Expat is a library, written in C, for parsing XML documents. It's
+the underlying XML parser for the open source Mozilla project, Perl's
+XML::Parser, Python's xml.parsers.expat, and
+other open-source XML parsers.
This library is the creation of James Clark, who's also given us +groff (an nroff look-alike), Jade (an implemention of ISO's DSSSL +stylesheet language for SGML), XP (a Java XML parser package), XT (a +Java XSL engine). James was also the technical lead on the XML +Working Group at W3C that produced the XML specification.
+ +This is free software, licensed under the MIT/X Consortium license. You may download it +from the Expat home page. +
+ +The bulk of this document was originally commissioned as an article +by XML.com. They graciously allowed +Clark Cooper to retain copyright and to distribute it with Expat. +This version has been substantially extended to include documentation +on features which have been added since the original article was +published, and additional information on using the original +interface.
+ ++
Table of Contents
+-
+
- Overview +
- Building and Installing +
- Using Expat +
- Reference
+
-
+
- Parser Creation Functions + + +
- Parsing Functions + + +
- Handler Setting Functions
+
-
+
- XML_SetStartElementHandler +
- XML_SetEndElementHandler +
- XML_SetElementHandler +
- XML_SetCharacterDataHandler +
- XML_SetProcessingInstructionHandler +
- XML_SetCommentHandler +
- XML_SetStartCdataSectionHandler +
- XML_SetEndCdataSectionHandler +
- XML_SetCdataSectionHandler +
- XML_SetDefaultHandler +
- XML_SetDefaultHandlerExpand +
- XML_SetExternalEntityRefHandler +
- XML_SetExternalEntityRefHandlerArg +
- XML_SetSkippedEntityHandler +
- XML_SetUnknownEncodingHandler +
- XML_SetStartNamespaceDeclHandler +
- XML_SetEndNamespaceDeclHandler +
- XML_SetNamespaceDeclHandler +
- XML_SetXmlDeclHandler +
- XML_SetStartDoctypeDeclHandler +
- XML_SetEndDoctypeDeclHandler +
- XML_SetDoctypeDeclHandler +
- XML_SetElementDeclHandler +
- XML_SetAttlistDeclHandler +
- XML_SetEntityDeclHandler +
- XML_SetUnparsedEntityDeclHandler +
- XML_SetNotationDeclHandler +
- XML_SetNotStandaloneHandler +
+ - Parse Position and Error Reporting Functions + + +
- Miscellaneous Functions
+
-
+
- XML_SetUserData +
- XML_GetUserData +
- XML_UseParserAsHandlerArg +
- XML_SetBase +
- XML_GetBase +
- XML_GetSpecifiedAttributeCount +
- XML_GetIdAttributeIndex +
- XML_GetAttributeInfo +
- XML_SetEncoding +
- XML_SetParamEntityParsing +
- XML_SetHashSalt +
- XML_UseForeignDTD +
- XML_SetReturnNSTriplet +
- XML_DefaultCurrent +
- XML_ExpatVersion +
- XML_ExpatVersionInfo +
- XML_GetFeatureList +
- XML_FreeContentModel +
- XML_MemMalloc +
- XML_MemRealloc +
- XML_MemFree +
+
+
+
Overview
+ +Expat is a stream-oriented parser. You register callback (or +handler) functions with the parser and then start feeding it the +document. As the parser recognizes parts of the document, it will +call the appropriate handler for that part (if you've registered one.) +The document is fed to the parser in pieces, so you can start parsing +before you have all the document. This also allows you to parse really +huge documents that won't fit into memory.
+ +Expat can be intimidating due to the many kinds of handlers and +options you can set. But you only need to learn four functions in +order to do 90% of what you'll want to do with it:
+ +-
+
+
XML_ParserCreate
+ - Create a new parser object. + +
XML_SetElementHandler
+ - Set handlers for start and end tags. + +
XML_SetCharacterDataHandler
+ - Set handler for text. + +
XML_Parse
+ - Pass a buffer full of document to the parser +
These functions and others are described in the reference part of this document. The reference +section also describes in detail the parameters passed to the +different types of handlers.
+ +Let's look at a very simple example program that only uses 3 of the
+above functions (it doesn't need to set a character handler.) The
+program outline.c prints an
+element outline, indenting child elements to distinguish them from the
+parent element that contains them. The start handler does all the
+work. It prints two indenting spaces for every level of ancestor
+elements, then it prints the element and attribute
+information. Finally it increments the global Depth
+variable.
+int Depth;
+
+void XMLCALL
+start(void *data, const char *el, const char **attr) {
+ int i;
+
+ for (i = 0; i < Depth; i++)
+ printf(" ");
+
+ printf("%s", el);
+
+ for (i = 0; attr[i]; i += 2) {
+ printf(" %s='%s'", attr[i], attr[i + 1]);
+ }
+
+ printf("\n");
+ Depth++;
+} /* End of start handler */
+
+
+The end tag simply does the bookkeeping work of decrementing
+Depth.
+void XMLCALL
+end(void *data, const char *el) {
+ Depth--;
+} /* End of end handler */
+
+
+Note the XMLCALL annotation used for the callbacks.
+This is used to ensure that the Expat and the callbacks are using the
+same calling convention in case the compiler options used for Expat
+itself and the client code are different. Expat tries not to care
+what the default calling convention is, though it may require that it
+be compiled with a default convention of "cdecl" on some platforms.
+For code which uses Expat, however, the calling convention is
+specified by the XMLCALL annotation on most platforms;
+callbacks should be defined using this annotation.
The XMLCALL annotation was added in Expat 1.95.7, but
+existing working Expat applications don't need to add it (since they
+are already using the "cdecl" calling convention, or they wouldn't be
+working). The annotation is only needed if the default calling
+convention may be something other than "cdecl". To use the annotation
+safely with older versions of Expat, you can conditionally define it
+after including Expat's header file:
+#include <expat.h> + +#ifndef XMLCALL +#if defined(_MSC_EXTENSIONS) && !defined(__BEOS__) && !defined(__CYGWIN__) +#define XMLCALL __cdecl +#elif defined(__GNUC__) +#define XMLCALL __attribute__((cdecl)) +#else +#define XMLCALL +#endif +#endif ++ +
After creating the parser, the main program just has the job of +shoveling the document to the parser so that it can do its work.
+ ++
Building and Installing Expat
+ +The Expat distribution comes as a compressed (with GNU gzip) tar +file. You may download the latest version from Source Forge. After +unpacking this, cd into the directory. Then follow either the Win32 +directions or Unix directions below.
+ +Building under Win32
+ +If you're using the GNU compiler under cygwin, follow the Unix +directions in the next section. Otherwise if you have Microsoft's +Developer Studio installed, then from Windows Explorer double-click on +"expat.dsp" in the lib directory and build and install in the usual +manner.
+ +Alternatively, you may download the Win32 binary package that +contains the "expat.h" include file and a pre-built DLL.
+ +Building under Unix (or GNU)
+ +First you'll need to run the configure shell script in order to +configure the Makefiles and headers for your system.
+ +If you're happy with all the defaults that configure picks for you, +and you have permission on your system to install into /usr/local, you +can install Expat with this sequence of commands:
+ ++./configure +make +make install ++ +
There are some options that you can provide to this script, but the
+only one we'll mention here is the --prefix option. You
+can find out all the options available by running configure with just
+the --help option.
By default, the configure script sets things up so that the library
+gets installed in /usr/local/lib and the associated
+header file in /usr/local/include. But if you were to
+give the option, --prefix=/home/me/mystuff, then the
+library and header would get installed in
+/home/me/mystuff/lib and
+/home/me/mystuff/include respectively.
Configuring Expat Using the Pre-Processor
+ +Expat's feature set can be configured using a small number of
+pre-processor definitions. The definition of this symbols does not
+affect the set of entry points for Expat, only the behavior of the API
+and the definition of character types in the case of
+XML_UNICODE_WCHAR_T. The symbols are:
-
+
- XML_DTD +
- Include support for using and reporting DTD-based content. If +this is defined, default attribute values from an external DTD subset +are reported and attribute value normalization occurs based on the +type of attributes defined in the external subset. Without +this, Expat has a smaller memory footprint and can be faster, but will +not load external entities or process conditional sections. This does +not affect the set of functions available in the API. + +
- XML_NS +
- When defined, support for the Namespaces in XML +specification is included. + +
- XML_UNICODE +
- When defined, character data reported to the application is
+encoded in UTF-16 using wide characters of the type
+
XML_Char. This is implied if +XML_UNICODE_WCHAR_Tis defined.
+
+ - XML_UNICODE_WCHAR_T +
- If defined, causes the
XML_Charcharacter type to be +defined using thewchar_ttype; otherwise,unsigned +shortis used. Defining this implies +XML_UNICODE.
+
+ - XML_LARGE_SIZE +
- If defined, causes the
XML_SizeandXML_Index+integer types to be at least 64 bits in size. This is intended to support +processing of very large input streams, where the return values of +XML_GetCurrentByteIndex, +XML_GetCurrentLineNumberand +XML_GetCurrentColumnNumber+could overflow. It may not be supported by all compilers, and is turned +off by default.
+
+ - XML_CONTEXT_BYTES +
- The number of input bytes of markup context which the parser will
+ensure are available for reporting via
XML_GetInputContext. This is +normally set to 1024, and must be set to a positive interger. If this +is not defined, the input context will not be available andXML_GetInputContextwill +always report NULL. Without this, Expat has a smaller memory +footprint and can be faster.
+
+ - XML_STATIC +
- On Windows, this should be set if Expat is going to be linked +statically with the code that calls it; this is required to get all +the right MSVC magic annotations correct. This is ignored on other +platforms. + +
- XML_ATTR_INFO +
- If defined, makes the the additional function
XML_GetAttributeInfoavailable +for reporting attribute byte offsets.
+
+
Using Expat
+ +Compiling and Linking Against Expat
+ +Unless you installed Expat in a location not expected by your
+compiler and linker, all you have to do to use Expat in your programs
+is to include the Expat header (#include <expat.h>)
+in your files that make calls to it and to tell the linker that it
+needs to link against the Expat library. On Unix systems, this would
+usually be done with the -lexpat argument. Otherwise,
+you'll need to tell the compiler where to look for the Expat header
+and the linker where to find the Expat library. You may also need to
+take steps to tell the operating system where to find this library at
+run time.
On a Unix-based system, here's what a Makefile might look like when +Expat is installed in a standard location:
+ ++CC=cc +LDFLAGS= +LIBS= -lexpat +xmlapp: xmlapp.o + $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS) ++ +
If you installed Expat in, say, /home/me/mystuff, then
+the Makefile would look like this:
+CC=cc +CFLAGS= -I/home/me/mystuff/include +LDFLAGS= +LIBS= -L/home/me/mystuff/lib -lexpat +xmlapp: xmlapp.o + $(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS) ++ +
You'd also have to set the environment variable
+LD_LIBRARY_PATH to /home/me/mystuff/lib (or
+to ${LD_LIBRARY_PATH}:/home/me/mystuff/lib if
+LD_LIBRARY_PATH already has some directories in it) in order to run
+your application.
Expat Basics
+ +As we saw in the example in the overview, the first step in parsing
+an XML document with Expat is to create a parser object. There are three functions in the Expat API for creating a
+parser object. However, only two of these (XML_ParserCreate and XML_ParserCreateNS) can be used for
+constructing a parser for a top-level document. The object returned
+by these functions is an opaque pointer (i.e. "expat.h" declares it as
+void *) to data with further internal structure. In order to free the
+memory associated with this object you must call XML_ParserFree. Note that if you have
+provided any user data that gets stored in the
+parser, then your application is responsible for freeing it prior to
+calling XML_ParserFree.
The objects returned by the parser creation functions are good for +parsing only one XML document or external parsed entity. If your +application needs to parse many XML documents, then it needs to create +a parser object for each one. The best way to deal with this is to +create a higher level object that contains all the default +initialization you want for your parser objects.
+ +Walking through a document hierarchy with a stream oriented parser +will require a good stack mechanism in order to keep track of current +context. For instance, to answer the simple question, "What element +does this text belong to?" requires a stack, since the parser may have +descended into other elements that are children of the current one and +has encountered this text on the way out.
+ +The things you're likely to want to keep on a stack are the +currently opened element and it's attributes. You push this +information onto the stack in the start handler and you pop it off in +the end handler.
+ +For some tasks, it is sufficient to just keep information on what +the depth of the stack is (or would be if you had one.) The outline +program shown above presents one example. Another such task would be +skipping over a complete element. When you see the start tag for the +element you want to skip, you set a skip flag and record the depth at +which the element started. When the end tag handler encounters the +same depth, the skipped element has ended and the flag may be +cleared. If you follow the convention that the root element starts at +1, then you can use the same variable for skip flag and skip +depth.
+ +
+void
+init_info(Parseinfo *info) {
+ info->skip = 0;
+ info->depth = 1;
+ /* Other initializations here */
+} /* End of init_info */
+
+void XMLCALL
+rawstart(void *data, const char *el, const char **attr) {
+ Parseinfo *inf = (Parseinfo *) data;
+
+ if (! inf->skip) {
+ if (should_skip(inf, el, attr)) {
+ inf->skip = inf->depth;
+ }
+ else
+ start(inf, el, attr); /* This does rest of start handling */
+ }
+
+ inf->depth++;
+} /* End of rawstart */
+
+void XMLCALL
+rawend(void *data, const char *el) {
+ Parseinfo *inf = (Parseinfo *) data;
+
+ inf->depth--;
+
+ if (! inf->skip)
+ end(inf, el); /* This does rest of end handling */
+
+ if (inf->skip == inf->depth)
+ inf->skip = 0;
+} /* End rawend */
+
+
+Notice in the above example the difference in how depth is +manipulated in the start and end handlers. The end tag handler should +be the mirror image of the start tag handler. This is necessary to +properly model containment. Since, in the start tag handler, we +incremented depth after the main body of start tag code, then +in the end handler, we need to manipulate it before the main +body. If we'd decided to increment it first thing in the start +handler, then we'd have had to decrement it last thing in the end +handler.
+ +Communicating between handlers
+ +In order to be able to pass information between different handlers
+without using globals, you'll need to define a data structure to hold
+the shared variables. You can then tell Expat (with the XML_SetUserData function) to pass a
+pointer to this structure to the handlers. This is the first
+argument received by most handlers. In the reference section, an argument to a callback function is named
+userData and have type void * if the user
+data is passed; it will have the type XML_Parser if the
+parser itself is passed. When the parser is passed, the user data may
+be retrieved using XML_GetUserData.
One common case where multiple calls to a single handler may need
+to communicate using an application data structure is the case when
+content passed to the character data handler (set by XML_SetCharacterDataHandler) needs to be accumulated. A
+common first-time mistake with any of the event-oriented interfaces to
+an XML parser is to expect all the text contained in an element to be
+reported by a single call to the character data handler. Expat, like
+many other XML parsers, reports such data as a sequence of calls;
+there's no way to know when the end of the sequence is reached until a
+different callback is made. A buffer referenced by the user data
+structure proves both an effective and convenient place to accumulate
+character data.
XML Version
+ +Expat is an XML 1.0 parser, and as such never complains based on
+the value of the version pseudo-attribute in the XML
+declaration, if present.
If an application needs to check the version number (to support
+alternate processing), it should use the XML_SetXmlDeclHandler function to
+set a handler that uses the information in the XML declaration to
+determine what to do. This example shows how to check that only a
+version number of "1.0" is accepted:
+static int wrong_version;
+static XML_Parser parser;
+
+static void XMLCALL
+xmldecl_handler(void *userData,
+ const XML_Char *version,
+ const XML_Char *encoding,
+ int standalone)
+{
+ static const XML_Char Version_1_0[] = {'1', '.', '0', 0};
+
+ int i;
+
+ for (i = 0; i < (sizeof(Version_1_0) / sizeof(Version_1_0[0])); ++i) {
+ if (version[i] != Version_1_0[i]) {
+ wrong_version = 1;
+ /* also clear all other handlers: */
+ XML_SetCharacterDataHandler(parser, NULL);
+ ...
+ return;
+ }
+ }
+ ...
+}
+
+
+Namespace Processing
+ +When the parser is created using the XML_ParserCreateNS, function, Expat
+performs namespace processing. Under namespace processing, Expat
+consumes xmlns and xmlns:... attributes,
+which declare namespaces for the scope of the element in which they
+occur. This means that your start handler will not see these
+attributes. Your application can still be informed of these
+declarations by setting namespace declaration handlers with XML_SetNamespaceDeclHandler.
Element type and attribute names that belong to a given namespace
+are passed to the appropriate handler in expanded form. By default
+this expanded form is a concatenation of the namespace URI, the
+separator character (which is the 2nd argument to XML_ParserCreateNS), and the local
+name (i.e. the part after the colon). Names with undeclared prefixes
+are not well-formed when namespace processing is enabled, and will
+trigger an error. Unprefixed attribute names are never expanded,
+and unprefixed element names are only expanded when they are in the
+scope of a default namespace.
However if XML_SetReturnNSTriplet has been called with a non-zero
+do_nst parameter, then the expanded form for names with
+an explicit prefix is a concatenation of: URI, separator, local name,
+separator, prefix.
You can set handlers for the start of a namespace declaration and
+for the end of a scope of a declaration with the XML_SetNamespaceDeclHandler
+function. The StartNamespaceDeclHandler is called prior to the start
+tag handler and the EndNamespaceDeclHandler is called after the
+corresponding end tag that ends the namespace's scope. The namespace
+start handler gets passed the prefix and URI for the namespace. For a
+default namespace declaration (xmlns='...'), the prefix will be null.
+The URI will be null for the case where the default namespace is being
+unset. The namespace end handler just gets the prefix for the closing
+scope.
These handlers are called for each declaration. So if, for +instance, a start tag had three namespace declarations, then the +StartNamespaceDeclHandler would be called three times before the start +tag handler is called, once for each declaration.
+ +Character Encodings
+ +While XML is based on Unicode, and every XML processor is required +to recognized UTF-8 and UTF-16 (1 and 2 byte encodings of Unicode), +other encodings may be declared in XML documents or entities. For the +main document, an XML declaration may contain an encoding +declaration:
++<?xml version="1.0" encoding="ISO-8859-2"?> ++ +
External parsed entities may begin with a text declaration, which +looks like an XML declaration with just an encoding declaration:
++<?xml encoding="Big5"?> ++ +
With Expat, you may also specify an encoding at the time of +creating a parser. This is useful when the encoding information may +come from a source outside the document itself (like a higher level +protocol.)
+ +There are four built-in encodings +in Expat:
+-
+
- UTF-8 +
- UTF-16 +
- ISO-8859-1 +
- US-ASCII +
Anything else discovered in an encoding declaration or in the
+protocol encoding specified in the parser constructor, triggers a call
+to the UnknownEncodingHandler. This handler gets passed
+the encoding name and a pointer to an XML_Encoding data
+structure. Your handler must fill in this structure and return
+XML_STATUS_OK if it knows how to deal with the
+encoding. Otherwise the handler should return
+XML_STATUS_ERROR. The handler also gets passed a pointer
+to an optional application data structure that you may indicate when
+you set the handler.
Expat places restrictions on character encodings that it can
+support by filling in the XML_Encoding structure.
+include file:
-
+
- Every ASCII character that can appear in a well-formed XML document +must be represented by a single byte, and that byte must correspond to +it's ASCII encoding (except for the characters $@\^'{}~) +
- Characters must be encoded in 4 bytes or less. +
- All characters encoded must have Unicode scalar values less than or +equal to 65535 (0xFFFF)This does not apply to the built-in support +for UTF-16 and UTF-8 +
- No character may be encoded by more that one distinct sequence of +bytes +
XML_Encoding contains an array of integers that
+correspond to the 1st byte of an encoding sequence. If the value in
+the array for a byte is zero or positive, then the byte is a single
+byte encoding that encodes the Unicode scalar value contained in the
+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
+sequence respectively. Multi-byte sequences are sent to the convert
+function pointed at in the XML_Encoding structure. This
+function should return the Unicode scalar value for the sequence or -1
+if the sequence is malformed.
One pitfall that novice Expat users are likely to fall into is that +although Expat may accept input in various encodings, the strings that +it passes to the handlers are always encoded in UTF-8 or UTF-16 +(depending on how Expat was compiled). Your application is responsible +for any translation of these strings into other encodings.
+ +Handling External Entity References
+ +Expat does not read or parse external entities directly. Note that
+any external DTD is a special case of an external entity. If you've
+set no ExternalEntityRefHandler, then external entity
+references are silently ignored. Otherwise, it calls your handler with
+the information needed to read and parse the external entity.
Your handler isn't actually responsible for parsing the entity, but
+it is responsible for creating a subsidiary parser with XML_ExternalEntityParserCreate that will do the job. This
+returns an instance of XML_Parser that has handlers and
+other data structures initialized from the parent parser. You may then
+use XML_Parse or XML_ParseBuffer calls against this
+parser. Since external entities my refer to other external entities,
+your handler should be prepared to be called recursively.
Parsing DTDs
+ +In order to parse parameter entities, before starting the parse,
+you must call XML_SetParamEntityParsing with one of the following
+arguments:
-
+
XML_PARAM_ENTITY_PARSING_NEVER
+- Don't parse parameter entities or the external subset +
XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE
+- Parse parameter entites and the external subset unless
+
standalonewas set to "yes" in the XML declaration.
+ XML_PARAM_ENTITY_PARSING_ALWAYS
+- Always parse parameter entities and the external subset +
In order to read an external DTD, you also have to set an external +entity reference handler as described above.
+ +Temporarily Stopping Parsing
+ +Expat 1.95.8 introduces a new feature: its now possible to stop +parsing temporarily from within a handler function, even if more data +has already been passed into the parser. Applications for this +include
+ +-
+
- Supporting the XInclude specification. + +
- Delaying further processing until additional information is + available from some other source. + +
- Adjusting processor load as task priorities shift within an + application. + +
- Stopping parsing completely (simply free or reset the parser + instead of resuming in the outer parsing loop). This can be useful + if a application-domain error is found in the XML being parsed or if + the result of the parse is determined not to be useful after + all. +
To take advantage of this feature, the main parsing loop of an +application needs to support this specifically. It cannot be +supported with a parsing loop compatible with Expat 1.95.7 or +earlier (though existing loops will continue to work without +supporting the stop/resume feature).
+ +An application that uses this feature for a single parser will have +the rough structure (in pseudo-code):
+ +
+fd = open_input()
+p = create_parser()
+
+if parse_xml(p, fd) {
+ /* suspended */
+
+ int suspended = 1;
+
+ while (suspended) {
+ do_something_else()
+ if ready_to_resume() {
+ suspended = continue_parsing(p, fd);
+ }
+ }
+}
+
+
+An application that may resume any of several parsers based on +input (either from the XML being parsed or some other source) will +certainly have more interesting control structures.
+ +This C function could be used for the parse_xml
+function mentioned in the pseudo-code above:
+#define BUFF_SIZE 10240
+
+/* Parse a document from the open file descriptor 'fd' until the parse
+ is complete (the document has been completely parsed, or there's
+ been an error), or the parse is stopped. Return non-zero when
+ the parse is merely suspended.
+*/
+int
+parse_xml(XML_Parser p, int fd)
+{
+ for (;;) {
+ int last_chunk;
+ int bytes_read;
+ enum XML_Status status;
+
+ void *buff = XML_GetBuffer(p, BUFF_SIZE);
+ if (buff == NULL) {
+ /* handle error... */
+ return 0;
+ }
+ bytes_read = read(fd, buff, BUFF_SIZE);
+ if (bytes_read < 0) {
+ /* handle error... */
+ return 0;
+ }
+ status = XML_ParseBuffer(p, bytes_read, bytes_read == 0);
+ switch (status) {
+ case XML_STATUS_ERROR:
+ /* handle error... */
+ return 0;
+ case XML_STATUS_SUSPENDED:
+ return 1;
+ }
+ if (bytes_read == 0)
+ return 0;
+ }
+}
+
+
+The corresponding continue_parsing function is
+somewhat simpler, since it only need deal with the return code from
+XML_ResumeParser; it can
+delegate the input handling to the parse_xml
+function:
+/* Continue parsing a document which had been suspended. The 'p' and
+ 'fd' arguments are the same as passed to parse_xml(). Return
+ non-zero when the parse is suspended.
+*/
+int
+continue_parsing(XML_Parser p, int fd)
+{
+ enum XML_Status status = XML_ResumeParser(p);
+ switch (status) {
+ case XML_STATUS_ERROR:
+ /* handle error... */
+ return 0;
+ case XML_ERROR_NOT_SUSPENDED:
+ /* handle error... */
+ return 0;.
+ case XML_STATUS_SUSPENDED:
+ return 1;
+ }
+ return parse_xml(p, fd);
+}
+
+
+Now that we've seen what a mess the top-level parsing loop can
+become, what have we gained? Very simply, we can now use the XML_StopParser function to stop
+parsing, without having to go to great lengths to avoid additional
+processing that we're expecting to ignore. As a bonus, we get to stop
+parsing temporarily, and come back to it when we're
+ready.
To stop parsing from a handler function, use the XML_StopParser function. This function
+takes two arguments; the parser being stopped and a flag indicating
+whether the parse can be resumed in the future.
+ + +
Expat Reference
+ +Parser Creation
+ ++XML_Parser XMLCALL +XML_ParserCreate(const XML_Char *encoding); ++
-
+
- US-ASCII +
- UTF-8 +
- UTF-16 +
- ISO-8859-1 +
+XML_Parser XMLCALL +XML_ParserCreateNS(const XML_Char *encoding, + XML_Char sep); ++
'\xFF' is not legal in UTF-8, and
+'\xFFFF' is not legal in UTF-16. There is a special case when
+sep is the null character '\0': the namespace URI and
+the local part will be concatenated without any separator - this is intended
+to support RDF processors. It is a programming error to use the null separator
+with namespace triplets.+XML_Parser XMLCALL +XML_ParserCreate_MM(const XML_Char *encoding, + const XML_Memory_Handling_Suite *ms, + const XML_Char *sep); ++
+typedef struct {
+ void *(XMLCALL *malloc_fcn)(size_t size);
+ void *(XMLCALL *realloc_fcn)(void *ptr, size_t size);
+ void (XMLCALL *free_fcn)(void *ptr);
+} XML_Memory_Handling_Suite;
+
+Construct a new parser using the suite of memory handling functions
+specified in ms. If ms is NULL, then use the
+standard set of memory management functions. If sep is
+non NULL, then namespace processing is enabled in the created parser
+and the character pointed at by sep is used as the separator between
+the namespace URI and the local part of the name.
+XML_Parser XMLCALL +XML_ExternalEntityParserCreate(XML_Parser p, + const XML_Char *context, + const XML_Char *encoding); ++
XML_Parser object for parsing an external
+general entity. Context is the context argument passed in a call to a
+ExternalEntityRefHandler. Other state information such as handlers,
+user data, namespace processing is inherited from the parser passed as
+the 1st argument. So you shouldn't need to call any of the behavior
+changing functions on this parser (unless you want it to act
+differently than the parent parser).
++void XMLCALL +XML_ParserFree(XML_Parser p); ++
+XML_Bool XMLCALL +XML_ParserReset(XML_Parser p, + const XML_Char *encoding); ++
parser is
+ready to start parsing a new document. All handlers are cleared from
+the parser, except for the unknownEncodingHandler. The parser's external
+state is re-initialized except for the values of ns and ns_triplets.
+This function may not be used on a parser created using XML_ExternalEntityParserCreate; it will return XML_FALSE in that case. Returns
+XML_TRUE on success. Your application is responsible for
+dealing with any memory associated with user data.
+Parsing
+ +To state the obvious: the three parsing functions XML_Parse,
+XML_ParseBuffer and
+XML_GetBuffer must not be called from within a handler
+unless they operate on a separate parser instance, that is, one that
+did not call the handler. For example, it is OK to call the parsing
+functions from within an XML_ExternalEntityRefHandler,
+if they apply to the parser created by
+XML_ExternalEntityParserCreate.
Note: the len argument passed to these functions
+should be considerably less than the maximum value for an integer,
+as it could create an integer overflow situation if the added
+lengths of a buffer and the unprocessed portion of the previous buffer
+exceed the maximum integer value. Input data at the end of a buffer
+will remain unprocessed if it is part of an XML token for which the
+end is not part of that buffer.
+enum XML_Status XMLCALL +XML_Parse(XML_Parser p, + const char *s, + int len, + int isFinal); ++
+enum XML_Status {
+ XML_STATUS_ERROR = 0,
+ XML_STATUS_OK = 1
+};
+
+s is a buffer
+containing part (or perhaps all) of the document. The number of bytes of s
+that are part of the document is indicated by len. This means
+that s doesn't have to be null terminated. It also means that
+if len is larger than the number of bytes in the block of
+memory that s points at, then a memory fault is likely. The
+isFinal parameter informs the parser that this is the last
+piece of the document. Frequently, the last piece is empty (i.e.
+len is zero.)
+If a parse error occurred, it returns XML_STATUS_ERROR.
+Otherwise it returns XML_STATUS_OK value.
++enum XML_Status XMLCALL +XML_ParseBuffer(XML_Parser p, + int len, + int isFinal); ++
XML_Parse,
+except in this case Expat provides the buffer. By obtaining the
+buffer from Expat with the XML_GetBuffer function, the application can avoid double
+copying of the input.
++void * XMLCALL +XML_GetBuffer(XML_Parser p, + int len); ++
len to read a piece of the document
+into. A NULL value is returned if Expat can't allocate enough memory for
+this buffer. This has to be called prior to every call to
+XML_ParseBuffer. A
+typical use would look like this:
+
+
+for (;;) {
+ int bytes_read;
+ void *buff = XML_GetBuffer(p, BUFF_SIZE);
+ if (buff == NULL) {
+ /* handle error */
+ }
+
+ bytes_read = read(docfd, buff, BUFF_SIZE);
+ if (bytes_read < 0) {
+ /* handle error */
+ }
+
+ if (! XML_ParseBuffer(p, bytes_read, bytes_read == 0)) {
+ /* handle parse error */
+ }
+
+ if (bytes_read == 0)
+ break;
+}
+
++enum XML_Status XMLCALL +XML_StopParser(XML_Parser p, + XML_Bool resumable); ++
Stops parsing, causing XML_Parse or XML_ParseBuffer to return. Must be called from within a
+call-back handler, except when aborting (when resumable
+is XML_FALSE) an already suspended parser. Some
+call-backs may still follow because they would otherwise get
+lost, including
+
-
+
- the end element handler for empty elements when stopped in the + start element handler, +
- the end namespace declaration handler when stopped in the end + element handler, +
- the character data handler when stopped in the character data handler + while making multiple call-backs on a contiguous chunk of characters, +
This can be called from most handlers, including DTD related
+call-backs, except when parsing an external parameter entity and
+resumable is XML_TRUE. Returns
+XML_STATUS_OK when successful,
+XML_STATUS_ERROR otherwise. The possible error codes
+are:
-
+
XML_ERROR_SUSPENDED
+ - when suspending an already suspended parser. +
XML_ERROR_FINISHED
+ - when the parser has already finished. +
XML_ERROR_SUSPEND_PE
+ - when suspending while parsing an external PE. +
Since the stop/resume feature requires application support in the +outer parsing loop, it is an error to call this function for a parser +not being handled appropriately; see Temporarily Stopping Parsing for more information.
+ +When resumable is XML_TRUE then parsing
+is suspended, that is, XML_Parse and XML_ParseBuffer return XML_STATUS_SUSPENDED.
+Otherwise, parsing is aborted, that is, XML_Parse and XML_ParseBuffer return
+XML_STATUS_ERROR with error code
+XML_ERROR_ABORTED.
Note:
+This will be applied to the current parser instance only, that is, if
+there is a parent parser then it will continue parsing when the
+external entity reference handler returns. It is up to the
+implementation of that handler to call XML_StopParser on the parent parser
+(recursively), if one wants to stop parsing altogether.
When suspended, parsing can be resumed by calling XML_ResumeParser.
New in Expat 1.95.8.
++enum XML_Status XMLCALL +XML_ResumeParser(XML_Parser p); ++
Resumes parsing after it has been suspended with XML_StopParser. Must not be called from
+within a handler call-back. Returns same status codes as XML_Parse or XML_ParseBuffer. An additional error
+code, XML_ERROR_NOT_SUSPENDED, will be returned if the
+parser was not currently suspended.
Note:
+This must be called on the most deeply nested child parser instance
+first, and on its parent parser only after the child parser has
+finished, to be applied recursively until the document entity's parser
+is restarted. That is, the parent parser will not resume by itself
+and it is up to the application to call XML_ResumeParser on it at the
+appropriate moment.
New in Expat 1.95.8.
++void XMLCALL +XML_GetParsingStatus(XML_Parser p, + XML_ParsingStatus *status); ++
+enum XML_Parsing {
+ XML_INITIALIZED,
+ XML_PARSING,
+ XML_FINISHED,
+ XML_SUSPENDED
+};
+
+typedef struct {
+ enum XML_Parsing parsing;
+ XML_Bool finalBuffer;
+} XML_ParsingStatus;
+
+Returns status of parser with respect to being initialized,
+parsing, finished, or suspended, and whether the final buffer is being
+processed. The status parameter must not be
+NULL.
New in Expat 1.95.8.
+Handler Setting
+ +Although handlers are typically set prior to parsing and left alone, an
+application may choose to set or change the handler for a parsing event
+while the parse is in progress. For instance, your application may choose
+to ignore all text not descended from a para element. One
+way it could do this is to set the character handler when a para start tag
+is seen, and unset it for the corresponding end tag.
A handler may be unset by providing a NULL pointer to the +appropriate handler setter. None of the handler setting functions have +a return value.
+ +Your handlers will be receiving strings in arrays of type
+XML_Char. This type is conditionally defined in expat.h as
+either char, wchar_t or unsigned short.
+The former implies UTF-8 encoding, the latter two imply UTF-16 encoding.
+Note that you'll receive them in this form independent of the original
+encoding of the document.
+void XMLCALL +XML_SetStartElementHandler(XML_Parser p, + XML_StartElementHandler start); ++
+typedef void +(XMLCALL *XML_StartElementHandler)(void *userData, + const XML_Char *name, + const XML_Char **atts); ++
Set handler for start (and empty) tags. Attributes are passed to the start +handler as a pointer to a vector of char pointers. Each attribute seen in +a start (or empty) tag occupies 2 consecutive places in this vector: the +attribute name followed by the attribute value. These pairs are terminated +by a null pointer.
+Note that an empty tag generates a call to both start and end handlers +(in that order).
++void XMLCALL +XML_SetEndElementHandler(XML_Parser p, + XML_EndElementHandler); ++
+typedef void +(XMLCALL *XML_EndElementHandler)(void *userData, + const XML_Char *name); ++
Set handler for end (and empty) tags. As noted above, an empty tag +generates a call to both start and end handlers.
++void XMLCALL +XML_SetElementHandler(XML_Parser p, + XML_StartElementHandler start, + XML_EndElementHandler end); ++
Set handlers for start and end tags with one call.
++void XMLCALL +XML_SetCharacterDataHandler(XML_Parser p, + XML_CharacterDataHandler charhndl) ++
+typedef void +(XMLCALL *XML_CharacterDataHandler)(void *userData, + const XML_Char *s, + int len); ++
Set a text handler. The string your handler receives +is NOT nul-terminated. You have to use the length argument +to deal with the end of the string. A single block of contiguous text +free of markup may still result in a sequence of calls to this handler. +In other words, if you're searching for a pattern in the text, it may +be split across calls to this handler. Note: Setting this handler to NULL +may NOT immediately terminate call-backs if the parser is currently +processing such a single block of contiguous markup-free text, as the parser +will continue calling back until the end of the block is reached.
++void XMLCALL +XML_SetProcessingInstructionHandler(XML_Parser p, + XML_ProcessingInstructionHandler proc) ++
+typedef void +(XMLCALL *XML_ProcessingInstructionHandler)(void *userData, + const XML_Char *target, + const XML_Char *data); + ++
Set a handler for processing instructions. The target is the first word +in the processing instruction. The data is the rest of the characters in +it after skipping all whitespace after the initial word.
++void XMLCALL +XML_SetCommentHandler(XML_Parser p, + XML_CommentHandler cmnt) ++
+typedef void +(XMLCALL *XML_CommentHandler)(void *userData, + const XML_Char *data); ++
Set a handler for comments. The data is all text inside the comment +delimiters.
++void XMLCALL +XML_SetStartCdataSectionHandler(XML_Parser p, + XML_StartCdataSectionHandler start); ++
+typedef void +(XMLCALL *XML_StartCdataSectionHandler)(void *userData); ++
Set a handler that gets called at the beginning of a CDATA section.
++void XMLCALL +XML_SetEndCdataSectionHandler(XML_Parser p, + XML_EndCdataSectionHandler end); ++
+typedef void +(XMLCALL *XML_EndCdataSectionHandler)(void *userData); ++
Set a handler that gets called at the end of a CDATA section.
++void XMLCALL +XML_SetCdataSectionHandler(XML_Parser p, + XML_StartCdataSectionHandler start, + XML_EndCdataSectionHandler end) ++
Sets both CDATA section handlers with one call.
++void XMLCALL +XML_SetDefaultHandler(XML_Parser p, + XML_DefaultHandler hndl) ++
+typedef void +(XMLCALL *XML_DefaultHandler)(void *userData, + const XML_Char *s, + int len); ++ +
Sets a handler for any characters in the document which wouldn't +otherwise be handled. This includes both data for which no handlers +can be set (like some kinds of DTD declarations) and data which could +be reported but which currently has no handler set. The characters +are passed exactly as they were present in the XML document except +that they will be encoded in UTF-8 or UTF-16. Line boundaries are not +normalized. Note that a byte order mark character is not passed to the +default handler. There are no guarantees about how characters are +divided between calls to the default handler: for example, a comment +might be split between multiple calls. Setting the handler with +this call has the side effect of turning off expansion of references +to internally defined general entities. Instead these references are +passed to the default handler.
+ +See also XML_DefaultCurrent.
+void XMLCALL +XML_SetDefaultHandlerExpand(XML_Parser p, + XML_DefaultHandler hndl) ++
+typedef void +(XMLCALL *XML_DefaultHandler)(void *userData, + const XML_Char *s, + int len); ++
This sets a default handler, but doesn't inhibit the expansion of +internal entity references. The entity reference will not be passed +to the default handler.
+ +See also XML_DefaultCurrent.
+void XMLCALL +XML_SetExternalEntityRefHandler(XML_Parser p, + XML_ExternalEntityRefHandler hndl) ++
+typedef int +(XMLCALL *XML_ExternalEntityRefHandler)(XML_Parser p, + const XML_Char *context, + const XML_Char *base, + const XML_Char *systemId, + const XML_Char *publicId); ++
Set an external entity reference handler. This handler is also
+called for processing an external DTD subset if parameter entity parsing
+is in effect. (See
+XML_SetParamEntityParsing.)
The context parameter specifies the parsing context in
+the format expected by the context argument to XML_ExternalEntityParserCreate. code is
+valid only until the handler returns, so if the referenced entity is
+to be parsed later, it must be copied. context is NULL
+only when the entity is a parameter entity, which is how one can
+differentiate between general and parameter entities.
The base parameter is the base to use for relative
+system identifiers. It is set by XML_SetBase and may be NULL. The
+publicId parameter is the public id given in the entity
+declaration and may be NULL. systemId is the system
+identifier specified in the entity declaration and is never NULL.
There are a couple of ways in which this handler differs from
+others. First, this handler returns a status indicator (an
+integer). XML_STATUS_OK should be returned for successful
+handling of the external entity reference. Returning
+XML_STATUS_ERROR indicates failure, and causes the
+calling parser to return an
+XML_ERROR_EXTERNAL_ENTITY_HANDLING error.
Second, instead of having the user data as its first argument, it
+receives the parser that encountered the entity reference. This, along
+with the context parameter, may be used as arguments to a call to
+XML_ExternalEntityParserCreate. Using the returned
+parser, the body of the external entity can be recursively parsed.
Since this handler may be called recursively, it should not be saving +information into global or static variables.
++void XMLCALL +XML_SetExternalEntityRefHandlerArg(XML_Parser p, + void *arg) ++
Set the argument passed to the ExternalEntityRefHandler. If
+arg is not NULL, it is the new value passed to the
+handler set using XML_SetExternalEntityRefHandler; if arg is
+NULL, the argument passed to the handler function will be the parser
+object itself.
Note:
+The type of arg and the type of the first argument to the
+ExternalEntityRefHandler do not match. This function takes a
+void * to be passed to the handler, while the handler
+accepts an XML_Parser. This is a historical accident,
+but will not be corrected before Expat 2.0 (at the earliest) to avoid
+causing compiler warnings for code that's known to work with this
+API. It is the responsibility of the application code to know the
+actual type of the argument passed to the handler and to manage it
+properly.
+void XMLCALL +XML_SetSkippedEntityHandler(XML_Parser p, + XML_SkippedEntityHandler handler) ++
+typedef void +(XMLCALL *XML_SkippedEntityHandler)(void *userData, + const XML_Char *entityName, + int is_parameter_entity); ++
Set a skipped entity handler. This is called in two situations:
+-
+
- An entity reference is encountered for which no declaration + has been read and this is not an error. +
- An internal entity reference is read, but not expanded, because
+
XML_SetDefaultHandler+ has been called.
+
The is_parameter_entity argument will be non-zero for
+a parameter entity and zero for a general entity.
Note: skipped +parameter entities in declarations and skipped general entities in +attribute values cannot be reported, because the event would be out of +sync with the reporting of the declarations or attribute values
++void XMLCALL +XML_SetUnknownEncodingHandler(XML_Parser p, + XML_UnknownEncodingHandler enchandler, + void *encodingHandlerData) ++
+typedef int
+(XMLCALL *XML_UnknownEncodingHandler)(void *encodingHandlerData,
+ const XML_Char *name,
+ XML_Encoding *info);
+
+typedef struct {
+ int map[256];
+ void *data;
+ int (XMLCALL *convert)(void *data, const char *s);
+ void (XMLCALL *release)(void *data);
+} XML_Encoding;
+
+Set a handler to deal with encodings other than the built in set. This should be done before
+XML_Parse or XML_ParseBuffer have been called on the
+given parser.
If the handler knows how to deal with an encoding
+with the given name, it should fill in the info data
+structure and return XML_STATUS_OK. Otherwise it
+should return XML_STATUS_ERROR. The handler will be called
+at most once per parsed (external) entity. The optional application
+data pointer encodingHandlerData will be passed back to
+the handler.
The map array contains information for every possible possible leading
+byte in a byte sequence. If the corresponding value is >= 0, then it's
+a single byte sequence and the byte encodes that Unicode value. If the
+value is -1, then that byte is invalid as the initial byte in a sequence.
+If the value is -n, where n is an integer > 1, then n is the number of
+bytes in the sequence and the actual conversion is accomplished by a
+call to the function pointed at by convert. This function may return -1
+if the sequence itself is invalid. The convert pointer may be null if
+there are only single byte codes. The data parameter passed to the convert
+function is the data pointer from XML_Encoding. The
+string s is NOT nul-terminated and points at the sequence of
+bytes to be converted.
The function pointed at by release is called by the
+parser when it is finished with the encoding. It may be NULL.
+void XMLCALL +XML_SetStartNamespaceDeclHandler(XML_Parser p, + XML_StartNamespaceDeclHandler start); ++
+typedef void +(XMLCALL *XML_StartNamespaceDeclHandler)(void *userData, + const XML_Char *prefix, + const XML_Char *uri); ++
Set a handler to be called when a namespace is declared. Namespace +declarations occur inside start tags. But the namespace declaration start +handler is called before the start tag handler for each namespace declared +in that start tag.
++void XMLCALL +XML_SetEndNamespaceDeclHandler(XML_Parser p, + XML_EndNamespaceDeclHandler end); ++
+typedef void +(XMLCALL *XML_EndNamespaceDeclHandler)(void *userData, + const XML_Char *prefix); ++
Set a handler to be called when leaving the scope of a namespace +declaration. This will be called, for each namespace declaration, +after the handler for the end tag of the element in which the +namespace was declared.
++void XMLCALL +XML_SetNamespaceDeclHandler(XML_Parser p, + XML_StartNamespaceDeclHandler start, + XML_EndNamespaceDeclHandler end) ++
Sets both namespace declaration handlers with a single call.
++void XMLCALL +XML_SetXmlDeclHandler(XML_Parser p, + XML_XmlDeclHandler xmldecl); ++
+typedef void +(XMLCALL *XML_XmlDeclHandler)(void *userData, + const XML_Char *version, + const XML_Char *encoding, + int standalone); ++
Sets a handler that is called for XML declarations and also for
+text declarations discovered in external entities. The way to
+distinguish is that the version parameter will be NULL
+for text declarations. The encoding parameter may be NULL
+for an XML declaration. The standalone argument will
+contain -1, 0, or 1 indicating respectively that there was no
+standalone parameter in the declaration, that it was given as no, or
+that it was given as yes.
+void XMLCALL +XML_SetStartDoctypeDeclHandler(XML_Parser p, + XML_StartDoctypeDeclHandler start); ++
+typedef void +(XMLCALL *XML_StartDoctypeDeclHandler)(void *userData, + const XML_Char *doctypeName, + const XML_Char *sysid, + const XML_Char *pubid, + int has_internal_subset); ++
Set a handler that is called at the start of a DOCTYPE declaration,
+before any external or internal subset is parsed. Both sysid
+and pubid may be NULL. The has_internal_subset
+will be non-zero if the DOCTYPE declaration has an internal subset.
+void XMLCALL +XML_SetEndDoctypeDeclHandler(XML_Parser p, + XML_EndDoctypeDeclHandler end); ++
+typedef void +(XMLCALL *XML_EndDoctypeDeclHandler)(void *userData); ++
Set a handler that is called at the end of a DOCTYPE declaration, +after parsing any external subset.
++void XMLCALL +XML_SetDoctypeDeclHandler(XML_Parser p, + XML_StartDoctypeDeclHandler start, + XML_EndDoctypeDeclHandler end); ++
Set both doctype handlers with one call.
++void XMLCALL +XML_SetElementDeclHandler(XML_Parser p, + XML_ElementDeclHandler eldecl); ++
+typedef void +(XMLCALL *XML_ElementDeclHandler)(void *userData, + const XML_Char *name, + XML_Content *model); ++
+enum XML_Content_Type {
+ XML_CTYPE_EMPTY = 1,
+ XML_CTYPE_ANY,
+ XML_CTYPE_MIXED,
+ XML_CTYPE_NAME,
+ XML_CTYPE_CHOICE,
+ XML_CTYPE_SEQ
+};
+
+enum XML_Content_Quant {
+ XML_CQUANT_NONE,
+ XML_CQUANT_OPT,
+ XML_CQUANT_REP,
+ XML_CQUANT_PLUS
+};
+
+typedef struct XML_cp XML_Content;
+
+struct XML_cp {
+ enum XML_Content_Type type;
+ enum XML_Content_Quant quant;
+ const XML_Char * name;
+ unsigned int numchildren;
+ XML_Content * children;
+};
+
+Sets a handler for element declarations in a DTD. The handler gets
+called with the name of the element in the declaration and a pointer
+to a structure that contains the element model. It is the
+application's responsibility to free this data structure using
+XML_FreeContentModel.
The model argument is the root of a tree of
+XML_Content nodes. If type equals
+XML_CTYPE_EMPTY or XML_CTYPE_ANY, then
+quant will be XML_CQUANT_NONE, and the other
+fields will be zero or NULL. If type is
+XML_CTYPE_MIXED, then quant will be
+XML_CQUANT_NONE or XML_CQUANT_REP and
+numchildren will contain the number of elements that are
+allowed to be mixed in and children points to an array of
+XML_Content structures that will all have type
+XML_CTYPE_NAME with no quantification. Only the root node can be type
+XML_CTYPE_EMPTY, XML_CTYPE_ANY, or
+XML_CTYPE_MIXED.
For type XML_CTYPE_NAME, the name field
+points to the name and the numchildren and
+children fields will be zero and NULL. The
+quant field will indicate any quantifiers placed on the
+name.
Types XML_CTYPE_CHOICE and XML_CTYPE_SEQ
+indicate a choice or sequence respectively. The
+numchildren field indicates how many nodes in the choice
+or sequence and children points to the nodes.
+void XMLCALL +XML_SetAttlistDeclHandler(XML_Parser p, + XML_AttlistDeclHandler attdecl); ++
+typedef void +(XMLCALL *XML_AttlistDeclHandler)(void *userData, + const XML_Char *elname, + const XML_Char *attname, + const XML_Char *att_type, + const XML_Char *dflt, + int isrequired); ++
Set a handler for attlist declarations in the DTD. This handler is
+called for each attribute. So a single attlist declaration
+with multiple attributes declared will generate multiple calls to this
+handler. The elname parameter returns the name of the
+element for which the attribute is being declared. The attribute name
+is in the attname parameter. The attribute type is in the
+att_type parameter. It is the string representing the
+type in the declaration with whitespace removed.
The dflt parameter holds the default value. It will be
+NULL in the case of "#IMPLIED" or "#REQUIRED" attributes. You can
+distinguish these two cases by checking the isrequired
+parameter, which will be true in the case of "#REQUIRED" attributes.
+Attributes which are "#FIXED" will have also have a true
+isrequired, but they will have the non-NULL fixed value
+in the dflt parameter.
+void XMLCALL +XML_SetEntityDeclHandler(XML_Parser p, + XML_EntityDeclHandler handler); ++
+typedef void +(XMLCALL *XML_EntityDeclHandler)(void *userData, + const XML_Char *entityName, + int is_parameter_entity, + const XML_Char *value, + int value_length, + const XML_Char *base, + const XML_Char *systemId, + const XML_Char *publicId, + const XML_Char *notationName); ++
Sets a handler that will be called for all entity declarations.
+The is_parameter_entity argument will be non-zero in the
+case of parameter entities and zero otherwise.
For internal entities (<!ENTITY foo "bar">),
+value will be non-NULL and systemId,
+publicId, and notationName will all be NULL.
+The value string is not NULL terminated; the length is
+provided in the value_length parameter. Do not use
+value_length to test for internal entities, since it is
+legal to have zero-length values. Instead check for whether or not
+value is NULL.
The notationName
+argument will have a non-NULL value only for unparsed entity
+declarations.
+void XMLCALL +XML_SetUnparsedEntityDeclHandler(XML_Parser p, + XML_UnparsedEntityDeclHandler h) ++
+typedef void +(XMLCALL *XML_UnparsedEntityDeclHandler)(void *userData, + const XML_Char *entityName, + const XML_Char *base, + const XML_Char *systemId, + const XML_Char *publicId, + const XML_Char *notationName); ++
Set a handler that receives declarations of unparsed entities. These +are entity declarations that have a notation (NDATA) field:
+ ++<!ENTITY logo SYSTEM "images/logo.gif" NDATA gif> +
This handler is obsolete and is provided for backwards +compatibility. Use instead XML_SetEntityDeclHandler.
++void XMLCALL +XML_SetNotationDeclHandler(XML_Parser p, + XML_NotationDeclHandler h) ++
+typedef void +(XMLCALL *XML_NotationDeclHandler)(void *userData, + const XML_Char *notationName, + const XML_Char *base, + const XML_Char *systemId, + const XML_Char *publicId); ++
Set a handler that receives notation declarations.
++void XMLCALL +XML_SetNotStandaloneHandler(XML_Parser p, + XML_NotStandaloneHandler h) ++
+typedef int +(XMLCALL *XML_NotStandaloneHandler)(void *userData); ++
Set a handler that is called if the document is not "standalone".
+This happens when there is an external subset or a reference to a
+parameter entity, but does not have standalone set to "yes" in an XML
+declaration. If this handler returns XML_STATUS_ERROR,
+then the parser will throw an XML_ERROR_NOT_STANDALONE
+error.
Parse position and error reporting functions
+ +These are the functions you'll want to call when the parse
+functions return XML_STATUS_ERROR (a parse error has
+occurred), although the position reporting functions are useful outside
+of errors. The position reported is the byte position (in the original
+document or entity encoding) of the first of the sequence of
+characters that generated the current event (or the error that caused
+the parse functions to return XML_STATUS_ERROR.) The
+exceptions are callbacks trigged by declarations in the document
+prologue, in which case they exact position reported is somewhere in the
+relevant markup, but not necessarily as meaningful as for other
+events.
The position reporting functions are accurate only outside of the +DTD. In other words, they usually return bogus information when +called from within a DTD declaration handler.
+ ++enum XML_Error XMLCALL +XML_GetErrorCode(XML_Parser p); ++
+const XML_LChar * XMLCALL +XML_ErrorString(enum XML_Error code); ++
XML_GetErrorCode.
++XML_Index XMLCALL +XML_GetCurrentByteIndex(XML_Parser p); ++
XML_GetCurrentLineNumber and XML_GetCurrentColumnNumber.
++XML_Size XMLCALL +XML_GetCurrentLineNumber(XML_Parser p); ++
1.
++XML_Size XMLCALL +XML_GetCurrentColumnNumber(XML_Parser p); ++
+int XMLCALL +XML_GetCurrentByteCount(XML_Parser p); ++
0 if the event is inside a reference to an internal
+entity and for the end-tag event for empty element tags (the later can
+be used to distinguish empty-element tags from empty elements using
+separate start and end tags).
++const char * XMLCALL +XML_GetInputContext(XML_Parser p, + int *offset, + int *size); ++
Returns the parser's input buffer, sets the integer pointed at by
+offset to the offset within this buffer of the current
+parse position, and set the integer pointed at by size to
+the size of the returned buffer.
This should only be called from within a handler during an active +parse and the returned buffer should only be referred to from within +the handler that made the call. This input buffer contains the +untranslated bytes of the input.
+ +Only a limited amount of context is kept, so if the event +triggering a call spans over a very large amount of input, the actual +parse position may be before the beginning of the buffer.
+ +If XML_CONTEXT_BYTES is not defined, this will always
+return NULL.
Miscellaneous functions
+ +The functions in this section either obtain state information from +the parser or can be used to dynamicly set parser options.
+ ++void XMLCALL +XML_SetUserData(XML_Parser p, + void *userData); ++
userData when it is finished with the parser. So if you
+call this when there's already a pointer there, and you haven't freed
+the memory associated with it, then you've probably just leaked
+memory.
++void * XMLCALL +XML_GetUserData(XML_Parser p); ++
+void XMLCALL +XML_UseParserAsHandlerArg(XML_Parser p); ++
userData arguments. The user data can still be obtained
+using the XML_GetUserData function.
++enum XML_Status XMLCALL +XML_SetBase(XML_Parser p, + const XML_Char *base); ++
XML_STATUS_ERROR if
+there's no memory to store base, otherwise it's
+XML_STATUS_OK.
++const XML_Char * XMLCALL +XML_GetBase(XML_Parser p); ++
+int XMLCALL +XML_GetSpecifiedAttributeCount(XML_Parser p); ++
atts array passed to the start tag handler of the first
+attribute set due to defaults. It supplies information for the last
+call to a start handler. If called inside a start handler, then that
+means the current call.
++int XMLCALL +XML_GetIdAttributeIndex(XML_Parser p); ++
XML_StartElementHandler, or -1 if there is no ID
+attribute. If called inside a start handler, then that means the
+current call.
++const XML_AttrInfo * XMLCALL +XML_GetAttributeInfo(XML_Parser parser); ++
+typedef struct {
+ XML_Index nameStart; /* Offset to beginning of the attribute name. */
+ XML_Index nameEnd; /* Offset after the attribute name's last byte. */
+ XML_Index valueStart; /* Offset to beginning of the attribute value. */
+ XML_Index valueEnd; /* Offset after the attribute value's last byte. */
+} XML_AttrInfo;
+
+XML_AttrInfo structures for the
+attribute/value pairs passed in the last call to the
+XML_StartElementHandler that were specified
+in the start-tag rather than defaulted. Each attribute/value pair counts
+as 1; thus the number of entries in the array is
+XML_GetSpecifiedAttributeCount(parser) / 2.
++enum XML_Status XMLCALL +XML_SetEncoding(XML_Parser p, + const XML_Char *encoding); ++
XML_Parse or XML_ParseBuffer have been called on the given parser.
+Returns XML_STATUS_OK on success or
+XML_STATUS_ERROR on error.
++int XMLCALL +XML_SetParamEntityParsing(XML_Parser p, + enum XML_ParamEntityParsing code); ++
code.
+The choices for code are:
+-
+
XML_PARAM_ENTITY_PARSING_NEVER
+XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE
+XML_PARAM_ENTITY_PARSING_ALWAYS
+
XML_SetParamEntityParsing is called after
+XML_Parse or XML_ParseBuffer, then it has
+no effect and will always return 0.
++int XMLCALL +XML_SetHashSalt(XML_Parser p, + unsigned long hash_salt); ++
XML_Parse or XML_ParseBuffer.
+Note: This call is optional, as the parser will auto-generate a new +random salt value if no value has been set at the start of parsing.
++enum XML_Error XMLCALL +XML_UseForeignDTD(XML_Parser parser, XML_Bool useDTD); ++
This function allows an application to provide an external subset
+for the document type declaration for documents which do not specify
+an external subset of their own. For documents which specify an
+external subset in their DOCTYPE declaration, the application-provided
+subset will be ignored. If the document does not contain a DOCTYPE
+declaration at all and useDTD is true, the
+application-provided subset will be parsed, but the
+startDoctypeDeclHandler and
+endDoctypeDeclHandler functions, if set, will not be
+called. The setting of parameter entity parsing, controlled using
+XML_SetParamEntityParsing, will be honored.
The application-provided external subset is read by calling the
+external entity reference handler set via XML_SetExternalEntityRefHandler with both
+publicId and systemId set to NULL.
If this function is called after parsing has begun, it returns
+XML_ERROR_CANT_CHANGE_FEATURE_ONCE_PARSING and ignores
+useDTD. If called when Expat has been compiled without
+DTD support, it returns
+XML_ERROR_FEATURE_REQUIRES_XML_DTD. Otherwise, it
+returns XML_ERROR_NONE.
Note: For the purpose of checking WFC: Entity Declared, passing
+useDTD == XML_TRUE will make the parser behave as if
+the document had a DTD with an external subset. This holds true even if
+the external entity reference handler returns without action.
+void XMLCALL +XML_SetReturnNSTriplet(XML_Parser parser, + int do_nst); ++
+This function only has an effect when using a parser created with
+XML_ParserCreateNS,
+i.e. when namespace processing is in effect. The do_nst
+sets whether or not prefixes are returned with names qualified with a
+namespace prefix. If this function is called with do_nst
+non-zero, then afterwards namespace qualified names (that is qualified
+with a prefix as opposed to belonging to a default namespace) are
+returned as a triplet with the three parts separated by the namespace
+separator specified when the parser was created. The order of
+returned parts is URI, local name, and prefix.
If
+do_nst is zero, then namespaces are reported in the
+default manner, URI then local_name separated by the namespace
+separator.
+void XMLCALL +XML_DefaultCurrent(XML_Parser parser); ++
XML_SetDefaultHandler or
+XML_SetDefaultHandlerExpand. It does nothing if there is
+not a default handler.
++XML_LChar * XMLCALL +XML_ExpatVersion(); ++
"expat_1.95.1").
++struct XML_Expat_Version XMLCALL +XML_ExpatVersionInfo(); ++
+typedef struct {
+ int major;
+ int minor;
+ int micro;
+} XML_Expat_Version;
+
+-
+
XML_MAJOR_VERSION
+XML_MINOR_VERSION
+XML_MICRO_VERSION
+
+const XML_Feature * XMLCALL +XML_GetFeatureList(); ++
+enum XML_FeatureEnum {
+ XML_FEATURE_END = 0,
+ XML_FEATURE_UNICODE,
+ XML_FEATURE_UNICODE_WCHAR_T,
+ XML_FEATURE_DTD,
+ XML_FEATURE_CONTEXT_BYTES,
+ XML_FEATURE_MIN_SIZE,
+ XML_FEATURE_SIZEOF_XML_CHAR,
+ XML_FEATURE_SIZEOF_XML_LCHAR,
+ XML_FEATURE_NS,
+ XML_FEATURE_LARGE_SIZE
+};
+
+typedef struct {
+ enum XML_FeatureEnum feature;
+ XML_LChar *name;
+ long int value;
+} XML_Feature;
+
+Returns a list of "feature" records, providing details on how +Expat was configured at compile time. Most applications should not +need to worry about this, but this information is otherwise not +available from Expat. This function allows code that does need to +check these features to do so at runtime.
+ +The return value is an array of XML_Feature,
+terminated by a record with a feature of
+XML_FEATURE_END and name of NULL,
+identifying the feature-test macros Expat was compiled with. Since an
+application that requires this kind of information needs to determine
+the type of character the name points to, records for the
+XML_FEATURE_SIZEOF_XML_CHAR and
+XML_FEATURE_SIZEOF_XML_LCHAR will be located at the
+beginning of the list, followed by XML_FEATURE_UNICODE
+and XML_FEATURE_UNICODE_WCHAR_T, if they are present at
+all.
Some features have an associated value. If there isn't an
+associated value, the value field is set to 0. At this
+time, the following features have been defined to have values:
-
+
XML_FEATURE_SIZEOF_XML_CHAR
+ - The number of bytes occupied by one
XML_Char+ character.
+ XML_FEATURE_SIZEOF_XML_LCHAR
+ - The number of bytes occupied by one
XML_LChar+ character.
+ XML_FEATURE_CONTEXT_BYTES
+ - The maximum number of characters of context which can be
+ reported by
XML_GetInputContext.
+
+void XMLCALL +XML_FreeContentModel(XML_Parser parser, XML_Content *model); ++
model argument passed to the
+XML_ElementDeclHandler callback set using XML_ElementDeclHandler.
+This function should not be used for any other purpose.
+The following functions allow external code to share the memory
+allocator an XML_Parser has been configured to use. This
+is especially useful for third-party libraries that interact with a
+parser object created by application code, or heavily layered
+applications. This can be essential when using dynamically loaded
+libraries which use different C standard libraries (this can happen on
+Windows, at least).
+void * XMLCALL +XML_MemMalloc(XML_Parser parser, size_t size); ++
size bytes of memory using the allocator the
+parser object has been configured to use. Returns a
+pointer to the memory or NULL on failure. Memory allocated in this
+way must be freed using XML_MemFree.
++void * XMLCALL +XML_MemRealloc(XML_Parser parser, void *ptr, size_t size); ++
size bytes of memory using the allocator the
+parser object has been configured to use.
+ptr must point to a block of memory allocated by XML_MemMalloc or
+XML_MemRealloc, or be NULL. This function tries to
+expand the block pointed to by ptr if possible. Returns
+a pointer to the memory or NULL on failure. On success, the original
+block has either been expanded or freed. On failure, the original
+block has not been freed; the caller is responsible for freeing the
+original block. Memory allocated in this way must be freed using
+XML_MemFree.
++void XMLCALL +XML_MemFree(XML_Parser parser, void *ptr); ++
ptr. The block must
+have been allocated by XML_MemMalloc or XML_MemRealloc, or be NULL.
++
