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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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