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Expat(3) User Contributed Perl Documentation Expat(3)
NAME
XML::Parser::Expat - Lowlevel access to James Clark’s expat XML parser
SYNOPSIS
use XML::Parser::Expat;
$parser = new XML::Parser::Expat;
$parser->setHandlers(’Start’ => \&sh,
’End’ => \&eh,
’Char’ => \&ch);
open(FOO, ’info.xml’) or die "Couldn’t open";
$parser->parse(*FOO);
close(FOO);
# $parser->parse(’<foo id="me"> here <em>we</em> go </foo>’);
sub sh
{
my ($p, $el, %atts) = @_;
$p->setHandlers(’Char’ => \&spec)
if ($el eq ’special’);
...
}
sub eh
{
my ($p, $el) = @_;
$p->setHandlers(’Char’ => \&ch) # Special elements won’t contain
if ($el eq ’special’); # other special elements
...
}
DESCRIPTION
This module provides an interface to James Clark’s XML parser, expat. As in expat,
a single instance of the parser can only parse one document. Calls to parsestring
after the first for a given instance will die.
Expat (and XML::Parser::Expat) are event based. As the parser recognizes parts of
the document (say the start or end of an XML element), then any handlers registered
for that type of an event are called with suitable parameters.
METHODS
new This is a class method, the constructor for XML::Parser::Expat. Options are
passed as keyword value pairs. The recognized options are:
* ProtocolEncoding
The protocol encoding name. The default is none. The expat built-in encod-
ings are: "UTF-8", "ISO-8859-1", "UTF-16", and "US-ASCII". Other encodings
may be used if they have encoding maps in one of the directories in the
@Encoding_Path list. Setting the protocol encoding overrides any encoding
in the XML declaration.
* Namespaces
When this option is given with a true value, then the parser does namespace
processing. By default, namespace processing is turned off. When it is
turned on, the parser consumes xmlns attributes and strips off prefixes
from element and attributes names where those prefixes have a defined
namespace. A name’s namespace can be found using the "namespace" method and
two names can be checked for absolute equality with the "eq_name" method.
* NoExpand
Normally, the parser will try to expand references to entities defined in
the internal subset. If this option is set to a true value, and a default
handler is also set, then the default handler will be called when an entity
reference is seen in text. This has no effect if a default handler has not
been registered, and it has no effect on the expansion of entity references
inside attribute values.
* Stream_Delimiter
This option takes a string value. When this string is found alone on a line
while parsing from a stream, then the parse is ended as if it saw an end of
file. The intended use is with a stream of xml documents in a MIME multi-
part format. The string should not contain a trailing newline.
* ErrorContext
When this option is defined, errors are reported in context. The value of
ErrorContext should be the number of lines to show on either side of the
line in which the error occurred.
* ParseParamEnt
Unless standalone is set to "yes" in the XML declaration, setting this to a
true value allows the external DTD to be read, and parameter entities to be
parsed and expanded.
* Base
The base to use for relative pathnames or URLs. This can also be done by
using the base method.
setHandlers(TYPE, HANDLER [, TYPE, HANDLER [...]])
This method registers handlers for the various events. If no handlers are reg-
istered, then a call to parsestring or parsefile will only determine if the
corresponding XML document is well formed (by returning without error.) This
may be called from within a handler, after the parse has started.
Setting a handler to something that evaluates to false unsets that handler.
This method returns a list of type, handler pairs corresponding to the input.
The handlers returned are the ones that were in effect before the call to
setHandlers.
The recognized events and the parameters passed to the corresponding handlers
are:
* Start (Parser, Element [, Attr, Val [,...]])
This event is generated when an XML start tag is recognized. Parser is an
XML::Parser::Expat instance. Element is the name of the XML element that is
opened with the start tag. The Attr & Val pairs are generated for each
attribute in the start tag.
* End (Parser, Element)
This event is generated when an XML end tag is recognized. Note that an XML
empty tag (<foo/>) generates both a start and an end event.
There is always a lower level start and end handler installed that wrap the
corresponding callbacks. This is to handle the context mechanism. A conse-
quence of this is that the default handler (see below) will not see a start
tag or end tag unless the default_current method is called.
* Char (Parser, String)
This event is generated when non-markup is recognized. The non-markup
sequence of characters is in String. A single non-markup sequence of char-
acters may generate multiple calls to this handler. Whatever the encoding
of the string in the original document, this is given to the handler in
UTF-8.
* Proc (Parser, Target, Data)
This event is generated when a processing instruction is recognized.
* Comment (Parser, String)
This event is generated when a comment is recognized.
* CdataStart (Parser)
This is called at the start of a CDATA section.
* CdataEnd (Parser)
This is called at the end of a CDATA section.
* Default (Parser, String)
This is called for any characters that don’t have a registered handler.
This includes both characters that are part of markup for which no events
are generated (markup declarations) and characters that could generate
events, but for which no handler has been registered.
Whatever the encoding in the original document, the string is returned to
the handler in UTF-8.
* Unparsed (Parser, Entity, Base, Sysid, Pubid, Notation)
This is called for a declaration of an unparsed entity. Entity is the name
of the entity. Base is the base to be used for resolving a relative URI.
Sysid is the system id. Pubid is the public id. Notation is the notation
name. Base and Pubid may be undefined.
* Notation (Parser, Notation, Base, Sysid, Pubid)
This is called for a declaration of notation. Notation is the notation
name. Base is the base to be used for resolving a relative URI. Sysid is
the system id. Pubid is the public id. Base, Sysid, and Pubid may all be
undefined.
* ExternEnt (Parser, Base, Sysid, Pubid)
This is called when an external entity is referenced. Base is the base to
be used for resolving a relative URI. Sysid is the system id. Pubid is the
public id. Base, and Pubid may be undefined.
This handler should either return a string, which represents the contents
of the external entity, or return an open filehandle that can be read to
obtain the contents of the external entity, or return undef, which indi-
cates the external entity couldn’t be found and will generate a parse
error.
If an open filehandle is returned, it must be returned as either a glob
(*FOO) or as a reference to a glob (e.g. an instance of IO::Handle).
* ExternEntFin (Parser)
This is called after an external entity has been parsed. It allows applica-
tions to perform cleanup on actions performed in the above ExternEnt han-
dler.
* Entity (Parser, Name, Val, Sysid, Pubid, Ndata, IsParam)
This is called when an entity is declared. For internal entities, the Val
parameter will contain the value and the remaining three parameters will be
undefined. For external entities, the Val parameter will be undefined, the
Sysid parameter will have the system id, the Pubid parameter will have the
public id if it was provided (it will be undefined otherwise), the Ndata
parameter will contain the notation for unparsed entities. If this is a
parameter entity declaration, then the IsParam parameter is true.
Note that this handler and the Unparsed handler above overlap. If both are
set, then this handler will not be called for unparsed entities.
* Element (Parser, Name, Model)
The element handler is called when an element declaration is found. Name is
the element name, and Model is the content model as an XML::Parser::Con-
tentModel object. See "XML::Parser::ContentModel Methods" for methods
available for this class.
* Attlist (Parser, Elname, Attname, Type, Default, Fixed)
This handler is called for each attribute in an ATTLIST declaration. So an
ATTLIST declaration that has multiple attributes will generate multiple
calls to this handler. The Elname parameter is the name of the element with
which the attribute is being associated. The Attname parameter is the name
of the attribute. Type is the attribute type, given as a string. Default is
the default value, which will either be "#REQUIRED", "#IMPLIED" or a quoted
string (i.e. the returned string will begin and end with a quote charac-
ter). If Fixed is true, then this is a fixed attribute.
* Doctype (Parser, Name, Sysid, Pubid, Internal)
This handler is called for DOCTYPE declarations. Name is the document type
name. Sysid is the system id of the document type, if it was provided, oth-
erwise it’s undefined. Pubid is the public id of the document type, which
will be undefined if no public id was given. Internal will be true or
false, indicating whether or not the doctype declaration contains an inter-
nal subset.
* DoctypeFin (Parser)
This handler is called after parsing of the DOCTYPE declaration has fin-
ished, including any internal or external DTD declarations.
* XMLDecl (Parser, Version, Encoding, Standalone)
This handler is called for XML declarations. Version is a string containg
the version. Encoding is either undefined or contains an encoding string.
Standalone is either undefined, or true or false. Undefined indicates that
no standalone parameter was given in the XML declaration. True or false
indicates "yes" or "no" respectively.
namespace(name)
Return the URI of the namespace that the name belongs to. If the name doesn’t
belong to any namespace, an undef is returned. This is only valid on names
received through the Start or End handlers from a single document, or through a
call to the generate_ns_name method. In other words, don’t use names generated
from one instance of XML::Parser::Expat with other instances.
eq_name(name1, name2)
Return true if name1 and name2 are identical (i.e. same name and from the same
namespace.) This is only meaningful if both names were obtained through the
Start or End handlers from a single document, or through a call to the gener-
ate_ns_name method.
generate_ns_name(name, namespace)
Return a name, associated with a given namespace, good for using with the above
2 methods. The namespace argument should be the namespace URI, not a prefix.
new_ns_prefixes
When called from a start tag handler, returns namespace prefixes declared with
this start tag. If called elsewere (or if there were no namespace prefixes
declared), it returns an empty list. Setting of the default namespace is indi-
cated with ’#default’ as a prefix.
expand_ns_prefix(prefix)
Return the uri to which the given prefix is currently bound. Returns undef if
the prefix isn’t currently bound. Use ’#default’ to find the current binding of
the default namespace (if any).
current_ns_prefixes
Return a list of currently bound namespace prefixes. The order of the the pre-
fixes in the list has no meaning. If the default namespace is currently bound,
’#default’ appears in the list.
recognized_string
Returns the string from the document that was recognized in order to call the
current handler. For instance, when called from a start handler, it will give
us the the start-tag string. The string is encoded in UTF-8. This method
doesn’t return a meaningful string inside declaration handlers.
original_string
Returns the verbatim string from the document that was recognized in order to
call the current handler. The string is in the original document encoding. This
method doesn’t return a meaningful string inside declaration handlers.
default_current
When called from a handler, causes the sequence of characters that generated
the corresponding event to be sent to the default handler (if one is regis-
tered). Use of this method is deprecated in favor the recognized_string method,
which you can use without installing a default handler. This method doesn’t
deliver a meaningful string to the default handler when called from inside dec-
laration handlers.
xpcroak(message)
Concatenate onto the given message the current line number within the XML docu-
ment plus the message implied by ErrorContext. Then croak with the formed mes-
sage.
xpcarp(message)
Concatenate onto the given message the current line number within the XML docu-
ment plus the message implied by ErrorContext. Then carp with the formed mes-
sage.
current_line
Returns the line number of the current position of the parse.
current_column
Returns the column number of the current position of the parse.
current_byte
Returns the current position of the parse.
base([NEWBASE]);
Returns the current value of the base for resolving relative URIs. If NEWBASE
is supplied, changes the base to that value.
context
Returns a list of element names that represent open elements, with the last one
being the innermost. Inside start and end tag handlers, this will be the tag of
the parent element.
current_element
Returns the name of the innermost currently opened element. Inside start or end
handlers, returns the parent of the element associated with those tags.
in_element(NAME)
Returns true if NAME is equal to the name of the innermost currently opened
element. If namespace processing is being used and you want to check against a
name that may be in a namespace, then use the generate_ns_name method to create
the NAME argument.
within_element(NAME)
Returns the number of times the given name appears in the context list. If
namespace processing is being used and you want to check against a name that
may be in a namespace, then use the generate_ns_name method to create the NAME
argument.
depth
Returns the size of the context list.
element_index
Returns an integer that is the depth-first visit order of the current element.
This will be zero outside of the root element. For example, this will return 1
when called from the start handler for the root element start tag.
skip_until(INDEX)
INDEX is an integer that represents an element index. When this method is
called, all handlers are suspended until the start tag for an element that has
an index number equal to INDEX is seen. If a start handler has been set, then
this is the first tag that the start handler will see after skip_until has been
called.
position_in_context(LINES)
Returns a string that shows the current parse position. LINES should be an
integer >= 0 that represents the number of lines on either side of the current
parse line to place into the returned string.
xml_escape(TEXT [, CHAR [, CHAR ...]])
Returns TEXT with markup characters turned into character entities. Any addi-
tional characters provided as arguments are also turned into character refer-
ences where found in TEXT.
parse (SOURCE)
The SOURCE parameter should either be a string containing the whole XML docu-
ment, or it should be an open IO::Handle. Only a single document may be parsed
for a given instance of XML::Parser::Expat, so this will croak if it’s been
called previously for this instance.
parsestring(XML_DOC_STRING)
Parses the given string as an XML document. Only a single document may be
parsed for a given instance of XML::Parser::Expat, so this will die if either
parsestring or parsefile has been called for this instance previously.
This method is deprecated in favor of the parse method.
parsefile(FILENAME)
Parses the XML document in the given file. Will die if parsestring or parsefile
has been called previously for this instance.
is_defaulted(ATTNAME)
NO LONGER WORKS. To find out if an attribute is defaulted please use the speci-
fied_attr method.
specified_attr
When the start handler receives lists of attributes and values, the non-
defaulted (i.e. explicitly specified) attributes occur in the list first. This
method returns the number of specified items in the list. So if this number is
equal to the length of the list, there were no defaulted values. Otherwise the
number points to the index of the first defaulted attribute name.
finish
Unsets all handlers (including internal ones that set context), but expat con-
tinues parsing to the end of the document or until it finds an error. It
should finish up a lot faster than with the handlers set.
release
There are data structures used by XML::Parser::Expat that have circular refer-
ences. This means that these structures will never be garbage collected unless
these references are explicitly broken. Calling this method breaks those refer-
ences (and makes the instance unusable.)
Normally, higher level calls handle this for you, but if you are using
XML::Parser::Expat directly, then it’s your responsibility to call it.
XML::Parser::ContentModel Methods
The element declaration handlers are passed objects of this class as the content
model of the element declaration. They also represent content particles, components
of a content model.
When referred to as a string, these objects are automagicly converted to a string
representation of the model (or content particle).
isempty
This method returns true if the object is "EMPTY", false otherwise.
isany
This method returns true if the object is "ANY", false otherwise.
ismixed
This method returns true if the object is "(#PCDATA)" or "(#PCDATA│...)*",
false otherwise.
isname
This method returns if the object is an element name.
ischoice
This method returns true if the object is a choice of content particles.
isseq
This method returns true if the object is a sequence of content particles.
quant
This method returns undef or a string representing the quantifier (’?’, ’*’,
’+’) associated with the model or particle.
children
This method returns undef or (for mixed, choice, and sequence types) an array
of component content particles. There will always be at least one component for
choices and sequences, but for a mixed content model of pure PCDATA,
"(#PCDATA)", then an undef is returned.
XML::Parser::ExpatNB Methods
The class XML::Parser::ExpatNB is a subclass of XML::Parser::Expat used for non-
blocking access to the expat library. It does not support the parse, parsestring,
or parsefile methods, but it does have these additional methods:
parse_more(DATA)
Feed expat more text to munch on.
parse_done
Tell expat that it’s gotten the whole document.
FUNCTIONS
XML::Parser::Expat::load_encoding(ENCODING)
Load an external encoding. ENCODING is either the name of an encoding or the
name of a file. The basename is converted to lowercase and a ’.enc’ extension
is appended unless there’s one already there. Then, unless it’s an absolute
pathname (i.e. begins with ’/’), the first file by that name discovered in the
@Encoding_Path path list is used.
The encoding in the file is loaded and kept in the %Encoding_Table table. Ear-
lier encodings of the same name are replaced.
This function is automaticly called by expat when it encounters an encoding it
doesn’t know about. Expat shouldn’t call this twice for the same encoding name.
The only reason users should use this function is to explicitly load an encod-
ing not contained in the @Encoding_Path list.
AUTHORS
Larry Wall <larry AT wall.org> wrote version 1.0.
Clark Cooper <coopercc AT netheaven.com> picked up support, changed the API for this
version (2.x), provided documentation, and added some standard package features.
perl v5.8.6 2003-08-18 Expat(3)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache/1.3.41 (Unix) PHP/5.2.5 mod_perl/1.30 mod_gzip/1.3.26.1a
Under GNU General Public License
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