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 2.0.0</td> 23 <td></td> 24 </tr> 25 </table> 26<div class="content"> 27 28<p>Expat is a library, written in C, for parsing XML documents. It's 29the underlying XML parser for the open source Mozilla project, Perl's 30<code>XML::Parser</code>, Python's <code>xml.parsers.expat</code>, and 31other open-source XML parsers.</p> 32 33<p>This library is the creation of James Clark, who's also given us 34groff (an nroff look-alike), Jade (an implemention of ISO's DSSSL 35stylesheet language for SGML), XP (a Java XML parser package), XT (a 36Java XSL engine). James was also the technical lead on the XML 37Working Group at W3C that produced the XML specification.</p> 38 39<p>This is free software, licensed under the <a 40href="../COPYING">MIT/X Consortium license</a>. You may download it 41from <a href="http://www.libexpat.org/">the Expat home page</a>. 42</p> 43 44<p>The bulk of this document was originally commissioned as an article 45by <a href="http://www.xml.com/">XML.com</a>. They graciously allowed 46Clark Cooper to retain copyright and to distribute it with Expat. 47This version has been substantially extended to include documentation 48on features which have been added since the original article was 49published, and additional information on using the original 50interface.</p> 51 52<hr /> 53<h2>Table of Contents</h2> 54<ul> 55 <li><a href="#overview">Overview</a></li> 56 <li><a href="#building">Building and Installing</a></li> 57 <li><a href="#using">Using Expat</a></li> 58 <li><a href="#reference">Reference</a> 59 <ul> 60 <li><a href="#creation">Parser Creation Functions</a> 61 <ul> 62 <li><a href="#XML_ParserCreate">XML_ParserCreate</a></li> 63 <li><a href="#XML_ParserCreateNS">XML_ParserCreateNS</a></li> 64 <li><a href="#XML_ParserCreate_MM">XML_ParserCreate_MM</a></li> 65 <li><a href="#XML_ExternalEntityParserCreate">XML_ExternalEntityParserCreate</a></li> 66 <li><a href="#XML_ParserFree">XML_ParserFree</a></li> 67 <li><a href="#XML_ParserReset">XML_ParserReset</a></li> 68 </ul> 69 </li> 70 <li><a href="#parsing">Parsing Functions</a> 71 <ul> 72 <li><a href="#XML_Parse">XML_Parse</a></li> 73 <li><a href="#XML_ParseBuffer">XML_ParseBuffer</a></li> 74 <li><a href="#XML_GetBuffer">XML_GetBuffer</a></li> 75 <li><a href="#XML_StopParser">XML_StopParser</a></li> 76 <li><a href="#XML_ResumeParser">XML_ResumeParser</a></li> 77 <li><a href="#XML_GetParsingStatus">XML_GetParsingStatus</a></li> 78 </ul> 79 </li> 80 <li><a href="#setting">Handler Setting Functions</a> 81 <ul> 82 <li><a href="#XML_SetStartElementHandler">XML_SetStartElementHandler</a></li> 83 <li><a href="#XML_SetEndElementHandler">XML_SetEndElementHandler</a></li> 84 <li><a href="#XML_SetElementHandler">XML_SetElementHandler</a></li> 85 <li><a href="#XML_SetCharacterDataHandler">XML_SetCharacterDataHandler</a></li> 86 <li><a href="#XML_SetProcessingInstructionHandler">XML_SetProcessingInstructionHandler</a></li> 87 <li><a href="#XML_SetCommentHandler">XML_SetCommentHandler</a></li> 88 <li><a href="#XML_SetStartCdataSectionHandler">XML_SetStartCdataSectionHandler</a></li> 89 <li><a href="#XML_SetEndCdataSectionHandler">XML_SetEndCdataSectionHandler</a></li> 90 <li><a href="#XML_SetCdataSectionHandler">XML_SetCdataSectionHandler</a></li> 91 <li><a href="#XML_SetDefaultHandler">XML_SetDefaultHandler</a></li> 92 <li><a href="#XML_SetDefaultHandlerExpand">XML_SetDefaultHandlerExpand</a></li> 93 <li><a href="#XML_SetExternalEntityRefHandler">XML_SetExternalEntityRefHandler</a></li> 94 <li><a href="#XML_SetExternalEntityRefHandlerArg">XML_SetExternalEntityRefHandlerArg</a></li> 95 <li><a href="#XML_SetSkippedEntityHandler">XML_SetSkippedEntityHandler</a></li> 96 <li><a href="#XML_SetUnknownEncodingHandler">XML_SetUnknownEncodingHandler</a></li> 97 <li><a href="#XML_SetStartNamespaceDeclHandler">XML_SetStartNamespaceDeclHandler</a></li> 98 <li><a href="#XML_SetEndNamespaceDeclHandler">XML_SetEndNamespaceDeclHandler</a></li> 99 <li><a href="#XML_SetNamespaceDeclHandler">XML_SetNamespaceDeclHandler</a></li> 100 <li><a href="#XML_SetXmlDeclHandler">XML_SetXmlDeclHandler</a></li> 101 <li><a href="#XML_SetStartDoctypeDeclHandler">XML_SetStartDoctypeDeclHandler</a></li> 102 <li><a href="#XML_SetEndDoctypeDeclHandler">XML_SetEndDoctypeDeclHandler</a></li> 103 <li><a href="#XML_SetDoctypeDeclHandler">XML_SetDoctypeDeclHandler</a></li> 104 <li><a href="#XML_SetElementDeclHandler">XML_SetElementDeclHandler</a></li> 105 <li><a href="#XML_SetAttlistDeclHandler">XML_SetAttlistDeclHandler</a></li> 106 <li><a href="#XML_SetEntityDeclHandler">XML_SetEntityDeclHandler</a></li> 107 <li><a href="#XML_SetUnparsedEntityDeclHandler">XML_SetUnparsedEntityDeclHandler</a></li> 108 <li><a href="#XML_SetNotationDeclHandler">XML_SetNotationDeclHandler</a></li> 109 <li><a href="#XML_SetNotStandaloneHandler">XML_SetNotStandaloneHandler</a></li> 110 </ul> 111 </li> 112 <li><a href="#position">Parse Position and Error Reporting Functions</a> 113 <ul> 114 <li><a href="#XML_GetErrorCode">XML_GetErrorCode</a></li> 115 <li><a href="#XML_ErrorString">XML_ErrorString</a></li> 116 <li><a href="#XML_GetCurrentByteIndex">XML_GetCurrentByteIndex</a></li> 117 <li><a href="#XML_GetCurrentLineNumber">XML_GetCurrentLineNumber</a></li> 118 <li><a href="#XML_GetCurrentColumnNumber">XML_GetCurrentColumnNumber</a></li> 119 <li><a href="#XML_GetCurrentByteCount">XML_GetCurrentByteCount</a></li> 120 <li><a href="#XML_GetInputContext">XML_GetInputContext</a></li> 121 </ul> 122 </li> 123 <li><a href="#miscellaneous">Miscellaneous Functions</a> 124 <ul> 125 <li><a href="#XML_SetUserData">XML_SetUserData</a></li> 126 <li><a href="#XML_GetUserData">XML_GetUserData</a></li> 127 <li><a href="#XML_UseParserAsHandlerArg">XML_UseParserAsHandlerArg</a></li> 128 <li><a href="#XML_SetBase">XML_SetBase</a></li> 129 <li><a href="#XML_GetBase">XML_GetBase</a></li> 130 <li><a href="#XML_GetSpecifiedAttributeCount">XML_GetSpecifiedAttributeCount</a></li> 131 <li><a href="#XML_GetIdAttributeIndex">XML_GetIdAttributeIndex</a></li> 132 <li><a href="#XML_SetEncoding">XML_SetEncoding</a></li> 133 <li><a href="#XML_SetParamEntityParsing">XML_SetParamEntityParsing</a></li> 134 <li><a href="#XML_UseForeignDTD">XML_UseForeignDTD</a></li> 135 <li><a href="#XML_SetReturnNSTriplet">XML_SetReturnNSTriplet</a></li> 136 <li><a href="#XML_DefaultCurrent">XML_DefaultCurrent</a></li> 137 <li><a href="#XML_ExpatVersion">XML_ExpatVersion</a></li> 138 <li><a href="#XML_ExpatVersionInfo">XML_ExpatVersionInfo</a></li> 139 <li><a href="#XML_GetFeatureList">XML_GetFeatureList</a></li> 140 <li><a href="#XML_FreeContentModel">XML_FreeContentModel</a></li> 141 <li><a href="#XML_MemMalloc">XML_MemMalloc</a></li> 142 <li><a href="#XML_MemRealloc">XML_MemRealloc</a></li> 143 <li><a href="#XML_MemFree">XML_MemFree</a></li> 144 </ul> 145 </li> 146 </ul> 147 </li> 148</ul> 149 150<hr /> 151<h2><a name="overview">Overview</a></h2> 152 153<p>Expat is a stream-oriented parser. You register callback (or 154handler) functions with the parser and then start feeding it the 155document. As the parser recognizes parts of the document, it will 156call the appropriate handler for that part (if you've registered one.) 157The document is fed to the parser in pieces, so you can start parsing 158before you have all the document. This also allows you to parse really 159huge documents that won't fit into memory.</p> 160 161<p>Expat can be intimidating due to the many kinds of handlers and 162options you can set. But you only need to learn four functions in 163order to do 90% of what you'll want to do with it:</p> 164 165<dl> 166 167<dt><code><a href= "#XML_ParserCreate" 168 >XML_ParserCreate</a></code></dt> 169 <dd>Create a new parser object.</dd> 170 171<dt><code><a href= "#XML_SetElementHandler" 172 >XML_SetElementHandler</a></code></dt> 173 <dd>Set handlers for start and end tags.</dd> 174 175<dt><code><a href= "#XML_SetCharacterDataHandler" 176 >XML_SetCharacterDataHandler</a></code></dt> 177 <dd>Set handler for text.</dd> 178 179<dt><code><a href= "#XML_Parse" 180 >XML_Parse</a></code></dt> 181 <dd>Pass a buffer full of document to the parser</dd> 182</dl> 183 184<p>These functions and others are described in the <a 185href="#reference">reference</a> part of this document. The reference 186section also describes in detail the parameters passed to the 187different types of handlers.</p> 188 189<p>Let's look at a very simple example program that only uses 3 of the 190above functions (it doesn't need to set a character handler.) The 191program <a href="../examples/outline.c">outline.c</a> prints an 192element outline, indenting child elements to distinguish them from the 193parent element that contains them. The start handler does all the 194work. It prints two indenting spaces for every level of ancestor 195elements, then it prints the element and attribute 196information. Finally it increments the global <code>Depth</code> 197variable.</p> 198 199<pre class="eg"> 200int Depth; 201 202void XMLCALL 203start(void *data, const char *el, const char **attr) { 204 int i; 205 206 for (i = 0; i < Depth; i++) 207 printf(" "); 208 209 printf("%s", el); 210 211 for (i = 0; attr[i]; i += 2) { 212 printf(" %s='%s'", attr[i], attr[i + 1]); 213 } 214 215 printf("\n"); 216 Depth++; 217} /* End of start handler */ 218</pre> 219 220<p>The end tag simply does the bookkeeping work of decrementing 221<code>Depth</code>.</p> 222<pre class="eg"> 223void XMLCALL 224end(void *data, const char *el) { 225 Depth--; 226} /* End of end handler */ 227</pre> 228 229<p>Note the <code>XMLCALL</code> annotation used for the callbacks. 230This is used to ensure that the Expat and the callbacks are using the 231same calling convention in case the compiler options used for Expat 232itself and the client code are different. Expat tries not to care 233what the default calling convention is, though it may require that it 234be compiled with a default convention of "cdecl" on some platforms. 235For code which uses Expat, however, the calling convention is 236specified by the <code>XMLCALL</code> annotation on most platforms; 237callbacks should be defined using this annotation.</p> 238 239<p>The <code>XMLCALL</code> annotation was added in Expat 1.95.7, but 240existing working Expat applications don't need to add it (since they 241are already using the "cdecl" calling convention, or they wouldn't be 242working). The annotation is only needed if the default calling 243convention may be something other than "cdecl". To use the annotation 244safely with older versions of Expat, you can conditionally define it 245<em>after</em> including Expat's header file:</p> 246 247<pre class="eg"> 248#include <expat.h> 249 250#ifndef XMLCALL 251#if defined(_MSC_EXTENSIONS) && !defined(__BEOS__) && !defined(__CYGWIN__) 252#define XMLCALL __cdecl 253#elif defined(__GNUC__) 254#define XMLCALL __attribute__((cdecl)) 255#else 256#define XMLCALL 257#endif 258#endif 259</pre> 260 261<p>After creating the parser, the main program just has the job of 262shoveling the document to the parser so that it can do its work.</p> 263 264<hr /> 265<h2><a name="building">Building and Installing Expat</a></h2> 266 267<p>The Expat distribution comes as a compressed (with GNU gzip) tar 268file. You may download the latest version from <a href= 269"http://sourceforge.net/projects/expat/" >Source Forge</a>. After 270unpacking this, cd into the directory. Then follow either the Win32 271directions or Unix directions below.</p> 272 273<h3>Building under Win32</h3> 274 275<p>If you're using the GNU compiler under cygwin, follow the Unix 276directions in the next section. Otherwise if you have Microsoft's 277Developer Studio installed, then from Windows Explorer double-click on 278"expat.dsp" in the lib directory and build and install in the usual 279manner.</p> 280 281<p>Alternatively, you may download the Win32 binary package that 282contains the "expat.h" include file and a pre-built DLL.</p> 283 284<h3>Building under Unix (or GNU)</h3> 285 286<p>First you'll need to run the configure shell script in order to 287configure the Makefiles and headers for your system.</p> 288 289<p>If you're happy with all the defaults that configure picks for you, 290and you have permission on your system to install into /usr/local, you 291can install Expat with this sequence of commands:</p> 292 293<pre class="eg"> 294./configure 295make 296make install 297</pre> 298 299<p>There are some options that you can provide to this script, but the 300only one we'll mention here is the <code>--prefix</code> option. You 301can find out all the options available by running configure with just 302the <code>--help</code> option.</p> 303 304<p>By default, the configure script sets things up so that the library 305gets installed in <code>/usr/local/lib</code> and the associated 306header file in <code>/usr/local/include</code>. But if you were to 307give the option, <code>--prefix=/home/me/mystuff</code>, then the 308library and header would get installed in 309<code>/home/me/mystuff/lib</code> and 310<code>/home/me/mystuff/include</code> respectively.</p> 311 312<h3>Configuring Expat Using the Pre-Processor</h3> 313 314<p>Expat's feature set can be configured using a small number of 315pre-processor definitions. The definition of this symbols does not 316affect the set of entry points for Expat, only the behavior of the API 317and the definition of character types in the case of 318<code>XML_UNICODE_WCHAR_T</code>. The symbols are:</p> 319 320<dl class="cpp-symbols"> 321<dt>XML_DTD</dt> 322<dd>Include support for using and reporting DTD-based content. If 323this is defined, default attribute values from an external DTD subset 324are reported and attribute value normalization occurs based on the 325type of attributes defined in the external subset. Without 326this, Expat has a smaller memory footprint and can be faster, but will 327not load external entities or process conditional sections. This does 328not affect the set of functions available in the API.</dd> 329 330<dt>XML_NS</dt> 331<dd>When defined, support for the <cite><a href= 332"http://www.w3.org/TR/REC-xml-names/" >Namespaces in XML</a></cite> 333specification is included.</dd> 334 335<dt>XML_UNICODE</dt> 336<dd>When defined, character data reported to the application is 337encoded in UTF-16 using wide characters of the type 338<code>XML_Char</code>. This is implied if 339<code>XML_UNICODE_WCHAR_T</code> is defined.</dd> 340 341<dt>XML_UNICODE_WCHAR_T</dt> 342<dd>If defined, causes the <code>XML_Char</code> character type to be 343defined using the <code>wchar_t</code> type; otherwise, <code>unsigned 344short</code> is used. Defining this implies 345<code>XML_UNICODE</code>.</dd> 346 347<dt>XML_LARGE_SIZE</dt> 348<dd>If defined, causes the <code>XML_Size</code> and <code>XML_Index</code> 349integer types to be at least 64 bits in size. This is intended to support 350processing of very large input streams, where the return values of 351<code><a href="#XML_GetCurrentByteIndex" >XML_GetCurrentByteIndex</a></code>, 352<code><a href="#XML_GetCurrentLineNumber" >XML_GetCurrentLineNumber</a></code> and 353<code><a href="#XML_GetCurrentColumnNumber" >XML_GetCurrentColumnNumber</a></code> 354could overflow. It may not be supported by all compilers, and is turned 355off by default.</dd> 356 357<dt>XML_CONTEXT_BYTES</dt> 358<dd>The number of input bytes of markup context which the parser will 359ensure are available for reporting via <code><a href= 360"#XML_GetInputContext" >XML_GetInputContext</a></code>. This is 361normally set to 1024, and must be set to a positive interger. If this 362is not defined, the input context will not be available and <code><a 363href= "#XML_GetInputContext" >XML_GetInputContext</a></code> will 364always report NULL. Without this, Expat has a smaller memory 365footprint and can be faster.</dd> 366 367<dt>XML_STATIC</dt> 368<dd>On Windows, this should be set if Expat is going to be linked 369statically with the code that calls it; this is required to get all 370the right MSVC magic annotations correct. This is ignored on other 371platforms.</dd> 372</dl> 373 374<hr /> 375<h2><a name="using">Using Expat</a></h2> 376 377<h3>Compiling and Linking Against Expat</h3> 378 379<p>Unless you installed Expat in a location not expected by your 380compiler and linker, all you have to do to use Expat in your programs 381is to include the Expat header (<code>#include <expat.h></code>) 382in your files that make calls to it and to tell the linker that it 383needs to link against the Expat library. On Unix systems, this would 384usually be done with the <code>-lexpat</code> argument. Otherwise, 385you'll need to tell the compiler where to look for the Expat header 386and the linker where to find the Expat library. You may also need to 387take steps to tell the operating system where to find this libary at 388run time.</p> 389 390<p>On a Unix-based system, here's what a Makefile might look like when 391Expat is installed in a standard location:</p> 392 393<pre class="eg"> 394CC=cc 395LDFLAGS= 396LIBS= -lexpat 397xmlapp: xmlapp.o 398 $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS) 399</pre> 400 401<p>If you installed Expat in, say, <code>/home/me/mystuff</code>, then 402the Makefile would look like this:</p> 403 404<pre class="eg"> 405CC=cc 406CFLAGS= -I/home/me/mystuff/include 407LDFLAGS= 408LIBS= -L/home/me/mystuff/lib -lexpat 409xmlapp: xmlapp.o 410 $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS) 411</pre> 412 413<p>You'd also have to set the environment variable 414<code>LD_LIBRARY_PATH</code> to <code>/home/me/mystuff/lib</code> (or 415to <code>${LD_LIBRARY_PATH}:/home/me/mystuff/lib</code> if 416LD_LIBRARY_PATH already has some directories in it) in order to run 417your application.</p> 418 419<h3>Expat Basics</h3> 420 421<p>As we saw in the example in the overview, the first step in parsing 422an XML document with Expat is to create a parser object. There are <a 423href="#creation">three functions</a> in the Expat API for creating a 424parser object. However, only two of these (<code><a href= 425"#XML_ParserCreate" >XML_ParserCreate</a></code> and <code><a href= 426"#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>) can be used for 427constructing a parser for a top-level document. The object returned 428by these functions is an opaque pointer (i.e. "expat.h" declares it as 429void *) to data with further internal structure. In order to free the 430memory associated with this object you must call <code><a href= 431"#XML_ParserFree" >XML_ParserFree</a></code>. Note that if you have 432provided any <a href="#userdata">user data</a> that gets stored in the 433parser, then your application is responsible for freeing it prior to 434calling <code>XML_ParserFree</code>.</p> 435 436<p>The objects returned by the parser creation functions are good for 437parsing only one XML document or external parsed entity. If your 438application needs to parse many XML documents, then it needs to create 439a parser object for each one. The best way to deal with this is to 440create a higher level object that contains all the default 441initialization you want for your parser objects.</p> 442 443<p>Walking through a document hierarchy with a stream oriented parser 444will require a good stack mechanism in order to keep track of current 445context. For instance, to answer the simple question, "What element 446does this text belong to?" requires a stack, since the parser may have 447descended into other elements that are children of the current one and 448has encountered this text on the way out.</p> 449 450<p>The things you're likely to want to keep on a stack are the 451currently opened element and it's attributes. You push this 452information onto the stack in the start handler and you pop it off in 453the end handler.</p> 454 455<p>For some tasks, it is sufficient to just keep information on what 456the depth of the stack is (or would be if you had one.) The outline 457program shown above presents one example. Another such task would be 458skipping over a complete element. When you see the start tag for the 459element you want to skip, you set a skip flag and record the depth at 460which the element started. When the end tag handler encounters the 461same depth, the skipped element has ended and the flag may be 462cleared. If you follow the convention that the root element starts at 4631, then you can use the same variable for skip flag and skip 464depth.</p> 465 466<pre class="eg"> 467void 468init_info(Parseinfo *info) { 469 info->skip = 0; 470 info->depth = 1; 471 /* Other initializations here */ 472} /* End of init_info */ 473 474void XMLCALL 475rawstart(void *data, const char *el, const char **attr) { 476 Parseinfo *inf = (Parseinfo *) data; 477 478 if (! inf->skip) { 479 if (should_skip(inf, el, attr)) { 480 inf->skip = inf->depth; 481 } 482 else 483 start(inf, el, attr); /* This does rest of start handling */ 484 } 485 486 inf->depth++; 487} /* End of rawstart */ 488 489void XMLCALL 490rawend(void *data, const char *el) { 491 Parseinfo *inf = (Parseinfo *) data; 492 493 inf->depth--; 494 495 if (! inf->skip) 496 end(inf, el); /* This does rest of end handling */ 497 498 if (inf->skip == inf->depth) 499 inf->skip = 0; 500} /* End rawend */ 501</pre> 502 503<p>Notice in the above example the difference in how depth is 504manipulated in the start and end handlers. The end tag handler should 505be the mirror image of the start tag handler. This is necessary to 506properly model containment. Since, in the start tag handler, we 507incremented depth <em>after</em> the main body of start tag code, then 508in the end handler, we need to manipulate it <em>before</em> the main 509body. If we'd decided to increment it first thing in the start 510handler, then we'd have had to decrement it last thing in the end 511handler.</p> 512 513<h3 id="userdata">Communicating between handlers</h3> 514 515<p>In order to be able to pass information between different handlers 516without using globals, you'll need to define a data structure to hold 517the shared variables. You can then tell Expat (with the <code><a href= 518"#XML_SetUserData" >XML_SetUserData</a></code> function) to pass a 519pointer to this structure to the handlers. This is the first 520argument received by most handlers. In the <a href="#reference" 521>reference section</a>, an argument to a callback function is named 522<code>userData</code> and have type <code>void *</code> if the user 523data is passed; it will have the type <code>XML_Parser</code> if the 524parser itself is passed. When the parser is passed, the user data may 525be retrieved using <code><a href="#XML_GetUserData" 526>XML_GetUserData</a></code>.</p> 527 528<p>One common case where multiple calls to a single handler may need 529to communicate using an application data structure is the case when 530content passed to the character data handler (set by <code><a href= 531"#XML_SetCharacterDataHandler" 532>XML_SetCharacterDataHandler</a></code>) needs to be accumulated. A 533common first-time mistake with any of the event-oriented interfaces to 534an XML parser is to expect all the text contained in an element to be 535reported by a single call to the character data handler. Expat, like 536many other XML parsers, reports such data as a sequence of calls; 537there's no way to know when the end of the sequence is reached until a 538different callback is made. A buffer referenced by the user data 539structure proves both an effective and convenient place to accumulate 540character data.</p> 541 542<!-- XXX example needed here --> 543 544 545<h3>XML Version</h3> 546 547<p>Expat is an XML 1.0 parser, and as such never complains based on 548the value of the <code>version</code> pseudo-attribute in the XML 549declaration, if present.</p> 550 551<p>If an application needs to check the version number (to support 552alternate processing), it should use the <code><a href= 553"#XML_SetXmlDeclHandler" >XML_SetXmlDeclHandler</a></code> function to 554set a handler that uses the information in the XML declaration to 555determine what to do. This example shows how to check that only a 556version number of <code>"1.0"</code> is accepted:</p> 557 558<pre class="eg"> 559static int wrong_version; 560static XML_Parser parser; 561 562static void XMLCALL 563xmldecl_handler(void *userData, 564 const XML_Char *version, 565 const XML_Char *encoding, 566 int standalone) 567{ 568 static const XML_Char Version_1_0[] = {'1', '.', '0', 0}; 569 570 int i; 571 572 for (i = 0; i < (sizeof(Version_1_0) / sizeof(Version_1_0[0])); ++i) { 573 if (version[i] != Version_1_0[i]) { 574 wrong_version = 1; 575 /* also clear all other handlers: */ 576 XML_SetCharacterDataHandler(parser, NULL); 577 ... 578 return; 579 } 580 } 581 ... 582} 583</pre> 584 585<h3>Namespace Processing</h3> 586 587<p>When the parser is created using the <code><a href= 588"#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>, function, Expat 589performs namespace processing. Under namespace processing, Expat 590consumes <code>xmlns</code> and <code>xmlns:...</code> attributes, 591which declare namespaces for the scope of the element in which they 592occur. This means that your start handler will not see these 593attributes. Your application can still be informed of these 594declarations by setting namespace declaration handlers with <a href= 595"#XML_SetNamespaceDeclHandler" 596><code>XML_SetNamespaceDeclHandler</code></a>.</p> 597 598<p>Element type and attribute names that belong to a given namespace 599are passed to the appropriate handler in expanded form. By default 600this expanded form is a concatenation of the namespace URI, the 601separator character (which is the 2nd argument to <code><a href= 602"#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>), and the local 603name (i.e. the part after the colon). Names with undeclared prefixes 604are not well-formed when namespace processing is enabled, and will 605trigger an error. Unprefixed attribute names are never expanded, 606and unprefixed element names are only expanded when they are in the 607scope of a default namespace.</p> 608 609<p>However if <code><a href= "#XML_SetReturnNSTriplet" 610>XML_SetReturnNSTriplet</a></code> has been called with a non-zero 611<code>do_nst</code> parameter, then the expanded form for names with 612an explicit prefix is a concatenation of: URI, separator, local name, 613separator, prefix.</p> 614 615<p>You can set handlers for the start of a namespace declaration and 616for the end of a scope of a declaration with the <code><a href= 617"#XML_SetNamespaceDeclHandler" >XML_SetNamespaceDeclHandler</a></code> 618function. The StartNamespaceDeclHandler is called prior to the start 619tag handler and the EndNamespaceDeclHandler is called after the 620corresponding end tag that ends the namespace's scope. The namespace 621start handler gets passed the prefix and URI for the namespace. For a 622default namespace declaration (xmlns='...'), the prefix will be null. 623The URI will be null for the case where the default namespace is being 624unset. The namespace end handler just gets the prefix for the closing 625scope.</p> 626 627<p>These handlers are called for each declaration. So if, for 628instance, a start tag had three namespace declarations, then the 629StartNamespaceDeclHandler would be called three times before the start 630tag handler is called, once for each declaration.</p> 631 632<h3>Character Encodings</h3> 633 634<p>While XML is based on Unicode, and every XML processor is required 635to recognized UTF-8 and UTF-16 (1 and 2 byte encodings of Unicode), 636other encodings may be declared in XML documents or entities. For the 637main document, an XML declaration may contain an encoding 638declaration:</p> 639<pre> 640<?xml version="1.0" encoding="ISO-8859-2"?> 641</pre> 642 643<p>External parsed entities may begin with a text declaration, which 644looks like an XML declaration with just an encoding declaration:</p> 645<pre> 646<?xml encoding="Big5"?> 647</pre> 648 649<p>With Expat, you may also specify an encoding at the time of 650creating a parser. This is useful when the encoding information may 651come from a source outside the document itself (like a higher level 652protocol.)</p> 653 654<p><a name="builtin_encodings"></a>There are four built-in encodings 655in Expat:</p> 656<ul> 657<li>UTF-8</li> 658<li>UTF-16</li> 659<li>ISO-8859-1</li> 660<li>US-ASCII</li> 661</ul> 662 663<p>Anything else discovered in an encoding declaration or in the 664protocol encoding specified in the parser constructor, triggers a call 665to the <code>UnknownEncodingHandler</code>. This handler gets passed 666the encoding name and a pointer to an <code>XML_Encoding</code> data 667structure. Your handler must fill in this structure and return 668<code>XML_STATUS_OK</code> if it knows how to deal with the 669encoding. Otherwise the handler should return 670<code>XML_STATUS_ERROR</code>. The handler also gets passed a pointer 671to an optional application data structure that you may indicate when 672you set the handler.</p> 673 674<p>Expat places restrictions on character encodings that it can 675support by filling in the <code>XML_Encoding</code> structure. 676include file:</p> 677<ol> 678<li>Every ASCII character that can appear in a well-formed XML document 679must be represented by a single byte, and that byte must correspond to 680it's ASCII encoding (except for the characters $@\^'{}~)</li> 681<li>Characters must be encoded in 4 bytes or less.</li> 682<li>All characters encoded must have Unicode scalar values less than or 683equal to 65535 (0xFFFF)<em>This does not apply to the built-in support 684for UTF-16 and UTF-8</em></li> 685<li>No character may be encoded by more that one distinct sequence of 686bytes</li> 687</ol> 688 689<p><code>XML_Encoding</code> contains an array of integers that 690correspond to the 1st byte of an encoding sequence. If the value in 691the array for a byte is zero or positive, then the byte is a single 692byte encoding that encodes the Unicode scalar value contained in the 693array. A -1 in this array indicates a malformed byte. If the value is 694-2, -3, or -4, then the byte is the beginning of a 2, 3, or 4 byte 695sequence respectively. Multi-byte sequences are sent to the convert 696function pointed at in the <code>XML_Encoding</code> structure. This 697function should return the Unicode scalar value for the sequence or -1 698if the sequence is malformed.</p> 699 700<p>One pitfall that novice Expat users are likely to fall into is that 701although Expat may accept input in various encodings, the strings that 702it passes to the handlers are always encoded in UTF-8 or UTF-16 703(depending on how Expat was compiled). Your application is responsible 704for any translation of these strings into other encodings.</p> 705 706<h3>Handling External Entity References</h3> 707 708<p>Expat does not read or parse external entities directly. Note that 709any external DTD is a special case of an external entity. If you've 710set no <code>ExternalEntityRefHandler</code>, then external entity 711references are silently ignored. Otherwise, it calls your handler with 712the information needed to read and parse the external entity.</p> 713 714<p>Your handler isn't actually responsible for parsing the entity, but 715it is responsible for creating a subsidiary parser with <code><a href= 716"#XML_ExternalEntityParserCreate" 717>XML_ExternalEntityParserCreate</a></code> that will do the job. This 718returns an instance of <code>XML_Parser</code> that has handlers and 719other data structures initialized from the parent parser. You may then 720use <code><a href= "#XML_Parse" >XML_Parse</a></code> or <code><a 721href= "#XML_ParseBuffer">XML_ParseBuffer</a></code> calls against this 722parser. Since external entities my refer to other external entities, 723your handler should be prepared to be called recursively.</p> 724 725<h3>Parsing DTDs</h3> 726 727<p>In order to parse parameter entities, before starting the parse, 728you must call <code><a href= "#XML_SetParamEntityParsing" 729>XML_SetParamEntityParsing</a></code> with one of the following 730arguments:</p> 731<dl> 732<dt><code>XML_PARAM_ENTITY_PARSING_NEVER</code></dt> 733<dd>Don't parse parameter entities or the external subset</dd> 734<dt><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></dt> 735<dd>Parse parameter entites and the external subset unless 736<code>standalone</code> was set to "yes" in the XML declaration.</dd> 737<dt><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></dt> 738<dd>Always parse parameter entities and the external subset</dd> 739</dl> 740 741<p>In order to read an external DTD, you also have to set an external 742entity reference handler as described above.</p> 743 744<h3 id="stop-resume">Temporarily Stopping Parsing</h3> 745 746<p>Expat 1.95.8 introduces a new feature: its now possible to stop 747parsing temporarily from within a handler function, even if more data 748has already been passed into the parser. Applications for this 749include</p> 750 751<ul> 752 <li>Supporting the <a href= "http://www.w3.org/TR/xinclude/" 753 >XInclude</a> specification.</li> 754 755 <li>Delaying further processing until additional information is 756 available from some other source.</li> 757 758 <li>Adjusting processor load as task priorities shift within an 759 application.</li> 760 761 <li>Stopping parsing completely (simply free or reset the parser 762 instead of resuming in the outer parsing loop). This can be useful 763 if a application-domain error is found in the XML being parsed or if 764 the result of the parse is determined not to be useful after 765 all.</li> 766</ul> 767 768<p>To take advantage of this feature, the main parsing loop of an 769application needs to support this specifically. It cannot be 770supported with a parsing loop compatible with Expat 1.95.7 or 771earlier (though existing loops will continue to work without 772supporting the stop/resume feature).</p> 773 774<p>An application that uses this feature for a single parser will have 775the rough structure (in pseudo-code):</p> 776 777<pre class="pseudocode"> 778fd = open_input() 779p = create_parser() 780 781if parse_xml(p, fd) { 782 /* suspended */ 783 784 int suspended = 1; 785 786 while (suspended) { 787 do_something_else() 788 if ready_to_resume() { 789 suspended = continue_parsing(p, fd); 790 } 791 } 792} 793</pre> 794 795<p>An application that may resume any of several parsers based on 796input (either from the XML being parsed or some other source) will 797certainly have more interesting control structures.</p> 798 799<p>This C function could be used for the <code>parse_xml</code> 800function mentioned in the pseudo-code above:</p> 801 802<pre class="eg"> 803#define BUFF_SIZE 10240 804 805/* Parse a document from the open file descriptor 'fd' until the parse 806 is complete (the document has been completely parsed, or there's 807 been an error), or the parse is stopped. Return non-zero when 808 the parse is merely suspended. 809*/ 810int 811parse_xml(XML_Parser p, int fd) 812{ 813 for (;;) { 814 int last_chunk; 815 int bytes_read; 816 enum XML_Status status; 817 818 void *buff = XML_GetBuffer(p, BUFF_SIZE); 819 if (buff == NULL) { 820 /* handle error... */ 821 return 0; 822 } 823 bytes_read = read(fd, buff, BUFF_SIZE); 824 if (bytes_read < 0) { 825 /* handle error... */ 826 return 0; 827 } 828 status = XML_ParseBuffer(p, bytes_read, bytes_read == 0); 829 switch (status) { 830 case XML_STATUS_ERROR: 831 /* handle error... */ 832 return 0; 833 case XML_STATUS_SUSPENDED: 834 return 1; 835 } 836 if (bytes_read == 0) 837 return 0; 838 } 839} 840</pre> 841 842<p>The corresponding <code>continue_parsing</code> function is 843somewhat simpler, since it only need deal with the return code from 844<code><a href= "#XML_ResumeParser">XML_ResumeParser</a></code>; it can 845delegate the input handling to the <code>parse_xml</code> 846function:</p> 847 848<pre class="eg"> 849/* Continue parsing a document which had been suspended. The 'p' and 850 'fd' arguments are the same as passed to parse_xml(). Return 851 non-zero when the parse is suspended. 852*/ 853int 854continue_parsing(XML_Parser p, int fd) 855{ 856 enum XML_Status status = XML_ResumeParser(p); 857 switch (status) { 858 case XML_STATUS_ERROR: 859 /* handle error... */ 860 return 0; 861 case XML_ERROR_NOT_SUSPENDED: 862 /* handle error... */ 863 return 0;. 864 case XML_STATUS_SUSPENDED: 865 return 1; 866 } 867 return parse_xml(p, fd); 868} 869</pre> 870 871<p>Now that we've seen what a mess the top-level parsing loop can 872become, what have we gained? Very simply, we can now use the <code><a 873href= "#XML_StopParser" >XML_StopParser</a></code> function to stop 874parsing, without having to go to great lengths to avoid additional 875processing that we're expecting to ignore. As a bonus, we get to stop 876parsing <em>temporarily</em>, and come back to it when we're 877ready.</p> 878 879<p>To stop parsing from a handler function, use the <code><a href= 880"#XML_StopParser" >XML_StopParser</a></code> function. This function 881takes two arguments; the parser being stopped and a flag indicating 882whether the parse can be resumed in the future.</p> 883 884<!-- XXX really need more here --> 885 886 887<hr /> 888<!-- ================================================================ --> 889 890<h2><a name="reference">Expat Reference</a></h2> 891 892<h3><a name="creation">Parser Creation</a></h3> 893 894<pre class="fcndec" id="XML_ParserCreate"> 895XML_Parser XMLCALL 896XML_ParserCreate(const XML_Char *encoding); 897</pre> 898<div class="fcndef"> 899Construct a new parser. If encoding is non-null, it specifies a 900character encoding to use for the document. This overrides the document 901encoding declaration. There are four built-in encodings: 902<ul> 903<li>US-ASCII</li> 904<li>UTF-8</li> 905<li>UTF-16</li> 906<li>ISO-8859-1</li> 907</ul> 908Any other value will invoke a call to the UnknownEncodingHandler. 909</div> 910 911<pre class="fcndec" id="XML_ParserCreateNS"> 912XML_Parser XMLCALL 913XML_ParserCreateNS(const XML_Char *encoding, 914 XML_Char sep); 915</pre> 916<div class="fcndef"> 917Constructs a new parser that has namespace processing in effect. Namespace 918expanded element names and attribute names are returned as a concatenation 919of the namespace URI, <em>sep</em>, and the local part of the name. This 920means that you should pick a character for <em>sep</em> that can't be 921part of a legal URI. There is a special case when <em>sep</em> is the null 922character <code>'\0'</code>: the namespace URI and the local part will be 923concatenated without any separator - this is intended to support RDF processors. 924It is a programming error to use the null separator with 925<a href= "#XML_SetReturnNSTriplet">namespace triplets</a>.</div> 926 927<pre class="fcndec" id="XML_ParserCreate_MM"> 928XML_Parser XMLCALL 929XML_ParserCreate_MM(const XML_Char *encoding, 930 const XML_Memory_Handling_Suite *ms, 931 const XML_Char *sep); 932</pre> 933<pre class="signature"> 934typedef struct { 935 void *(XMLCALL *malloc_fcn)(size_t size); 936 void *(XMLCALL *realloc_fcn)(void *ptr, size_t size); 937 void (XMLCALL *free_fcn)(void *ptr); 938} XML_Memory_Handling_Suite; 939</pre> 940<div class="fcndef"> 941<p>Construct a new parser using the suite of memory handling functions 942specified in <code>ms</code>. If <code>ms</code> is NULL, then use the 943standard set of memory management functions. If <code>sep</code> is 944non NULL, then namespace processing is enabled in the created parser 945and the character pointed at by sep is used as the separator between 946the namespace URI and the local part of the name.</p> 947</div> 948 949<pre class="fcndec" id="XML_ExternalEntityParserCreate"> 950XML_Parser XMLCALL 951XML_ExternalEntityParserCreate(XML_Parser p, 952 const XML_Char *context, 953 const XML_Char *encoding); 954</pre> 955<div class="fcndef"> 956Construct a new <code>XML_Parser</code> object for parsing an external 957general entity. Context is the context argument passed in a call to a 958ExternalEntityRefHandler. Other state information such as handlers, 959user data, namespace processing is inherited from the parser passed as 960the 1st argument. So you shouldn't need to call any of the behavior 961changing functions on this parser (unless you want it to act 962differently than the parent parser). 963</div> 964 965<pre class="fcndec" id="XML_ParserFree"> 966void XMLCALL 967XML_ParserFree(XML_Parser p); 968</pre> 969<div class="fcndef"> 970Free memory used by the parser. Your application is responsible for 971freeing any memory associated with <a href="#userdata">user data</a>. 972</div> 973 974<pre class="fcndec" id="XML_ParserReset"> 975XML_Bool XMLCALL 976XML_ParserReset(XML_Parser p, 977 const XML_Char *encoding); 978</pre> 979<div class="fcndef"> 980Clean up the memory structures maintained by the parser so that it may 981be used again. After this has been called, <code>parser</code> is 982ready to start parsing a new document. All handlers are cleared from 983the parser, except for the unknownEncodingHandler. The parser's external 984state is re-initialized except for the values of ns and ns_triplets. 985This function may not be used on a parser created using <code><a href= 986"#XML_ExternalEntityParserCreate" >XML_ExternalEntityParserCreate</a 987></code>; it will return <code>XML_FALSE</code> in that case. Returns 988<code>XML_TRUE</code> on success. Your application is responsible for 989dealing with any memory associated with <a href="#userdata">user data</a>. 990</div> 991 992<h3><a name="parsing">Parsing</a></h3> 993 994<p>To state the obvious: the three parsing functions <code><a href= 995"#XML_Parse" >XML_Parse</a></code>, <code><a href= "#XML_ParseBuffer"> 996XML_ParseBuffer</a></code> and <code><a href= "#XML_GetBuffer"> 997XML_GetBuffer</a></code> must not be called from within a handler 998unless they operate on a separate parser instance, that is, one that 999did not call the handler. For example, it is OK to call the parsing 1000functions from within an <code>XML_ExternalEntityRefHandler</code>, 1001if they apply to the parser created by 1002<code><a href= "#XML_ExternalEntityParserCreate" 1003>XML_ExternalEntityParserCreate</a></code>.</p> 1004 1005<p>Note: the <code>len</code> argument passed to these functions 1006should be considerably less than the maximum value for an integer, 1007as it could create an integer overflow situation if the added 1008lengths of a buffer and the unprocessed portion of the previous buffer 1009exceed the maximum integer value. Input data at the end of a buffer 1010will remain unprocessed if it is part of an XML token for which the 1011end is not part of that buffer.</p> 1012 1013<pre class="fcndec" id="XML_Parse"> 1014enum XML_Status XMLCALL 1015XML_Parse(XML_Parser p, 1016 const char *s, 1017 int len, 1018 int isFinal); 1019</pre> 1020<pre class="signature"> 1021enum XML_Status { 1022 XML_STATUS_ERROR = 0, 1023 XML_STATUS_OK = 1 1024}; 1025</pre> 1026<div class="fcndef"> 1027Parse some more of the document. The string <code>s</code> is a buffer 1028containing part (or perhaps all) of the document. The number of bytes of s 1029that are part of the document is indicated by <code>len</code>. This means 1030that <code>s</code> doesn't have to be null terminated. It also means that 1031if <code>len</code> is larger than the number of bytes in the block of 1032memory that <code>s</code> points at, then a memory fault is likely. The 1033<code>isFinal</code> parameter informs the parser that this is the last 1034piece of the document. Frequently, the last piece is empty (i.e. 1035<code>len</code> is zero.) 1036If a parse error occurred, it returns <code>XML_STATUS_ERROR</code>. 1037Otherwise it returns <code>XML_STATUS_OK</code> value. 1038</div> 1039 1040<pre class="fcndec" id="XML_ParseBuffer"> 1041enum XML_Status XMLCALL 1042XML_ParseBuffer(XML_Parser p, 1043 int len, 1044 int isFinal); 1045</pre> 1046<div class="fcndef"> 1047This is just like <code><a href= "#XML_Parse" >XML_Parse</a></code>, 1048except in this case Expat provides the buffer. By obtaining the 1049buffer from Expat with the <code><a href= "#XML_GetBuffer" 1050>XML_GetBuffer</a></code> function, the application can avoid double 1051copying of the input. 1052</div> 1053 1054<pre class="fcndec" id="XML_GetBuffer"> 1055void * XMLCALL 1056XML_GetBuffer(XML_Parser p, 1057 int len); 1058</pre> 1059<div class="fcndef"> 1060Obtain a buffer of size <code>len</code> to read a piece of the document 1061into. A NULL value is returned if Expat can't allocate enough memory for 1062this buffer. This has to be called prior to every call to 1063<code><a href= "#XML_ParseBuffer" >XML_ParseBuffer</a></code>. A 1064typical use would look like this: 1065 1066<pre class="eg"> 1067for (;;) { 1068 int bytes_read; 1069 void *buff = XML_GetBuffer(p, BUFF_SIZE); 1070 if (buff == NULL) { 1071 /* handle error */ 1072 } 1073 1074 bytes_read = read(docfd, buff, BUFF_SIZE); 1075 if (bytes_read < 0) { 1076 /* handle error */ 1077 } 1078 1079 if (! XML_ParseBuffer(p, bytes_read, bytes_read == 0)) { 1080 /* handle parse error */ 1081 } 1082 1083 if (bytes_read == 0) 1084 break; 1085} 1086</pre> 1087</div> 1088 1089<pre class="fcndec" id="XML_StopParser"> 1090enum XML_Status XMLCALL 1091XML_StopParser(XML_Parser p, 1092 XML_Bool resumable); 1093</pre> 1094<div class="fcndef"> 1095 1096<p>Stops parsing, causing <code><a href= "#XML_Parse" 1097>XML_Parse</a></code> or <code><a href= "#XML_ParseBuffer" 1098>XML_ParseBuffer</a></code> to return. Must be called from within a 1099call-back handler, except when aborting (when <code>resumable</code> 1100is <code>XML_FALSE</code>) an already suspended parser. Some 1101call-backs may still follow because they would otherwise get 1102lost, including 1103<ul> 1104 <li> the end element handler for empty elements when stopped in the 1105 start element handler,</li> 1106 <li> end namespace declaration handler when stopped in the end 1107 element handler,</li> 1108</ul> 1109and possibly others.</p> 1110 1111<p>This can be called from most handlers, including DTD related 1112call-backs, except when parsing an external parameter entity and 1113<code>resumable</code> is <code>XML_TRUE</code>. Returns 1114<code>XML_STATUS_OK</code> when successful, 1115<code>XML_STATUS_ERROR</code> otherwise. The possible error codes 1116are:</p> 1117<dl> 1118 <dt><code>XML_ERROR_SUSPENDED</code></dt> 1119 <dd>when suspending an already suspended parser.</dd> 1120 <dt><code>XML_ERROR_FINISHED</code></dt> 1121 <dd>when the parser has already finished.</dd> 1122 <dt><code>XML_ERROR_SUSPEND_PE</code></dt> 1123 <dd>when suspending while parsing an external PE.</dd> 1124</dl> 1125 1126<p>Since the stop/resume feature requires application support in the 1127outer parsing loop, it is an error to call this function for a parser 1128not being handled appropriately; see <a href= "#stop-resume" 1129>Temporarily Stopping Parsing</a> for more information.</p> 1130 1131<p>When <code>resumable</code> is <code>XML_TRUE</code> then parsing 1132is <em>suspended</em>, that is, <code><a href= "#XML_Parse" 1133>XML_Parse</a></code> and <code><a href= "#XML_ParseBuffer" 1134>XML_ParseBuffer</a></code> return <code>XML_STATUS_SUSPENDED</code>. 1135Otherwise, parsing is <em>aborted</em>, that is, <code><a href= 1136"#XML_Parse" >XML_Parse</a></code> and <code><a href= 1137"#XML_ParseBuffer" >XML_ParseBuffer</a></code> return 1138<code>XML_STATUS_ERROR</code> with error code 1139<code>XML_ERROR_ABORTED</code>.</p> 1140 1141<p><strong>Note:</strong> 1142This will be applied to the current parser instance only, that is, if 1143there is a parent parser then it will continue parsing when the 1144external entity reference handler returns. It is up to the 1145implementation of that handler to call <code><a href= 1146"#XML_StopParser" >XML_StopParser</a></code> on the parent parser 1147(recursively), if one wants to stop parsing altogether.</p> 1148 1149<p>When suspended, parsing can be resumed by calling <code><a href= 1150"#XML_ResumeParser" >XML_ResumeParser</a></code>.</p> 1151 1152<p>New in Expat 1.95.8.</p> 1153</div> 1154 1155<pre class="fcndec" id="XML_ResumeParser"> 1156enum XML_Status XMLCALL 1157XML_ResumeParser(XML_Parser p); 1158</pre> 1159<div class="fcndef"> 1160<p>Resumes parsing after it has been suspended with <code><a href= 1161"#XML_StopParser" >XML_StopParser</a></code>. Must not be called from 1162within a handler call-back. Returns same status codes as <code><a 1163href= "#XML_Parse">XML_Parse</a></code> or <code><a href= 1164"#XML_ParseBuffer" >XML_ParseBuffer</a></code>. An additional error 1165code, <code>XML_ERROR_NOT_SUSPENDED</code>, will be returned if the 1166parser was not currently suspended.</p> 1167 1168<p><strong>Note:</strong> 1169This must be called on the most deeply nested child parser instance 1170first, and on its parent parser only after the child parser has 1171finished, to be applied recursively until the document entity's parser 1172is restarted. That is, the parent parser will not resume by itself 1173and it is up to the application to call <code><a href= 1174"#XML_ResumeParser" >XML_ResumeParser</a></code> on it at the 1175appropriate moment.</p> 1176 1177<p>New in Expat 1.95.8.</p> 1178</div> 1179 1180<pre class="fcndec" id="XML_GetParsingStatus"> 1181void XMLCALL 1182XML_GetParsingStatus(XML_Parser p, 1183 XML_ParsingStatus *status); 1184</pre> 1185<pre class="signature"> 1186enum XML_Parsing { 1187 XML_INITIALIZED, 1188 XML_PARSING, 1189 XML_FINISHED, 1190 XML_SUSPENDED 1191}; 1192 1193typedef struct { 1194 enum XML_Parsing parsing; 1195 XML_Bool finalBuffer; 1196} XML_ParsingStatus; 1197</pre> 1198<div class="fcndef"> 1199<p>Returns status of parser with respect to being initialized, 1200parsing, finished, or suspended, and whether the final buffer is being 1201processed. The <code>status</code> parameter <em>must not</em> be 1202NULL.</p> 1203 1204<p>New in Expat 1.95.8.</p> 1205</div> 1206 1207 1208<h3><a name="setting">Handler Setting</a></h3> 1209 1210<p>Although handlers are typically set prior to parsing and left alone, an 1211application may choose to set or change the handler for a parsing event 1212while the parse is in progress. For instance, your application may choose 1213to ignore all text not descended from a <code>para</code> element. One 1214way it could do this is to set the character handler when a para start tag 1215is seen, and unset it for the corresponding end tag.</p> 1216 1217<p>A handler may be <em>unset</em> by providing a NULL pointer to the 1218appropriate handler setter. None of the handler setting functions have 1219a return value.</p> 1220 1221<p>Your handlers will be receiving strings in arrays of type 1222<code>XML_Char</code>. This type is conditionally defined in expat.h as 1223either <code>char</code>, <code>wchar_t</code> or <code>unsigned short</code>. 1224The former implies UTF-8 encoding, the latter two imply UTF-16 encoding. 1225Note that you'll receive them in this form independent of the original 1226encoding of the document.</p> 1227 1228<div class="handler"> 1229<pre class="setter" id="XML_SetStartElementHandler"> 1230void XMLCALL 1231XML_SetStartElementHandler(XML_Parser p, 1232 XML_StartElementHandler start); 1233</pre> 1234<pre class="signature"> 1235typedef void 1236(XMLCALL *XML_StartElementHandler)(void *userData, 1237 const XML_Char *name, 1238 const XML_Char **atts); 1239</pre> 1240<p>Set handler for start (and empty) tags. Attributes are passed to the start 1241handler as a pointer to a vector of char pointers. Each attribute seen in 1242a start (or empty) tag occupies 2 consecutive places in this vector: the 1243attribute name followed by the attribute value. These pairs are terminated 1244by a null pointer.</p> 1245<p>Note that an empty tag generates a call to both start and end handlers 1246(in that order).</p> 1247</div> 1248 1249<div class="handler"> 1250<pre class="setter" id="XML_SetEndElementHandler"> 1251void XMLCALL 1252XML_SetEndElementHandler(XML_Parser p, 1253 XML_EndElementHandler); 1254</pre> 1255<pre class="signature"> 1256typedef void 1257(XMLCALL *XML_EndElementHandler)(void *userData, 1258 const XML_Char *name); 1259</pre> 1260<p>Set handler for end (and empty) tags. As noted above, an empty tag 1261generates a call to both start and end handlers.</p> 1262</div> 1263 1264<div class="handler"> 1265<pre class="setter" id="XML_SetElementHandler"> 1266void XMLCALL 1267XML_SetElementHandler(XML_Parser p, 1268 XML_StartElementHandler start, 1269 XML_EndElementHandler end); 1270</pre> 1271<p>Set handlers for start and end tags with one call.</p> 1272</div> 1273 1274<div class="handler"> 1275<pre class="setter" id="XML_SetCharacterDataHandler"> 1276void XMLCALL 1277XML_SetCharacterDataHandler(XML_Parser p, 1278 XML_CharacterDataHandler charhndl) 1279</pre> 1280<pre class="signature"> 1281typedef void 1282(XMLCALL *XML_CharacterDataHandler)(void *userData, 1283 const XML_Char *s, 1284 int len); 1285</pre> 1286<p>Set a text handler. The string your handler receives 1287is <em>NOT nul-terminated</em>. You have to use the length argument 1288to deal with the end of the string. A single block of contiguous text 1289free of markup may still result in a sequence of calls to this handler. 1290In other words, if you're searching for a pattern in the text, it may 1291be split across calls to this handler.</p> 1292</div> 1293 1294<div class="handler"> 1295<pre class="setter" id="XML_SetProcessingInstructionHandler"> 1296void XMLCALL 1297XML_SetProcessingInstructionHandler(XML_Parser p, 1298 XML_ProcessingInstructionHandler proc) 1299</pre> 1300<pre class="signature"> 1301typedef void 1302(XMLCALL *XML_ProcessingInstructionHandler)(void *userData, 1303 const XML_Char *target, 1304 const XML_Char *data); 1305 1306</pre> 1307<p>Set a handler for processing instructions. The target is the first word 1308in the processing instruction. The data is the rest of the characters in 1309it after skipping all whitespace after the initial word.</p> 1310</div> 1311 1312<div class="handler"> 1313<pre class="setter" id="XML_SetCommentHandler"> 1314void XMLCALL 1315XML_SetCommentHandler(XML_Parser p, 1316 XML_CommentHandler cmnt) 1317</pre> 1318<pre class="signature"> 1319typedef void 1320(XMLCALL *XML_CommentHandler)(void *userData, 1321 const XML_Char *data); 1322</pre> 1323<p>Set a handler for comments. The data is all text inside the comment 1324delimiters.</p> 1325</div> 1326 1327<div class="handler"> 1328<pre class="setter" id="XML_SetStartCdataSectionHandler"> 1329void XMLCALL 1330XML_SetStartCdataSectionHandler(XML_Parser p, 1331 XML_StartCdataSectionHandler start); 1332</pre> 1333<pre class="signature"> 1334typedef void 1335(XMLCALL *XML_StartCdataSectionHandler)(void *userData); 1336</pre> 1337<p>Set a handler that gets called at the beginning of a CDATA section.</p> 1338</div> 1339 1340<div class="handler"> 1341<pre class="setter" id="XML_SetEndCdataSectionHandler"> 1342void XMLCALL 1343XML_SetEndCdataSectionHandler(XML_Parser p, 1344 XML_EndCdataSectionHandler end); 1345</pre> 1346<pre class="signature"> 1347typedef void 1348(XMLCALL *XML_EndCdataSectionHandler)(void *userData); 1349</pre> 1350<p>Set a handler that gets called at the end of a CDATA section.</p> 1351</div> 1352 1353<div class="handler"> 1354<pre class="setter" id="XML_SetCdataSectionHandler"> 1355void XMLCALL 1356XML_SetCdataSectionHandler(XML_Parser p, 1357 XML_StartCdataSectionHandler start, 1358 XML_EndCdataSectionHandler end) 1359</pre> 1360<p>Sets both CDATA section handlers with one call.</p> 1361</div> 1362 1363<div class="handler"> 1364<pre class="setter" id="XML_SetDefaultHandler"> 1365void XMLCALL 1366XML_SetDefaultHandler(XML_Parser p, 1367 XML_DefaultHandler hndl) 1368</pre> 1369<pre class="signature"> 1370typedef void 1371(XMLCALL *XML_DefaultHandler)(void *userData, 1372 const XML_Char *s, 1373 int len); 1374</pre> 1375 1376<p>Sets a handler for any characters in the document which wouldn't 1377otherwise be handled. This includes both data for which no handlers 1378can be set (like some kinds of DTD declarations) and data which could 1379be reported but which currently has no handler set. The characters 1380are passed exactly as they were present in the XML document except 1381that they will be encoded in UTF-8 or UTF-16. Line boundaries are not 1382normalized. Note that a byte order mark character is not passed to the 1383default handler. There are no guarantees about how characters are 1384divided between calls to the default handler: for example, a comment 1385might be split between multiple calls. Setting the handler with 1386this call has the side effect of turning off expansion of references 1387to internally defined general entities. Instead these references are 1388passed to the default handler.</p> 1389 1390<p>See also <code><a 1391href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p> 1392</div> 1393 1394<div class="handler"> 1395<pre class="setter" id="XML_SetDefaultHandlerExpand"> 1396void XMLCALL 1397XML_SetDefaultHandlerExpand(XML_Parser p, 1398 XML_DefaultHandler hndl) 1399</pre> 1400<pre class="signature"> 1401typedef void 1402(XMLCALL *XML_DefaultHandler)(void *userData, 1403 const XML_Char *s, 1404 int len); 1405</pre> 1406<p>This sets a default handler, but doesn't inhibit the expansion of 1407internal entity references. The entity reference will not be passed 1408to the default handler.</p> 1409 1410<p>See also <code><a 1411href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p> 1412</div> 1413 1414<div class="handler"> 1415<pre class="setter" id="XML_SetExternalEntityRefHandler"> 1416void XMLCALL 1417XML_SetExternalEntityRefHandler(XML_Parser p, 1418 XML_ExternalEntityRefHandler hndl) 1419</pre> 1420<pre class="signature"> 1421typedef int 1422(XMLCALL *XML_ExternalEntityRefHandler)(XML_Parser p, 1423 const XML_Char *context, 1424 const XML_Char *base, 1425 const XML_Char *systemId, 1426 const XML_Char *publicId); 1427</pre> 1428<p>Set an external entity reference handler. This handler is also 1429called for processing an external DTD subset if parameter entity parsing 1430is in effect. (See <a href="#XML_SetParamEntityParsing"> 1431<code>XML_SetParamEntityParsing</code></a>.)</p> 1432 1433<p>The <code>context</code> parameter specifies the parsing context in 1434the format expected by the <code>context</code> argument to <code><a 1435href="#XML_ExternalEntityParserCreate" 1436>XML_ExternalEntityParserCreate</a></code>. <code>code</code> is 1437valid only until the handler returns, so if the referenced entity is 1438to be parsed later, it must be copied. <code>context</code> is NULL 1439only when the entity is a parameter entity, which is how one can 1440differentiate between general and parameter entities.</p> 1441 1442<p>The <code>base</code> parameter is the base to use for relative 1443system identifiers. It is set by <code><a 1444href="#XML_SetBase">XML_SetBase</a></code> and may be NULL. The 1445<code>publicId</code> parameter is the public id given in the entity 1446declaration and may be NULL. <code>systemId</code> is the system 1447identifier specified in the entity declaration and is never NULL.</p> 1448 1449<p>There are a couple of ways in which this handler differs from 1450others. First, this handler returns a status indicator (an 1451integer). <code>XML_STATUS_OK</code> should be returned for successful 1452handling of the external entity reference. Returning 1453<code>XML_STATUS_ERROR</code> indicates failure, and causes the 1454calling parser to return an 1455<code>XML_ERROR_EXTERNAL_ENTITY_HANDLING</code> error.</p> 1456 1457<p>Second, instead of having the user data as its first argument, it 1458receives the parser that encountered the entity reference. This, along 1459with the context parameter, may be used as arguments to a call to 1460<code><a href= "#XML_ExternalEntityParserCreate" 1461>XML_ExternalEntityParserCreate</a></code>. Using the returned 1462parser, the body of the external entity can be recursively parsed.</p> 1463 1464<p>Since this handler may be called recursively, it should not be saving 1465information into global or static variables.</p> 1466</div> 1467 1468<pre class="fcndec" id="XML_SetExternalEntityRefHandlerArg"> 1469void XMLCALL 1470XML_SetExternalEntityRefHandlerArg(XML_Parser p, 1471 void *arg) 1472</pre> 1473<div class="fcndef"> 1474<p>Set the argument passed to the ExternalEntityRefHandler. If 1475<code>arg</code> is not NULL, it is the new value passed to the 1476handler set using <code><a href="#XML_SetExternalEntityRefHandler" 1477>XML_SetExternalEntityRefHandler</a></code>; if <code>arg</code> is 1478NULL, the argument passed to the handler function will be the parser 1479object itself.</p> 1480 1481<p><strong>Note:</strong> 1482The type of <code>arg</code> and the type of the first argument to the 1483ExternalEntityRefHandler do not match. This function takes a 1484<code>void *</code> to be passed to the handler, while the handler 1485accepts an <code>XML_Parser</code>. This is a historical accident, 1486but will not be corrected before Expat 2.0 (at the earliest) to avoid 1487causing compiler warnings for code that's known to work with this 1488API. It is the responsibility of the application code to know the 1489actual type of the argument passed to the handler and to manage it 1490properly.</p> 1491</div> 1492 1493<div class="handler"> 1494<pre class="setter" id="XML_SetSkippedEntityHandler"> 1495void XMLCALL 1496XML_SetSkippedEntityHandler(XML_Parser p, 1497 XML_SkippedEntityHandler handler) 1498</pre> 1499<pre class="signature"> 1500typedef void 1501(XMLCALL *XML_SkippedEntityHandler)(void *userData, 1502 const XML_Char *entityName, 1503 int is_parameter_entity); 1504</pre> 1505<p>Set a skipped entity handler. This is called in two situations:</p> 1506<ol> 1507 <li>An entity reference is encountered for which no declaration 1508 has been read <em>and</em> this is not an error.</li> 1509 <li>An internal entity reference is read, but not expanded, because 1510 <a href="#XML_SetDefaultHandler"><code>XML_SetDefaultHandler</code></a> 1511 has been called.</li> 1512</ol> 1513<p>The <code>is_parameter_entity</code> argument will be non-zero for 1514a parameter entity and zero for a general entity.</p> <p>Note: skipped 1515parameter entities in declarations and skipped general entities in 1516attribute values cannot be reported, because the event would be out of 1517sync with the reporting of the declarations or attribute values</p> 1518</div> 1519 1520<div class="handler"> 1521<pre class="setter" id="XML_SetUnknownEncodingHandler"> 1522void XMLCALL 1523XML_SetUnknownEncodingHandler(XML_Parser p, 1524 XML_UnknownEncodingHandler enchandler, 1525 void *encodingHandlerData) 1526</pre> 1527<pre class="signature"> 1528typedef int 1529(XMLCALL *XML_UnknownEncodingHandler)(void *encodingHandlerData, 1530 const XML_Char *name, 1531 XML_Encoding *info); 1532 1533typedef struct { 1534 int map[256]; 1535 void *data; 1536 int (XMLCALL *convert)(void *data, const char *s); 1537 void (XMLCALL *release)(void *data); 1538} XML_Encoding; 1539</pre> 1540<p>Set a handler to deal with encodings other than the <a 1541href="#builtin_encodings">built in set</a>. This should be done before 1542<code><a href= "#XML_Parse" >XML_Parse</a></code> or <code><a href= 1543"#XML_ParseBuffer" >XML_ParseBuffer</a></code> have been called on the 1544given parser.</p> <p>If the handler knows how to deal with an encoding 1545with the given name, it should fill in the <code>info</code> data 1546structure and return <code>XML_STATUS_OK</code>. Otherwise it 1547should return <code>XML_STATUS_ERROR</code>. The handler will be called 1548at most once per parsed (external) entity. The optional application 1549data pointer <code>encodingHandlerData</code> will be passed back to 1550the handler.</p> 1551 1552<p>The map array contains information for every possible possible leading 1553byte in a byte sequence. If the corresponding value is >= 0, then it's 1554a single byte sequence and the byte encodes that Unicode value. If the 1555value is -1, then that byte is invalid as the initial byte in a sequence. 1556If the value is -n, where n is an integer > 1, then n is the number of 1557bytes in the sequence and the actual conversion is accomplished by a 1558call to the function pointed at by convert. This function may return -1 1559if the sequence itself is invalid. The convert pointer may be null if 1560there are only single byte codes. The data parameter passed to the convert 1561function is the data pointer from <code>XML_Encoding</code>. The 1562string s is <em>NOT</em> nul-terminated and points at the sequence of 1563bytes to be converted.</p> 1564 1565<p>The function pointed at by <code>release</code> is called by the 1566parser when it is finished with the encoding. It may be NULL.</p> 1567</div> 1568 1569<div class="handler"> 1570<pre class="setter" id="XML_SetStartNamespaceDeclHandler"> 1571void XMLCALL 1572XML_SetStartNamespaceDeclHandler(XML_Parser p, 1573 XML_StartNamespaceDeclHandler start); 1574</pre> 1575<pre class="signature"> 1576typedef void 1577(XMLCALL *XML_StartNamespaceDeclHandler)(void *userData, 1578 const XML_Char *prefix, 1579 const XML_Char *uri); 1580</pre> 1581<p>Set a handler to be called when a namespace is declared. Namespace 1582declarations occur inside start tags. But the namespace declaration start 1583handler is called before the start tag handler for each namespace declared 1584in that start tag.</p> 1585</div> 1586 1587<div class="handler"> 1588<pre class="setter" id="XML_SetEndNamespaceDeclHandler"> 1589void XMLCALL 1590XML_SetEndNamespaceDeclHandler(XML_Parser p, 1591 XML_EndNamespaceDeclHandler end); 1592</pre> 1593<pre class="signature"> 1594typedef void 1595(XMLCALL *XML_EndNamespaceDeclHandler)(void *userData, 1596 const XML_Char *prefix); 1597</pre> 1598<p>Set a handler to be called when leaving the scope of a namespace 1599declaration. This will be called, for each namespace declaration, 1600after the handler for the end tag of the element in which the 1601namespace was declared.</p> 1602</div> 1603 1604<div class="handler"> 1605<pre class="setter" id="XML_SetNamespaceDeclHandler"> 1606void XMLCALL 1607XML_SetNamespaceDeclHandler(XML_Parser p, 1608 XML_StartNamespaceDeclHandler start, 1609 XML_EndNamespaceDeclHandler end) 1610</pre> 1611<p>Sets both namespace declaration handlers with a single call.</p> 1612</div> 1613 1614<div class="handler"> 1615<pre class="setter" id="XML_SetXmlDeclHandler"> 1616void XMLCALL 1617XML_SetXmlDeclHandler(XML_Parser p, 1618 XML_XmlDeclHandler xmldecl); 1619</pre> 1620<pre class="signature"> 1621typedef void 1622(XMLCALL *XML_XmlDeclHandler)(void *userData, 1623 const XML_Char *version, 1624 const XML_Char *encoding, 1625 int standalone); 1626</pre> 1627<p>Sets a handler that is called for XML declarations and also for 1628text declarations discovered in external entities. The way to 1629distinguish is that the <code>version</code> parameter will be NULL 1630for text declarations. The <code>encoding</code> parameter may be NULL 1631for an XML declaration. The <code>standalone</code> argument will 1632contain -1, 0, or 1 indicating respectively that there was no 1633standalone parameter in the declaration, that it was given as no, or 1634that it was given as yes.</p> 1635</div> 1636 1637<div class="handler"> 1638<pre class="setter" id="XML_SetStartDoctypeDeclHandler"> 1639void XMLCALL 1640XML_SetStartDoctypeDeclHandler(XML_Parser p, 1641 XML_StartDoctypeDeclHandler start); 1642</pre> 1643<pre class="signature"> 1644typedef void 1645(XMLCALL *XML_StartDoctypeDeclHandler)(void *userData, 1646 const XML_Char *doctypeName, 1647 const XML_Char *sysid, 1648 const XML_Char *pubid, 1649 int has_internal_subset); 1650</pre> 1651<p>Set a handler that is called at the start of a DOCTYPE declaration, 1652before any external or internal subset is parsed. Both <code>sysid</code> 1653and <code>pubid</code> may be NULL. The <code>has_internal_subset</code> 1654will be non-zero if the DOCTYPE declaration has an internal subset.</p> 1655</div> 1656 1657<div class="handler"> 1658<pre class="setter" id="XML_SetEndDoctypeDeclHandler"> 1659void XMLCALL 1660XML_SetEndDoctypeDeclHandler(XML_Parser p, 1661 XML_EndDoctypeDeclHandler end); 1662</pre> 1663<pre class="signature"> 1664typedef void 1665(XMLCALL *XML_EndDoctypeDeclHandler)(void *userData); 1666</pre> 1667<p>Set a handler that is called at the end of a DOCTYPE declaration, 1668after parsing any external subset.</p> 1669</div> 1670 1671<div class="handler"> 1672<pre class="setter" id="XML_SetDoctypeDeclHandler"> 1673void XMLCALL 1674XML_SetDoctypeDeclHandler(XML_Parser p, 1675 XML_StartDoctypeDeclHandler start, 1676 XML_EndDoctypeDeclHandler end); 1677</pre> 1678<p>Set both doctype handlers with one call.</p> 1679</div> 1680 1681<div class="handler"> 1682<pre class="setter" id="XML_SetElementDeclHandler"> 1683void XMLCALL 1684XML_SetElementDeclHandler(XML_Parser p, 1685 XML_ElementDeclHandler eldecl); 1686</pre> 1687<pre class="signature"> 1688typedef void 1689(XMLCALL *XML_ElementDeclHandler)(void *userData, 1690 const XML_Char *name, 1691 XML_Content *model); 1692</pre> 1693<pre class="signature"> 1694enum XML_Content_Type { 1695 XML_CTYPE_EMPTY = 1, 1696 XML_CTYPE_ANY, 1697 XML_CTYPE_MIXED, 1698 XML_CTYPE_NAME, 1699 XML_CTYPE_CHOICE, 1700 XML_CTYPE_SEQ 1701}; 1702 1703enum XML_Content_Quant { 1704 XML_CQUANT_NONE, 1705 XML_CQUANT_OPT, 1706 XML_CQUANT_REP, 1707 XML_CQUANT_PLUS 1708}; 1709 1710typedef struct XML_cp XML_Content; 1711 1712struct XML_cp { 1713 enum XML_Content_Type type; 1714 enum XML_Content_Quant quant; 1715 const XML_Char * name; 1716 unsigned int numchildren; 1717 XML_Content * children; 1718}; 1719</pre> 1720<p>Sets a handler for element declarations in a DTD. The handler gets 1721called with the name of the element in the declaration and a pointer 1722to a structure that contains the element model. It is the 1723application's responsibility to free this data structure using 1724<code><a href="#XML_FreeContentModel" 1725>XML_FreeContentModel</a></code>.</p> 1726 1727<p>The <code>model</code> argument is the root of a tree of 1728<code>XML_Content</code> nodes. If <code>type</code> equals 1729<code>XML_CTYPE_EMPTY</code> or <code>XML_CTYPE_ANY</code>, then 1730<code>quant</code> will be <code>XML_CQUANT_NONE</code>, and the other 1731fields will be zero or NULL. If <code>type</code> is 1732<code>XML_CTYPE_MIXED</code>, then <code>quant</code> will be 1733<code>XML_CQUANT_NONE</code> or <code>XML_CQUANT_REP</code> and 1734<code>numchildren</code> will contain the number of elements that are 1735allowed to be mixed in and <code>children</code> points to an array of 1736<code>XML_Content</code> structures that will all have type 1737XML_CTYPE_NAME with no quantification. Only the root node can be type 1738<code>XML_CTYPE_EMPTY</code>, <code>XML_CTYPE_ANY</code>, or 1739<code>XML_CTYPE_MIXED</code>.</p> 1740 1741<p>For type <code>XML_CTYPE_NAME</code>, the <code>name</code> field 1742points to the name and the <code>numchildren</code> and 1743<code>children</code> fields will be zero and NULL. The 1744<code>quant</code> field will indicate any quantifiers placed on the 1745name.</p> 1746 1747<p>Types <code>XML_CTYPE_CHOICE</code> and <code>XML_CTYPE_SEQ</code> 1748indicate a choice or sequence respectively. The 1749<code>numchildren</code> field indicates how many nodes in the choice 1750or sequence and <code>children</code> points to the nodes.</p> 1751</div> 1752 1753<div class="handler"> 1754<pre class="setter" id="XML_SetAttlistDeclHandler"> 1755void XMLCALL 1756XML_SetAttlistDeclHandler(XML_Parser p, 1757 XML_AttlistDeclHandler attdecl); 1758</pre> 1759<pre class="signature"> 1760typedef void 1761(XMLCALL *XML_AttlistDeclHandler)(void *userData, 1762 const XML_Char *elname, 1763 const XML_Char *attname, 1764 const XML_Char *att_type, 1765 const XML_Char *dflt, 1766 int isrequired); 1767</pre> 1768<p>Set a handler for attlist declarations in the DTD. This handler is 1769called for <em>each</em> attribute. So a single attlist declaration 1770with multiple attributes declared will generate multiple calls to this 1771handler. The <code>elname</code> parameter returns the name of the 1772element for which the attribute is being declared. The attribute name 1773is in the <code>attname</code> parameter. The attribute type is in the 1774<code>att_type</code> parameter. It is the string representing the 1775type in the declaration with whitespace removed.</p> 1776 1777<p>The <code>dflt</code> parameter holds the default value. It will be 1778NULL in the case of "#IMPLIED" or "#REQUIRED" attributes. You can 1779distinguish these two cases by checking the <code>isrequired</code> 1780parameter, which will be true in the case of "#REQUIRED" attributes. 1781Attributes which are "#FIXED" will have also have a true 1782<code>isrequired</code>, but they will have the non-NULL fixed value 1783in the <code>dflt</code> parameter.</p> 1784</div> 1785 1786<div class="handler"> 1787<pre class="setter" id="XML_SetEntityDeclHandler"> 1788void XMLCALL 1789XML_SetEntityDeclHandler(XML_Parser p, 1790 XML_EntityDeclHandler handler); 1791</pre> 1792<pre class="signature"> 1793typedef void 1794(XMLCALL *XML_EntityDeclHandler)(void *userData, 1795 const XML_Char *entityName, 1796 int is_parameter_entity, 1797 const XML_Char *value, 1798 int value_length, 1799 const XML_Char *base, 1800 const XML_Char *systemId, 1801 const XML_Char *publicId, 1802 const XML_Char *notationName); 1803</pre> 1804<p>Sets a handler that will be called for all entity declarations. 1805The <code>is_parameter_entity</code> argument will be non-zero in the 1806case of parameter entities and zero otherwise.</p> 1807 1808<p>For internal entities (<code><!ENTITY foo "bar"></code>), 1809<code>value</code> will be non-NULL and <code>systemId</code>, 1810<code>publicId</code>, and <code>notationName</code> will all be NULL. 1811The value string is <em>not</em> NULL terminated; the length is 1812provided in the <code>value_length</code> parameter. Do not use 1813<code>value_length</code> to test for internal entities, since it is 1814legal to have zero-length values. Instead check for whether or not 1815<code>value</code> is NULL.</p> <p>The <code>notationName</code> 1816argument will have a non-NULL value only for unparsed entity 1817declarations.</p> 1818</div> 1819 1820<div class="handler"> 1821<pre class="setter" id="XML_SetUnparsedEntityDeclHandler"> 1822void XMLCALL 1823XML_SetUnparsedEntityDeclHandler(XML_Parser p, 1824 XML_UnparsedEntityDeclHandler h) 1825</pre> 1826<pre class="signature"> 1827typedef void 1828(XMLCALL *XML_UnparsedEntityDeclHandler)(void *userData, 1829 const XML_Char *entityName, 1830 const XML_Char *base, 1831 const XML_Char *systemId, 1832 const XML_Char *publicId, 1833 const XML_Char *notationName); 1834</pre> 1835<p>Set a handler that receives declarations of unparsed entities. These 1836are entity declarations that have a notation (NDATA) field:</p> 1837 1838<div id="eg"><pre> 1839<!ENTITY logo SYSTEM "images/logo.gif" NDATA gif> 1840</pre></div> 1841<p>This handler is obsolete and is provided for backwards 1842compatibility. Use instead <a href= "#XML_SetEntityDeclHandler" 1843>XML_SetEntityDeclHandler</a>.</p> 1844</div> 1845 1846<div class="handler"> 1847<pre class="setter" id="XML_SetNotationDeclHandler"> 1848void XMLCALL 1849XML_SetNotationDeclHandler(XML_Parser p, 1850 XML_NotationDeclHandler h) 1851</pre> 1852<pre class="signature"> 1853typedef void 1854(XMLCALL *XML_NotationDeclHandler)(void *userData, 1855 const XML_Char *notationName, 1856 const XML_Char *base, 1857 const XML_Char *systemId, 1858 const XML_Char *publicId); 1859</pre> 1860<p>Set a handler that receives notation declarations.</p> 1861</div> 1862 1863<div class="handler"> 1864<pre class="setter" id="XML_SetNotStandaloneHandler"> 1865void XMLCALL 1866XML_SetNotStandaloneHandler(XML_Parser p, 1867 XML_NotStandaloneHandler h) 1868</pre> 1869<pre class="signature"> 1870typedef int 1871(XMLCALL *XML_NotStandaloneHandler)(void *userData); 1872</pre> 1873<p>Set a handler that is called if the document is not "standalone". 1874This happens when there is an external subset or a reference to a 1875parameter entity, but does not have standalone set to "yes" in an XML 1876declaration. If this handler returns <code>XML_STATUS_ERROR</code>, 1877then the parser will throw an <code>XML_ERROR_NOT_STANDALONE</code> 1878error.</p> 1879</div> 1880 1881<h3><a name="position">Parse position and error reporting functions</a></h3> 1882 1883<p>These are the functions you'll want to call when the parse 1884functions return <code>XML_STATUS_ERROR</code> (a parse error has 1885occurred), although the position reporting functions are useful outside 1886of errors. The position reported is the byte position (in the original 1887document or entity encoding) of the first of the sequence of 1888characters that generated the current event (or the error that caused 1889the parse functions to return <code>XML_STATUS_ERROR</code>.) The 1890exceptions are callbacks trigged by declarations in the document 1891prologue, in which case they exact position reported is somewhere in the 1892relevant markup, but not necessarily as meaningful as for other 1893events.</p> 1894 1895<p>The position reporting functions are accurate only outside of the 1896DTD. In other words, they usually return bogus information when 1897called from within a DTD declaration handler.</p> 1898 1899<pre class="fcndec" id="XML_GetErrorCode"> 1900enum XML_Error XMLCALL 1901XML_GetErrorCode(XML_Parser p); 1902</pre> 1903<div class="fcndef"> 1904Return what type of error has occurred. 1905</div> 1906 1907<pre class="fcndec" id="XML_ErrorString"> 1908const XML_LChar * XMLCALL 1909XML_ErrorString(enum XML_Error code); 1910</pre> 1911<div class="fcndef"> 1912Return a string describing the error corresponding to code. 1913The code should be one of the enums that can be returned from 1914<code><a href= "#XML_GetErrorCode" >XML_GetErrorCode</a></code>. 1915</div> 1916 1917<pre class="fcndec" id="XML_GetCurrentByteIndex"> 1918XML_Index XMLCALL 1919XML_GetCurrentByteIndex(XML_Parser p); 1920</pre> 1921<div class="fcndef"> 1922Return the byte offset of the position. This always corresponds to 1923the values returned by <code><a href= "#XML_GetCurrentLineNumber" 1924>XML_GetCurrentLineNumber</a></code> and <code><a href= 1925"#XML_GetCurrentColumnNumber" >XML_GetCurrentColumnNumber</a></code>. 1926</div> 1927 1928<pre class="fcndec" id="XML_GetCurrentLineNumber"> 1929XML_Size XMLCALL 1930XML_GetCurrentLineNumber(XML_Parser p); 1931</pre> 1932<div class="fcndef"> 1933Return the line number of the position. The first line is reported as 1934<code>1</code>. 1935</div> 1936 1937<pre class="fcndec" id="XML_GetCurrentColumnNumber"> 1938XML_Size XMLCALL 1939XML_GetCurrentColumnNumber(XML_Parser p); 1940</pre> 1941<div class="fcndef"> 1942Return the offset, from the beginning of the current line, of 1943the position. 1944</div> 1945 1946<pre class="fcndec" id="XML_GetCurrentByteCount"> 1947int XMLCALL 1948XML_GetCurrentByteCount(XML_Parser p); 1949</pre> 1950<div class="fcndef"> 1951Return the number of bytes in the current event. Returns 1952<code>0</code> if the event is inside a reference to an internal 1953entity and for the end-tag event for empty element tags (the later can 1954be used to distinguish empty-element tags from empty elements using 1955separate start and end tags). 1956</div> 1957 1958<pre class="fcndec" id="XML_GetInputContext"> 1959const char * XMLCALL 1960XML_GetInputContext(XML_Parser p, 1961 int *offset, 1962 int *size); 1963</pre> 1964<div class="fcndef"> 1965 1966<p>Returns the parser's input buffer, sets the integer pointed at by 1967<code>offset</code> to the offset within this buffer of the current 1968parse position, and set the integer pointed at by <code>size</code> to 1969the size of the returned buffer.</p> 1970 1971<p>This should only be called from within a handler during an active 1972parse and the returned buffer should only be referred to from within 1973the handler that made the call. This input buffer contains the 1974untranslated bytes of the input.</p> 1975 1976<p>Only a limited amount of context is kept, so if the event 1977triggering a call spans over a very large amount of input, the actual 1978parse position may be before the beginning of the buffer.</p> 1979 1980<p>If <code>XML_CONTEXT_BYTES</code> is not defined, this will always 1981return NULL.</p> 1982</div> 1983 1984<h3><a name="miscellaneous">Miscellaneous functions</a></h3> 1985 1986<p>The functions in this section either obtain state information from 1987the parser or can be used to dynamicly set parser options.</p> 1988 1989<pre class="fcndec" id="XML_SetUserData"> 1990void XMLCALL 1991XML_SetUserData(XML_Parser p, 1992 void *userData); 1993</pre> 1994<div class="fcndef"> 1995This sets the user data pointer that gets passed to handlers. It 1996overwrites any previous value for this pointer. Note that the 1997application is responsible for freeing the memory associated with 1998<code>userData</code> when it is finished with the parser. So if you 1999call this when there's already a pointer there, and you haven't freed 2000the memory associated with it, then you've probably just leaked 2001memory. 2002</div> 2003 2004<pre class="fcndec" id="XML_GetUserData"> 2005void * XMLCALL 2006XML_GetUserData(XML_Parser p); 2007</pre> 2008<div class="fcndef"> 2009This returns the user data pointer that gets passed to handlers. 2010It is actually implemented as a macro. 2011</div> 2012 2013<pre class="fcndec" id="XML_UseParserAsHandlerArg"> 2014void XMLCALL 2015XML_UseParserAsHandlerArg(XML_Parser p); 2016</pre> 2017<div class="fcndef"> 2018After this is called, handlers receive the parser in their 2019<code>userData</code> arguments. The user data can still be obtained 2020using the <code><a href= "#XML_GetUserData" 2021>XML_GetUserData</a></code> function. 2022</div> 2023 2024<pre class="fcndec" id="XML_SetBase"> 2025enum XML_Status XMLCALL 2026XML_SetBase(XML_Parser p, 2027 const XML_Char *base); 2028</pre> 2029<div class="fcndef"> 2030Set the base to be used for resolving relative URIs in system 2031identifiers. The return value is <code>XML_STATUS_ERROR</code> if 2032there's no memory to store base, otherwise it's 2033<code>XML_STATUS_OK</code>. 2034</div> 2035 2036<pre class="fcndec" id="XML_GetBase"> 2037const XML_Char * XMLCALL 2038XML_GetBase(XML_Parser p); 2039</pre> 2040<div class="fcndef"> 2041Return the base for resolving relative URIs. 2042</div> 2043 2044<pre class="fcndec" id="XML_GetSpecifiedAttributeCount"> 2045int XMLCALL 2046XML_GetSpecifiedAttributeCount(XML_Parser p); 2047</pre> 2048<div class="fcndef"> 2049When attributes are reported to the start handler in the atts vector, 2050attributes that were explicitly set in the element occur before any 2051attributes that receive their value from default information in an 2052ATTLIST declaration. This function returns the number of attributes 2053that were explicitly set times two, thus giving the offset in the 2054<code>atts</code> array passed to the start tag handler of the first 2055attribute set due to defaults. It supplies information for the last 2056call to a start handler. If called inside a start handler, then that 2057means the current call. 2058</div> 2059 2060<pre class="fcndec" id="XML_GetIdAttributeIndex"> 2061int XMLCALL 2062XML_GetIdAttributeIndex(XML_Parser p); 2063</pre> 2064<div class="fcndef"> 2065Returns the index of the ID attribute passed in the atts array in the 2066last call to <code><a href= "#XML_StartElementHandler" 2067>XML_StartElementHandler</a></code>, or -1 if there is no ID 2068attribute. If called inside a start handler, then that means the 2069current call. 2070</div> 2071 2072<pre class="fcndec" id="XML_SetEncoding"> 2073enum XML_Status XMLCALL 2074XML_SetEncoding(XML_Parser p, 2075 const XML_Char *encoding); 2076</pre> 2077<div class="fcndef"> 2078Set the encoding to be used by the parser. It is equivalent to 2079passing a non-null encoding argument to the parser creation functions. 2080It must not be called after <code><a href= "#XML_Parse" 2081>XML_Parse</a></code> or <code><a href= "#XML_ParseBuffer" 2082>XML_ParseBuffer</a></code> have been called on the given parser. 2083Returns <code>XML_STATUS_OK</code> on success or 2084<code>XML_STATUS_ERROR</code> on error. 2085</div> 2086 2087<pre class="fcndec" id="XML_SetParamEntityParsing"> 2088int XMLCALL 2089XML_SetParamEntityParsing(XML_Parser p, 2090 enum XML_ParamEntityParsing code); 2091</pre> 2092<div class="fcndef"> 2093This enables parsing of parameter entities, including the external 2094parameter entity that is the external DTD subset, according to 2095<code>code</code>. 2096The choices for <code>code</code> are: 2097<ul> 2098<li><code>XML_PARAM_ENTITY_PARSING_NEVER</code></li> 2099<li><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></li> 2100<li><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></li> 2101</ul> 2102</div> 2103 2104<pre class="fcndec" id="XML_UseForeignDTD"> 2105enum XML_Error XMLCALL 2106XML_UseForeignDTD(XML_Parser parser, XML_Bool useDTD); 2107</pre> 2108<div class="fcndef"> 2109<p>This function allows an application to provide an external subset 2110for the document type declaration for documents which do not specify 2111an external subset of their own. For documents which specify an 2112external subset in their DOCTYPE declaration, the application-provided 2113subset will be ignored. If the document does not contain a DOCTYPE 2114declaration at all and <code>useDTD</code> is true, the 2115application-provided subset will be parsed, but the 2116<code>startDoctypeDeclHandler</code> and 2117<code>endDoctypeDeclHandler</code> functions, if set, will not be 2118called. The setting of parameter entity parsing, controlled using 2119<code><a href= "#XML_SetParamEntityParsing" 2120>XML_SetParamEntityParsing</a></code>, will be honored.</p> 2121 2122<p>The application-provided external subset is read by calling the 2123external entity reference handler set via <code><a href= 2124"#XML_SetExternalEntityRefHandler" 2125>XML_SetExternalEntityRefHandler</a></code> with both 2126<code>publicId</code> and <code>systemId</code> set to NULL.</p> 2127 2128<p>If this function is called after parsing has begun, it returns 2129<code>XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING</code> and ignores 2130<code>useDTD</code>. If called when Expat has been compiled without 2131DTD support, it returns 2132<code>XML_ERROR_FEATURE_REQUIRES_XML_DTD</code>. Otherwise, it 2133returns <code>XML_ERROR_NONE</code>.</p> 2134 2135<p><b>Note:</b> For the purpose of checking WFC: Entity Declared, passing 2136<code>useDTD == XML_TRUE</code> will make the parser behave as if 2137the document had a DTD with an external subset. This holds true even if 2138the external entity reference handler returns without action.</p> 2139</div> 2140 2141<pre class="fcndec" id="XML_SetReturnNSTriplet"> 2142void XMLCALL 2143XML_SetReturnNSTriplet(XML_Parser parser, 2144 int do_nst); 2145</pre> 2146<div class="fcndef"> 2147<p> 2148This function only has an effect when using a parser created with 2149<code><a href= "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>, 2150i.e. when namespace processing is in effect. The <code>do_nst</code> 2151sets whether or not prefixes are returned with names qualified with a 2152namespace prefix. If this function is called with <code>do_nst</code> 2153non-zero, then afterwards namespace qualified names (that is qualified 2154with a prefix as opposed to belonging to a default namespace) are 2155returned as a triplet with the three parts separated by the namespace 2156separator specified when the parser was created. The order of 2157returned parts is URI, local name, and prefix.</p> <p>If 2158<code>do_nst</code> is zero, then namespaces are reported in the 2159default manner, URI then local_name separated by the namespace 2160separator.</p> 2161</div> 2162 2163<pre class="fcndec" id="XML_DefaultCurrent"> 2164void XMLCALL 2165XML_DefaultCurrent(XML_Parser parser); 2166</pre> 2167<div class="fcndef"> 2168This can be called within a handler for a start element, end element, 2169processing instruction or character data. It causes the corresponding 2170markup to be passed to the default handler set by <code><a 2171href="#XML_SetDefaultHandler" >XML_SetDefaultHandler</a></code> or 2172<code><a href="#XML_SetDefaultHandlerExpand" 2173>XML_SetDefaultHandlerExpand</a></code>. It does nothing if there is 2174not a default handler. 2175</div> 2176 2177<pre class="fcndec" id="XML_ExpatVersion"> 2178XML_LChar * XMLCALL 2179XML_ExpatVersion(); 2180</pre> 2181<div class="fcndef"> 2182Return the library version as a string (e.g. <code>"expat_1.95.1"</code>). 2183</div> 2184 2185<pre class="fcndec" id="XML_ExpatVersionInfo"> 2186struct XML_Expat_Version XMLCALL 2187XML_ExpatVersionInfo(); 2188</pre> 2189<pre class="signature"> 2190typedef struct { 2191 int major; 2192 int minor; 2193 int micro; 2194} XML_Expat_Version; 2195</pre> 2196<div class="fcndef"> 2197Return the library version information as a structure. 2198Some macros are also defined that support compile-time tests of the 2199library version: 2200<ul> 2201<li><code>XML_MAJOR_VERSION</code></li> 2202<li><code>XML_MINOR_VERSION</code></li> 2203<li><code>XML_MICRO_VERSION</code></li> 2204</ul> 2205Testing these constants is currently the best way to determine if 2206particular parts of the Expat API are available. 2207</div> 2208 2209<pre class="fcndec" id="XML_GetFeatureList"> 2210const XML_Feature * XMLCALL 2211XML_GetFeatureList(); 2212</pre> 2213<pre class="signature"> 2214enum XML_FeatureEnum { 2215 XML_FEATURE_END = 0, 2216 XML_FEATURE_UNICODE, 2217 XML_FEATURE_UNICODE_WCHAR_T, 2218 XML_FEATURE_DTD, 2219 XML_FEATURE_CONTEXT_BYTES, 2220 XML_FEATURE_MIN_SIZE, 2221 XML_FEATURE_SIZEOF_XML_CHAR, 2222 XML_FEATURE_SIZEOF_XML_LCHAR 2223}; 2224 2225typedef struct { 2226 enum XML_FeatureEnum feature; 2227 XML_LChar *name; 2228 long int value; 2229} XML_Feature; 2230</pre> 2231<div class="fcndef"> 2232<p>Returns a list of "feature" records, providing details on how 2233Expat was configured at compile time. Most applications should not 2234need to worry about this, but this information is otherwise not 2235available from Expat. This function allows code that does need to 2236check these features to do so at runtime.</p> 2237 2238<p>The return value is an array of <code>XML_Feature</code>, 2239terminated by a record with a <code>feature</code> of 2240<code>XML_FEATURE_END</code> and <code>name</code> of NULL, 2241identifying the feature-test macros Expat was compiled with. Since an 2242application that requires this kind of information needs to determine 2243the type of character the <code>name</code> points to, records for the 2244<code>XML_FEATURE_SIZEOF_XML_CHAR</code> and 2245<code>XML_FEATURE_SIZEOF_XML_LCHAR</code> will be located at the 2246beginning of the list, followed by <code>XML_FEATURE_UNICODE</code> 2247and <code>XML_FEATURE_UNICODE_WCHAR_T</code>, if they are present at 2248all.</p> 2249 2250<p>Some features have an associated value. If there isn't an 2251associated value, the <code>value</code> field is set to 0. At this 2252time, the following features have been defined to have values:</p> 2253 2254<dl> 2255 <dt><code>XML_FEATURE_SIZEOF_XML_CHAR</code></dt> 2256 <dd>The number of bytes occupied by one <code>XML_Char</code> 2257 character.</dd> 2258 <dt><code>XML_FEATURE_SIZEOF_XML_LCHAR</code></dt> 2259 <dd>The number of bytes occupied by one <code>XML_LChar</code> 2260 character.</dd> 2261 <dt><code>XML_FEATURE_CONTEXT_BYTES</code></dt> 2262 <dd>The maximum number of characters of context which can be 2263 reported by <code><a href= "#XML_GetInputContext" 2264 >XML_GetInputContext</a></code>.</dd> 2265</dl> 2266</div> 2267 2268<pre class="fcndec" id="XML_FreeContentModel"> 2269void XMLCALL 2270XML_FreeContentModel(XML_Parser parser, XML_Content *model); 2271</pre> 2272<div class="fcndef"> 2273Function to deallocate the <code>model</code> argument passed to the 2274<code>XML_ElementDeclHandler</code> callback set using <code><a 2275href="#XML_SetElementDeclHandler" >XML_ElementDeclHandler</a></code>. 2276This function should not be used for any other purpose. 2277</div> 2278 2279<p>The following functions allow external code to share the memory 2280allocator an <code>XML_Parser</code> has been configured to use. This 2281is especially useful for third-party libraries that interact with a 2282parser object created by application code, or heavily layered 2283applications. This can be essential when using dynamically loaded 2284libraries which use different C standard libraries (this can happen on 2285Windows, at least).</p> 2286 2287<pre class="fcndec" id="XML_MemMalloc"> 2288void * XMLCALL 2289XML_MemMalloc(XML_Parser parser, size_t size); 2290</pre> 2291<div class="fcndef"> 2292Allocate <code>size</code> bytes of memory using the allocator the 2293<code>parser</code> object has been configured to use. Returns a 2294pointer to the memory or NULL on failure. Memory allocated in this 2295way must be freed using <code><a href="#XML_MemFree" 2296>XML_MemFree</a></code>. 2297</div> 2298 2299<pre class="fcndec" id="XML_MemRealloc"> 2300void * XMLCALL 2301XML_MemRealloc(XML_Parser parser, void *ptr, size_t size); 2302</pre> 2303<div class="fcndef"> 2304Allocate <code>size</code> bytes of memory using the allocator the 2305<code>parser</code> object has been configured to use. 2306<code>ptr</code> must point to a block of memory allocated by <code><a 2307href="#XML_MemMalloc" >XML_MemMalloc</a></code> or 2308<code>XML_MemRealloc</code>, or be NULL. This function tries to 2309expand the block pointed to by <code>ptr</code> if possible. Returns 2310a pointer to the memory or NULL on failure. On success, the original 2311block has either been expanded or freed. On failure, the original 2312block has not been freed; the caller is responsible for freeing the 2313original block. Memory allocated in this way must be freed using 2314<code><a href="#XML_MemFree" 2315>XML_MemFree</a></code>. 2316</div> 2317 2318<pre class="fcndec" id="XML_MemFree"> 2319void XMLCALL 2320XML_MemFree(XML_Parser parser, void *ptr); 2321</pre> 2322<div class="fcndef"> 2323Free a block of memory pointed to by <code>ptr</code>. The block must 2324have been allocated by <code><a href="#XML_MemMalloc" 2325>XML_MemMalloc</a></code> or <code>XML_MemRealloc</code>, or be NULL. 2326</div> 2327 2328<hr /> 2329<p><a href="http://validator.w3.org/check/referer"><img 2330 src="valid-xhtml10.png" alt="Valid XHTML 1.0!" 2331 height="31" width="88" class="noborder" /></a></p> 2332</div> 2333</body> 2334</html> 2335
