src/expat/doc/reference.html

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  10   <title>Expat XML Parser</title>
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  18       <td class="corner"><img src="expat.png" alt="(Expat logo)" /></td>
  19       <td class="banner"><h1>The Expat XML Parser</h1></td>
  20     </tr>
  21     <tr>
  22       <td class="releaseno">Release 2.0.1</td>
  23       <td></td>
  24     </tr>
  25   </table>
  26 <div class="content">
  27
  28 <p>Expat is a library, written in C, for parsing XML documents. It's
  29 the underlying XML parser for the open source Mozilla project, Perl's
  30 <code>XML::Parser</code>, Python's <code>xml.parsers.expat</code>, and
  31 other open-source XML parsers.</p>
  32
  33 <p>This library is the creation of James Clark, who's also given us
  34 groff (an nroff look-alike), Jade (an implemention of ISO's DSSSL
  35 stylesheet language for SGML), XP (a Java XML parser package), XT (a
  36 Java XSL engine).  James was also the technical lead on the XML
  37 Working Group at W3C that produced the XML specification.</p>
  38
  39 <p>This is free software, licensed under the <a
  40 href="../COPYING">MIT/X Consortium license</a>. You may download it
  41 from <a href="http://www.libexpat.org/">the Expat home page</a>.
  42 </p>
  43
  44 <p>The bulk of this document was originally commissioned as an article
  45 by <a href="http://www.xml.com/">XML.com</a>. They graciously allowed
  46 Clark Cooper to retain copyright and to distribute it with Expat.
  47 This version has been substantially extended to include documentation
  48 on features which have been added since the original article was
  49 published, and additional information on using the original
  50 interface.</p>
  51
  52 <hr />
  53 <h2>Table of Contents</h2>
  54 <ul>
  55   <li><a href="#overview">Overview</a></li>
  56   <li><a href="#building">Building and Installing</a></li>
  57   <li><a href="#using">Using Expat</a></li>
  58   <li><a href="#reference">Reference</a>
  59   <ul>
  60     <li><a href="#creation">Parser Creation Functions</a>
  61     <ul>
  62       <li><a href="#XML_ParserCreate">XML_ParserCreate</a></li>
  63       <li><a href="#XML_ParserCreateNS">XML_ParserCreateNS</a></li>
  64       <li><a href="#XML_ParserCreate_MM">XML_ParserCreate_MM</a></li>
  65       <li><a href="#XML_ExternalEntityParserCreate">XML_ExternalEntityParserCreate</a></li>
  66       <li><a href="#XML_ParserFree">XML_ParserFree</a></li>
  67       <li><a href="#XML_ParserReset">XML_ParserReset</a></li>
  68     </ul>
  69     </li>
  70     <li><a href="#parsing">Parsing Functions</a>
  71     <ul>
  72       <li><a href="#XML_Parse">XML_Parse</a></li>
  73       <li><a href="#XML_ParseBuffer">XML_ParseBuffer</a></li>
  74       <li><a href="#XML_GetBuffer">XML_GetBuffer</a></li>
  75       <li><a href="#XML_StopParser">XML_StopParser</a></li>
  76       <li><a href="#XML_ResumeParser">XML_ResumeParser</a></li>
  77       <li><a href="#XML_GetParsingStatus">XML_GetParsingStatus</a></li>
  78     </ul>
  79     </li>
  80     <li><a href="#setting">Handler Setting Functions</a>
  81     <ul>
  82       <li><a href="#XML_SetStartElementHandler">XML_SetStartElementHandler</a></li>
  83       <li><a href="#XML_SetEndElementHandler">XML_SetEndElementHandler</a></li>
  84       <li><a href="#XML_SetElementHandler">XML_SetElementHandler</a></li>
  85       <li><a href="#XML_SetCharacterDataHandler">XML_SetCharacterDataHandler</a></li>
  86       <li><a href="#XML_SetProcessingInstructionHandler">XML_SetProcessingInstructionHandler</a></li>
  87       <li><a href="#XML_SetCommentHandler">XML_SetCommentHandler</a></li>
  88       <li><a href="#XML_SetStartCdataSectionHandler">XML_SetStartCdataSectionHandler</a></li>
  89       <li><a href="#XML_SetEndCdataSectionHandler">XML_SetEndCdataSectionHandler</a></li>
  90       <li><a href="#XML_SetCdataSectionHandler">XML_SetCdataSectionHandler</a></li>
  91       <li><a href="#XML_SetDefaultHandler">XML_SetDefaultHandler</a></li>
  92       <li><a href="#XML_SetDefaultHandlerExpand">XML_SetDefaultHandlerExpand</a></li>
  93       <li><a href="#XML_SetExternalEntityRefHandler">XML_SetExternalEntityRefHandler</a></li>
  94       <li><a href="#XML_SetExternalEntityRefHandlerArg">XML_SetExternalEntityRefHandlerArg</a></li>
  95       <li><a href="#XML_SetSkippedEntityHandler">XML_SetSkippedEntityHandler</a></li>
  96       <li><a href="#XML_SetUnknownEncodingHandler">XML_SetUnknownEncodingHandler</a></li>
  97       <li><a href="#XML_SetStartNamespaceDeclHandler">XML_SetStartNamespaceDeclHandler</a></li>
  98       <li><a href="#XML_SetEndNamespaceDeclHandler">XML_SetEndNamespaceDeclHandler</a></li>
  99       <li><a href="#XML_SetNamespaceDeclHandler">XML_SetNamespaceDeclHandler</a></li>
 100       <li><a href="#XML_SetXmlDeclHandler">XML_SetXmlDeclHandler</a></li>
 101       <li><a href="#XML_SetStartDoctypeDeclHandler">XML_SetStartDoctypeDeclHandler</a></li>
 102       <li><a href="#XML_SetEndDoctypeDeclHandler">XML_SetEndDoctypeDeclHandler</a></li>
 103       <li><a href="#XML_SetDoctypeDeclHandler">XML_SetDoctypeDeclHandler</a></li>
 104       <li><a href="#XML_SetElementDeclHandler">XML_SetElementDeclHandler</a></li>
 105       <li><a href="#XML_SetAttlistDeclHandler">XML_SetAttlistDeclHandler</a></li>
 106       <li><a href="#XML_SetEntityDeclHandler">XML_SetEntityDeclHandler</a></li>
 107       <li><a href="#XML_SetUnparsedEntityDeclHandler">XML_SetUnparsedEntityDeclHandler</a></li>
 108       <li><a href="#XML_SetNotationDeclHandler">XML_SetNotationDeclHandler</a></li>
 109       <li><a href="#XML_SetNotStandaloneHandler">XML_SetNotStandaloneHandler</a></li>
 110     </ul>
 111     </li>
 112     <li><a href="#position">Parse Position and Error Reporting Functions</a>
 113     <ul>
 114       <li><a href="#XML_GetErrorCode">XML_GetErrorCode</a></li>
 115       <li><a href="#XML_ErrorString">XML_ErrorString</a></li>
 116       <li><a href="#XML_GetCurrentByteIndex">XML_GetCurrentByteIndex</a></li>
 117       <li><a href="#XML_GetCurrentLineNumber">XML_GetCurrentLineNumber</a></li>
 118       <li><a href="#XML_GetCurrentColumnNumber">XML_GetCurrentColumnNumber</a></li>
 119       <li><a href="#XML_GetCurrentByteCount">XML_GetCurrentByteCount</a></li>
 120       <li><a href="#XML_GetInputContext">XML_GetInputContext</a></li>
 121     </ul>
 122     </li>
 123     <li><a href="#miscellaneous">Miscellaneous Functions</a>
 124     <ul>
 125       <li><a href="#XML_SetUserData">XML_SetUserData</a></li>
 126       <li><a href="#XML_GetUserData">XML_GetUserData</a></li>
 127       <li><a href="#XML_UseParserAsHandlerArg">XML_UseParserAsHandlerArg</a></li>
 128       <li><a href="#XML_SetBase">XML_SetBase</a></li>
 129       <li><a href="#XML_GetBase">XML_GetBase</a></li>
 130       <li><a href="#XML_GetSpecifiedAttributeCount">XML_GetSpecifiedAttributeCount</a></li>
 131       <li><a href="#XML_GetIdAttributeIndex">XML_GetIdAttributeIndex</a></li>
 132       <li><a href="#XML_GetAttributeInfo">XML_GetAttributeInfo</a></li>
 133       <li><a href="#XML_SetEncoding">XML_SetEncoding</a></li>
 134       <li><a href="#XML_SetParamEntityParsing">XML_SetParamEntityParsing</a></li>
 135       <li><a href="#XML_SetHashSalt">XML_SetHashSalt</a></li>
 136       <li><a href="#XML_UseForeignDTD">XML_UseForeignDTD</a></li>
 137       <li><a href="#XML_SetReturnNSTriplet">XML_SetReturnNSTriplet</a></li>
 138       <li><a href="#XML_DefaultCurrent">XML_DefaultCurrent</a></li>
 139       <li><a href="#XML_ExpatVersion">XML_ExpatVersion</a></li>
 140       <li><a href="#XML_ExpatVersionInfo">XML_ExpatVersionInfo</a></li>
 141       <li><a href="#XML_GetFeatureList">XML_GetFeatureList</a></li>
 142       <li><a href="#XML_FreeContentModel">XML_FreeContentModel</a></li>
 143       <li><a href="#XML_MemMalloc">XML_MemMalloc</a></li>
 144       <li><a href="#XML_MemRealloc">XML_MemRealloc</a></li>
 145       <li><a href="#XML_MemFree">XML_MemFree</a></li>
 146     </ul>
 147     </li>
 148   </ul>
 149   </li>
 150 </ul>
 151
 152 <hr />
 153 <h2><a name="overview">Overview</a></h2>
 154
 155 <p>Expat is a stream-oriented parser. You register callback (or
 156 handler) functions with the parser and then start feeding it the
 157 document.  As the parser recognizes parts of the document, it will
 158 call the appropriate handler for that part (if you've registered one.)
 159 The document is fed to the parser in pieces, so you can start parsing
 160 before you have all the document. This also allows you to parse really
 161 huge documents that won't fit into memory.</p>
 162
 163 <p>Expat can be intimidating due to the many kinds of handlers and
 164 options you can set. But you only need to learn four functions in
 165 order to do 90% of what you'll want to do with it:</p>
 166
 167 <dl>
 168
 169 <dt><code><a href= "#XML_ParserCreate"
 170              >XML_ParserCreate</a></code></dt>
 171   <dd>Create a new parser object.</dd>
 172
 173 <dt><code><a href= "#XML_SetElementHandler"
 174              >XML_SetElementHandler</a></code></dt>
 175   <dd>Set handlers for start and end tags.</dd>
 176
 177 <dt><code><a href= "#XML_SetCharacterDataHandler"
 178              >XML_SetCharacterDataHandler</a></code></dt>
 179   <dd>Set handler for text.</dd>
 180
 181 <dt><code><a href= "#XML_Parse"
 182              >XML_Parse</a></code></dt>
 183   <dd>Pass a buffer full of document to the parser</dd>
 184 </dl>
 185
 186 <p>These functions and others are described in the <a
 187 href="#reference">reference</a> part of this document. The reference
 188 section also describes in detail the parameters passed to the
 189 different types of handlers.</p>
 190
 191 <p>Let's look at a very simple example program that only uses 3 of the
 192 above functions (it doesn't need to set a character handler.) The
 193 program <a href="../examples/outline.c">outline.c</a> prints an
 194 element outline, indenting child elements to distinguish them from the
 195 parent element that contains them. The start handler does all the
 196 work.  It prints two indenting spaces for every level of ancestor
 197 elements, then it prints the element and attribute
 198 information. Finally it increments the global <code>Depth</code>
 199 variable.</p>
 200
 201 <pre class="eg">
 202 int Depth;
 203
 204 void XMLCALL
 205 start(void *data, const char *el, const char **attr) {
 206   int i;
 207
 208   for (i = 0; i &lt; Depth; i++)
 209     printf("  ");
 210
 211   printf("%s", el);
 212
 213   for (i = 0; attr[i]; i += 2) {
 214     printf(" %s='%s'", attr[i], attr[i + 1]);
 215   }
 216
 217   printf("\n");
 218   Depth++;
 219 }  /* End of start handler */
 220 </pre>
 221
 222 <p>The end tag simply does the bookkeeping work of decrementing
 223 <code>Depth</code>.</p>
 224 <pre class="eg">
 225 void XMLCALL
 226 end(void *data, const char *el) {
 227   Depth--;
 228 }  /* End of end handler */
 229 </pre>
 230
 231 <p>Note the <code>XMLCALL</code> annotation used for the callbacks.
 232 This is used to ensure that the Expat and the callbacks are using the
 233 same calling convention in case the compiler options used for Expat
 234 itself and the client code are different.  Expat tries not to care
 235 what the default calling convention is, though it may require that it
 236 be compiled with a default convention of "cdecl" on some platforms.
 237 For code which uses Expat, however, the calling convention is
 238 specified by the <code>XMLCALL</code> annotation on most platforms;
 239 callbacks should be defined using this annotation.</p>
 240
 241 <p>The <code>XMLCALL</code> annotation was added in Expat 1.95.7, but
 242 existing working Expat applications don't need to add it (since they
 243 are already using the "cdecl" calling convention, or they wouldn't be
 244 working).  The annotation is only needed if the default calling
 245 convention may be something other than "cdecl".  To use the annotation
 246 safely with older versions of Expat, you can conditionally define it
 247 <em>after</em> including Expat's header file:</p>
 248
 249 <pre class="eg">
 250 #include &lt;expat.h&gt;
 251
 252 #ifndef XMLCALL
 253 #if defined(_MSC_EXTENSIONS) &amp;&amp; !defined(__BEOS__) &amp;&amp; !defined(__CYGWIN__)
 254 #define XMLCALL __cdecl
 255 #elif defined(__GNUC__)
 256 #define XMLCALL __attribute__((cdecl))
 257 #else
 258 #define XMLCALL
 259 #endif
 260 #endif
 261 </pre>
 262
 263 <p>After creating the parser, the main program just has the job of
 264 shoveling the document to the parser so that it can do its work.</p>
 265
 266 <hr />
 267 <h2><a name="building">Building and Installing Expat</a></h2>
 268
 269 <p>The Expat distribution comes as a compressed (with GNU gzip) tar
 270 file.  You may download the latest version from <a href=
 271 "http://sourceforge.net/projects/expat/" >Source Forge</a>.  After
 272 unpacking this, cd into the directory. Then follow either the Win32
 273 directions or Unix directions below.</p>
 274
 275 <h3>Building under Win32</h3>
 276
 277 <p>If you're using the GNU compiler under cygwin, follow the Unix
 278 directions in the next section. Otherwise if you have Microsoft's
 279 Developer Studio installed, then from Windows Explorer double-click on
 280 "expat.dsp" in the lib directory and build and install in the usual
 281 manner.</p>
 282
 283 <p>Alternatively, you may download the Win32 binary package that
 284 contains the "expat.h" include file and a pre-built DLL.</p>
 285
 286 <h3>Building under Unix (or GNU)</h3>
 287
 288 <p>First you'll need to run the configure shell script in order to
 289 configure the Makefiles and headers for your system.</p>
 290
 291 <p>If you're happy with all the defaults that configure picks for you,
 292 and you have permission on your system to install into /usr/local, you
 293 can install Expat with this sequence of commands:</p>
 294
 295 <pre class="eg">
 296 ./configure
 297 make
 298 make install
 299 </pre>
 300
 301 <p>There are some options that you can provide to this script, but the
 302 only one we'll mention here is the <code>--prefix</code> option. You
 303 can find out all the options available by running configure with just
 304 the <code>--help</code> option.</p>
 305
 306 <p>By default, the configure script sets things up so that the library
 307 gets installed in <code>/usr/local/lib</code> and the associated
 308 header file in <code>/usr/local/include</code>.  But if you were to
 309 give the option, <code>--prefix=/home/me/mystuff</code>, then the
 310 library and header would get installed in
 311 <code>/home/me/mystuff/lib</code> and
 312 <code>/home/me/mystuff/include</code> respectively.</p>
 313
 314 <h3>Configuring Expat Using the Pre-Processor</h3>
 315
 316 <p>Expat's feature set can be configured using a small number of
 317 pre-processor definitions.  The definition of this symbols does not
 318 affect the set of entry points for Expat, only the behavior of the API
 319 and the definition of character types in the case of
 320 <code>XML_UNICODE_WCHAR_T</code>.  The symbols are:</p>
 321
 322 <dl class="cpp-symbols">
 323 <dt>XML_DTD</dt>
 324 <dd>Include support for using and reporting DTD-based content.  If
 325 this is defined, default attribute values from an external DTD subset
 326 are reported and attribute value normalization occurs based on the
 327 type of attributes defined in the external subset.  Without
 328 this, Expat has a smaller memory footprint and can be faster, but will
 329 not load external entities or process conditional sections.  This does
 330 not affect the set of functions available in the API.</dd>
 331
 332 <dt>XML_NS</dt>
 333 <dd>When defined, support for the <cite><a href=
 334 "http://www.w3.org/TR/REC-xml-names/" >Namespaces in XML</a></cite>
 335 specification is included.</dd>
 336
 337 <dt>XML_UNICODE</dt>
 338 <dd>When defined, character data reported to the application is
 339 encoded in UTF-16 using wide characters of the type
 340 <code>XML_Char</code>.  This is implied if
 341 <code>XML_UNICODE_WCHAR_T</code> is defined.</dd>
 342
 343 <dt>XML_UNICODE_WCHAR_T</dt>
 344 <dd>If defined, causes the <code>XML_Char</code> character type to be
 345 defined using the <code>wchar_t</code> type; otherwise, <code>unsigned
 346 short</code> is used.  Defining this implies
 347 <code>XML_UNICODE</code>.</dd>
 348
 349 <dt>XML_LARGE_SIZE</dt>
 350 <dd>If defined, causes the <code>XML_Size</code> and <code>XML_Index</code>
 351 integer types to be at least 64 bits in size. This is intended to support
 352 processing of very large input streams, where the return values of
 353 <code><a href="#XML_GetCurrentByteIndex" >XML_GetCurrentByteIndex</a></code>,
 354 <code><a href="#XML_GetCurrentLineNumber" >XML_GetCurrentLineNumber</a></code> and
 355 <code><a href="#XML_GetCurrentColumnNumber" >XML_GetCurrentColumnNumber</a></code>
 356 could overflow. It may not be supported by all compilers, and is turned
 357 off by default.</dd>
 358
 359 <dt>XML_CONTEXT_BYTES</dt>
 360 <dd>The number of input bytes of markup context which the parser will
 361 ensure are available for reporting via <code><a href=
 362 "#XML_GetInputContext" >XML_GetInputContext</a></code>.  This is
 363 normally set to 1024, and must be set to a positive interger.  If this
 364 is not defined, the input context will not be available and <code><a
 365 href= "#XML_GetInputContext" >XML_GetInputContext</a></code> will
 366 always report NULL.  Without this, Expat has a smaller memory
 367 footprint and can be faster.</dd>
 368
 369 <dt>XML_STATIC</dt>
 370 <dd>On Windows, this should be set if Expat is going to be linked
 371 statically with the code that calls it; this is required to get all
 372 the right MSVC magic annotations correct.  This is ignored on other
 373 platforms.</dd>
 374
 375 <dt>XML_ATTR_INFO</dt>
 376 <dd>If defined, makes the the additional function <code><a href=
 377 "#XML_GetAttributeInfo" >XML_GetAttributeInfo</a></code> available
 378 for reporting attribute byte offsets.</dd>
 379 </dl>
 380
 381 <hr />
 382 <h2><a name="using">Using Expat</a></h2>
 383
 384 <h3>Compiling and Linking Against Expat</h3>
 385
 386 <p>Unless you installed Expat in a location not expected by your
 387 compiler and linker, all you have to do to use Expat in your programs
 388 is to include the Expat header (<code>#include &lt;expat.h&gt;</code>)
 389 in your files that make calls to it and to tell the linker that it
 390 needs to link against the Expat library.  On Unix systems, this would
 391 usually be done with the <code>-lexpat</code> argument.  Otherwise,
 392 you'll need to tell the compiler where to look for the Expat header
 393 and the linker where to find the Expat library.  You may also need to
 394 take steps to tell the operating system where to find this library at
 395 run time.</p>
 396
 397 <p>On a Unix-based system, here's what a Makefile might look like when
 398 Expat is installed in a standard location:</p>
 399
 400 <pre class="eg">
 401 CC=cc
 402 LDFLAGS=
 403 LIBS= -lexpat
 404 xmlapp: xmlapp.o
 405         $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS)
 406 </pre>
 407
 408 <p>If you installed Expat in, say, <code>/home/me/mystuff</code>, then
 409 the Makefile would look like this:</p>
 410
 411 <pre class="eg">
 412 CC=cc
 413 CFLAGS= -I/home/me/mystuff/include
 414 LDFLAGS=
 415 LIBS= -L/home/me/mystuff/lib -lexpat
 416 xmlapp: xmlapp.o
 417         $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS)
 418 </pre>
 419
 420 <p>You'd also have to set the environment variable
 421 <code>LD_LIBRARY_PATH</code> to <code>/home/me/mystuff/lib</code> (or
 422 to <code>${LD_LIBRARY_PATH}:/home/me/mystuff/lib</code> if
 423 LD_LIBRARY_PATH already has some directories in it) in order to run
 424 your application.</p>
 425
 426 <h3>Expat Basics</h3>
 427
 428 <p>As we saw in the example in the overview, the first step in parsing
 429 an XML document with Expat is to create a parser object. There are <a
 430 href="#creation">three functions</a> in the Expat API for creating a
 431 parser object.  However, only two of these (<code><a href=
 432 "#XML_ParserCreate" >XML_ParserCreate</a></code> and <code><a href=
 433 "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>) can be used for
 434 constructing a parser for a top-level document.  The object returned
 435 by these functions is an opaque pointer (i.e. "expat.h" declares it as
 436 void *) to data with further internal structure. In order to free the
 437 memory associated with this object you must call <code><a href=
 438 "#XML_ParserFree" >XML_ParserFree</a></code>. Note that if you have
 439 provided any <a href="#userdata">user data</a> that gets stored in the
 440 parser, then your application is responsible for freeing it prior to
 441 calling <code>XML_ParserFree</code>.</p>
 442
 443 <p>The objects returned by the parser creation functions are good for
 444 parsing only one XML document or external parsed entity. If your
 445 application needs to parse many XML documents, then it needs to create
 446 a parser object for each one. The best way to deal with this is to
 447 create a higher level object that contains all the default
 448 initialization you want for your parser objects.</p>
 449
 450 <p>Walking through a document hierarchy with a stream oriented parser
 451 will require a good stack mechanism in order to keep track of current
 452 context.  For instance, to answer the simple question, "What element
 453 does this text belong to?" requires a stack, since the parser may have
 454 descended into other elements that are children of the current one and
 455 has encountered this text on the way out.</p>
 456
 457 <p>The things you're likely to want to keep on a stack are the
 458 currently opened element and it's attributes. You push this
 459 information onto the stack in the start handler and you pop it off in
 460 the end handler.</p>
 461
 462 <p>For some tasks, it is sufficient to just keep information on what
 463 the depth of the stack is (or would be if you had one.) The outline
 464 program shown above presents one example. Another such task would be
 465 skipping over a complete element. When you see the start tag for the
 466 element you want to skip, you set a skip flag and record the depth at
 467 which the element started.  When the end tag handler encounters the
 468 same depth, the skipped element has ended and the flag may be
 469 cleared. If you follow the convention that the root element starts at
 470 1, then you can use the same variable for skip flag and skip
 471 depth.</p>
 472
 473 <pre class="eg">
 474 void
 475 init_info(Parseinfo *info) {
 476   info->skip = 0;
 477   info->depth = 1;
 478   /* Other initializations here */
 479 }  /* End of init_info */
 480
 481 void XMLCALL
 482 rawstart(void *data, const char *el, const char **attr) {
 483   Parseinfo *inf = (Parseinfo *) data;
 484
 485   if (! inf->skip) {
 486     if (should_skip(inf, el, attr)) {
 487       inf->skip = inf->depth;
 488     }
 489     else
 490       start(inf, el, attr);     /* This does rest of start handling */
 491   }
 492
 493   inf->depth++;
 494 }  /* End of rawstart */
 495
 496 void XMLCALL
 497 rawend(void *data, const char *el) {
 498   Parseinfo *inf = (Parseinfo *) data;
 499
 500   inf->depth--;
 501
 502   if (! inf->skip)
 503     end(inf, el);              /* This does rest of end handling */
 504
 505   if (inf->skip == inf->depth)
 506     inf->skip = 0;
 507 }  /* End rawend */
 508 </pre>
 509
 510 <p>Notice in the above example the difference in how depth is
 511 manipulated in the start and end handlers. The end tag handler should
 512 be the mirror image of the start tag handler. This is necessary to
 513 properly model containment. Since, in the start tag handler, we
 514 incremented depth <em>after</em> the main body of start tag code, then
 515 in the end handler, we need to manipulate it <em>before</em> the main
 516 body.  If we'd decided to increment it first thing in the start
 517 handler, then we'd have had to decrement it last thing in the end
 518 handler.</p>
 519
 520 <h3 id="userdata">Communicating between handlers</h3>
 521
 522 <p>In order to be able to pass information between different handlers
 523 without using globals, you'll need to define a data structure to hold
 524 the shared variables. You can then tell Expat (with the <code><a href=
 525 "#XML_SetUserData" >XML_SetUserData</a></code> function) to pass a
 526 pointer to this structure to the handlers.  This is the first
 527 argument received by most handlers.  In the <a href="#reference"
 528 >reference section</a>, an argument to a callback function is named
 529 <code>userData</code> and have type <code>void *</code> if the user
 530 data is passed; it will have the type <code>XML_Parser</code> if the
 531 parser itself is passed.  When the parser is passed, the user data may
 532 be retrieved using <code><a href="#XML_GetUserData"
 533 >XML_GetUserData</a></code>.</p>
 534
 535 <p>One common case where multiple calls to a single handler may need
 536 to communicate using an application data structure is the case when
 537 content passed to the character data handler (set by <code><a href=
 538 "#XML_SetCharacterDataHandler"
 539 >XML_SetCharacterDataHandler</a></code>) needs to be accumulated.  A
 540 common first-time mistake with any of the event-oriented interfaces to
 541 an XML parser is to expect all the text contained in an element to be
 542 reported by a single call to the character data handler.  Expat, like
 543 many other XML parsers, reports such data as a sequence of calls;
 544 there's no way to know when the end of the sequence is reached until a
 545 different callback is made.  A buffer referenced by the user data
 546 structure proves both an effective and convenient place to accumulate
 547 character data.</p>
 548
 549 <!-- XXX example needed here -->
 550
 551
 552 <h3>XML Version</h3>
 553
 554 <p>Expat is an XML 1.0 parser, and as such never complains based on
 555 the value of the <code>version</code> pseudo-attribute in the XML
 556 declaration, if present.</p>
 557
 558 <p>If an application needs to check the version number (to support
 559 alternate processing), it should use the <code><a href=
 560 "#XML_SetXmlDeclHandler" >XML_SetXmlDeclHandler</a></code> function to
 561 set a handler that uses the information in the XML declaration to
 562 determine what to do.  This example shows how to check that only a
 563 version number of <code>"1.0"</code> is accepted:</p>
 564
 565 <pre class="eg">
 566 static int wrong_version;
 567 static XML_Parser parser;
 568
 569 static void XMLCALL
 570 xmldecl_handler(void            *userData,
 571                 const XML_Char  *version,
 572                 const XML_Char  *encoding,
 573                 int              standalone)
 574 {
 575   static const XML_Char Version_1_0[] = {'1', '.', '0', 0};
 576
 577   int i;
 578
 579   for (i = 0; i &lt; (sizeof(Version_1_0) / sizeof(Version_1_0[0])); ++i) {
 580     if (version[i] != Version_1_0[i]) {
 581       wrong_version = 1;
 582       /* also clear all other handlers: */
 583       XML_SetCharacterDataHandler(parser, NULL);
 584       ...
 585       return;
 586     }
 587   }
 588   ...
 589 }
 590 </pre>
 591
 592 <h3>Namespace Processing</h3>
 593
 594 <p>When the parser is created using the <code><a href=
 595 "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>, function, Expat
 596 performs namespace processing. Under namespace processing, Expat
 597 consumes <code>xmlns</code> and <code>xmlns:...</code> attributes,
 598 which declare namespaces for the scope of the element in which they
 599 occur. This means that your start handler will not see these
 600 attributes.  Your application can still be informed of these
 601 declarations by setting namespace declaration handlers with <a href=
 602 "#XML_SetNamespaceDeclHandler"
 603 ><code>XML_SetNamespaceDeclHandler</code></a>.</p>
 604
 605 <p>Element type and attribute names that belong to a given namespace
 606 are passed to the appropriate handler in expanded form. By default
 607 this expanded form is a concatenation of the namespace URI, the
 608 separator character (which is the 2nd argument to <code><a href=
 609 "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>), and the local
 610 name (i.e. the part after the colon). Names with undeclared prefixes
 611 are not well-formed when namespace processing is enabled, and will
 612 trigger an error. Unprefixed attribute names are never expanded,
 613 and unprefixed element names are only expanded when they are in the
 614 scope of a default namespace.</p>
 615
 616 <p>However if <code><a href= "#XML_SetReturnNSTriplet"
 617 >XML_SetReturnNSTriplet</a></code> has been called with a non-zero
 618 <code>do_nst</code> parameter, then the expanded form for names with
 619 an explicit prefix is a concatenation of: URI, separator, local name,
 620 separator, prefix.</p>
 621
 622 <p>You can set handlers for the start of a namespace declaration and
 623 for the end of a scope of a declaration with the <code><a href=
 624 "#XML_SetNamespaceDeclHandler" >XML_SetNamespaceDeclHandler</a></code>
 625 function.  The StartNamespaceDeclHandler is called prior to the start
 626 tag handler and the EndNamespaceDeclHandler is called after the
 627 corresponding end tag that ends the namespace's scope.  The namespace
 628 start handler gets passed the prefix and URI for the namespace.  For a
 629 default namespace declaration (xmlns='...'), the prefix will be null.
 630 The URI will be null for the case where the default namespace is being
 631 unset.  The namespace end handler just gets the prefix for the closing
 632 scope.</p>
 633
 634 <p>These handlers are called for each declaration. So if, for
 635 instance, a start tag had three namespace declarations, then the
 636 StartNamespaceDeclHandler would be called three times before the start
 637 tag handler is called, once for each declaration.</p>
 638
 639 <h3>Character Encodings</h3>
 640
 641 <p>While XML is based on Unicode, and every XML processor is required
 642 to recognized UTF-8 and UTF-16 (1 and 2 byte encodings of Unicode),
 643 other encodings may be declared in XML documents or entities. For the
 644 main document, an XML declaration may contain an encoding
 645 declaration:</p>
 646 <pre>
 647 &lt;?xml version="1.0" encoding="ISO-8859-2"?&gt;
 648 </pre>
 649
 650 <p>External parsed entities may begin with a text declaration, which
 651 looks like an XML declaration with just an encoding declaration:</p>
 652 <pre>
 653 &lt;?xml encoding="Big5"?&gt;
 654 </pre>
 655
 656 <p>With Expat, you may also specify an encoding at the time of
 657 creating a parser. This is useful when the encoding information may
 658 come from a source outside the document itself (like a higher level
 659 protocol.)</p>
 660
 661 <p><a name="builtin_encodings"></a>There are four built-in encodings
 662 in Expat:</p>
 663 <ul>
 664 <li>UTF-8</li>
 665 <li>UTF-16</li>
 666 <li>ISO-8859-1</li>
 667 <li>US-ASCII</li>
 668 </ul>
 669
 670 <p>Anything else discovered in an encoding declaration or in the
 671 protocol encoding specified in the parser constructor, triggers a call
 672 to the <code>UnknownEncodingHandler</code>. This handler gets passed
 673 the encoding name and a pointer to an <code>XML_Encoding</code> data
 674 structure. Your handler must fill in this structure and return
 675 <code>XML_STATUS_OK</code> if it knows how to deal with the
 676 encoding. Otherwise the handler should return
 677 <code>XML_STATUS_ERROR</code>.  The handler also gets passed a pointer
 678 to an optional application data structure that you may indicate when
 679 you set the handler.</p>
 680
 681 <p>Expat places restrictions on character encodings that it can
 682 support by filling in the <code>XML_Encoding</code> structure.
 683 include file:</p>
 684 <ol>
 685 <li>Every ASCII character that can appear in a well-formed XML document
 686 must be represented by a single byte, and that byte must correspond to
 687 it's ASCII encoding (except for the characters $@\^'{}~)</li>
 688 <li>Characters must be encoded in 4 bytes or less.</li>
 689 <li>All characters encoded must have Unicode scalar values less than or
 690 equal to 65535 (0xFFFF)<em>This does not apply to the built-in support
 691 for UTF-16 and UTF-8</em></li>
 692 <li>No character may be encoded by more that one distinct sequence of
 693 bytes</li>
 694 </ol>
 695
 696 <p><code>XML_Encoding</code> contains an array of integers that
 697 correspond to the 1st byte of an encoding sequence. If the value in
 698 the array for a byte is zero or positive, then the byte is a single
 699 byte encoding that encodes the Unicode scalar value contained in the
 700 array. A -1 in this array indicates a malformed byte. If the value is
 701 -2, -3, or -4, then the byte is the beginning of a 2, 3, or 4 byte
 702 sequence respectively. Multi-byte sequences are sent to the convert
 703 function pointed at in the <code>XML_Encoding</code> structure. This
 704 function should return the Unicode scalar value for the sequence or -1
 705 if the sequence is malformed.</p>
 706
 707 <p>One pitfall that novice Expat users are likely to fall into is that
 708 although Expat may accept input in various encodings, the strings that
 709 it passes to the handlers are always encoded in UTF-8 or UTF-16
 710 (depending on how Expat was compiled). Your application is responsible
 711 for any translation of these strings into other encodings.</p>
 712
 713 <h3>Handling External Entity References</h3>
 714
 715 <p>Expat does not read or parse external entities directly. Note that
 716 any external DTD is a special case of an external entity.  If you've
 717 set no <code>ExternalEntityRefHandler</code>, then external entity
 718 references are silently ignored. Otherwise, it calls your handler with
 719 the information needed to read and parse the external entity.</p>
 720
 721 <p>Your handler isn't actually responsible for parsing the entity, but
 722 it is responsible for creating a subsidiary parser with <code><a href=
 723 "#XML_ExternalEntityParserCreate"
 724 >XML_ExternalEntityParserCreate</a></code> that will do the job. This
 725 returns an instance of <code>XML_Parser</code> that has handlers and
 726 other data structures initialized from the parent parser. You may then
 727 use <code><a href= "#XML_Parse" >XML_Parse</a></code> or <code><a
 728 href= "#XML_ParseBuffer">XML_ParseBuffer</a></code> calls against this
 729 parser.  Since external entities my refer to other external entities,
 730 your handler should be prepared to be called recursively.</p>
 731
 732 <h3>Parsing DTDs</h3>
 733
 734 <p>In order to parse parameter entities, before starting the parse,
 735 you must call <code><a href= "#XML_SetParamEntityParsing"
 736 >XML_SetParamEntityParsing</a></code> with one of the following
 737 arguments:</p>
 738 <dl>
 739 <dt><code>XML_PARAM_ENTITY_PARSING_NEVER</code></dt>
 740 <dd>Don't parse parameter entities or the external subset</dd>
 741 <dt><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></dt>
 742 <dd>Parse parameter entites and the external subset unless
 743 <code>standalone</code> was set to "yes" in the XML declaration.</dd>
 744 <dt><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></dt>
 745 <dd>Always parse parameter entities and the external subset</dd>
 746 </dl>
 747
 748 <p>In order to read an external DTD, you also have to set an external
 749 entity reference handler as described above.</p>
 750
 751 <h3 id="stop-resume">Temporarily Stopping Parsing</h3>
 752
 753 <p>Expat 1.95.8 introduces a new feature: its now possible to stop
 754 parsing temporarily from within a handler function, even if more data
 755 has already been passed into the parser.  Applications for this
 756 include</p>
 757
 758 <ul>
 759   <li>Supporting the <a href= "http://www.w3.org/TR/xinclude/"
 760   >XInclude</a> specification.</li>
 761
 762   <li>Delaying further processing until additional information is
 763   available from some other source.</li>
 764
 765   <li>Adjusting processor load as task priorities shift within an
 766   application.</li>
 767
 768   <li>Stopping parsing completely (simply free or reset the parser
 769   instead of resuming in the outer parsing loop).  This can be useful
 770   if a application-domain error is found in the XML being parsed or if
 771   the result of the parse is determined not to be useful after
 772   all.</li>
 773 </ul>
 774
 775 <p>To take advantage of this feature, the main parsing loop of an
 776 application needs to support this specifically.  It cannot be
 777 supported with a parsing loop compatible with Expat 1.95.7 or
 778 earlier (though existing loops will continue to work without
 779 supporting the stop/resume feature).</p>
 780
 781 <p>An application that uses this feature for a single parser will have
 782 the rough structure (in pseudo-code):</p>
 783
 784 <pre class="pseudocode">
 785 fd = open_input()
 786 p = create_parser()
 787
 788 if parse_xml(p, fd) {
 789   /* suspended */
 790
 791   int suspended = 1;
 792
 793   while (suspended) {
 794     do_something_else()
 795     if ready_to_resume() {
 796       suspended = continue_parsing(p, fd);
 797     }
 798   }
 799 }
 800 </pre>
 801
 802 <p>An application that may resume any of several parsers based on
 803 input (either from the XML being parsed or some other source) will
 804 certainly have more interesting control structures.</p>
 805
 806 <p>This C function could be used for the <code>parse_xml</code>
 807 function mentioned in the pseudo-code above:</p>
 808
 809 <pre class="eg">
 810 #define BUFF_SIZE 10240
 811
 812 /* Parse a document from the open file descriptor 'fd' until the parse
 813    is complete (the document has been completely parsed, or there's
 814    been an error), or the parse is stopped.  Return non-zero when
 815    the parse is merely suspended.
 816 */
 817 int
 818 parse_xml(XML_Parser p, int fd)
 819 {
 820   for (;;) {
 821     int last_chunk;
 822     int bytes_read;
 823     enum XML_Status status;
 824
 825     void *buff = XML_GetBuffer(p, BUFF_SIZE);
 826     if (buff == NULL) {
 827       /* handle error... */
 828       return 0;
 829     }
 830     bytes_read = read(fd, buff, BUFF_SIZE);
 831     if (bytes_read &lt; 0) {
 832       /* handle error... */
 833       return 0;
 834     }
 835     status = XML_ParseBuffer(p, bytes_read, bytes_read == 0);
 836     switch (status) {
 837       case XML_STATUS_ERROR:
 838         /* handle error... */
 839         return 0;
 840       case XML_STATUS_SUSPENDED:
 841         return 1;
 842     }
 843     if (bytes_read == 0)
 844       return 0;
 845   }
 846 }
 847 </pre>
 848
 849 <p>The corresponding <code>continue_parsing</code> function is
 850 somewhat simpler, since it only need deal with the return code from
 851 <code><a href= "#XML_ResumeParser">XML_ResumeParser</a></code>; it can
 852 delegate the input handling to the <code>parse_xml</code>
 853 function:</p>
 854
 855 <pre class="eg">
 856 /* Continue parsing a document which had been suspended.  The 'p' and
 857    'fd' arguments are the same as passed to parse_xml().  Return
 858    non-zero when the parse is suspended.
 859 */
 860 int
 861 continue_parsing(XML_Parser p, int fd)
 862 {
 863   enum XML_Status status = XML_ResumeParser(p);
 864   switch (status) {
 865     case XML_STATUS_ERROR:
 866       /* handle error... */
 867       return 0;
 868     case XML_ERROR_NOT_SUSPENDED:
 869       /* handle error... */
 870       return 0;.
 871     case XML_STATUS_SUSPENDED:
 872       return 1;
 873   }
 874   return parse_xml(p, fd);
 875 }
 876 </pre>
 877
 878 <p>Now that we've seen what a mess the top-level parsing loop can
 879 become, what have we gained?  Very simply, we can now use the <code><a
 880 href= "#XML_StopParser" >XML_StopParser</a></code> function to stop
 881 parsing, without having to go to great lengths to avoid additional
 882 processing that we're expecting to ignore.  As a bonus, we get to stop
 883 parsing <em>temporarily</em>, and come back to it when we're
 884 ready.</p>
 885
 886 <p>To stop parsing from a handler function, use the <code><a href=
 887 "#XML_StopParser" >XML_StopParser</a></code> function.  This function
 888 takes two arguments; the parser being stopped and a flag indicating
 889 whether the parse can be resumed in the future.</p>
 890
 891 <!-- XXX really need more here -->
 892
 893
 894 <hr />
 895 <!-- ================================================================ -->
 896
 897 <h2><a name="reference">Expat Reference</a></h2>
 898
 899 <h3><a name="creation">Parser Creation</a></h3>
 900
 901 <pre class="fcndec" id="XML_ParserCreate">
 902 XML_Parser XMLCALL
 903 XML_ParserCreate(const XML_Char *encoding);
 904 </pre>
 905 <div class="fcndef">
 906 Construct a new parser. If encoding is non-null, it specifies a
 907 character encoding to use for the document. This overrides the document
 908 encoding declaration. There are four built-in encodings:
 909 <ul>
 910 <li>US-ASCII</li>
 911 <li>UTF-8</li>
 912 <li>UTF-16</li>
 913 <li>ISO-8859-1</li>
 914 </ul>
 915 Any other value will invoke a call to the UnknownEncodingHandler.
 916 </div>
 917
 918 <pre class="fcndec" id="XML_ParserCreateNS">
 919 XML_Parser XMLCALL
 920 XML_ParserCreateNS(const XML_Char *encoding,
 921                    XML_Char sep);
 922 </pre>
 923 <div class="fcndef">
 924 Constructs a new parser that has namespace processing in effect. Namespace
 925 expanded element names and attribute names are returned as a concatenation
 926 of the namespace URI, <em>sep</em>, and the local part of the name. This
 927 means that you should pick a character for <em>sep</em> that can't be part
 928 of an URI. Since Expat does not check namespace URIs for conformance, the
 929 only safe choice for a namespace separator is a character that is illegal
 930 in XML. For instance, <code>'\xFF'</code> is not legal in UTF-8, and
 931 <code>'\xFFFF'</code> is not legal in UTF-16. There is a special case when
 932 <em>sep</em> is the null character <code>'\0'</code>: the namespace URI and
 933 the local part will be concatenated without any separator - this is intended
 934 to support RDF processors. It is a programming error to use the null separator
 935 with <a href= "#XML_SetReturnNSTriplet">namespace triplets</a>.</div>
 936
 937 <pre class="fcndec" id="XML_ParserCreate_MM">
 938 XML_Parser XMLCALL
 939 XML_ParserCreate_MM(const XML_Char *encoding,
 940                     const XML_Memory_Handling_Suite *ms,
 941                     const XML_Char *sep);
 942 </pre>
 943 <pre class="signature">
 944 typedef struct {
 945   void *(XMLCALL *malloc_fcn)(size_t size);
 946   void *(XMLCALL *realloc_fcn)(void *ptr, size_t size);
 947   void (XMLCALL *free_fcn)(void *ptr);
 948 } XML_Memory_Handling_Suite;
 949 </pre>
 950 <div class="fcndef">
 951 <p>Construct a new parser using the suite of memory handling functions
 952 specified in <code>ms</code>. If <code>ms</code> is NULL, then use the
 953 standard set of memory management functions. If <code>sep</code> is
 954 non NULL, then namespace processing is enabled in the created parser
 955 and the character pointed at by sep is used as the separator between
 956 the namespace URI and the local part of the name.</p>
 957 </div>
 958
 959 <pre class="fcndec" id="XML_ExternalEntityParserCreate">
 960 XML_Parser XMLCALL
 961 XML_ExternalEntityParserCreate(XML_Parser p,
 962                                const XML_Char *context,
 963                                const XML_Char *encoding);
 964 </pre>
 965 <div class="fcndef">
 966 Construct a new <code>XML_Parser</code> object for parsing an external
 967 general entity. Context is the context argument passed in a call to a
 968 ExternalEntityRefHandler. Other state information such as handlers,
 969 user data, namespace processing is inherited from the parser passed as
 970 the 1st argument. So you shouldn't need to call any of the behavior
 971 changing functions on this parser (unless you want it to act
 972 differently than the parent parser).
 973 </div>
 974
 975 <pre class="fcndec" id="XML_ParserFree">
 976 void XMLCALL
 977 XML_ParserFree(XML_Parser p);
 978 </pre>
 979 <div class="fcndef">
 980 Free memory used by the parser. Your application is responsible for
 981 freeing any memory associated with <a href="#userdata">user data</a>.
 982 </div>
 983
 984 <pre class="fcndec" id="XML_ParserReset">
 985 XML_Bool XMLCALL
 986 XML_ParserReset(XML_Parser p,
 987                 const XML_Char *encoding);
 988 </pre>
 989 <div class="fcndef">
 990 Clean up the memory structures maintained by the parser so that it may
 991 be used again.  After this has been called, <code>parser</code> is
 992 ready to start parsing a new document.  All handlers are cleared from
 993 the parser, except for the unknownEncodingHandler.  The parser's external
 994 state is re-initialized except for the values of ns and ns_triplets.
 995 This function may not be used on a parser created using <code><a href=
 996 "#XML_ExternalEntityParserCreate" >XML_ExternalEntityParserCreate</a
 997 ></code>; it will return <code>XML_FALSE</code> in that case.  Returns
 998 <code>XML_TRUE</code> on success.  Your application is responsible for
 999 dealing with any memory associated with <a href="#userdata">user data</a>.
1000 </div>
1001
1002 <h3><a name="parsing">Parsing</a></h3>
1003
1004 <p>To state the obvious: the three parsing functions <code><a href=
1005 "#XML_Parse" >XML_Parse</a></code>, <code><a href= "#XML_ParseBuffer">
1006 XML_ParseBuffer</a></code> and <code><a href= "#XML_GetBuffer">
1007 XML_GetBuffer</a></code> must not be called from within a handler
1008 unless they operate on a separate parser instance, that is, one that
1009 did not call the handler. For example, it is OK to call the parsing
1010 functions from within an <code>XML_ExternalEntityRefHandler</code>,
1011 if they apply to the parser created by
1012 <code><a href= "#XML_ExternalEntityParserCreate"
1013 >XML_ExternalEntityParserCreate</a></code>.</p>
1014
1015 <p>Note: the <code>len</code> argument passed to these functions
1016 should be considerably less than the maximum value for an integer,
1017 as it could create an integer overflow situation if the added
1018 lengths of a buffer and the unprocessed portion of the previous buffer
1019 exceed the maximum integer value. Input data at the end of a buffer
1020 will remain unprocessed if it is part of an XML token for which the
1021 end is not part of that buffer.</p>
1022
1023 <pre class="fcndec" id="XML_Parse">
1024 enum XML_Status XMLCALL
1025 XML_Parse(XML_Parser p,
1026           const char *s,
1027           int len,
1028           int isFinal);
1029 </pre>
1030 <pre class="signature">
1031 enum XML_Status {
1032   XML_STATUS_ERROR = 0,
1033   XML_STATUS_OK = 1
1034 };
1035 </pre>
1036 <div class="fcndef">
1037 Parse some more of the document. The string <code>s</code> is a buffer
1038 containing part (or perhaps all) of the document. The number of bytes of s
1039 that are part of the document is indicated by <code>len</code>. This means
1040 that <code>s</code> doesn't have to be null terminated. It also means that
1041 if <code>len</code> is larger than the number of bytes in the block of
1042 memory that <code>s</code> points at, then a memory fault is likely. The
1043 <code>isFinal</code> parameter informs the parser that this is the last
1044 piece of the document. Frequently, the last piece is empty (i.e.
1045 <code>len</code> is zero.)
1046 If a parse error occurred, it returns <code>XML_STATUS_ERROR</code>.
1047 Otherwise it returns <code>XML_STATUS_OK</code> value.
1048 </div>
1049
1050 <pre class="fcndec" id="XML_ParseBuffer">
1051 enum XML_Status XMLCALL
1052 XML_ParseBuffer(XML_Parser p,
1053                 int len,
1054                 int isFinal);
1055 </pre>
1056 <div class="fcndef">
1057 This is just like <code><a href= "#XML_Parse" >XML_Parse</a></code>,
1058 except in this case Expat provides the buffer.  By obtaining the
1059 buffer from Expat with the <code><a href= "#XML_GetBuffer"
1060 >XML_GetBuffer</a></code> function, the application can avoid double
1061 copying of the input.
1062 </div>
1063
1064 <pre class="fcndec" id="XML_GetBuffer">
1065 void * XMLCALL
1066 XML_GetBuffer(XML_Parser p,
1067               int len);
1068 </pre>
1069 <div class="fcndef">
1070 Obtain a buffer of size <code>len</code> to read a piece of the document
1071 into. A NULL value is returned if Expat can't allocate enough memory for
1072 this buffer. This has to be called prior to every call to
1073 <code><a href= "#XML_ParseBuffer" >XML_ParseBuffer</a></code>. A
1074 typical use would look like this:
1075
1076 <pre class="eg">
1077 for (;;) {
1078   int bytes_read;
1079   void *buff = XML_GetBuffer(p, BUFF_SIZE);
1080   if (buff == NULL) {
1081     /* handle error */
1082   }
1083
1084   bytes_read = read(docfd, buff, BUFF_SIZE);
1085   if (bytes_read &lt; 0) {
1086     /* handle error */
1087   }
1088
1089   if (! XML_ParseBuffer(p, bytes_read, bytes_read == 0)) {
1090     /* handle parse error */
1091   }
1092
1093   if (bytes_read == 0)
1094     break;
1095 }
1096 </pre>
1097 </div>
1098
1099 <pre class="fcndec" id="XML_StopParser">
1100 enum XML_Status XMLCALL
1101 XML_StopParser(XML_Parser p,
1102                XML_Bool resumable);
1103 </pre>
1104 <div class="fcndef">
1105
1106 <p>Stops parsing, causing <code><a href= "#XML_Parse"
1107 >XML_Parse</a></code> or <code><a href= "#XML_ParseBuffer"
1108 >XML_ParseBuffer</a></code> to return.  Must be called from within a
1109 call-back handler, except when aborting (when <code>resumable</code>
1110 is <code>XML_FALSE</code>) an already suspended parser.  Some
1111 call-backs may still follow because they would otherwise get
1112 lost, including
1113 <ul>
1114   <li> the end element handler for empty elements when stopped in the
1115        start element handler,</li>
1116   <li> the end namespace declaration handler when stopped in the end
1117        element handler,</li>
1118   <li> the character data handler when stopped in the character data handler
1119        while making multiple call-backs on a contiguous chunk of characters,</li>
1120 </ul>
1121 and possibly others.</p>
1122
1123 <p>This can be called from most handlers, including DTD related
1124 call-backs, except when parsing an external parameter entity and
1125 <code>resumable</code> is <code>XML_TRUE</code>.  Returns
1126 <code>XML_STATUS_OK</code> when successful,
1127 <code>XML_STATUS_ERROR</code> otherwise.  The possible error codes
1128 are:</p>
1129 <dl>
1130   <dt><code>XML_ERROR_SUSPENDED</code></dt>
1131   <dd>when suspending an already suspended parser.</dd>
1132   <dt><code>XML_ERROR_FINISHED</code></dt>
1133   <dd>when the parser has already finished.</dd>
1134   <dt><code>XML_ERROR_SUSPEND_PE</code></dt>
1135   <dd>when suspending while parsing an external PE.</dd>
1136 </dl>
1137
1138 <p>Since the stop/resume feature requires application support in the
1139 outer parsing loop, it is an error to call this function for a parser
1140 not being handled appropriately; see <a href= "#stop-resume"
1141 >Temporarily Stopping Parsing</a> for more information.</p>
1142
1143 <p>When <code>resumable</code> is <code>XML_TRUE</code> then parsing
1144 is <em>suspended</em>, that is, <code><a href= "#XML_Parse"
1145 >XML_Parse</a></code> and <code><a href= "#XML_ParseBuffer"
1146 >XML_ParseBuffer</a></code> return <code>XML_STATUS_SUSPENDED</code>.
1147 Otherwise, parsing is <em>aborted</em>, that is, <code><a href=
1148 "#XML_Parse" >XML_Parse</a></code> and <code><a href=
1149 "#XML_ParseBuffer" >XML_ParseBuffer</a></code> return
1150 <code>XML_STATUS_ERROR</code> with error code
1151 <code>XML_ERROR_ABORTED</code>.</p>
1152
1153 <p><strong>Note:</strong>
1154 This will be applied to the current parser instance only, that is, if
1155 there is a parent parser then it will continue parsing when the
1156 external entity reference handler returns.  It is up to the
1157 implementation of that handler to call <code><a href=
1158 "#XML_StopParser" >XML_StopParser</a></code> on the parent parser
1159 (recursively), if one wants to stop parsing altogether.</p>
1160
1161 <p>When suspended, parsing can be resumed by calling <code><a href=
1162 "#XML_ResumeParser" >XML_ResumeParser</a></code>.</p>
1163
1164 <p>New in Expat 1.95.8.</p>
1165 </div>
1166
1167 <pre class="fcndec" id="XML_ResumeParser">
1168 enum XML_Status XMLCALL
1169 XML_ResumeParser(XML_Parser p);
1170 </pre>
1171 <div class="fcndef">
1172 <p>Resumes parsing after it has been suspended with <code><a href=
1173 "#XML_StopParser" >XML_StopParser</a></code>.  Must not be called from
1174 within a handler call-back.  Returns same status codes as <code><a
1175 href= "#XML_Parse">XML_Parse</a></code> or <code><a href=
1176 "#XML_ParseBuffer" >XML_ParseBuffer</a></code>.  An additional error
1177 code, <code>XML_ERROR_NOT_SUSPENDED</code>, will be returned if the
1178 parser was not currently suspended.</p>
1179
1180 <p><strong>Note:</strong>
1181 This must be called on the most deeply nested child parser instance
1182 first, and on its parent parser only after the child parser has
1183 finished, to be applied recursively until the document entity's parser
1184 is restarted.  That is, the parent parser will not resume by itself
1185 and it is up to the application to call <code><a href=
1186 "#XML_ResumeParser" >XML_ResumeParser</a></code> on it at the
1187 appropriate moment.</p>
1188
1189 <p>New in Expat 1.95.8.</p>
1190 </div>
1191
1192 <pre class="fcndec" id="XML_GetParsingStatus">
1193 void XMLCALL
1194 XML_GetParsingStatus(XML_Parser p,
1195                      XML_ParsingStatus *status);
1196 </pre>
1197 <pre class="signature">
1198 enum XML_Parsing {
1199   XML_INITIALIZED,
1200   XML_PARSING,
1201   XML_FINISHED,
1202   XML_SUSPENDED
1203 };
1204
1205 typedef struct {
1206   enum XML_Parsing parsing;
1207   XML_Bool finalBuffer;
1208 } XML_ParsingStatus;
1209 </pre>
1210 <div class="fcndef">
1211 <p>Returns status of parser with respect to being initialized,
1212 parsing, finished, or suspended, and whether the final buffer is being
1213 processed.  The <code>status</code> parameter <em>must not</em> be
1214 NULL.</p>
1215
1216 <p>New in Expat 1.95.8.</p>
1217 </div>
1218
1219
1220 <h3><a name="setting">Handler Setting</a></h3>
1221
1222 <p>Although handlers are typically set prior to parsing and left alone, an
1223 application may choose to set or change the handler for a parsing event
1224 while the parse is in progress. For instance, your application may choose
1225 to ignore all text not descended from a <code>para</code> element. One
1226 way it could do this is to set the character handler when a para start tag
1227 is seen, and unset it for the corresponding end tag.</p>
1228
1229 <p>A handler may be <em>unset</em> by providing a NULL pointer to the
1230 appropriate handler setter. None of the handler setting functions have
1231 a return value.</p>
1232
1233 <p>Your handlers will be receiving strings in arrays of type
1234 <code>XML_Char</code>. This type is conditionally defined in expat.h as
1235 either <code>char</code>, <code>wchar_t</code> or <code>unsigned short</code>.
1236 The former implies UTF-8 encoding, the latter two imply UTF-16 encoding.
1237 Note that you'll receive them in this form independent of the original
1238 encoding of the document.</p>
1239
1240 <div class="handler">
1241 <pre class="setter" id="XML_SetStartElementHandler">
1242 void XMLCALL
1243 XML_SetStartElementHandler(XML_Parser p,
1244                            XML_StartElementHandler start);
1245 </pre>
1246 <pre class="signature">
1247 typedef void
1248 (XMLCALL *XML_StartElementHandler)(void *userData,
1249                                    const XML_Char *name,
1250                                    const XML_Char **atts);
1251 </pre>
1252 <p>Set handler for start (and empty) tags. Attributes are passed to the start
1253 handler as a pointer to a vector of char pointers. Each attribute seen in
1254 a start (or empty) tag occupies 2 consecutive places in this vector: the
1255 attribute name followed by the attribute value. These pairs are terminated
1256 by a null pointer.</p>
1257 <p>Note that an empty tag generates a call to both start and end handlers
1258 (in that order).</p>
1259 </div>
1260
1261 <div class="handler">
1262 <pre class="setter" id="XML_SetEndElementHandler">
1263 void XMLCALL
1264 XML_SetEndElementHandler(XML_Parser p,
1265                          XML_EndElementHandler);
1266 </pre>
1267 <pre class="signature">
1268 typedef void
1269 (XMLCALL *XML_EndElementHandler)(void *userData,
1270                                  const XML_Char *name);
1271 </pre>
1272 <p>Set handler for end (and empty) tags. As noted above, an empty tag
1273 generates a call to both start and end handlers.</p>
1274 </div>
1275
1276 <div class="handler">
1277 <pre class="setter" id="XML_SetElementHandler">
1278 void XMLCALL
1279 XML_SetElementHandler(XML_Parser p,
1280                       XML_StartElementHandler start,
1281                       XML_EndElementHandler end);
1282 </pre>
1283 <p>Set handlers for start and end tags with one call.</p>
1284 </div>
1285
1286 <div class="handler">
1287 <pre class="setter" id="XML_SetCharacterDataHandler">
1288 void XMLCALL
1289 XML_SetCharacterDataHandler(XML_Parser p,
1290                             XML_CharacterDataHandler charhndl)
1291 </pre>
1292 <pre class="signature">
1293 typedef void
1294 (XMLCALL *XML_CharacterDataHandler)(void *userData,
1295                                     const XML_Char *s,
1296                                     int len);
1297 </pre>
1298 <p>Set a text handler. The string your handler receives
1299 is <em>NOT nul-terminated</em>. You have to use the length argument
1300 to deal with the end of the string. A single block of contiguous text
1301 free of markup may still result in a sequence of calls to this handler.
1302 In other words, if you're searching for a pattern in the text, it may
1303 be split across calls to this handler. Note: Setting this handler to NULL
1304 may <em>NOT immediately</em> terminate call-backs if the parser is currently
1305 processing such a single block of contiguous markup-free text, as the parser
1306 will continue calling back until the end of the block is reached.</p>
1307 </div>
1308
1309 <div class="handler">
1310 <pre class="setter" id="XML_SetProcessingInstructionHandler">
1311 void XMLCALL
1312 XML_SetProcessingInstructionHandler(XML_Parser p,
1313                                     XML_ProcessingInstructionHandler proc)
1314 </pre>
1315 <pre class="signature">
1316 typedef void
1317 (XMLCALL *XML_ProcessingInstructionHandler)(void *userData,
1318                                             const XML_Char *target,
1319                                             const XML_Char *data);
1320
1321 </pre>
1322 <p>Set a handler for processing instructions. The target is the first word
1323 in the processing instruction. The data is the rest of the characters in
1324 it after skipping all whitespace after the initial word.</p>
1325 </div>
1326
1327 <div class="handler">
1328 <pre class="setter" id="XML_SetCommentHandler">
1329 void XMLCALL
1330 XML_SetCommentHandler(XML_Parser p,
1331                       XML_CommentHandler cmnt)
1332 </pre>
1333 <pre class="signature">
1334 typedef void
1335 (XMLCALL *XML_CommentHandler)(void *userData,
1336                               const XML_Char *data);
1337 </pre>
1338 <p>Set a handler for comments. The data is all text inside the comment
1339 delimiters.</p>
1340 </div>
1341
1342 <div class="handler">
1343 <pre class="setter" id="XML_SetStartCdataSectionHandler">
1344 void XMLCALL
1345 XML_SetStartCdataSectionHandler(XML_Parser p,
1346                                 XML_StartCdataSectionHandler start);
1347 </pre>
1348 <pre class="signature">
1349 typedef void
1350 (XMLCALL *XML_StartCdataSectionHandler)(void *userData);
1351 </pre>
1352 <p>Set a handler that gets called at the beginning of a CDATA section.</p>
1353 </div>
1354
1355 <div class="handler">
1356 <pre class="setter" id="XML_SetEndCdataSectionHandler">
1357 void XMLCALL
1358 XML_SetEndCdataSectionHandler(XML_Parser p,
1359                               XML_EndCdataSectionHandler end);
1360 </pre>
1361 <pre class="signature">
1362 typedef void
1363 (XMLCALL *XML_EndCdataSectionHandler)(void *userData);
1364 </pre>
1365 <p>Set a handler that gets called at the end of a CDATA section.</p>
1366 </div>
1367
1368 <div class="handler">
1369 <pre class="setter" id="XML_SetCdataSectionHandler">
1370 void XMLCALL
1371 XML_SetCdataSectionHandler(XML_Parser p,
1372                            XML_StartCdataSectionHandler start,
1373                            XML_EndCdataSectionHandler end)
1374 </pre>
1375 <p>Sets both CDATA section handlers with one call.</p>
1376 </div>
1377
1378 <div class="handler">
1379 <pre class="setter" id="XML_SetDefaultHandler">
1380 void XMLCALL
1381 XML_SetDefaultHandler(XML_Parser p,
1382                       XML_DefaultHandler hndl)
1383 </pre>
1384 <pre class="signature">
1385 typedef void
1386 (XMLCALL *XML_DefaultHandler)(void *userData,
1387                               const XML_Char *s,
1388                               int len);
1389 </pre>
1390
1391 <p>Sets a handler for any characters in the document which wouldn't
1392 otherwise be handled. This includes both data for which no handlers
1393 can be set (like some kinds of DTD declarations) and data which could
1394 be reported but which currently has no handler set.  The characters
1395 are passed exactly as they were present in the XML document except
1396 that they will be encoded in UTF-8 or UTF-16. Line boundaries are not
1397 normalized. Note that a byte order mark character is not passed to the
1398 default handler. There are no guarantees about how characters are
1399 divided between calls to the default handler: for example, a comment
1400 might be split between multiple calls.  Setting the handler with
1401 this call has the side effect of turning off expansion of references
1402 to internally defined general entities. Instead these references are
1403 passed to the default handler.</p>
1404
1405 <p>See also <code><a
1406 href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p>
1407 </div>
1408
1409 <div class="handler">
1410 <pre class="setter" id="XML_SetDefaultHandlerExpand">
1411 void XMLCALL
1412 XML_SetDefaultHandlerExpand(XML_Parser p,
1413                             XML_DefaultHandler hndl)
1414 </pre>
1415 <pre class="signature">
1416 typedef void
1417 (XMLCALL *XML_DefaultHandler)(void *userData,
1418                               const XML_Char *s,
1419                               int len);
1420 </pre>
1421 <p>This sets a default handler, but doesn't inhibit the expansion of
1422 internal entity references.  The entity reference will not be passed
1423 to the default handler.</p>
1424
1425 <p>See also <code><a
1426 href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p>
1427 </div>
1428
1429 <div class="handler">
1430 <pre class="setter" id="XML_SetExternalEntityRefHandler">
1431 void XMLCALL
1432 XML_SetExternalEntityRefHandler(XML_Parser p,
1433                                 XML_ExternalEntityRefHandler hndl)
1434 </pre>
1435 <pre class="signature">
1436 typedef int
1437 (XMLCALL *XML_ExternalEntityRefHandler)(XML_Parser p,
1438                                         const XML_Char *context,
1439                                         const XML_Char *base,
1440                                         const XML_Char *systemId,
1441                                         const XML_Char *publicId);
1442 </pre>
1443 <p>Set an external entity reference handler. This handler is also
1444 called for processing an external DTD subset if parameter entity parsing
1445 is in effect. (See <a href="#XML_SetParamEntityParsing">
1446 <code>XML_SetParamEntityParsing</code></a>.)</p>
1447
1448 <p>The <code>context</code> parameter specifies the parsing context in
1449 the format expected by the <code>context</code> argument to <code><a
1450 href="#XML_ExternalEntityParserCreate"
1451 >XML_ExternalEntityParserCreate</a></code>.  <code>code</code> is
1452 valid only until the handler returns, so if the referenced entity is
1453 to be parsed later, it must be copied.  <code>context</code> is NULL
1454 only when the entity is a parameter entity, which is how one can
1455 differentiate between general and parameter entities.</p>
1456
1457 <p>The <code>base</code> parameter is the base to use for relative
1458 system identifiers.  It is set by <code><a
1459 href="#XML_SetBase">XML_SetBase</a></code> and may be NULL. The
1460 <code>publicId</code> parameter is the public id given in the entity
1461 declaration and may be NULL.  <code>systemId</code> is the system
1462 identifier specified in the entity declaration and is never NULL.</p>
1463
1464 <p>There are a couple of ways in which this handler differs from
1465 others.  First, this handler returns a status indicator (an
1466 integer). <code>XML_STATUS_OK</code> should be returned for successful
1467 handling of the external entity reference.  Returning
1468 <code>XML_STATUS_ERROR</code> indicates failure, and causes the
1469 calling parser to return an
1470 <code>XML_ERROR_EXTERNAL_ENTITY_HANDLING</code> error.</p>
1471
1472 <p>Second, instead of having the user data as its first argument, it
1473 receives the parser that encountered the entity reference. This, along
1474 with the context parameter, may be used as arguments to a call to
1475 <code><a href= "#XML_ExternalEntityParserCreate"
1476 >XML_ExternalEntityParserCreate</a></code>.  Using the returned
1477 parser, the body of the external entity can be recursively parsed.</p>
1478
1479 <p>Since this handler may be called recursively, it should not be saving
1480 information into global or static variables.</p>
1481 </div>
1482
1483 <pre class="fcndec" id="XML_SetExternalEntityRefHandlerArg">
1484 void XMLCALL
1485 XML_SetExternalEntityRefHandlerArg(XML_Parser p,
1486                                    void *arg)
1487 </pre>
1488 <div class="fcndef">
1489 <p>Set the argument passed to the ExternalEntityRefHandler.  If
1490 <code>arg</code> is not NULL, it is the new value passed to the
1491 handler set using <code><a href="#XML_SetExternalEntityRefHandler"
1492 >XML_SetExternalEntityRefHandler</a></code>; if <code>arg</code> is
1493 NULL, the argument passed to the handler function will be the parser
1494 object itself.</p>
1495
1496 <p><strong>Note:</strong>
1497 The type of <code>arg</code> and the type of the first argument to the
1498 ExternalEntityRefHandler do not match.  This function takes a
1499 <code>void *</code> to be passed to the handler, while the handler
1500 accepts an <code>XML_Parser</code>.  This is a historical accident,
1501 but will not be corrected before Expat 2.0 (at the earliest) to avoid
1502 causing compiler warnings for code that's known to work with this
1503 API.  It is the responsibility of the application code to know the
1504 actual type of the argument passed to the handler and to manage it
1505 properly.</p>
1506 </div>
1507
1508 <div class="handler">
1509 <pre class="setter" id="XML_SetSkippedEntityHandler">
1510 void XMLCALL
1511 XML_SetSkippedEntityHandler(XML_Parser p,
1512                             XML_SkippedEntityHandler handler)
1513 </pre>
1514 <pre class="signature">
1515 typedef void
1516 (XMLCALL *XML_SkippedEntityHandler)(void *userData,
1517                                     const XML_Char *entityName,
1518                                     int is_parameter_entity);
1519 </pre>
1520 <p>Set a skipped entity handler. This is called in two situations:</p>
1521 <ol>
1522    <li>An entity reference is encountered for which no declaration
1523        has been read <em>and</em> this is not an error.</li>
1524    <li>An internal entity reference is read, but not expanded, because
1525        <a href="#XML_SetDefaultHandler"><code>XML_SetDefaultHandler</code></a>
1526            has been called.</li>
1527 </ol>
1528 <p>The <code>is_parameter_entity</code> argument will be non-zero for
1529 a parameter entity and zero for a general entity.</p> <p>Note: skipped
1530 parameter entities in declarations and skipped general entities in
1531 attribute values cannot be reported, because the event would be out of
1532 sync with the reporting of the declarations or attribute values</p>
1533 </div>
1534
1535 <div class="handler">
1536 <pre class="setter" id="XML_SetUnknownEncodingHandler">
1537 void XMLCALL
1538 XML_SetUnknownEncodingHandler(XML_Parser p,
1539                               XML_UnknownEncodingHandler enchandler,
1540                               void *encodingHandlerData)
1541 </pre>
1542 <pre class="signature">
1543 typedef int
1544 (XMLCALL *XML_UnknownEncodingHandler)(void *encodingHandlerData,
1545                                       const XML_Char *name,
1546                                       XML_Encoding *info);
1547
1548 typedef struct {
1549   int map[256];
1550   void *data;
1551   int (XMLCALL *convert)(void *data, const char *s);
1552   void (XMLCALL *release)(void *data);
1553 } XML_Encoding;
1554 </pre>
1555 <p>Set a handler to deal with encodings other than the <a
1556 href="#builtin_encodings">built in set</a>. This should be done before
1557 <code><a href= "#XML_Parse" >XML_Parse</a></code> or <code><a href=
1558 "#XML_ParseBuffer" >XML_ParseBuffer</a></code> have been called on the
1559 given parser.</p> <p>If the handler knows how to deal with an encoding
1560 with the given name, it should fill in the <code>info</code> data
1561 structure and return <code>XML_STATUS_OK</code>. Otherwise it
1562 should return <code>XML_STATUS_ERROR</code>. The handler will be called
1563 at most once per parsed (external) entity. The optional application
1564 data pointer <code>encodingHandlerData</code> will be passed back to
1565 the handler.</p>
1566
1567 <p>The map array contains information for every possible possible leading
1568 byte in a byte sequence. If the corresponding value is &gt;= 0, then it's
1569 a single byte sequence and the byte encodes that Unicode value. If the
1570 value is -1, then that byte is invalid as the initial byte in a sequence.
1571 If the value is -n, where n is an integer &gt; 1, then n is the number of
1572 bytes in the sequence and the actual conversion is accomplished by a
1573 call to the function pointed at by convert. This function may return -1
1574 if the sequence itself is invalid. The convert pointer may be null if
1575 there are only single byte codes. The data parameter passed to the convert
1576 function is the data pointer from <code>XML_Encoding</code>. The
1577 string s is <em>NOT</em> nul-terminated and points at the sequence of
1578 bytes to be converted.</p>
1579
1580 <p>The function pointed at by <code>release</code> is called by the
1581 parser when it is finished with the encoding. It may be NULL.</p>
1582 </div>
1583
1584 <div class="handler">
1585 <pre class="setter" id="XML_SetStartNamespaceDeclHandler">
1586 void XMLCALL
1587 XML_SetStartNamespaceDeclHandler(XML_Parser p,
1588                                  XML_StartNamespaceDeclHandler start);
1589 </pre>
1590 <pre class="signature">
1591 typedef void
1592 (XMLCALL *XML_StartNamespaceDeclHandler)(void *userData,
1593                                          const XML_Char *prefix,
1594                                          const XML_Char *uri);
1595 </pre>
1596 <p>Set a handler to be called when a namespace is declared. Namespace
1597 declarations occur inside start tags. But the namespace declaration start
1598 handler is called before the start tag handler for each namespace declared
1599 in that start tag.</p>
1600 </div>
1601
1602 <div class="handler">
1603 <pre class="setter" id="XML_SetEndNamespaceDeclHandler">
1604 void XMLCALL
1605 XML_SetEndNamespaceDeclHandler(XML_Parser p,
1606                                XML_EndNamespaceDeclHandler end);
1607 </pre>
1608 <pre class="signature">
1609 typedef void
1610 (XMLCALL *XML_EndNamespaceDeclHandler)(void *userData,
1611                                        const XML_Char *prefix);
1612 </pre>
1613 <p>Set a handler to be called when leaving the scope of a namespace
1614 declaration. This will be called, for each namespace declaration,
1615 after the handler for the end tag of the element in which the
1616 namespace was declared.</p>
1617 </div>
1618
1619 <div class="handler">
1620 <pre class="setter" id="XML_SetNamespaceDeclHandler">
1621 void XMLCALL
1622 XML_SetNamespaceDeclHandler(XML_Parser p,
1623                             XML_StartNamespaceDeclHandler start,
1624                             XML_EndNamespaceDeclHandler end)
1625 </pre>
1626 <p>Sets both namespace declaration handlers with a single call.</p>
1627 </div>
1628
1629 <div class="handler">
1630 <pre class="setter" id="XML_SetXmlDeclHandler">
1631 void XMLCALL
1632 XML_SetXmlDeclHandler(XML_Parser p,
1633                       XML_XmlDeclHandler xmldecl);
1634 </pre>
1635 <pre class="signature">
1636 typedef void
1637 (XMLCALL *XML_XmlDeclHandler)(void            *userData,
1638                               const XML_Char  *version,
1639                               const XML_Char  *encoding,
1640                               int             standalone);
1641 </pre>
1642 <p>Sets a handler that is called for XML declarations and also for
1643 text declarations discovered in external entities. The way to
1644 distinguish is that the <code>version</code> parameter will be NULL
1645 for text declarations. The <code>encoding</code> parameter may be NULL
1646 for an XML declaration. The <code>standalone</code> argument will
1647 contain -1, 0, or 1 indicating respectively that there was no
1648 standalone parameter in the declaration, that it was given as no, or
1649 that it was given as yes.</p>
1650 </div>
1651
1652 <div class="handler">
1653 <pre class="setter" id="XML_SetStartDoctypeDeclHandler">
1654 void XMLCALL
1655 XML_SetStartDoctypeDeclHandler(XML_Parser p,
1656                                XML_StartDoctypeDeclHandler start);
1657 </pre>
1658 <pre class="signature">
1659 typedef void
1660 (XMLCALL *XML_StartDoctypeDeclHandler)(void           *userData,
1661                                        const XML_Char *doctypeName,
1662                                        const XML_Char *sysid,
1663                                        const XML_Char *pubid,
1664                                        int            has_internal_subset);
1665 </pre>
1666 <p>Set a handler that is called at the start of a DOCTYPE declaration,
1667 before any external or internal subset is parsed. Both <code>sysid</code>
1668 and <code>pubid</code> may be NULL. The <code>has_internal_subset</code>
1669 will be non-zero if the DOCTYPE declaration has an internal subset.</p>
1670 </div>
1671
1672 <div class="handler">
1673 <pre class="setter" id="XML_SetEndDoctypeDeclHandler">
1674 void XMLCALL
1675 XML_SetEndDoctypeDeclHandler(XML_Parser p,
1676                              XML_EndDoctypeDeclHandler end);
1677 </pre>
1678 <pre class="signature">
1679 typedef void
1680 (XMLCALL *XML_EndDoctypeDeclHandler)(void *userData);
1681 </pre>
1682 <p>Set a handler that is called at the end of a DOCTYPE declaration,
1683 after parsing any external subset.</p>
1684 </div>
1685
1686 <div class="handler">
1687 <pre class="setter" id="XML_SetDoctypeDeclHandler">
1688 void XMLCALL
1689 XML_SetDoctypeDeclHandler(XML_Parser p,
1690                           XML_StartDoctypeDeclHandler start,
1691                           XML_EndDoctypeDeclHandler end);
1692 </pre>
1693 <p>Set both doctype handlers with one call.</p>
1694 </div>
1695
1696 <div class="handler">
1697 <pre class="setter" id="XML_SetElementDeclHandler">
1698 void XMLCALL
1699 XML_SetElementDeclHandler(XML_Parser p,
1700                           XML_ElementDeclHandler eldecl);
1701 </pre>
1702 <pre class="signature">
1703 typedef void
1704 (XMLCALL *XML_ElementDeclHandler)(void *userData,
1705                                   const XML_Char *name,
1706                                   XML_Content *model);
1707 </pre>
1708 <pre class="signature">
1709 enum XML_Content_Type {
1710   XML_CTYPE_EMPTY = 1,
1711   XML_CTYPE_ANY,
1712   XML_CTYPE_MIXED,
1713   XML_CTYPE_NAME,
1714   XML_CTYPE_CHOICE,
1715   XML_CTYPE_SEQ
1716 };
1717
1718 enum XML_Content_Quant {
1719   XML_CQUANT_NONE,
1720   XML_CQUANT_OPT,
1721   XML_CQUANT_REP,
1722   XML_CQUANT_PLUS
1723 };
1724
1725 typedef struct XML_cp XML_Content;
1726
1727 struct XML_cp {
1728   enum XML_Content_Type         type;
1729   enum XML_Content_Quant        quant;
1730   const XML_Char *              name;
1731   unsigned int                  numchildren;
1732   XML_Content *                 children;
1733 };
1734 </pre>
1735 <p>Sets a handler for element declarations in a DTD. The handler gets
1736 called with the name of the element in the declaration and a pointer
1737 to a structure that contains the element model. It is the
1738 application's responsibility to free this data structure using
1739 <code><a href="#XML_FreeContentModel"
1740 >XML_FreeContentModel</a></code>.</p>
1741
1742 <p>The <code>model</code> argument is the root of a tree of
1743 <code>XML_Content</code> nodes. If <code>type</code> equals
1744 <code>XML_CTYPE_EMPTY</code> or <code>XML_CTYPE_ANY</code>, then
1745 <code>quant</code> will be <code>XML_CQUANT_NONE</code>, and the other
1746 fields will be zero or NULL.  If <code>type</code> is
1747 <code>XML_CTYPE_MIXED</code>, then <code>quant</code> will be
1748 <code>XML_CQUANT_NONE</code> or <code>XML_CQUANT_REP</code> and
1749 <code>numchildren</code> will contain the number of elements that are
1750 allowed to be mixed in and <code>children</code> points to an array of
1751 <code>XML_Content</code> structures that will all have type
1752 XML_CTYPE_NAME with no quantification.  Only the root node can be type
1753 <code>XML_CTYPE_EMPTY</code>, <code>XML_CTYPE_ANY</code>, or
1754 <code>XML_CTYPE_MIXED</code>.</p>
1755
1756 <p>For type <code>XML_CTYPE_NAME</code>, the <code>name</code> field
1757 points to the name and the <code>numchildren</code> and
1758 <code>children</code> fields will be zero and NULL. The
1759 <code>quant</code> field will indicate any quantifiers placed on the
1760 name.</p>
1761
1762 <p>Types <code>XML_CTYPE_CHOICE</code> and <code>XML_CTYPE_SEQ</code>
1763 indicate a choice or sequence respectively. The
1764 <code>numchildren</code> field indicates how many nodes in the choice
1765 or sequence and <code>children</code> points to the nodes.</p>
1766 </div>
1767
1768 <div class="handler">
1769 <pre class="setter" id="XML_SetAttlistDeclHandler">
1770 void XMLCALL
1771 XML_SetAttlistDeclHandler(XML_Parser p,
1772                           XML_AttlistDeclHandler attdecl);
1773 </pre>
1774 <pre class="signature">
1775 typedef void
1776 (XMLCALL *XML_AttlistDeclHandler)(void           *userData,
1777                                   const XML_Char *elname,
1778                                   const XML_Char *attname,
1779                                   const XML_Char *att_type,
1780                                   const XML_Char *dflt,
1781                                   int            isrequired);
1782 </pre>
1783 <p>Set a handler for attlist declarations in the DTD. This handler is
1784 called for <em>each</em> attribute. So a single attlist declaration
1785 with multiple attributes declared will generate multiple calls to this
1786 handler. The <code>elname</code> parameter returns the name of the
1787 element for which the attribute is being declared. The attribute name
1788 is in the <code>attname</code> parameter. The attribute type is in the
1789 <code>att_type</code> parameter.  It is the string representing the
1790 type in the declaration with whitespace removed.</p>
1791
1792 <p>The <code>dflt</code> parameter holds the default value. It will be
1793 NULL in the case of "#IMPLIED" or "#REQUIRED" attributes. You can
1794 distinguish these two cases by checking the <code>isrequired</code>
1795 parameter, which will be true in the case of "#REQUIRED" attributes.
1796 Attributes which are "#FIXED" will have also have a true
1797 <code>isrequired</code>, but they will have the non-NULL fixed value
1798 in the <code>dflt</code> parameter.</p>
1799 </div>
1800
1801 <div class="handler">
1802 <pre class="setter" id="XML_SetEntityDeclHandler">
1803 void XMLCALL
1804 XML_SetEntityDeclHandler(XML_Parser p,
1805                          XML_EntityDeclHandler handler);
1806 </pre>
1807 <pre class="signature">
1808 typedef void
1809 (XMLCALL *XML_EntityDeclHandler)(void           *userData,
1810                                  const XML_Char *entityName,
1811                                  int            is_parameter_entity,
1812                                  const XML_Char *value,
1813                                  int            value_length,
1814                                  const XML_Char *base,
1815                                  const XML_Char *systemId,
1816                                  const XML_Char *publicId,
1817                                  const XML_Char *notationName);
1818 </pre>
1819 <p>Sets a handler that will be called for all entity declarations.
1820 The <code>is_parameter_entity</code> argument will be non-zero in the
1821 case of parameter entities and zero otherwise.</p>
1822
1823 <p>For internal entities (<code>&lt;!ENTITY foo "bar"&gt;</code>),
1824 <code>value</code> will be non-NULL and <code>systemId</code>,
1825 <code>publicId</code>, and <code>notationName</code> will all be NULL.
1826 The value string is <em>not</em> NULL terminated; the length is
1827 provided in the <code>value_length</code> parameter. Do not use
1828 <code>value_length</code> to test for internal entities, since it is
1829 legal to have zero-length values. Instead check for whether or not
1830 <code>value</code> is NULL.</p> <p>The <code>notationName</code>
1831 argument will have a non-NULL value only for unparsed entity
1832 declarations.</p>
1833 </div>
1834
1835 <div class="handler">
1836 <pre class="setter" id="XML_SetUnparsedEntityDeclHandler">
1837 void XMLCALL
1838 XML_SetUnparsedEntityDeclHandler(XML_Parser p,
1839                                  XML_UnparsedEntityDeclHandler h)
1840 </pre>
1841 <pre class="signature">
1842 typedef void
1843 (XMLCALL *XML_UnparsedEntityDeclHandler)(void *userData,
1844                                          const XML_Char *entityName,
1845                                          const XML_Char *base,
1846                                          const XML_Char *systemId,
1847                                          const XML_Char *publicId,
1848                                          const XML_Char *notationName);
1849 </pre>
1850 <p>Set a handler that receives declarations of unparsed entities. These
1851 are entity declarations that have a notation (NDATA) field:</p>
1852
1853 <div id="eg"><pre>
1854 &lt;!ENTITY logo SYSTEM "images/logo.gif" NDATA gif&gt;
1855 </pre></div>
1856 <p>This handler is obsolete and is provided for backwards
1857 compatibility.  Use instead <a href= "#XML_SetEntityDeclHandler"
1858 >XML_SetEntityDeclHandler</a>.</p>
1859 </div>
1860
1861 <div class="handler">
1862 <pre class="setter" id="XML_SetNotationDeclHandler">
1863 void XMLCALL
1864 XML_SetNotationDeclHandler(XML_Parser p,
1865                            XML_NotationDeclHandler h)
1866 </pre>
1867 <pre class="signature">
1868 typedef void
1869 (XMLCALL *XML_NotationDeclHandler)(void *userData,
1870                                    const XML_Char *notationName,
1871                                    const XML_Char *base,
1872                                    const XML_Char *systemId,
1873                                    const XML_Char *publicId);
1874 </pre>
1875 <p>Set a handler that receives notation declarations.</p>
1876 </div>
1877
1878 <div class="handler">
1879 <pre class="setter" id="XML_SetNotStandaloneHandler">
1880 void XMLCALL
1881 XML_SetNotStandaloneHandler(XML_Parser p,
1882                             XML_NotStandaloneHandler h)
1883 </pre>
1884 <pre class="signature">
1885 typedef int
1886 (XMLCALL *XML_NotStandaloneHandler)(void *userData);
1887 </pre>
1888 <p>Set a handler that is called if the document is not "standalone".
1889 This happens when there is an external subset or a reference to a
1890 parameter entity, but does not have standalone set to "yes" in an XML
1891 declaration.  If this handler returns <code>XML_STATUS_ERROR</code>,
1892 then the parser will throw an <code>XML_ERROR_NOT_STANDALONE</code>
1893 error.</p>
1894 </div>
1895
1896 <h3><a name="position">Parse position and error reporting functions</a></h3>
1897
1898 <p>These are the functions you'll want to call when the parse
1899 functions return <code>XML_STATUS_ERROR</code> (a parse error has
1900 occurred), although the position reporting functions are useful outside
1901 of errors. The position reported is the byte position (in the original
1902 document or entity encoding) of the first of the sequence of
1903 characters that generated the current event (or the error that caused
1904 the parse functions to return <code>XML_STATUS_ERROR</code>.)  The
1905 exceptions are callbacks trigged by declarations in the document
1906 prologue, in which case they exact position reported is somewhere in the
1907 relevant markup, but not necessarily as meaningful as for other
1908 events.</p>
1909
1910 <p>The position reporting functions are accurate only outside of the
1911 DTD.  In other words, they usually return bogus information when
1912 called from within a DTD declaration handler.</p>
1913
1914 <pre class="fcndec" id="XML_GetErrorCode">
1915 enum XML_Error XMLCALL
1916 XML_GetErrorCode(XML_Parser p);
1917 </pre>
1918 <div class="fcndef">
1919 Return what type of error has occurred.
1920 </div>
1921
1922 <pre class="fcndec" id="XML_ErrorString">
1923 const XML_LChar * XMLCALL
1924 XML_ErrorString(enum XML_Error code);
1925 </pre>
1926 <div class="fcndef">
1927 Return a string describing the error corresponding to code.
1928 The code should be one of the enums that can be returned from
1929 <code><a href= "#XML_GetErrorCode" >XML_GetErrorCode</a></code>.
1930 </div>
1931
1932 <pre class="fcndec" id="XML_GetCurrentByteIndex">
1933 XML_Index XMLCALL
1934 XML_GetCurrentByteIndex(XML_Parser p);
1935 </pre>
1936 <div class="fcndef">
1937 Return the byte offset of the position.  This always corresponds to
1938 the values returned by <code><a href= "#XML_GetCurrentLineNumber"
1939 >XML_GetCurrentLineNumber</a></code> and <code><a href=
1940 "#XML_GetCurrentColumnNumber" >XML_GetCurrentColumnNumber</a></code>.
1941 </div>
1942
1943 <pre class="fcndec" id="XML_GetCurrentLineNumber">
1944 XML_Size XMLCALL
1945 XML_GetCurrentLineNumber(XML_Parser p);
1946 </pre>
1947 <div class="fcndef">
1948 Return the line number of the position.  The first line is reported as
1949 <code>1</code>.
1950 </div>
1951
1952 <pre class="fcndec" id="XML_GetCurrentColumnNumber">
1953 XML_Size XMLCALL
1954 XML_GetCurrentColumnNumber(XML_Parser p);
1955 </pre>
1956 <div class="fcndef">
1957 Return the offset, from the beginning of the current line, of
1958 the position.
1959 </div>
1960
1961 <pre class="fcndec" id="XML_GetCurrentByteCount">
1962 int XMLCALL
1963 XML_GetCurrentByteCount(XML_Parser p);
1964 </pre>
1965 <div class="fcndef">
1966 Return the number of bytes in the current event. Returns
1967 <code>0</code> if the event is inside a reference to an internal
1968 entity and for the end-tag event for empty element tags (the later can
1969 be used to distinguish empty-element tags from empty elements using
1970 separate start and end tags).
1971 </div>
1972
1973 <pre class="fcndec" id="XML_GetInputContext">
1974 const char * XMLCALL
1975 XML_GetInputContext(XML_Parser p,
1976                     int *offset,
1977                     int *size);
1978 </pre>
1979 <div class="fcndef">
1980
1981 <p>Returns the parser's input buffer, sets the integer pointed at by
1982 <code>offset</code> to the offset within this buffer of the current
1983 parse position, and set the integer pointed at by <code>size</code> to
1984 the size of the returned buffer.</p>
1985
1986 <p>This should only be called from within a handler during an active
1987 parse and the returned buffer should only be referred to from within
1988 the handler that made the call. This input buffer contains the
1989 untranslated bytes of the input.</p>
1990
1991 <p>Only a limited amount of context is kept, so if the event
1992 triggering a call spans over a very large amount of input, the actual
1993 parse position may be before the beginning of the buffer.</p>
1994
1995 <p>If <code>XML_CONTEXT_BYTES</code> is not defined, this will always
1996 return NULL.</p>
1997 </div>
1998
1999 <h3><a name="miscellaneous">Miscellaneous functions</a></h3>
2000
2001 <p>The functions in this section either obtain state information from
2002 the parser or can be used to dynamicly set parser options.</p>
2003
2004 <pre class="fcndec" id="XML_SetUserData">
2005 void XMLCALL
2006 XML_SetUserData(XML_Parser p,
2007                 void *userData);
2008 </pre>
2009 <div class="fcndef">
2010 This sets the user data pointer that gets passed to handlers.  It
2011 overwrites any previous value for this pointer. Note that the
2012 application is responsible for freeing the memory associated with
2013 <code>userData</code> when it is finished with the parser. So if you
2014 call this when there's already a pointer there, and you haven't freed
2015 the memory associated with it, then you've probably just leaked
2016 memory.
2017 </div>
2018
2019 <pre class="fcndec" id="XML_GetUserData">
2020 void * XMLCALL
2021 XML_GetUserData(XML_Parser p);
2022 </pre>
2023 <div class="fcndef">
2024 This returns the user data pointer that gets passed to handlers.
2025 It is actually implemented as a macro.
2026 </div>
2027
2028 <pre class="fcndec" id="XML_UseParserAsHandlerArg">
2029 void XMLCALL
2030 XML_UseParserAsHandlerArg(XML_Parser p);
2031 </pre>
2032 <div class="fcndef">
2033 After this is called, handlers receive the parser in their
2034 <code>userData</code> arguments.  The user data can still be obtained
2035 using the <code><a href= "#XML_GetUserData"
2036 >XML_GetUserData</a></code> function.
2037 </div>
2038
2039 <pre class="fcndec" id="XML_SetBase">
2040 enum XML_Status XMLCALL
2041 XML_SetBase(XML_Parser p,
2042             const XML_Char *base);
2043 </pre>
2044 <div class="fcndef">
2045 Set the base to be used for resolving relative URIs in system
2046 identifiers.  The return value is <code>XML_STATUS_ERROR</code> if
2047 there's no memory to store base, otherwise it's
2048 <code>XML_STATUS_OK</code>.
2049 </div>
2050
2051 <pre class="fcndec" id="XML_GetBase">
2052 const XML_Char * XMLCALL
2053 XML_GetBase(XML_Parser p);
2054 </pre>
2055 <div class="fcndef">
2056 Return the base for resolving relative URIs.
2057 </div>
2058
2059 <pre class="fcndec" id="XML_GetSpecifiedAttributeCount">
2060 int XMLCALL
2061 XML_GetSpecifiedAttributeCount(XML_Parser p);
2062 </pre>
2063 <div class="fcndef">
2064 When attributes are reported to the start handler in the atts vector,
2065 attributes that were explicitly set in the element occur before any
2066 attributes that receive their value from default information in an
2067 ATTLIST declaration. This function returns the number of attributes
2068 that were explicitly set times two, thus giving the offset in the
2069 <code>atts</code> array passed to the start tag handler of the first
2070 attribute set due to defaults. It supplies information for the last
2071 call to a start handler. If called inside a start handler, then that
2072 means the current call.
2073 </div>
2074
2075 <pre class="fcndec" id="XML_GetIdAttributeIndex">
2076 int XMLCALL
2077 XML_GetIdAttributeIndex(XML_Parser p);
2078 </pre>
2079 <div class="fcndef">
2080 Returns the index of the ID attribute passed in the atts array in the
2081 last call to <code><a href= "#XML_StartElementHandler"
2082 >XML_StartElementHandler</a></code>, or -1 if there is no ID
2083 attribute. If called inside a start handler, then that means the
2084 current call.
2085 </div>
2086
2087 <pre class="fcndec" id="XML_GetAttributeInfo">
2088 const XML_AttrInfo * XMLCALL
2089 XML_GetAttributeInfo(XML_Parser parser);
2090 </pre>
2091 <pre class="signature">
2092 typedef struct {
2093   XML_Index  nameStart;  /* Offset to beginning of the attribute name. */
2094   XML_Index  nameEnd;    /* Offset after the attribute name's last byte. */
2095   XML_Index  valueStart; /* Offset to beginning of the attribute value. */
2096   XML_Index  valueEnd;   /* Offset after the attribute value's last byte. */
2097 } XML_AttrInfo;
2098 </pre>
2099 <div class="fcndef">
2100 Returns an array of <code>XML_AttrInfo</code> structures for the
2101 attribute/value pairs passed in the last call to the
2102 <code>XML_StartElementHandler</code> that were specified
2103 in the start-tag rather than defaulted. Each attribute/value pair counts
2104 as 1; thus the number of entries in the array is
2105 <code>XML_GetSpecifiedAttributeCount(parser) / 2</code>.
2106 </div>
2107
2108 <pre class="fcndec" id="XML_SetEncoding">
2109 enum XML_Status XMLCALL
2110 XML_SetEncoding(XML_Parser p,
2111                 const XML_Char *encoding);
2112 </pre>
2113 <div class="fcndef">
2114 Set the encoding to be used by the parser. It is equivalent to
2115 passing a non-null encoding argument to the parser creation functions.
2116 It must not be called after <code><a href= "#XML_Parse"
2117 >XML_Parse</a></code> or <code><a href= "#XML_ParseBuffer"
2118 >XML_ParseBuffer</a></code> have been called on the given parser.
2119 Returns <code>XML_STATUS_OK</code> on success or
2120 <code>XML_STATUS_ERROR</code> on error.
2121 </div>
2122
2123 <pre class="fcndec" id="XML_SetParamEntityParsing">
2124 int XMLCALL
2125 XML_SetParamEntityParsing(XML_Parser p,
2126                           enum XML_ParamEntityParsing code);
2127 </pre>
2128 <div class="fcndef">
2129 This enables parsing of parameter entities, including the external
2130 parameter entity that is the external DTD subset, according to
2131 <code>code</code>.
2132 The choices for <code>code</code> are:
2133 <ul>
2134 <li><code>XML_PARAM_ENTITY_PARSING_NEVER</code></li>
2135 <li><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></li>
2136 <li><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></li>
2137 </ul>
2138 <b>Note:</b> If <code>XML_SetParamEntityParsing</code> is called after
2139 <code>XML_Parse</code> or <code>XML_ParseBuffer</code>, then it has
2140 no effect and will always return 0.
2141 </div>
2142
2143 <pre class="fcndec" id="XML_SetHashSalt">
2144 int XMLCALL
2145 XML_SetHashSalt(XML_Parser p,
2146                 unsigned long hash_salt);
2147 </pre>
2148 <div class="fcndef">
2149 Sets the hash salt to use for internal hash calculations.
2150 Helps in preventing DoS attacks based on predicting hash
2151 function behavior. In order to have an effect this must be called
2152 before parsing has started. Returns 1 if successful, 0 when called
2153 after <code>XML_Parse</code> or <code>XML_ParseBuffer</code>.
2154 <p><b>Note:</b> This call is optional, as the parser will auto-generate a new
2155 random salt value if no value has been set at the start of parsing.</p>
2156 </div>
2157
2158 <pre class="fcndec" id="XML_UseForeignDTD">
2159 enum XML_Error XMLCALL
2160 XML_UseForeignDTD(XML_Parser parser, XML_Bool useDTD);
2161 </pre>
2162 <div class="fcndef">
2163 <p>This function allows an application to provide an external subset
2164 for the document type declaration for documents which do not specify
2165 an external subset of their own.  For documents which specify an
2166 external subset in their DOCTYPE declaration, the application-provided
2167 subset will be ignored.  If the document does not contain a DOCTYPE
2168 declaration at all and <code>useDTD</code> is true, the
2169 application-provided subset will be parsed, but the
2170 <code>startDoctypeDeclHandler</code> and
2171 <code>endDoctypeDeclHandler</code> functions, if set, will not be
2172 called.  The setting of parameter entity parsing, controlled using
2173 <code><a href= "#XML_SetParamEntityParsing"
2174 >XML_SetParamEntityParsing</a></code>, will be honored.</p>
2175
2176 <p>The application-provided external subset is read by calling the
2177 external entity reference handler set via <code><a href=
2178 "#XML_SetExternalEntityRefHandler"
2179 >XML_SetExternalEntityRefHandler</a></code> with both
2180 <code>publicId</code> and <code>systemId</code> set to NULL.</p>
2181
2182 <p>If this function is called after parsing has begun, it returns
2183 <code>XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING</code> and ignores
2184 <code>useDTD</code>.  If called when Expat has been compiled without
2185 DTD support, it returns
2186 <code>XML_ERROR_FEATURE_REQUIRES_XML_DTD</code>.  Otherwise, it
2187 returns <code>XML_ERROR_NONE</code>.</p>
2188
2189 <p><b>Note:</b> For the purpose of checking WFC: Entity Declared, passing
2190 <code>useDTD == XML_TRUE</code> will make the parser behave as if
2191 the document had a DTD with an external subset. This holds true even if
2192 the external entity reference handler returns without action.</p>
2193 </div>
2194
2195 <pre class="fcndec" id="XML_SetReturnNSTriplet">
2196 void XMLCALL
2197 XML_SetReturnNSTriplet(XML_Parser parser,
2198                        int        do_nst);
2199 </pre>
2200 <div class="fcndef">
2201 <p>
2202 This function only has an effect when using a parser created with
2203 <code><a href= "#XML_ParserCreateNS" >XML_ParserCreateNS</a></code>,
2204 i.e. when namespace processing is in effect. The <code>do_nst</code>
2205 sets whether or not prefixes are returned with names qualified with a
2206 namespace prefix. If this function is called with <code>do_nst</code>
2207 non-zero, then afterwards namespace qualified names (that is qualified
2208 with a prefix as opposed to belonging to a default namespace) are
2209 returned as a triplet with the three parts separated by the namespace
2210 separator specified when the parser was created.  The order of
2211 returned parts is URI, local name, and prefix.</p> <p>If
2212 <code>do_nst</code> is zero, then namespaces are reported in the
2213 default manner, URI then local_name separated by the namespace
2214 separator.</p>
2215 </div>
2216
2217 <pre class="fcndec" id="XML_DefaultCurrent">
2218 void XMLCALL
2219 XML_DefaultCurrent(XML_Parser parser);
2220 </pre>
2221 <div class="fcndef">
2222 This can be called within a handler for a start element, end element,
2223 processing instruction or character data.  It causes the corresponding
2224 markup to be passed to the default handler set by <code><a
2225 href="#XML_SetDefaultHandler" >XML_SetDefaultHandler</a></code> or
2226 <code><a href="#XML_SetDefaultHandlerExpand"
2227 >XML_SetDefaultHandlerExpand</a></code>.  It does nothing if there is
2228 not a default handler.
2229 </div>
2230
2231 <pre class="fcndec" id="XML_ExpatVersion">
2232 XML_LChar * XMLCALL
2233 XML_ExpatVersion();
2234 </pre>
2235 <div class="fcndef">
2236 Return the library version as a string (e.g. <code>"expat_1.95.1"</code>).
2237 </div>
2238
2239 <pre class="fcndec" id="XML_ExpatVersionInfo">
2240 struct XML_Expat_Version XMLCALL
2241 XML_ExpatVersionInfo();
2242 </pre>
2243 <pre class="signature">
2244 typedef struct {
2245   int major;
2246   int minor;
2247   int micro;
2248 } XML_Expat_Version;
2249 </pre>
2250 <div class="fcndef">
2251 Return the library version information as a structure.
2252 Some macros are also defined that support compile-time tests of the
2253 library version:
2254 <ul>
2255 <li><code>XML_MAJOR_VERSION</code></li>
2256 <li><code>XML_MINOR_VERSION</code></li>
2257 <li><code>XML_MICRO_VERSION</code></li>
2258 </ul>
2259 Testing these constants is currently the best way to determine if
2260 particular parts of the Expat API are available.
2261 </div>
2262
2263 <pre class="fcndec" id="XML_GetFeatureList">
2264 const XML_Feature * XMLCALL
2265 XML_GetFeatureList();
2266 </pre>
2267 <pre class="signature">
2268 enum XML_FeatureEnum {
2269   XML_FEATURE_END = 0,
2270   XML_FEATURE_UNICODE,
2271   XML_FEATURE_UNICODE_WCHAR_T,
2272   XML_FEATURE_DTD,
2273   XML_FEATURE_CONTEXT_BYTES,
2274   XML_FEATURE_MIN_SIZE,
2275   XML_FEATURE_SIZEOF_XML_CHAR,
2276   XML_FEATURE_SIZEOF_XML_LCHAR,
2277   XML_FEATURE_NS,
2278   XML_FEATURE_LARGE_SIZE
2279 };
2280
2281 typedef struct {
2282   enum XML_FeatureEnum  feature;
2283   XML_LChar            *name;
2284   long int              value;
2285 } XML_Feature;
2286 </pre>
2287 <div class="fcndef">
2288 <p>Returns a list of "feature" records, providing details on how
2289 Expat was configured at compile time.  Most applications should not
2290 need to worry about this, but this information is otherwise not
2291 available from Expat.  This function allows code that does need to
2292 check these features to do so at runtime.</p>
2293
2294 <p>The return value is an array of <code>XML_Feature</code>,
2295 terminated by a record with a <code>feature</code> of
2296 <code>XML_FEATURE_END</code> and <code>name</code> of NULL,
2297 identifying the feature-test macros Expat was compiled with.  Since an
2298 application that requires this kind of information needs to determine
2299 the type of character the <code>name</code> points to, records for the
2300 <code>XML_FEATURE_SIZEOF_XML_CHAR</code> and
2301 <code>XML_FEATURE_SIZEOF_XML_LCHAR</code> will be located at the
2302 beginning of the list, followed by <code>XML_FEATURE_UNICODE</code>
2303 and <code>XML_FEATURE_UNICODE_WCHAR_T</code>, if they are present at
2304 all.</p>
2305
2306 <p>Some features have an associated value.  If there isn't an
2307 associated value, the <code>value</code> field is set to 0.  At this
2308 time, the following features have been defined to have values:</p>
2309
2310 <dl>
2311   <dt><code>XML_FEATURE_SIZEOF_XML_CHAR</code></dt>
2312   <dd>The number of bytes occupied by one <code>XML_Char</code>
2313   character.</dd>
2314   <dt><code>XML_FEATURE_SIZEOF_XML_LCHAR</code></dt>
2315   <dd>The number of bytes occupied by one <code>XML_LChar</code>
2316   character.</dd>
2317   <dt><code>XML_FEATURE_CONTEXT_BYTES</code></dt>
2318   <dd>The maximum number of characters of context which can be
2319   reported by <code><a href= "#XML_GetInputContext"
2320   >XML_GetInputContext</a></code>.</dd>
2321 </dl>
2322 </div>
2323
2324 <pre class="fcndec" id="XML_FreeContentModel">
2325 void XMLCALL
2326 XML_FreeContentModel(XML_Parser parser, XML_Content *model);
2327 </pre>
2328 <div class="fcndef">
2329 Function to deallocate the <code>model</code> argument passed to the
2330 <code>XML_ElementDeclHandler</code> callback set using <code><a
2331 href="#XML_SetElementDeclHandler" >XML_ElementDeclHandler</a></code>.
2332 This function should not be used for any other purpose.
2333 </div>
2334
2335 <p>The following functions allow external code to share the memory
2336 allocator an <code>XML_Parser</code> has been configured to use.  This
2337 is especially useful for third-party libraries that interact with a
2338 parser object created by application code, or heavily layered
2339 applications.  This can be essential when using dynamically loaded
2340 libraries which use different C standard libraries (this can happen on
2341 Windows, at least).</p>
2342
2343 <pre class="fcndec" id="XML_MemMalloc">
2344 void * XMLCALL
2345 XML_MemMalloc(XML_Parser parser, size_t size);
2346 </pre>
2347 <div class="fcndef">
2348 Allocate <code>size</code> bytes of memory using the allocator the
2349 <code>parser</code> object has been configured to use.  Returns a
2350 pointer to the memory or NULL on failure.  Memory allocated in this
2351 way must be freed using <code><a href="#XML_MemFree"
2352 >XML_MemFree</a></code>.
2353 </div>
2354
2355 <pre class="fcndec" id="XML_MemRealloc">
2356 void * XMLCALL
2357 XML_MemRealloc(XML_Parser parser, void *ptr, size_t size);
2358 </pre>
2359 <div class="fcndef">
2360 Allocate <code>size</code> bytes of memory using the allocator the
2361 <code>parser</code> object has been configured to use.
2362 <code>ptr</code> must point to a block of memory allocated by <code><a
2363 href="#XML_MemMalloc" >XML_MemMalloc</a></code> or
2364 <code>XML_MemRealloc</code>, or be NULL.  This function tries to
2365 expand the block pointed to by <code>ptr</code> if possible.  Returns
2366 a pointer to the memory or NULL on failure.  On success, the original
2367 block has either been expanded or freed.  On failure, the original
2368 block has not been freed; the caller is responsible for freeing the
2369 original block.  Memory allocated in this way must be freed using
2370 <code><a href="#XML_MemFree"
2371 >XML_MemFree</a></code>.
2372 </div>
2373
2374 <pre class="fcndec" id="XML_MemFree">
2375 void XMLCALL
2376 XML_MemFree(XML_Parser parser, void *ptr);
2377 </pre>
2378 <div class="fcndef">
2379 Free a block of memory pointed to by <code>ptr</code>.  The block must
2380 have been allocated by <code><a href="#XML_MemMalloc"
2381 >XML_MemMalloc</a></code> or <code>XML_MemRealloc</code>, or be NULL.
2382 </div>
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