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8 This is free software. You may distribute or modify according to

9 the terms of the MIT/X License -->

10 <title>Expat XML Parser</title>

   <meta name="author" content="Clark Cooper, coopercc@netheaven.com" />

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15 <body>

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17 <tr>

       <td class="corner"><img src="expat.png" alt="(Expat logo)" /></td>

       <td class="banner"><h1>The Expat XML Parser</h1></td>

20 </tr>

21 <tr>

       <td class="releaseno">Release 2.0.1</td>

23 <td></td>

24 </tr>

25 </table>

26 <div class="content">

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>

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>

39 <p>This is free software, licensed under the <a

40 href="../COPYING">MIT/X Consortium license</a>. You may download it

 from <a href="http://www.libexpat.org/">the Expat home page</a>.

42 </p>

44 <p>The bulk of this document was originally commissioned as an article

 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>

52 <hr />

53 <h2>Table of Contents</h2>

54 <ul>

   <li><a href="#overview">Overview</a></li>

   <li><a href="#building">Building and Installing</a></li>

   <li><a href="#using">Using Expat</a></li>

   <li><a href="#reference">Reference</a>

59 <ul>

     <li><a href="#creation">Parser Creation Functions</a>

61 <ul>

       <li><a href="#XML_ParserCreate">XML_ParserCreate</a></li>

       <li><a href="#XML_ParserCreateNS">XML_ParserCreateNS</a></li>

       <li><a href="#XML_ParserCreate_MM">XML_ParserCreate_MM</a></li>

       <li><a href="#XML_ExternalEntityParserCreate">XML_ExternalEntityParserCreate</a></li>

       <li><a href="#XML_ParserFree">XML_ParserFree</a></li>

       <li><a href="#XML_ParserReset">XML_ParserReset</a></li>

68 </ul>

69 </li>

     <li><a href="#parsing">Parsing Functions</a>

71 <ul>

       <li><a href="#XML_Parse">XML_Parse</a></li>

       <li><a href="#XML_ParseBuffer">XML_ParseBuffer</a></li>

       <li><a href="#XML_GetBuffer">XML_GetBuffer</a></li>

       <li><a href="#XML_StopParser">XML_StopParser</a></li>

       <li><a href="#XML_ResumeParser">XML_ResumeParser</a></li>

       <li><a href="#XML_GetParsingStatus">XML_GetParsingStatus</a></li>

78 </ul>

79 </li>

     <li><a href="#setting">Handler Setting Functions</a>

81 <ul>

       <li><a href="#XML_SetStartElementHandler">XML_SetStartElementHandler</a></li>

       <li><a href="#XML_SetEndElementHandler">XML_SetEndElementHandler</a></li>

       <li><a href="#XML_SetElementHandler">XML_SetElementHandler</a></li>

       <li><a href="#XML_SetCharacterDataHandler">XML_SetCharacterDataHandler</a></li>

       <li><a href="#XML_SetProcessingInstructionHandler">XML_SetProcessingInstructionHandler</a></li>

       <li><a href="#XML_SetCommentHandler">XML_SetCommentHandler</a></li>

       <li><a href="#XML_SetStartCdataSectionHandler">XML_SetStartCdataSectionHandler</a></li>

       <li><a href="#XML_SetEndCdataSectionHandler">XML_SetEndCdataSectionHandler</a></li>

       <li><a href="#XML_SetCdataSectionHandler">XML_SetCdataSectionHandler</a></li>

       <li><a href="#XML_SetDefaultHandler">XML_SetDefaultHandler</a></li>

       <li><a href="#XML_SetDefaultHandlerExpand">XML_SetDefaultHandlerExpand</a></li>

       <li><a href="#XML_SetExternalEntityRefHandler">XML_SetExternalEntityRefHandler</a></li>

       <li><a href="#XML_SetExternalEntityRefHandlerArg">XML_SetExternalEntityRefHandlerArg</a></li>

       <li><a href="#XML_SetSkippedEntityHandler">XML_SetSkippedEntityHandler</a></li>

       <li><a href="#XML_SetUnknownEncodingHandler">XML_SetUnknownEncodingHandler</a></li>

       <li><a href="#XML_SetStartNamespaceDeclHandler">XML_SetStartNamespaceDeclHandler</a></li>

       <li><a href="#XML_SetEndNamespaceDeclHandler">XML_SetEndNamespaceDeclHandler</a></li>

       <li><a href="#XML_SetNamespaceDeclHandler">XML_SetNamespaceDeclHandler</a></li>

       <li><a href="#XML_SetXmlDeclHandler">XML_SetXmlDeclHandler</a></li>                 

       <li><a href="#XML_SetStartDoctypeDeclHandler">XML_SetStartDoctypeDeclHandler</a></li>

       <li><a href="#XML_SetEndDoctypeDeclHandler">XML_SetEndDoctypeDeclHandler</a></li>

       <li><a href="#XML_SetDoctypeDeclHandler">XML_SetDoctypeDeclHandler</a></li>

       <li><a href="#XML_SetElementDeclHandler">XML_SetElementDeclHandler</a></li>

       <li><a href="#XML_SetAttlistDeclHandler">XML_SetAttlistDeclHandler</a></li>

       <li><a href="#XML_SetEntityDeclHandler">XML_SetEntityDeclHandler</a></li>

       <li><a href="#XML_SetUnparsedEntityDeclHandler">XML_SetUnparsedEntityDeclHandler</a></li>

       <li><a href="#XML_SetNotationDeclHandler">XML_SetNotationDeclHandler</a></li>

       <li><a href="#XML_SetNotStandaloneHandler">XML_SetNotStandaloneHandler</a></li>

110 </ul>

111 </li>

     <li><a href="#position">Parse Position and Error Reporting Functions</a>

113 <ul>

       <li><a href="#XML_GetErrorCode">XML_GetErrorCode</a></li>

       <li><a href="#XML_ErrorString">XML_ErrorString</a></li>

       <li><a href="#XML_GetCurrentByteIndex">XML_GetCurrentByteIndex</a></li>

       <li><a href="#XML_GetCurrentLineNumber">XML_GetCurrentLineNumber</a></li>

       <li><a href="#XML_GetCurrentColumnNumber">XML_GetCurrentColumnNumber</a></li>

       <li><a href="#XML_GetCurrentByteCount">XML_GetCurrentByteCount</a></li>

       <li><a href="#XML_GetInputContext">XML_GetInputContext</a></li>

121 </ul>

122 </li>

     <li><a href="#miscellaneous">Miscellaneous Functions</a>

124 <ul>

       <li><a href="#XML_SetUserData">XML_SetUserData</a></li>

       <li><a href="#XML_GetUserData">XML_GetUserData</a></li>

       <li><a href="#XML_UseParserAsHandlerArg">XML_UseParserAsHandlerArg</a></li>

       <li><a href="#XML_SetBase">XML_SetBase</a></li>

       <li><a href="#XML_GetBase">XML_GetBase</a></li>

       <li><a href="#XML_GetSpecifiedAttributeCount">XML_GetSpecifiedAttributeCount</a></li>

       <li><a href="#XML_GetIdAttributeIndex">XML_GetIdAttributeIndex</a></li>

       <li><a href="#XML_GetAttributeInfo">XML_GetAttributeInfo</a></li>

       <li><a href="#XML_SetEncoding">XML_SetEncoding</a></li>

       <li><a href="#XML_SetParamEntityParsing">XML_SetParamEntityParsing</a></li>

       <li><a href="#XML_SetHashSalt">XML_SetHashSalt</a></li>

       <li><a href="#XML_UseForeignDTD">XML_UseForeignDTD</a></li>

       <li><a href="#XML_SetReturnNSTriplet">XML_SetReturnNSTriplet</a></li>

       <li><a href="#XML_DefaultCurrent">XML_DefaultCurrent</a></li>

       <li><a href="#XML_ExpatVersion">XML_ExpatVersion</a></li>

       <li><a href="#XML_ExpatVersionInfo">XML_ExpatVersionInfo</a></li>

       <li><a href="#XML_GetFeatureList">XML_GetFeatureList</a></li>

       <li><a href="#XML_FreeContentModel">XML_FreeContentModel</a></li>

       <li><a href="#XML_MemMalloc">XML_MemMalloc</a></li>

       <li><a href="#XML_MemRealloc">XML_MemRealloc</a></li>

       <li><a href="#XML_MemFree">XML_MemFree</a></li>

146 </ul>

147 </li>

148 </ul>

149 </li>

150 </ul>

151

152 <hr />

 <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

 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 < 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 <expat.h>

251

252 #ifndef XMLCALL

253 #if defined(_MSC_EXTENSIONS) && !defined(__BEOS__) && !defined(__CYGWIN__)

254 #define XMLCALL __cdecl

255 #elif defined(__GNUC__)

256 #define XMLCALL __attribute__((cdecl))

257 #else

258 #define XMLCALL

259 #endif

260 #endif

261 </pre>

262

263 <p>After creating the parser, the main program just has the job of

264 shoveling the document to the parser so that it can do its work.</p>

265

266 <hr />

 <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>

 <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

 <code><a href="#XML_GetCurrentByteIndex" >XML_GetCurrentByteIndex</a></code>,

 <code><a href="#XML_GetCurrentLineNumber" >XML_GetCurrentLineNumber</a></code> and

 <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 />

 <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 <expat.h></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

 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

 <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

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 < (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>

 &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 <?xml encoding="Big5"?>

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

 -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

 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

 <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 < 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

892

893

894 <hr />

895

896

 <h2><a name="reference">Expat Reference</a></h2>

898

 <h3><a name="creation">Parser Creation</a></h3>

900

 <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

 <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

 <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

 with <a href= "#XML_SetReturnNSTriplet">namespace triplets</a>.</div>

936

 <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

 <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

 <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

 freeing any memory associated with <a href="#userdata">user data</a>.

982 </div>

983

 <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

 dealing with any memory associated with <a href="#userdata">user data</a>.

1000 </div>

1001

 <h3><a name="parsing">Parsing</a></h3>

1003

1004 <p>To state the obvious: the three parsing functions <code><a href=

 "#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

 <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

 <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

 <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 < 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

 <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

 <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

 <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

 <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

 <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

 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">

 <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">

 <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">

 <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">

 <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">

 <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">

 <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">

 <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">

 <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">

 <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">

 <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

 href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p>

1407 </div>

1408

1409 <div class="handler">

 <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

 href="#XML_DefaultCurrent">XML_DefaultCurrent</a></code>.</p>

1427 </div>

1428

1429 <div class="handler">

 <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

 <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">

 <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

        <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">

 <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

 <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 >= 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 > 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">

 <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">

 <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">

 <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">

 <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">

 <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">

 <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">

 <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">

 <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

 <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

 <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">

 <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">

 <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

 <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

 <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">

 <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 <!ENTITY logo SYSTEM "images/logo.gif" NDATA gif>

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">

 <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">

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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

 <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>

2383

2384 <hr />

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