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Clark Cooper c135be083d These are the first check-ins for the libexpat task: create configuration 
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
"http://www.w3.org/TR/REC-html40/loose.dtd">
<html>
<head>
<!-- Copyright 1999,2000 Clark Cooper <coopercc@netheaven.com>
All rights reserved.
This is free software. You may distribute or modify according to
the terms of the MIT/X License -->
<title>Expat XML Parser</title>
<meta name="author" content="Clark Cooper, coopercc@netheaven.com">
<meta http-equiv="Content-Style-Type" content="text/css">
<link href="style.css" rel="stylesheet" type="text/css">
</head>
<body>
<h1>Expat XML Parser</h1>
<p>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, and other open-source XML parsers.</p>
<p>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 W3 that produced
the XML specification.</p>
<p>This is free software, licensed under the
<a href="../COPYING">MIT/X Consortium license</a>. You may download it from
<a href="http://expat.sourceforge.net">the expat homepage on Source Forge</a>.
</p>
<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 me to retain
copyright and to distribute it with expat.
<hr>
<h2>Table of Contents</h2>
<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="#examples">Some examples</a></li>
<li><a href="#reference">Reference</a>
<ul>
<li><a href="#creation">Parser Creation Functions</a>
<ul>
<li><a href="#XML_ParserCreate">XML_ParserCreate</a></li>
<li><a href="#XML_ParserCreateNS">XML_ParserCreateNS</a></li>
<li><a href="#XML_ExternalEntityParserCreate">XML_ExternalEntityParserCreate</a><li>
<li><a href="#XML_ParserFree">XML_ParserFree</a></li>
</ul>
</li>
<li><a href="#parsing">Parsing Functions</a>
<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>
</ul>
</li>
<li><a href="#setting">Handler Setting Functions</a>
<ul>
<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_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_SetUnknownEncodingHandler">XML_SetUnknownEncodingHandler</a></li>
<li><a href="#XML_SetNamespaceDeclHandler">XML_SetNamespaceDeclHandler</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>
</ul>
</li>
<li><a href="#position">Parse Position and Error Reporting Functions</a>
<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>
</ul>
</li>
<li><a href="#miscellaneous">Miscellaneous Functions</a>
<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_SetEncoding">XML_SetEncoding</a></li>
<li><a href="#XML_SetParamEntityParsing">XML_SetParamEntityParsing</a></li>
</ul>
</li>
</ul>
</li>
</ul>
<hr>
<h2><a name="overview">Overview</a></h2>
<p>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.</p>
<p>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:</p>
<dl>
<dt><code>XML_ParserCreate</code></dt>
<dd>Create a new parser object.</dd>
<dt><code>XML_SetElementHandler</code></dt>
<dd>Set handlers for start and end tags.</dd>
<dt><code>XML_SetCharacterDataHandler</code></dt>
<dd>Set handler for text.</dd>
<dt><code>XML_Parse</code></dt>
<dd>Pass a buffer full of document to the parser</dd>
</dl>
<p>These functions and others are described in the
<a href="#reference">reference</a> part of this document. The reference
section also describes in detail the parameters passed to the different
types of handlers.
<p>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
<a href="../examples/outline.c">outline.c</a>
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.
<div class="eg">
<pre>
int Depth;
void
start(void *data, const char *el, const char **attr) {
int i;
for (i = 0; i &lt; 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 */
</pre>
</div>
<p>The end tag simply does the bookkeeping work of decrementing the Depth.
<div class="eg">
<pre>
void
end(void *data, const char *el) {
Depth--;
} /* End of end handler */
</pre>
</div>
<p>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.
<hr>
<h2><a name="building">Building and Installing expat</a></h2>
<p>The expat distribution comes as a compressed (with GNU gzip) tar file.
After unpacking this, cd into the directory and run the configure shell
script.
</p>
<p>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:</p>
<pre>
./configure
make
make install
</pre>
<p>There are some options that you can provide to this script, but the
only one we'll mention here is the <code>--prefix</code> option. You can
find out all the options available by running configure with just the
<code>--help</code> option.
</p>
By default, the configure script sets things up so that the library gets
installed in <code>/usr/local/lib</code> and the associated header file in
<code>/usr/local/include</code>.
But if you were to give the option, <code>--prefix=/home/me/mystuff</code>,
then the library and header would get installed in
<code>/home/me/mystuff/lib</code> and <code>/home/me/mystuff/include</code>
respectively.
</p>
<hr>
<h2><a name="using">Using Expat</a></h2>
<h3>Compiling and Linking against expat</h3>
<p>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 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
be the <code>-lexpat</code> 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 libary at run time.
</p>
<p>On a Unix based system, here's what a Makefile might look like when expat
is installed in a standard location:</p>
<div class="eg">
<pre>
CC=cc
LDFLAGS=
LIBS= -lexpat
xmlapp: xmlapp.o
$(CC) $(LDFLAGS) -o xmlapp xmlapp.o $(LIBS)
</pre>
</div>
<p>If you installed expat in, say, <code>/home/me/mystuff</code>, then
the Makefile would look like this:</p>
<div class="eg">
<pre>
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 $(LIBS)
</pre>
</div>
<p>You'd also have to set the environment variable <code>LD_LIBRARY_PATH</code>
to <code>/home/me/mystuff/lib</code> (or to
<code>${LD_LIBRARY_PATH}:/home/me/mystuff/lib</code> if LD_LIBRARY_PATH
already has some directories in it) in order to run your application.
</p>
<h3>Expat Basics</h3>
<p>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
<a href="#creation">three functions</a> in the expat API for creating a
parser object.
However, only two of these
(<a href="#XML_ParserCreate"><code>XML_ParserCreate</code></a> and
<a href="#XML_ParserCreateNS"><code>XML_ParserCreateNS</code></a>)
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
<a href="#XML_ParserFree"><code>XML_ParserFree</code></a>. Note that if
you have provided any <a href="userdata">user data</a> that gets stored
in the parser, then your application is responsible for freeing it prior to
calling XML_ParserFree.
</p>
<p>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.
<p>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.
<p>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.
<p>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.
<div class="eg">
<pre>
void
init_info(Parseinfo *info) {
info->skip = 0;
info->depth = 1;
/* Other initializations here */
} /* End of init_info */
void
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
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 */
</pre>
</div>
<p>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 <em>after</em> the main body of start tag code, then in
the end handler, we need to manipulate it <em>before</em> 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.
<h3>Communicating between handlers</h3>
<p>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 typically the first argument received
by most handlers.
<h3>Namespace Processing</h3>
<p>When the parser is created using the <code>XML_ParserCreateNS</code>,
function, expat performs namespace processing. Under namespace processing,
expat consumes <code>xmlns</code> and <code>xmlns:...</code> 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
<a href="#XML_SetNamespaceDeclHandler">
<code>XML_SetNamespaceDeclHandler</code></a>.
<p>Element type and attribute names that belong to a given namespace are
passed to the appropriate handler in expanded form. This expanded form
is a concatenation of the namespace URI, the separator character (which
is the 2nd argument to <code>XML_ParserCreateNS</code>), and the local
name (i.e. the part after the colon). Names with undeclared prefixes are
passed through to the handlers unchanged, with the prefix and colon still
attached. Unprefixed attribute names are never expanded, and unprefixed
element names are only expanded when they are in the scope of a default
namespace.
<p>You can set handlers for the start of a namespace declaration and for
the end of a scope of a declaration with the
<code>XML_SetNamespaceDeclHandler</code> function.
The StartNamespaceDeclHandler is called prior to the start tag handler
and the EndNamespaceDeclHandler is called before 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.
<p>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.
<p>The <a href="src/namespace.c">namespace.c</a> example demonstrates the
use of these features. Like outline.c, it produces an outline, but
in addition it annotates when a namespace scope starts and when it ends.
This example also demonstrates use of application user data.
<h3>Character Encodings</h3>
<p>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:
<pre>
&lt;?xml version="1.0" encoding="ISO-8859-2"?&gt;
</pre>
<p>External parsed entities may begin with a text declaration, which
looks like an XML declaration with just an encoding declaration:
<pre>
&lt;?xml encoding="Big5"?&gt;
</pre>
<p>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.)
<p><a name="builtin_encodings"></a>There are four built-in encodings in expat:
<ul>
<li>UTF-8
<li>UTF-16
<li>ISO-8859-1
<li>US-ASCII
</ul>
<p>Anything else discovered in an encoding declaration or in the
protocol encoding specified in the parser constructor, triggers a call
to the <code>UnknownEncodingHandler</code>. This handler gets passed
the encoding name and a pointer to an <code>XML_Encoding</code> data
structure. Your handler must fill in this structure and return 1 if
it knows how to deal with the encoding. Otherwise the handler should
return 0.
The handler also gets passed a pointer to an
optional application data structure that you may indicate when you set
the handler.
<p>Expat places restrictions on character encodings that it can support
by filling in the <code>XML_Encoding</code> structure.
include file:
<ol>
<li>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 $@\^'{}~)</li>
<li>Characters must be encoded in 4 bytes or less.</li>
<li>All characters encoded must have Unicode scalar values less than or
equal to 65535 (0xFFFF)<em>This does not apply to the built-in support
for UTF-16 and UTF-8</em></li>
<li>No character may be encoded by more that one distinct sequence of
bytes</li>
</ol>
<p><code>XML_Encoding</code> 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 <code>XML_Encoding</code> structure. This function should return
the Unicode scalar value for the sequence or -1 if the sequence is malformed.
<p>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. Your application is
responsible for any translation of these strings into other encodings.
<h3>Handling External Entity References</h3>
<p>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 <code>ExternalEntityRefHandler</code>, then external
entity references are silently ignored. Otherwise, it calls your handler with
the information needed to read and parse the external entity.
<p>Your handler
isn't actually responsible for parsing the entity, but it is responsible
for creating a subsidiary parser with
<code>XML_ExternalEntityParserCreate</code> that will do the job. This returns
an instance of <code>XML_Parser</code> that has handlers and other data
structures initialized from the parent parser. You may then use
<code>XML_Parse</code> or <code>XML_ParseBuffer</code> calls against this
parser.
Since external entities my refer to other external entities, your handler
should be prepared to be called recursively.
<h3>Parsing DTDs</h3>
<p>In order to parse parameter entities, before starting the parse, you must
call <code>XML_SetParamEntityParsing</code> with one of the following
arguments:
<dl>
<dt><code>XML_PARAM_ENTITY_PARSING_NEVER</code></dt>
<dd>Don't parse parameter entities or the external subset</dd>
<dt><code>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE</code></dt>
<dd>Parse parameter entites and the external subset unless
<code>standalone</code> was set to "yes" in the XML declaration.</dd>
<dt><code>XML_PARAM_ENTITY_PARSING_ALWAYS</code></dt>
<dd>Always parse parameter entities and the external subset</dd>
</dl>
<p>In order to read an external DTD, you also have to set an
external entity reference handler as described above.
<hr>
<h2><a name="examples">Some expat Examples</a></h2>
<hr>
<!-- ================================================================ -->
<h2><a name="reference">Expat Reference</a></h2>
<h3><a name="creation">Parser Creation</a></h3>
<div class="fcndec"><a name="XML_ParserCreate"><pre>
XML_Parser
XML_ParserCreate(const XML_Char *encoding)
</pre></a></div>
<div class="fcndef">
Construct a new parser. If encoding is non-null, it specifies a
character encoding to use for the document. This overrides the document
encoding declaration. There are four built-in encodings:
<ul>
<li>US-ASCII
<li>UTF-8
<li>UTF-16
<li>ISO-8859-1
</ul>
Any other value will invoke a call to the UnknownEncodingHandler.
</div>
<div class="fcndec"><a name="XML_ParserCreateNS"><pre>
XML_Parser
XML_ParserCreateNS(const XML_Char *encoding,
XML_Char sep)
</pre></a></div>
<div class="fcndef">
Constructs a new parser that has namespace processing in effect. Namespace
expanded element names and attribute names are returned as a concatenation
of the namespace URI, <em>sep</em>, and the local part of the name. This
means that you should pick a character for <em>sep</em> that can't be
part of a legal URI.</div>
<div class="fcndec"><a name="XML_ExternalEntityParserCreate"><pre>
XML_Parser
XML_ExternalEntityParserCreate(XML_Parser p,
const XML_Char *context,
const XML_Char *encoding)
</pre></a></div>
<div class="fcndef">
Construct a new 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.)
</div>
<div class="fcndec"><a name="XML_ParserFree"><pre>
void
XML_ParserFree(XML_Parser p)
</pre></a></div>
<div class="fcndef">
Free memory used by the parser. Your application is responsible for
freeing any memory associated with <a href="#userdata">UserData</a>.
</div>
<h3><a name="parsing">Parsing</a></h3>
<div class="fcndec"><a name="XML_Parse"><pre>
int
XML_Parse(XML_Parser p,
const char *s,
int len,
int isFinal)
</pre></a></div>
<div class="fcndef">
Parse some more of the document. The string <code>s</code> 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 <code>len</code>. This means
that <code>s</code> doesn't have to be null terminated. It also means that
if <code>len</code> is larger than the number of bytes in the block of
memory that <code>s</code> points at, then a memory fault is likely. The
<code>isFinal</code> parameter informs the parser that this is the last
piece of the document. Frequently, the last piece is empty (i.e.
<code>len</code> is zero.)
If a parse error occurred, it returns 0. Otherwise it returns a non-zero
value.
</div>
<div class="fcndec"><a name="XML_ParseBuffer"><pre>
int
XML_ParseBuffer(XML_Parser p,
int len,
int isFinal)
</pre></a></div>
<div class="fcndef">
This is just like XML_Parse, except in this case expat provides the buffer.
By obtaining the buffer from expat with the <code>XML_GetBuffer</code>
function, the application can avoid double copying of the input.
</div>
<div class="fcndec"><a name="XML_GetBuffer"><pre>
void *
XML_GetBuffer(XML_Parser p,
int len)
</pre></a></div>
<div class="fcndef">
Obtain a buffer of size <code>len</code> 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
<code>XML_ParseBuffer</code>. A typical use would look like this:
<div id="eg">
<pre>
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;
}
</pre>
</div>
</div>
<h3><a name="setting">Handler Setting</a></h3>
<p>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 <code>para</code> 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.
<p>A handler may be <em>unset</em> by providing a NULL pointer to the
appropriate handler setter. None of the handler setting functions have
a return value.
<p>Your handlers will be receiving strings in arrays of type
<code>XML_Char</code>. This type is defined in expat.h as <code>char *</code>
and contains bytes encoding UTF-8.
Note that you'll receive them in this form independent of the original
encoding of the document.
<div class="handler">
<div class="setter"><a name="XML_SetElementHandler"><pre>
XML_SetElementHandler(XML_Parser p,
XML_StartElementHandler start,
XML_EndElementHandler end);
</pre></a></div>
<div class="signature">
<pre>
typedef void
(*XML_StartElementHandler)(void *userData,
const XML_Char *name,
const XML_Char **atts);
</pre>
</div>
<div class="signature">
<pre>
typedef void
(*XML_EndElementHandler)(void *userData,
const XML_Char *name);
</pre>
</div>
<p>Set handlers for start and end 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.
</div>
<div class="handler">
<div class="setter"><a name="XML_SetCharacterDataHandler"><pre>
XML_SetCharacterDataHandler(XML_Parser p,
XML_CharacterDataHandler charhndl)
</pre></a></div>
<div class="signature">
<pre>
typedef void
(*XML_CharacterDataHandler)(void *userData,
const XML_Char *s,
int len);
</pre>
</div>
<p>Set a text handler. The string your handler receives
is <em>NOT zero terminated</em>. 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.
</div>
<div class="handler">
<div class="setter">
<a name="XML_SetProcessingInstructionHandler">
<pre>
XML_SetProcessingInstructionHandler(XML_Parser p,
XML_ProcessingInstructionHandler proc)
</pre>
</a>
</div>
<div class="signature">
<pre>
typedef void
(*XML_ProcessingInstructionHandler)(void *userData,
const XML_Char *target,
const XML_Char *data);
</pre>
</div>
<p>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.
</div>
<div class="handler">
<div class="setter">
<a name="XML_SetCommentHandler">
<pre>
XML_SetCommentHandler(XML_Parser p,
XML_CommentHandler cmnt)
</pre>
</a>
</div>
<div class="signature">
<pre>
typedef void
(*XML_CommentHandler)(void *userData,
const XML_Char *data);
</pre>
</div>
<p>Set a handler for comments. The data is all text inside the comment
delimiters.
</div>
<div class="handler">
<div class="setter">
<a name="XML_SetCdataSectionHandler">
<pre>
XML_SetCdataSectionHandler(XML_Parser p,
XML_StartCdataSectionHandler start,
XML_EndCdataSectionHandler end)
</pre>
</a>
</div>
<div class="signature">
<pre>
typedef void
(*XML_StartCdataSectionHandler)(void *userData);
</pre>
</div>
<div class="signature">
<pre>
typedef void
(*XML_EndCdataSectionHandler)(void *userData);
</pre>
</div>
<p>Sets handlers that get called at the beginning and end of a
CDATA section.
</div>
<div class="handler">
<div class="setter">
<a name="XML_SetDefaultHandler">
<pre>
XML_SetDefaultHandler(XML_Parser p,
XML_DefaultHandler hndl)
</pre>
</a>
</div>
<div class="signature">
<pre>
typedef void
(*XML_DefaultHandler)(void *userData,
const XML_Char *s,
int len);
</pre>
</div>
<p>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. Note that a contiguous piece of
data that is destined to be reported to the default handler may actually
be reported over several calls to the handler. 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.
</div>
<div class="handler">
<div class="setter">
<a name="XML_SetDefaultHandlerExpand">
<pre>
XML_SetDefaultHandlerExpand(XML_Parser p,
XML_DefaultHandler hndl)
</pre>
</a>
</div>
<div class="signature">
<pre>
typedef void
(*XML_DefaultHandler)(void *userData,
const XML_Char *s,
int len);
</pre>
</div>
<p>This sets a default handler, but doesn't affect expansion of internal
entity references.
</div>
<div class="handler">
<div class="setter">
<a name="XML_SetExternalEntityRefHandler">
<pre>
XML_SetExternalEntityRefHandler(XML_Parser p,
XML_ExternalEntityRefHandler hndl)
</pre>
</a>
</div>
<div class="signature">
<pre>
typedef int
(*XML_ExternalEntityRefHandler)(XML_Parser parser,
const XML_Char *context,
const XML_Char *base,
const XML_Char *systemId,
const XML_Char *publicId);
</pre>
</div>
<p>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 <a href="#XML_SetParamEntityParsing">
<code>XML_SetParamEntityParsing</code></a>.)
<p>The base parameter is the base to use for relative system identifiers.
It is set by <a href="#XML_SetBase">XML_SetBase</a> and may be null. The
public id parameter is the public id given in the entity declaration and
may be null. The system id is the system identifier specified in the entity
declaration and is never null.
<p>There are a couple of ways in which this handler differs from others.
First, this handler returns an integer. A non-zero value should be returned
for successful handling of the external entity reference. Returning a zero
indicates failure, and causes the calling parser to return
an XML_ERROR_EXTERNAL_ENTITY_HANDLING error.
<p>Second, instead of having userData 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
<a href="#XML_ExternalEntityParserCreate">XML_ExternalEntityParserCreate</a>. Using the
returned parser, the body of the external entity can be recursively
parsed.
<p>Since this handler may be called recursively, it should not be saving
information into global or static variables.
</div>
<div class="handler">
<div class="setter">
<a name="XML_SetUnknownEncodingHandler">
<pre>
XML_SetUnknownEncodingHandler(XML_Parser p,
XML_UnknownEncodingHandler enchandler,
void *encodingHandlerData)
</pre>
</a>
</div>
<div class="signature">
<pre>
typedef int
(*XML_UnknownEncodingHandler)(void *encodingHandlerData,
const XML_Char *name,
XML_Encoding *info);
</pre>
</div>
<p>Set a handler to deal with encodings other than the
<a href="#builtin_encodings">built in set</a>. If the handler knows how
to deal with an encoding with the given name, it should fill in the info
data structure and return 1. Otherwise it should return 0.
<pre>
typedef struct {
int map[256];
void *data;
int (*convert)(void *data, const char *s);
void (*release)(void *data);
} XML_Encoding;
</pre>
<p>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 <em>NOT</em>
null terminated and points at the sequence of bytes to be converted.
<p>The function pointed at by release is called by the parser when it is
finished with the encoding. It may be null.
</div>
<div class="handler">
<div class="setter">
<a name="XML_SetNamespaceDeclHandler">
<pre>
XML_SetNamespaceDeclHandler(XML_Parser p,
XML_StartNamespaceDeclHandler start,
XML_EndNamespaceDeclHandler end)
</pre>
</a>
</div>
<div class="signature">
<pre>
typedef void
(*XML_StartNamespaceDeclHandler)(void *userData,
const XML_Char *prefix,
const XML_Char *uri);
</pre>
</div>
<div class="signature">
<pre>
typedef void
(*XML_EndNamespaceDeclHandler)(void *userData,
const XML_Char *prefix);
</pre>
</div>
<p>Set handlers for namespace declarations. 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. The
corresponding namespace end handler is called after the end tag for the
element the namespace is associated with.
</div>
<div class="handler">
<div class="setter">
<a name="XML_SetUnparsedEntityDeclHandler">
<pre>
XML_SetUnparsedEntityDeclHandler(XML_Parser p,
XML_UnparsedEntityDeclHandler h)
</pre>
</a>
</div>
<div class="signature">
<pre>
typedef void
(*XML_UnparsedEntityDeclHandler)(void *userData,
const XML_Char *entityName,
const XML_Char *base,
const XML_Char *systemId,
const XML_Char *publicId,
const XML_Char *notationName);
</pre>
</div>
<p>Set a handler that receives declarations of unparsed entities. These
are entity declarations that have a notation (NDATA) field:
<div id="eg">
<pre>
&lt;!ENTITY logo SYSTEM "images/logo.gif" NDATA gif&gt;
</pre>
</div>
<p>So for this example, the entityName would be "logo", the systemId
would be "images/logo.gif" and notationName would be "gif". For this
example the publicId parameter is null. The base parameter would be
whatever has been set with <code><a href="#XML_SetBase">XML_SetBase</a></code>.
If not set, it would be null.
</div>
<div class="handler">
<div class="setter">
<a name="XML_SetNotationDeclHandler">
<pre>
XML_SetNotationDeclHandler(XML_Parser p,
XML_NotationDeclHandler h)
</pre>
</a>
</div>
<div class="signature">
<pre>
typedef void
(*XML_NotationDeclHandler)(void *userData,
const XML_Char *notationName,
const XML_Char *base,
const XML_Char *systemId,
const XML_Char *publicId);
</pre>
</div>
<p>Set a handler that receives notation declarations.
</div>
<div class="handler">
<div class="setter">
<a name="XML_SetNotStandaloneHandler">
<pre>
XML_SetNotStandaloneHandler(XML_Parser p,
XML_NotStandaloneHandler h)
</pre>
</a>
</div>
<div class="signature">
<pre>
typedef int
(*XML_NotStandaloneHandler)(void *userData);
</pre>
</div>
<p>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 0, then the parser will throw an
XML_ERROR_NOT_STANDALONE error.
</div>
<h3><a name="position">Parse position and error reporting functions</a></h3>
<p>These are the functions you'll want to call when the parse functions
return 0, 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 0.)
<div class="fcndec"><a name="XML_GetErrorCode"><pre>
enum XML_Error
XML_GetErrorCode(XML_Parser p)
</pre></a></div>
<div class="fcndef">
Return what type of error has occurred.
</div>
<div class="fcndec"><a name="XML_ErrorString"><pre>
const XML_LChar *
XML_ErrorString(int code)
</pre></a></div>
<div class="fcndef">
Return a string describing the error corresponding to code.
The code should be one of the enums that can be returned from
XML_GetErrorCode.
</div>
<div class="fcndec"><a name="XML_GetCurrentByteIndex"><pre>
long
XML_GetCurrentByteIndex(XML_Parser p)
</pre></a></div>
<div class="fcndef">
Return the byte offset of the position.
</div>
<div class="fcndec"><a name="XML_GetCurrentLineNumber"><pre>
int
XML_GetCurrentLineNumber(XML_Parser p)
</pre></a></div>
<div class="fcndef">
Return the line number of the position.
</div>
<div class="fcndec"><a name="XML_GetCurrentColumnNumber"><pre>
int
XML_GetCurrentColumnNumber(XML_Parser p)
</pre></a></div>
<div class="fcndef">
Return the offset, from the beginning of the current line, of
the position.
</div>
<h3><a name="miscellaneous">Miscellaneous functions</a></h3>
<p>The functions in this section either obtain state information from the
parser or can be used to dynamicly set parser options.
<div class="fcndec"><a name="XML_SetUserData"><pre>
void
XML_SetUserData(XML_Parser p,
void *userData)
</pre></a></div>
<div class="fcndef">
This sets the user data pointer that gets passed to handlers.
It overwrites any previous value for this pointer. Note that the
application is responsible for freeing the memory associated with
<code>userData</code> 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.
</div>
<div class="fcndec"><a name="XML_GetUserData"><pre>
void *
XML_GetUserData(XML_Parser p)
</pre></a></div>
<div class="fcndef">
This returns the user data pointer that gets passed to handlers.
It is actually implemented as a macro.
</div>
<div class="fcndec"><a name="XML_UseParserAsHandlerArg"><pre>
void
XML_UseParserAsHandlerArg(XML_Parser p)
</pre></a></div>
<div class="fcndef">
After this is called, handlers receive the parser in the
userData argument. The userData information can still be obtained using
the XML_GetUserData function.
</div>
<div class="fcndec"><a name="XML_SetBase"><pre>
int
XML_SetBase(XML_Parser p,
const XML_Char *base)
</pre></a></div>
<div class="fcndef">
Set the base to be used for resolving relative URIs in system identifiers.
The return value is 0 if there's no memory to store base, otherwise it's
non-zero.
</div>
<div class="fcndec"><a name="XML_GetBase"><pre>
const XML_Char *
XML_GetBase(XML_Parser p)
</pre></a></div>
<div class="fcndef">
Return the base for resolving relative URIs.
</div>
<div class="fcndec"><a name="XML_GetSpecifiedAttributeCount"><pre>
int
XML_GetSpecifiedAttributeCount(XML_Parser p)
</pre></a></div>
<div class="fcndef">
When attributes are reported to the start handler in the atts vector,
attributes that were explicitly set in the element occur before any
attributes that receive their value from default information in an
ATTLIST declaration. This function returns the number of attributes that
were explicitly set, thus giving the offset of the first attribute set
due to defaults. It supplies information for the last call to a start
handler. If you're in a start handler, then that means the current call.
</div>
<div class="fcndec"><a name="XML_SetEncoding"><pre>
int
XML_SetEncoding(XML_Parser p,
const XML_Char *encoding)
</pre></a></div>
<div class="fcndef">
Set the encoding to be used by the parser. It is equivalent to
passing a non-null encoding argument to the parser creation functions.
It must not be called after XML_Parser or XML_ParseBuffer have been
called on the given parser.
</div>
<div class="fcndec"><a name="XML_SetParamEntityParsing"><pre>
int
XML_SetParamEntityParsing(XML_Parser p,
enum XML_ParamEntityParsing code)
</pre></a></div>
<div class="fcndef">
This enables parsing of parameter entities, including the external
parameter entity that is the external DTD subset, according to
<code>code</code>.
The choices for <code>code</code> are:
<ul>
<li>XML_PARAM_ENTITY_PARSING_NEVER
<li>XML_PARAM_ENTITY_PARSING_UNLESS_STANDALONE
<li>XML_PARAM_ENTITY_PARSING_ALWAYS
</ul>
</div>
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