XML::Parser::Expat(top10.html) - phpMan

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 = XML::Parser::Expat->new;
        $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:
           o   ProtocolEncoding
               The protocol encoding name. The default is none. The expat
               built-in encodings 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.
           o   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.
           o   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.
           o   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 multipart format. The string
               should not contain a trailing newline.
           o   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.
           o   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.
           o   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 registered, 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:
           o   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.
           o   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 consequence 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.
           o   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 characters 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.
           o   Proc              (Parser, Target, Data)
               This event is generated when a processing instruction is
               recognized.
           o   Comment           (Parser, String)
               This event is generated when a comment is recognized.
           o   CdataStart        (Parser)
               This is called at the start of a CDATA section.
           o   CdataEnd          (Parser)
               This is called at the end of a CDATA section.
           o   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.
           o   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.
           o   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.
           o   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 indicates 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).
           o   ExternEntFin      (Parser)
               This is called after an external entity has been parsed. It
               allows applications to perform cleanup on actions performed in
               the above ExternEnt handler.
           o   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.
           o   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::ContentModel object. See
               "XML::Parser::ContentModel Methods" for methods available for
               this class.
           o   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 character). If Fixed is
               true, then this is a fixed attribute.
           o   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, otherwise 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
               internal subset.
           o   DoctypeFin        (Parser)
               This handler is called after parsing of the DOCTYPE declaration
               has finished, including any internal or external DTD
               declarations.
           o   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 generate_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 indicated 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 prefixes 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 registered). 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 declaration
           handlers.
       xpcroak(message)
           Concatenate onto the given message the current line number within
           the XML document plus the message implied by ErrorContext. Then
           croak with the formed message.
       xpcarp(message)
           Concatenate onto the given message the current line number within
           the XML document plus the message implied by ErrorContext. Then
           carp with the formed message.
       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 additional characters provided as arguments are also turned
           into character references where found in TEXT.
       parse (SOURCE)
           The SOURCE parameter should either be a string containing the whole
           XML document, 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 specified_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 continues 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 references. This means that these structures will never be
           garbage collected unless these references are explicitly broken.
           Calling this method breaks those references (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. Earlier encodings of the same name are replaced.
           This function is automatically 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 encoding 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 v5.16.3                      2011-06-03                          Expat(3)