src/expat/doc/reference.html

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