xml::patact::toobjects(3spemr)

NAME

XML::PatAct::ToObjects - An action module for creating Perl objects

SYNOPSIS

use XML::PatAct::ToObjects;
my $patterns = [ PATTERN => [ OPTIONS ],
                 PATTERN => "PERL-CODE",
                 ... ];
my $matcher = XML::PatAct::ToObjects->new( Patterns => $patterns,
                                           Matcher => $matcher,
                                           CopyId => 1,
                                           CopyAttributes => 1 );

DESCRIPTION

XML::PatAct::ToObjects is a PerlSAX handler for applying pattern-action lists to XML parses or trees. XML::PatAct::ToObjects creates Perl
objects of the types and contents of the action items you define.

New XML::PatAct::ToObject instances are creating by calling `new()'. Parameters can be passed as a list of key, value pairs or a hash.
`new()' requires the Patterns and Matcher parameters, the rest are optional:

Patterns: The pattern-action list to apply.
Matcher: An instance of the pattern or query matching module.
CopyId: Causes the `ID' attribute, if any, in a source XML element to be
copied to an `ID' attribute in newly created objects. Note that
IDs may be lost of no pattern matches that element or an object is not created ("-make") for that element.
CopyAttributes: Causes all attributes of the element to be copied to the newly
created objects.
Each action can either be a list of options defined below or a string containing a fragment of Perl code. If the action is a string of Perl code then simple then some simple substitutions are made as described further below.
Options that can be used in an action item containing an option-list:
-holder: Ignore this element, but continue processing it's children (compare to -ignore). "-pcdata" may be used with this option.
-ignore: Ignore (discard) this element and it's children (compare to
-holder).
-pcdata: Character data in this element should be copied to the "Contents"
field.
-make PACKAGE: Create an object blessed into PACKAGE, and continue processing this element and it's children. PACKAGE may be the type `"HASH"' to simply create an anonyous hash.
-args ARGUMENTS: Use ARGUMENTS in creating the object specified by -make. This is commonly used to copy element attributes into fields in the newly
created object. For example:

-make => 'HASH', -args => 'URL => %{href}'; would copy the `"href"' attribute in an element to the `"URL"'
field of the newly created hash.
-field FIELD: Store this element, object, or children of this element in the
parent object's field named by FIELD.
-push-field FIELD: Similar to -field, except that FIELD is an array and the contents are pushed onto that array.
-value VALUE: Use VALUE as a literal value to store in FIELD, otherwise ignoring this element and it's children. Only valid with -field or -push-field. `"%{ATTRIBUTE}"' notation can be used to substitute the value of an attribute into the literal value.
-as-string: Convert the contents of this element to a string (as in
"XML::Grove::AsString") and store in FIELD. Only valid with -field or -push-field.
-grove: Copy this element to FIELD without further processing. The element can then be processed later as the Perl objects are manipulated.
Only valid with -field or -push-field. If ToObjects is used with PerlSAX, this will use XML::Grove::Builder to build the grove
element.
-grove-contents: Used with -make, -grove-contents creates an object but then takes all of the content of that element and stores it in Contents.
If an action item is a string, that string is treated as a fragment of Perl code. The following simple substitutions are performed on the fragment to provide easy access to the information being converted:
@ELEM@: The object that caused this action to be called. If ToObjects is
used with PerlSAX this will be a hash with the element name and
attributes, with XML::Grove this will be the element object, with
Data::Grove it will be the matching object, and with XML::DOM it
will be an XML::DOM::Element.

EXAMPLE

The example pattern-action list below will convert the following XML representing a Database schema:: <schema>
<table>
<name>MyTable</name>
<summary>A short summary</summary>
<description>A long description that may
contain a subset of HTML</description>

<column>

<name>MyColumn1</name>
<summary>A short summary</summary>
<description>A long description</description>
<unique/>
<non-null/>
<default>42</default>

</column>

</table>; </schema>
into Perl objects looking like:: [
{ Name => "MyTable",
Summary => "A short summary",
Description => $grove_object,
Columns => [
{ Name => "MyColumn1",
Summary => "A short summary",
Description => $grove_object,
Unique => 1,
NonNull => 1,
Default => 42

}

]

}; ]
Here is a Perl script and pattern-action list that will perform the conversion using the simple name matching pattern module XML::PatAct::MatchName. The script accepts a Schema XML file as an argument ($ARGV[0]) to the script. This script creates a grove as one of it's objects, so it requires the XML::Grove module.: use XML::Parser::PerlSAX;
use XML::PatAct::MatchName;
use XML::PatAct::ToObjects;; my $patterns = [
'schema' => [ qw{ -holder } ], 'table' => [ qw{ -make Schema::Table } ], 'name' => [ qw{ -field Name -as-string } ], 'summary' => [ qw{ -field Summary -as-string } ], 'description' => [ qw{ -field Description -grove } ], 'column' => [ qw{ -make Schema::Column -push-field Columns } ], 'unique' => [ qw{ -field Unique -value 1 } ], 'non-null' => [ qw{ -field NonNull -value 1 } ], 'default' => [ qw{ -field Default -as-string } ],; ];; my $matcher = XML::PatAct::MatchName->new( Patterns => $patterns );
my $handler = XML::PatAct::ToObjects->new( Patterns => $patterns,
Matcher => $matcher);
my $parser = XML::Parser::PerlSAX->new( Handler => $handler ); my $schema = $parser->parse(Source => { SystemId => $ARGV[0] } );

TODO

o It'd be nice if patterns could be applied even in -as-string and: -grove.
o Implement Perl code actions.
o -as-xml to write XML into the field.

AUTHOR

Ken MacLeod, ken@bitsko.slc.ut.us

docs.sk

comprehensive documentation repository

In section

See also