364typedef void 1365(XMLCALL *XML_EndCdataSectionHandler)(void *userData); 1366</pre> 1367<p>Set a handler that gets called at the end of a CDATA section.</p> 1368</div> 1369 1370<div class="handler"> 1371<pre class="setter" id="XML_SetCdataSectionHandler"> 1372void XMLCALL 1373XML_SetCdataSectionHandler(XML_Parser p, 1374 XML_StartCdataSectionHandler start, 1375 XML_EndCdataSectionHandler end) 1376</pre> 1377<p>Sets both CDATA section handlers with one call.</p> 1378</div> 1379 1380<div class="handler"> 1381<pre class="setter" id="XML_SetDefaultHandler"> 1382void XMLCALL 1383XML_SetDefaultHandler(XML_Parser p, 1384 XML_DefaultHandler hndl) 1385</pre> 1386<pre class="signature"> 1387typedef void 1388(XMLCALL *XML_DefaultHandler)(void *userData, 1389 const XML_Char *s, 1390 int len); 1391</pre> 1392 1393<p>Sets a handler for any characters in the document which wouldn't 1394otherwise be handled. This includes both data for which no handlers 1395can be set (like some kinds of DTD declarations) and data which could 1396be reported but which currently has no handler set. The characters 1397are passed exactly as they were present in the XML document except 1398that they will be encoded in UTF-8 or UTF-16. Line boundaries are not 1399normalized. Note that a byte order mark character is not passed to the 1400default handler. There are no guarantees about how characters are 1401divided between calls to the default handler: for example, a comment 1402might be split between multiple calls. Setting the handler with 1403this call has the side effect of turning off expansion of references 1404to internally defined general entities. Instead these references are 1405passed to the default handler.</p> 1406 1407<p>See also <code><a 1408href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p> 1409</div> 1410 1411<div class="handler"> 1412<pre class="setter" id="XML_SetDefaultHandlerExpand"> 1413void XMLCALL 1414XML_SetDefaultHandlerExpand(XML_Parser p, 1415 XML_DefaultHandler hndl) 1416</pre> 1417<pre class="signature"> 1418typedef void 1419(XMLCALL *XML_DefaultHandler)(void *userData, 1420 const XML_Char *s, 1421 int len); 1422</pre> 1423<p>This sets a default handler, but doesn't inhibit the expansion of 1424internal entity references. The entity reference will not be passed 1425to the default handler.</p> 1426 1427<p>See also <code><a 1428href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p> 1429</div> 1430 1431<div class="handler"> 1432<pre class="setter" id="XML_SetExternalEntityRefHandler"> 1433void XMLCALL 1434XML_SetExternalEntityRefHandler(XML_Parser p, 1435 XML_ExternalEntityRefHandler hndl) 1436</pre> 1437<pre class="signature"> 1438typedef int 1439(XMLCALL *XML_ExternalEntityRefHandler)(XML_Parser p, 1440 const XML_Char *context, 1441 const XML_Char *base, 1442 const XML_Char *systemId, 1443 const XML_Char *publicId); 1444</pre> 1445<p>Set an external entity reference handler. This handler is also 1446called for processing an external DTD subset if parameter entity parsing 1447is in effect. (See <a href="#XML_SetParamEntityParsing"> 1448<code>XML_SetParamEntityParsing</code></a>.)</p> 1449 1450<p>The <code>context</code> parameter specifies the parsing context in 1451the format expected by the <code>context</code> argument to <code><a 1452href="#XML_ExternalEntityParserCreate" 1453>XML_ExternalEntityParserCreate</a></code>. <code>code</code> is 1454valid only until the handler returns, so if the referenced entity is 1455to be parsed later, it must be copied. <code>context</code> is NULL 1456only when the entity is a parameter entity, which is how one can 1457differentiate between general and parameter entities.</p> 1458 1459<p>The <code>base</code> parameter is the base to use for relative 1460system identifiers. It is set by <code><a 1461href="#XML_SetBase">XML_SetBase</a></code> and may be NULL. The 1462<code>publicId</code> parameter is the public id given in the entity 1463declaration and may be NULL. <code>systemId</code> is the system 1464identifier specified in the entity declaration and is never NULL.</p> 1465 1466<p>There are a couple of ways in which this handler differs from 1467others. First, this handler returns a status indicator (an 1468integer). <code>XML_STATUS_OK</code> should be returned for successful 1469handling of the external entity reference. Returning 1470<code>XML_STATUS_ERROR</code> indicates failure, and causes the 1471calling parser to return an 1472<code>XML_ERROR_EXTERNAL_ENTITY_HANDLING</code> error.</p> 1473 1474<p>Second, instead of having the user data as its first argument, it 1475receives the parser that encountered the entity reference. This, along 1476with the context parameter, may be used as arguments to a call to 1477<code><a href= "#XML_ExternalEntityParserCreate" 1478>XML_ExternalEntityParserCreate</a></code>. Using the returned 1479parser, the body of the external entity can be recursively parsed.</p> 1480 1481<p>Since this handler may be called recursively, it should not be saving 1482information into global or static variables.</p> 1483</div> 1484 1485<pre class="fcndec" id="XML_SetExternalEntityRefHandlerArg"> 1486void XMLCALL 1487XML_SetExternalEntityRefHandlerArg(XML_Parser p, 1488 void *arg) 1489</pre> 1490<div class="fcndef"> 1491<p>Set the argument passed to the ExternalEntityRefHandler. If 1492<code>arg</code> is not NULL, it is the new value passed to the 1493handler set using <code><a href="#XML_SetExternalEntityRefHandler" 1494>XML_SetExternalEntityRefHandler</a></code>; if <code>arg</code> is 1495NULL, the argument passed to the handler function will be the parser 1496object itself.</p> 1497 1498<p><strong>Note:</strong> 1499The type of <code>arg</code> and the type of the first argument to the 1500ExternalEntityRefHandler do not match. This function takes a 1501<code>void *</code> to be passed to the handler, while the handler 1502accepts an <code>XML_Parser</code>. This is a historical accident, 1503but will not be corrected before Expat 2.0 (at the earliest) to avoid 1504causing compiler warnings for code that's known to work with this 1505API. It is the responsibility of the application code to know the 1506actual type of the argument passed to the handler and to manage it 1507properly.</p> 1508</div> 1509 1510<div class="handler"> 1511<pre class="setter" id="XML_SetSkippedEntityHandler"> 1512void XMLCALL 1513XML_SetSkippedEntityHandler(XML_Parser p, 1514 XML_SkippedEntityHandler handler) 1515</pre> 1516<pre class="signature"> 1517typedef void 1518(XMLCALL *XML_SkippedEntityHandler)(void *userData, 1519 const XML_Char *entityName, 1520 int is_parameter_entity); 1521</pre> 1522<p>Set a skipped entity handler. This is called in two situations:</p> 1523<ol> 1524 <li>An entity reference is encountered for which no declaration 1525 has been read <em>and</em> this is not an error.</li> 1526 <li>An internal entity reference is read, but not expanded, because 1527 <a href="#XML_SetDefaultHandler"><code>XML_SetDefaultHandler</code></a> 1528 has been called.</li> 1529</ol> 1530<p>The <code>is_parameter_entity</code> argument will be non-zero for 1531a parameter entity and zero for a general entity.</p> <p>Note: skipped 1532parameter entities in declarations and skipped general entities in 1533attribute values cannot be reported, because the event would be out of 1534sync with the reporting of the declarations or attribute values</p> 1535</div> 1536 1537<div class="handler"> 1538<pre class="setter" id="XML_SetUnknownEncodingHandler"> 1539void XMLCALL 1540XML_SetUnknownEncodingHandler(XML_Parser p, 1541 XML_UnknownEncodingHandler enchandler, 1542 void *encodingHandlerData) 1543</pre> 1544<pre class="signature"> 1545typedef int 1546(XMLCALL *XML_UnknownEncodingHandler)(void *encodingHandlerData, 1547 const XML_Char *name, 1548 XML_Encoding *info); 1549 1550typedef struct { 1551 int map[256]; 1552 void *data; 1553 int (XMLCALL *convert)(void *data, const char *s); 1554 void (XMLCALL *release)(void *data); 1555} XML_Encoding; 1556</pre> 1557<p>Set a handler to deal with encodings other than the <a 1558href="#builtin_encodings">built in set</a>. This should be done before 1559<code><a href= "#XML_Parse" >XML_Parse</a></code> or <code><a href= 1560"#XML_ParseBuffer" >XML_ParseBuffer</a></code> have been called on the 1561given parser.</p> <p>If the handler knows how to deal with an encoding 1562with the given name, it should fill in the <code>info</code> data 1563structure and return <code>XML_STATUS_OK</code>. Otherwise it 1564should return <code>XML_STATUS_ERROR</code>. The handler will be called 1565at most once per parsed (external) entity. The optional application 1566data pointer <code>encodingHandlerData</code> will be passed back to 1567the handler.</p> 1568 1569<p>The map array contains information for every possible leading 1570byte in a byte sequence. If the corresponding value is >= 0, then it's 1571a single byte sequence and the byte encodes that Unicode value. If the 1572value is -1, then that byte is invalid as the initial byte in a sequence. 1573If the value is -n, where n is an integer > 1, then n is the number of 1574bytes in the sequence and the actual conversion is accomplished by a 1575call to the function pointed at by convert. This function may return -1 1576if the sequence itself is invalid. The convert pointer may be null if 1577there are only single byte codes. The data parameter passed to the convert 1578function is the data pointer from <code>XML_Encoding</code>. The 1579string s is <em>NOT</em> nul-terminated and points at the sequence of 1580bytes to be converted.</p> 1581 1582<p>The function pointed at by <code>release</code> is called by the 1583parser when it is finished with the encoding. It may be NULL.</p> 1584</div> 1585 1586<div class="handler"> 1587<pre class="setter" id="XML_SetStartNamespaceDeclHandler"> 1588void XMLCALL 1589XML_SetStartNamespaceDeclHandler(XML_Parser p, 1590 XML_StartNamespaceDeclHandler start); 1591</pre> 1592<pre class="signature"> 1593typedef void 1594(XMLCALL *XML_StartNamespaceDeclHandler)(void *userData, 1595 const XML_Char *prefix, 1596 const XML_Char *uri); 1597</pre> 1598<p>Set a handler to be called when a namespace is declared. Namespace 1599declarations occur inside start tags. But the namespace declaration start 1600handler is called before the start tag handler for each namespace declared 1601in that start tag.</p> 1602</div> 1603 1604<div class="handler"> 1605<pre class="setter" id="XML_SetEndNamespaceDeclHandler"> 1606void XMLCALL 1607XML_SetEndNamespaceDeclHandler(XML_Parser p, 1608 XML_EndNamespaceDeclHandler end); 1609</pre> 1610<pre class="signature"> 1611typedef void 1612(XMLCALL *XML_EndNamespaceDeclHandler)(void *userData, 1613 const XML_Char *prefix); 1614</pre> 1615<p>Set a handler to be called when leaving the scope of a namespace 1616declaration. This will be called, for each namespace declaration, 1617after the handler for the end tag of the element in which the 1618namespace was declared.</p> 1619</div> 1620 1621<div class="handler"> 1622<pre class="setter" id="XML_SetNamespaceDeclHandler"> 1623void XMLCALL 1624XML_SetNamespaceDeclHandler(XML_Parser p, 1625 XML_StartNamespaceDeclHandler start, 1626 XML_EndNamespaceDeclHandler end) 1627</pre> 1628<p>Sets both namespace declaration handlers with a single call.</p> 1629</div> 1630 1631<div class="handler"> 1632<pre class="setter" id="XML_SetXmlDeclHandler"> 1633void XMLCALL 1634XML_SetXmlDeclHandler(XML_Parser p, 1635 XML_XmlDeclHandler xmldecl); 1636</pre> 1637<pre class="signature"> 1638typedef void 1639(XMLCALL *XML_XmlDeclHandler)(void *userData, 1640 const XML_Char *version, 1641 const XML_Char *encoding, 1642 int standalone); 1643</pre> 1644<p>Sets a handler that is called for XML declarations and also for 1645text declarations discovered in external entities. The way to 1646distinguish is that the <code>version</code> parameter will be NULL 1647for text declarations. The <code>encoding</code> parameter may be NULL 1648for an XML declaration. The <code>standalone</code> argument will 1649contain -1, 0, or 1 indicating respectively that there was no 1650standalone parameter in the declaration, that it was given as no, or 1651that it was given as yes.</p> 1652</div> 1653 1654<div class="handler"> 1655<pre class="setter" id="XML_SetStartDoctypeDeclHandler"> 1656void XMLCALL 1657XML_SetStartDoctypeDeclHandler(XML_Parser p, 1658 XML_StartDoctypeDeclHandler start); 1659</pre> 1660<pre class="signature"> 1661typedef void 1662(XMLCALL *XML_StartDoctypeDeclHandler)(void *userData, 1663 const XML_Char *doctypeName, 1664 const XML_Char *sysid, 1665 const XML_Char *pubid, 1666 int has_internal_subset); 1667</pre> 1668<p>Set a handler that is called at the start of a DOCTYPE declaration, 1669before any external or internal subset is parsed. Both <code>sysid</code> 1670and <code>pubid</code> may be NULL. The <code>has_internal_subset</code> 1671will be non-zero if the DOCTYPE declaration has an internal subset.</p> 1672</div> 1673 1674<div class="handler"> 1675<pre class="setter" id="XML_SetEndDoctypeDeclHandler"> 1676void XMLCALL 1677XML_SetEndDoctypeDeclHandler(XML_Parser p, 1678 XML_EndDoctypeDeclHandler end); 1679</pre> 1680<pre class="signature"> 1681typedef void 1682(XMLCALL *XML_EndDoctypeDeclHandler)(void *userData); 1683</pre> 1684<p>Set a handler that is called at the end of a DOCTYPE declaration, 1685after parsing any external subset.</p> 1686</div> 1687 1688<div class="handler"> 1689<pre class="setter" id="XML_SetDoctypeDeclHandler"> 1690void XMLCALL 1691XML_SetDoctypeDeclHandler(XML_Parser p, 1692 XML_StartDoctypeDeclHandler start, 1693 XML_EndDoctypeDeclHandler end); 1694</pre> 1695<p>Set both doctype handlers with one call.</p> 1696</div> 1697 1698<div class="handler"> 1699<pre class="setter" id="XML_SetElementDeclHandler"> 1700void XMLCALL 1701XML_SetElementDeclHandler(XML_Parser p, 1702 XML_ElementDeclHandler eldecl); 1703</pre> 1704<pre class="signature"> 1705typedef void 1706(XMLCALL *XML_ElementDeclHandler)(void *userData, 1707 const XML_Char *name, 1708 XML_Content *model); 1709</pre> 1710<pre class="signature"> 1711enum XML_Content_Type { 1712 XML_CTYPE_EMPTY = 1, 1713 XML_CTYPE_ANY, 1714 XML_CTYPE_MIXED, 1715 XML_CTYPE_NAME, 1716 XML_CTYPE_CHOICE, 1717 XML_CTYPE_SEQ 1718}; 1719 1720enum XML_Content_Quant { 1721 XML_CQUANT_NONE, 1722 XML_CQUANT_OPT, 1723 XML_CQUANT_REP, 1724 XML_CQUANT_PLUS 1725}; 1726 1727typedef struct XML_cp XML_Content; 1728 1729struct XML_cp { 1730 enum XML_Content_Type type; 1731 enum XML_Content_Quant quant; 1732 const XML_Char * name; 1733 unsigned int numchildren; 1734 XML_Content * children; 1735}; 1736</pre> 1737<p>Sets a handler for element declarations in a DTD. The handler gets 1738called with the name of the element in the declaration and a pointer 1739to a structure that contains the element model. It is the 1740application's responsibility to free this data structure using 1741<code><a href="#XML_FreeContentModel" 1742>XML_FreeContentModel</a></code>.</p> 1743 1744<p>The <code>model</code> argument is the root of a tree of 1745<code>XML_Content</code> nodes. If <code>type</code> equals 1746<code>XML_CTYPE_EMPTY</code> or <code>XML_CTYPE_ANY</code>, then 1747<code>quant</code> will be <code>XML_CQUANT_NONE</code>, and the other 1748fields will be zero or NULL. If <code>type</code> is 1749<code>XML_CTYPE_MIXED</code>, then <code>quant</code> will be 1750<code>XML_CQUANT_NONE</code> or <code>XML_CQUANT_REP</code> and 1751<code>numchildren</code> will contain the number of elements that are 1752allowed to be mixed in and <code>children</code> points to an array of 1753<code>XML_Content</code> structures that will all have type 1754XML_CTYPE_NAME with no quantification. Only the root node can be type 1755<code>XML_CTYPE_EMPTY</code>, <code>XML_CTYPE_ANY</code>, or 1756<code>XML_CTYPE_MIXED</code>.</p> 1757 1758<p>For type <code>XML_CTYPE_NAME</code>, the <code>name</code> field 1759points to the name and the <code>numchildren</code> and 1760<code>children</code> fields will be zero and NULL. The 1761<code>quant</code> field will indicate any quantifiers placed on the 1762name.</p> 1763 1764<p>Types <code>XML_CTYPE_CHOICE</code> and <code>XML_CTYPE_SEQ</code> 1765indicate a choice or sequence respectively. The 1766<code>numchildren</code> field indicates how many nodes in the choice 1767or sequence and <code>children</code> points to the nodes.</p> 1768</div> 1769 1770<div class="handler"> 1771<pre class="setter" id="XML_SetAttlistDeclHandler"> 1772void XMLCALL 1773XML_SetAttlistDeclHandler(XML_Parser p, 1774 XML_AttlistDeclHandler attdecl); 1775</pre> 1776<pre class="signature"> 1777typedef void 1778(XMLCALL *XML_AttlistDeclHandler)(void *userData, 1779 const XML_Char *elname, 1780 const XML_Char *attname, 1781 const XML_Char *att_type, 1782 const XML_Char *dflt, 1783 int isrequired); 1784</pre> 1785<p>Set a handler for attlist declarations in the DTD. This handler is 1786called for <em>each</em> attribute. So a single attlist declaration 1787with multiple attributes declared will generate multiple calls to this 1788handler. The <code>elname</code> parameter returns the name of the 1789element for which the attribute is being declared. The attribute name 1790is in the <code>attname</code> parameter. The attribute type is in the 1791<code>att_type</code> parameter. It is the string representing the 1792type in the declaration with whitespace removed.</p> 1793 1794<p>The <code>dflt</code> parameter holds the default value. It will be 1795NULL in the case of "#IMPLIED" or "#REQUIRED" attributes. You can 1796distinguish these two cases by checking the <code>isrequired</code> 1797parameter, which will be true in the case of "#REQUIRED" attributes. 1798Attributes which are "#FIXED" will have also have a true 1799<code>isrequired</code>, but they will have the non-NULL fixed value 1800in the <code>dflt</code> parameter.</p> 1801</div> 1802 1803<div class="handler"> 1804<pre class="setter" id="XML_SetEntityDeclHandler"> 1805void XMLCALL 1806XML_SetEntityDeclHandler(XML_Parser p, 1807 XML_EntityDeclHandler handler); 1808</pre> 1809<pre class="signature"> 1810typedef void 1811(XMLCALL *XML_EntityDeclHandler)(void *userData, 1812 const XML_Char *entityName, 1813 int is_parameter_entity, 1814 const XML_Char *value, 1815 int value_length, 1816 const XML_Char *base, 1817 const XML_Char *systemId, 1818 const XML_Char *publicId, 1819 const XML_Char *notationName); 1820</pre> 1821<p>Sets a handler that will be called for all entity declarations. 1822The <code>is_parameter_entity</code> argument will be non-zero in the 1823case of parameter entities and zero otherwise.</p> 1824 1825<p>For internal entities (<code><!ENTITY foo "bar"></code>), 1826<code>value</code> will be non-NULL and <code>systemId</code>, 1827<code>publicId</code>, and <code>notationName</code> will all be NULL. 1828The value string is <em>not</em> NULL terminated; the length is 1829provided in the <code>value_length</code> parameter. Do not use 1830<code>value_length</code> to test for internal entities, since it is 1831legal to have zero-length values. Instead check for whether or not 1832<code>value</code> is NULL.</p> <p>The <code>notationName</code> 1833argument will have a non-NULL value only for unparsed entity 1834declarations.</p> 1835</div> 1836 1837<div class="handler"> 1838<pre class="setter" id="XML_SetUnparsedEntityDeclHandler"> 1839void XMLCALL 1840XML_SetUnparsedEntityDeclHandler(XML_Parser p, 1841 XML_UnparsedEntityDeclHandler h) 1842</pre> 1843<pre class="signature"> 1844typedef void 1845(XMLCALL *XML_UnparsedEntityDeclHandler)(void *userData, 1846 const XML_Char *entityName, 1847 const XML_Char *base, 1848 const XML_Char *systemId, 1849 const XML_Char *publicId, 1850 const XML_Char *notationName); 1851</pre> 1852<p>Set a handler that receives declarations of unparsed entities. These 1853are entity declarations that have a notation (NDATA) field:</p> 1854 1855<div id="eg"><pre> 1856<!ENTITY logo SYSTEM "images/logo.gif" NDATA gif> 1857</pre></div> 1858<p>This handler is obsolete and is provided for backwards 1859compatibility. Use instead <a href= "#XML_SetEntityDeclHandler" 1860>XML_SetEntityDeclHandler</a>.</p> 1861</div> 1862 1863<div class="handler"> 1864<pre class="setter" id="XML_SetNotationDeclHandler"> 1865void XMLCALL 1866XML_SetNotationDeclHandler(XML_Parser p, 1867 XML_NotationDeclHandler h) 1868</pre> 1869<pre class="signature"> 1870typedef void 1871(XMLCALL *XML_NotationDeclHandler)(void *userData, 1872 const XML_Char *notationName, 1873 const XML_Char *base, 1874 const XML_Char *systemId, 1875 const XML_Char *publicId); 1876</pre> 1877<p>Set a handler that receives notation declarations.</p> 1878</div> 1879 1880<div class="handler"> 1881<pre class="setter" id="XML_SetNotStandaloneHandler"> 1882void XMLCALL 1883XML_SetNotStandaloneHandler(XML_Parser p, 1884 XML_NotStandaloneHandler h) 1885</pre> 1886<pre class="signature"> 1887typedef int 1888(XMLCALL *XML_NotStandaloneHandler)(void *userData); 1889</pre> 1890<p>Set a handler that is called if the document is not "standalone". 1891This happens when there is an external subset or a reference to a 1892parameter entity, but does not have standalone set to "yes" in an XML 1893declaration. If this handler returns <code>XML_STATUS_ERROR</code>, 1894then the parser will throw an <code>XML_ERROR_NOT_STANDALONE</code> 1895error.</p> 1896</div> 1897 1898<h3><a name="position">Parse position and error reporting functions</a></h3> 1899 1900<p>These are the functions you'll want to call when the parse 1901functions return <code>XML_STATUS_ERROR</code> (a parse error has 1902occurred), although the position reporting functions are useful outside 1903of errors. The position reported is the byte position (in the original 1904document or entity encoding) of the first of the sequence of 1905characters that generated the current event (or the error that caused 1906the parse functions to return <code>XML_STATUS_ERROR</code>.) The 1907exceptions are callbacks trigged by declarations in the document 1908prologue, in which case they exact position reported is somewhere in the 1909relevant markup, but not necessarily as meaningful as for other 1910events.</p> 1911 1912<p>The position reporting functions are accurate only outside of the 1913DTD. In other words, they usually return bogus information when 1914called from within a DTD declaration handler.</p> 1915 1916<pre class="fcndec" id="XML_GetErrorCode"> 1917enum XML_Error XMLCALL 1918XML_GetErrorCode(XML_Parser p); 1919</pre> 1920<div class="fcndef"> 1921Return what type of error has occurred. 1922</div> 1923 1924<pre class="fcndec" id="XML_ErrorString"> 1925const XML_LChar * XMLCALL 1926XML_ErrorString(enum XML_Error code); 1927</pre> 1928<div class="fcndef"> 1929Return a string describing the error corresponding to code. 1930The code should be one of the enums that can be returned from 1931<code><a href= "#XML_GetErrorCode" >XML_GetErrorCode</a></code>. 1932</div> 1933 1934<pre class="fcndec" id="XML_GetCurrentByteIndex"> 1935XML_Index XMLCALL 1936XML_GetCurrentByteIndex(XML_Parser p); 1937</pre> 1938<div class="fcndef"> 1939Return the byte offset of the position. This always corresponds to 1940the values returned by <code><a href= "#XML_GetCurrentLineNumber" 1941>XML_GetCurrentLineNumber</a></code> and <code><a href= 1942"#XML_GetCurrentColumnNumber" >XML_GetCurrentColumnNumber</a></code>. 1943</div> 1944 1945<pre class="fcndec" id="XML_GetCurrentLineNumber"> 1946XML_Size XMLCALL 1947XML_GetCurrentLineNumber(XML_Parser p); 1948</pre> 1949<div class="fcndef"> 1950Return the line number of the position. The first line is reported as 1951<code>1</code>. 1952</div> 1953 1954<pre class="fcndec" id="XML_GetCurrentColumnNumber"> 1955XML_Size XMLCALL 1956XML_GetCurrentColumnNumber(XML_Parser p); 1957</pre> 1958<div class="fcndef"> 1959Return the offset, from the beginning of the current line, of 1960the position. 1961</div> 1962 1963<pre class="fcndec" id="XML_GetCurrentByteCount"> 1964int XMLCALL 1965XML_GetCurrentByteCount(XML_Parser p); 1966</pre> 1967<div class="fcndef"> 1968Return the number of bytes in the current event. Returns 1969<code>0</code> if the event is inside a reference to an internal 1970entity and for the end-tag event for empty element tags (the later can 1971be used to distinguish empty-element tags from empty elements using 1972separate start and end tags). 1973</div> 1974 1975<pre class="fcndec" id="XML_GetInputContext"> 1976const char * XMLCALL 1977XML_GetInputContext(XML_Parser p, 1978 int *offset, 1979 int *size); 1980</pre> 1981<div class="fcndef"> 1982 1983<p>Returns the parser's input buffer, sets the integer pointed at by 1984<code>offset</code> to the offset within this buffer of the current 1985parse position, and set the integer pointed at by <code>size</code> to 1986the size of the returned buffer.</p> 1987 1988<p>This should only be called from within a handler during an active 1989parse and the returned buffer should only be referred to from within 1990the handler that made the call. This input buffer contains the 1991untranslated bytes of the input.</p> 1992 1993<p>Only a limited amount of context is kept, so if the event 1994triggering a call spans over a very large amount of input, the actual 1995parse position may be before the beginning of the buffer.</p> 1996 1997<p>If <code>XML_CONTEXT_BYTES</code> is not defined, this will always 1998return NULL.</p> 1999</div> 2000 2001<h3><a name="miscellaneous">Miscellaneous functions</a></h3> 2002 2003<p>The functions in this section either obtain state information from 2004the parser or can be used to dynamically set parser options.</p> 2005 2006<pre class="fcndec" id="XML_SetUserData"> 2007void XMLCALL 2008XML_SetUserData(XML_Parser p, 2009 void *userData); 2010</pre> 2011<div class="fcndef"> 2012This sets the user data pointer that gets passed to handlers. It 2013overwrites any previous value for this pointer. Note that the 2014application is responsible for freeing the memory associated with 2015<code>userData</code> when it is finished with the parser. So if you 2016call this when there's already a pointer there, and you haven't freed 2017the memory associated with it, then you've probably just leaked 2018memory. 2019</div> 2020 2021<pre class="fcndec" id="XML_GetUserData"> 2022void * XMLCALL 2023XML_GetUserData(XML_Parser p); 2024</pre> 2025<div class="fcndef"> 2026This returns the user data pointer that gets passed to handlers. 2027It is actually implemented as a macro. 2028</div> 2029 2030<pre class="fcndec" id="XML_UseParserAsHandlerArg"> 2031void XMLCALL 2032XML_UseParserAsHandlerArg(XML_Parser p); 2033</pre> 2034<div class="fcndef"> 2035After this is called, handlers receive the parser in their 2036<code>userData</code> arguments. The user data can still be obtained 2037using the <code><a href= "#XML_GetUserData" 2038>XML_GetUserData</a></code> function. 2039</div> 2040 2041<pre class="fcndec" id="XML_SetBase"> 2042enum XML_Status XMLCALL 2043XML_SetBase(XML_Parser p, 2044 const XML_Char *base); 2045</pre> 2046<div class="fcndef"> 2047Set the base to be used for resolving relative URIs in system 2048identifiers. The return value is <code>XML_STATUS_ERROR</code> if 2049there's no memory to store base, otherwise it's 2050<code>XML_STATUS_OK</code>. 2051</div> 2052 2053<pre class="fcndec" id="XML_GetBase"> 2054const XML_Char * XMLCALL 2055XML_GetBase(XML_Parser p); 2056</pre> 2057<div class="fcndef"> 2058Return the base for resolving relative URIs. 2059</div> 2060 2061<pre class="fcndec" id="XML_GetSpecifiedAttributeCount"> 2062int XMLCALL 2063XML_GetSpecifiedAttributeCount(XML_Parser p); 2064</pre> 2065<div class="fcndef"> 2066When attributes are reported to the start handler in the atts vector, 2067attributes that were explicitly set in the element occur before any 2068attributes that receive their value from default information in an 2069ATTLIST declaration. This function returns the number of attributes 2070that were explicitly set times two, thus giving the offset in the 2071<code>atts</code> array passed to the start tag handler of the first 2072attribute set due to defaults. It supplies information for the last 2073call to a start handler. If called inside a start handler, then that 2074means the current call. 2075</div> 2076 2077<pre class="fcndec" id="XML_GetIdAttributeIndex"> 2078int XMLCALL 2079XML_GetIdAttributeIndex(XML_Parser p); 2080</pre> 2081<div class="fcndef"> 2082Returns the index of the ID attribute passed in the atts array in the 2083last call to <code><a href= "#XML_StartElementHandler" 2084>XML_StartElementHandler</a></code>, or -1 if there is no ID 2085attribute. If called inside a start handler, then that means the 2086current call. 2087</div> 2088 2089<pre class="fcndec" id="XML_GetAttributeInfo"> 2090const XML_AttrInfo * XMLCALL 2091XML_GetAttributeInfo(XML_Parser parser); 2092</pre> 2093<pre class="signature"> 2094typedef struct { 2095 XML_Index nameStart; /* Offset to beginning of the attribute name. */ 2096 XML_Index nameEnd; /* Offset after the attribute name's last byte. */ 2097 XML_Index valueStart; /* Offset to beginning of the attribute value. */ 2098 XML_Index valueEnd; /* Offset after the attribute value's last byte. */ 2099} XML_AttrInfo; 2100</pre> 2101<div class="fcndef"> 2102Returns an array of <code>XML_AttrInfo</code> structures for the 2103attribute/value pairs passed in the last call to the 2104<code>XML_StartElementHandler</code> that were specified 2105in the start-tag rather than defaulted. Each attribute/value pair counts 2106as 1; thus the number of entries in the array is 2107<code>XML_GetSpecifiedAttributeCount(parser) / 2</code>. 2108</div> 2109 2110<pre class="fcndec" id="XML_SetEncoding"> 2111enum XML_Status XMLCALL 2112XML_SetEncoding(XML_Parser p, 2113 const XML_Char *encoding); 2114</pre> 2115<div class="fcndef"> 2116Set the encoding to be used by the parser. It is equivalent to 2117passing a non-null encoding argument to the parser creation functions. 2118It must not be called after <code><a href= "#XML_Parse" 2119>XML_Parse</a></code> or <code><a href= "#XML_ParseBuffer" 2120>XML_ParseBuffer</a></code> have been called on the given parser. 2121Returns <code>XML_STATUS_OK</code> on success or 2122<code>XML_STATUS_ERROR</code> on error. 2123</div> 2124 2125<pre class="fcndec" id="XML_SetParamEntityParsing"> 2126int XMLCALL 2127XML_SetParamEntityParsing(XML_Parser p, 2128 enum XML_ParamEntityParsing code); 2129</pre> 2130<div class="fcndef"> 2131This enables parsing of parameter entities, including the external 2132parameter entity that is the external DTD subset, according to 2133<code>code</code>. 2134The choices for <code>code</code> are: 2135<ul> 2136<li><code>XML_PARAM_ENTITY_PARSING_NEVER</code></li> 2137<li><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></li> 2138<li><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></li> 2139</ul> 2140<b>Note:</b> If <code>XML_SetParamEntityParsing</code> is called after 2141<code>XML_Parse</code> or <code>XML_ParseBuffer</code>, then it has 2142no effect and will always return 0. 2143</div> 2144 2145<pre class="fcndec" id="XML_SetHashSalt"> 2146int XMLCALL 2147XML_SetHashSalt(XML_Parser p, 2148 unsigned long hash_salt); 2149</pre> 2150<div class="fcndef"> 2151Sets the hash salt to use for internal hash calculations. 2152Helps in preventing DoS attacks based on predicting hash 2153function behavior. In order to have an effect this must be called 2154before parsing has started. Returns 1 if successful, 0 when called 2155after <code>XML_Parse</code> or <code>XML_ParseBuffer</code>. 2156<p><b>Note:</b>This call is optional, as the parser will auto-generate 2157a new random salt value if no value has been set at the start of parsing.</p> 2158<p><b>Note:</b>One should not call <code>XML_SetHashSalt</code> with a 2159hash salt value of 0, as this value is used as sentinel value to indicate 2160that <code>XML_SetHashSalt</code> has <b>not</b> been called. Consequently 2161such a call will have no effect, even if it returns 1.</p> 2162</div> 2163 2164<pre class="fcndec" id="XML_UseForeignDTD"> 2165enum XML_Error XMLCALL 2166XML_UseForeignDTD(XML_Parser parser, XML_Bool useDTD); 2167</pre> 2168<div class="fcndef"> 2169<p>This function allows an application to provide an external subset 2170for the document type declaration for documents which do not specify 2171an external subset of their own. For documents which specify an 2172external subset in their DOCTYPE declaration, the application-provided 2173subset will be ignored. If the document does not contain a DOCTYPE 2174declaration at all and <code>useDTD</code> is true, the 2175application-provided subset will be parsed, but the 2176<code>startDoctypeDeclHandler</code> and 2177<code>endDoctypeDeclHandler</code> functions, if set, will not be 2178called. The setting of parameter entity parsing, controlled using 2179<code><a href= "#XML_SetParamEntityParsing" 2180>XML_SetParamEntityParsing</a></code>, will be honored.</p> 2181 2182<p>The application-provided external subset is read by calling the 2183external entity reference handler set via <code><a href= 2184"#XML_SetExternalEntityRefHandler" 2185>XML_SetExternalEntityRefHandler</a></code> with both 2186<code>publicId</code> and <code>systemId</code> set to NULL.</p> 2187 2188<p>If this function is called after parsing has begun, it returns 2189<code>XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING</code> and ignores 2190<code>useDTD</code>. If called when Expat has been compiled without 2191DTD support, it returns 2192<code>XML_ERROR_FEATURE_REQUIRES_XML_DTD</code>. Otherwise, it 2193returns <code>XML_ERROR_NONE</code>.</p> 2194 2195<p><b>Note:</b> For the purpose of checking WFC: Entity Declared, passing 2196<code>useDTD == XML_TRUE</code> will make the parser behave as if 2197the document had a DTD with an external subset. This holds true even if 2198the external entity reference handler returns without action.</p> 2199</div> 2200 2201<pre class="fcndec" id="XML_SetReturnNSTriplet"> 2202void XMLCALL 2203XML_SetReturnNSTriplet(XML_Parser parser, 2204 int do_nst); 2205</pre> 2206<div class="fcndef"> 2207<p> 2208This function only has an effect when using a parser created with 2209<code><a href= "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>, 2210i.e. when namespace processing is in effect. The <code>do_nst</code> 2211sets whether or not prefixes are returned with names qualified with a 2212namespace prefix. If this function is called with <code>do_nst</code> 2213non-zero, then afterwards namespace qualified names (that is qualified 2214with a prefix as opposed to belonging to a default namespace) are 2215returned as a triplet with the three parts separated by the namespace 2216separator specified when the parser was created. The order of 2217returned parts is URI, local name, and prefix.</p> <p>If 2218<code>do_nst</code> is zero, then namespaces are reported in the 2219default manner, URI then local_name separated by the namespace 2220separator.</p> 2221</div> 2222 2223<pre class="fcndec" id="XML_DefaultCurrent"> 2224void XMLCALL 2225XML_DefaultCurrent(XML_Parser parser); 2226</pre> 2227<div class="fcndef"> 2228This can be called within a handler for a start element, end element, 2229processing instruction or character data. It causes the corresponding 2230markup to be passed to the default handler set by <code><a 2231href="#XML_SetDefaultHandler" >XML_SetDefaultHandler</a></code> or 2232<code><a href="#XML_SetDefaultHandlerExpand" 2233>XML_SetDefaultHandlerExpand</a></code>. It does nothing if there is 2234not a default handler. 2235</div> 2236 2237<pre class="fcndec" id="XML_ExpatVersion"> 2238XML_LChar * XMLCALL 2239XML_ExpatVersion(); 2240</pre> 2241<div class="fcndef"> 2242Return the library version as a string (e.g. <code>"expat_1.95.1"</code>). 2243</div> 2244 2245<pre class="fcndec" id="XML_ExpatVersionInfo"> 2246struct XML_Expat_Version XMLCALL 2247XML_ExpatVersionInfo(); 2248</pre> 2249<pre class="signature"> 2250typedef struct { 2251 int major; 2252 int minor; 2253 int micro; 2254} XML_Expat_Version; 2255</pre> 2256<div class="fcndef"> 2257Return the library version information as a structure. 2258Some macros are also defined that support compile-time tests of the 2259library version: 2260<ul> 2261<li><code>XML_MAJOR_VERSION</code></li> 2262<li><code>XML_MINOR_VERSION</code></li> 2263<li><code>XML_MICRO_VERSION</code></li> 2264</ul> 2265Testing these constants is currently the best way to determine if 2266particular parts of the Expat API are available. 2267</div> 2268 2269<pre class="fcndec" id="XML_GetFeatureList"> 2270const XML_Feature * XMLCALL 2271XML_GetFeatureList(); 2272</pre> 2273<pre class="signature"> 2274enum XML_FeatureEnum { 2275 XML_FEATURE_END = 0, 2276 XML_FEATURE_UNICODE, 2277 XML_FEATURE_UNICODE_WCHAR_T, 2278 XML_FEATURE_DTD, 2279 XML_FEATURE_CONTEXT_BYTES, 2280 XML_FEATURE_MIN_SIZE, 2281 XML_FEATURE_SIZEOF_XML_CHAR, 2282 XML_FEATURE_SIZEOF_XML_LCHAR, 2283 XML_FEATURE_NS, 2284 XML_FEATURE_LARGE_SIZE 2285}; 2286 2287typedef struct { 2288 enum XML_FeatureEnum feature; 2289 XML_LChar *name; 2290 long int value; 2291} XML_Feature; 2292</pre> 2293<div class="fcndef"> 2294<p>Returns a list of "feature" records, providing details on how 2295Expat was configured at compile time. Most applications should not 2296need to worry about this, but this information is otherwise not 2297available from Expat. This function allows code that does need to 2298check these features to do so at runtime.</p> 2299 2300<p>The return value is an array of <code>XML_Feature</code>, 2301terminated by a record with a <code>feature</code> of 2302<code>XML_FEATURE_END</code> and <code>name</code> of NULL, 2303identifying the feature-test macros Expat was compiled with. Since an 2304application that requires this kind of information needs to determine 2305the type of character the <code>name</code> points to, records for the 2306<code>XML_FEATURE_SIZEOF_XML_CHAR</code> and 2307<code>XML_FEATURE_SIZEOF_XML_LCHAR</code> will be located at the 2308beginning of the list, followed by <code>XML_FEATURE_UNICODE</code> 2309and <code>XML_FEATURE_UNICODE_WCHAR_T</code>, if they are present at 2310all.</p> 2311 2312<p>Some features have an associated value. If there isn't an 2313associated value, the <code>value</code> field is set to 0. At this 2314time, the following features have been defined to have values:</p> 2315 2316<dl> 2317 <dt><code>XML_FEATURE_SIZEOF_XML_CHAR</code></dt> 2318 <dd>The number of bytes occupied by one <code>XML_Char</code> 2319 character.</dd> 2320 <dt><code>XML_FEATURE_SIZEOF_XML_LCHAR</code></dt> 2321 <dd>The number of bytes occupied by one <code>XML_LChar</code> 2322 character.</dd> 2323 <dt><code>XML_FEATURE_CONTEXT_BYTES</code></dt> 2324 <dd>The maximum number of characters of context which can be 2325 reported by <code><a href= "#XML_GetInputContext" 2326 >XML_GetInputContext</a></code>.</dd> 2327</dl> 2328</div> 2329 2330<pre class="fcndec" id="XML_FreeContentModel"> 2331void XMLCALL 2332XML_FreeContentModel(XML_Parser parser, XML_Content *model); 2333</pre> 2334<div class="fcndef"> 2335Function to deallocate the <code>model</code> argument passed to the 2336<code>XML_ElementDeclHandler</code> callback set using <code><a 2337href="#XML_SetElementDeclHandler" >XML_ElementDeclHandler</a></code>. 2338This function should not be used for any other purpose. 2339</div> 2340 2341<p>The following functions allow external code to share the memory 2342allocator an <code>XML_Parser</code> has been configured to use. This 2343is especially useful for third-party libraries that interact with a 2344parser object created by application code, or heavily layered 2345applications. This can be essential when using dynamically loaded 2346libraries which use different C standard libraries (this can happen on 2347Windows, at least).</p> 2348 2349<pre class="fcndec" id="XML_MemMalloc"> 2350void * XMLCALL 2351XML_MemMalloc(XML_Parser parser, size_t size); 2352</pre> 2353<div class="fcndef"> 2354Allocate <code>size</code> bytes of memory using the allocator the 2355<code>parser</code> object has been configured to use. Returns a 2356pointer to the memory or NULL on failure. Memory allocated in this 2357way must be freed using <code><a href="#XML_MemFree" 2358>XML_MemFree</a></code>. 2359</div> 2360 2361<pre class="fcndec" id="XML_MemRealloc"> 2362void * XMLCALL 2363XML_MemRealloc(XML_Parser parser, void *ptr, size_t size); 2364</pre> 2365<div class="fcndef"> 2366Allocate <code>size</code> bytes of memory using the allocator the 2367<code>parser</code> object has been configured to use. 2368<code>ptr</code> must point to a block of memory allocated by <code><a 2369href="#XML_MemMalloc" >XML_MemMalloc</a></code> or 2370<code>XML_MemRealloc</code>, or be NULL. This function tries to 2371expand the block pointed to by <code>ptr</code> if possible. Returns 2372a pointer to the memory or NULL on failure. On success, the original 2373block has either been expanded or freed. On failure, the original 2374block has not been freed; the caller is responsible for freeing the 2375original block. Memory allocated in this way must be freed using 2376<code><a href="#XML_MemFree" 2377>XML_MemFree</a></code>. 2378</div> 2379 2380<pre class="fcndec" id="XML_MemFree"> 2381void XMLCALL 2382XML_MemFree(XML_Parser parser, void *ptr); 2383</pre> 2384<div class="fcndef"> 2385Free a block of memory pointed to by <code>ptr</code>. The block must 2386have been allocated by <code><a href="#XML_MemMalloc" 2387>XML_MemMalloc</a></code> or <code>XML_MemRealloc</code>, or be NULL. 2388</div> 2389 2390<hr /> 2391<p><a href="http://validator.w3.org/check/referer"><img 2392 src="valid-xhtml10.png" alt="Valid XHTML 1.0!" 2393 height="31" width="88" class="noborder" /></a></p> 2394</div> 2395</body> 2396</html> 2397
