Hi,
I quite often have to deal with complex data structures, which structure I
have little info on. Typically this could be data created by XML::Simple,
from various XML files.
So I have written a little module, Data::Traverse, that lets me either
extract data from a data structure (all scalars, or all references of a
certain type), or create iterators on the data structure.
Does this make sense? Is there something already available on CPAN that
would do just this (I looked in the Data namespace and did not see
anything)? Would it be worth releasing on CPAN?
An alpha version of the module is at
http://xmltwig.com/module/data-traverse/
SYNOPSIS
Data::Traverse supports 2 modes: a simple procedural interface and an
object-oriented interface.
The procedural interface
The procedural interface can be used to retrieve parts of a complex
data structure.
It is used through use Data::Traverse qw(:lists)
use Data::Traverse qw(:lists);
my $data= ...; # a complex data structure
my @values= scalars( $data); # all scalars in the structure
my @values= refs( $data, 'LWP::Simple'); # all LWP::Simple objects
The OO interface
The OO interface is used to write iterators that go through a data
structure.
my $iter= Data::Traverse-new( $data);
$iter-traverse( sub { my( $iter, $item)= @_;
print $item\n if( $iter-item_key eq 'id');
return $iter-prune
if( $iter-path_matches( '/foo/bar'));
}
);
$iter-traverse( sub { $_[1]++ if( $_[0]-is_scalar); }); # changes the data
More methods are available to get information on the current context
DESCRIPTION
Data::Traverse lets you traverse complex data structures without
needing to know all about them.
It can be used for example with the data structure created by
XML::Simple
Procedural Interface
refs ($data, $ref, $optional_level)
return the list of references of the $ref type (as per
UNIVERSAL::isa( $field, $ref)) in the data structure, in the
order of traversal (hashes are traversed through the dictionary
order of their keys).
The $optional_level argument can be used to limit the depth in the
data structure, 0 being $data itself.
scalars ($data, $optional_level)
return the list of scalar values in the data structure, in the
order of traversal (hashes are traversed through the dictionary
order of their keys).
The $optional_level argument can be used to limit the depth in the
data structure, 0 being $data itself..
refs_level ($data, $ref, $level)
return the list of references to $ref at $level in the data
structure.
scalars_level ($data, $level)
return the list of scalar values at $level in the data structure.
Object-Oriented Interface
The Object-Oriented interface provides iterators on arbitrary data
structures. A handler is associated with the iterator and is called
for every item in the data structure. Within the handler a host of
methods can be called to get information about the current context.
new ($data)
create an iterator on $data
traverse ($handler)
traverse the data structure and apply the handler to all item of
the data structure. An item is anything in the data structure,
scalar, arrayref or hashref.
the handler is called with the iterator and the current item as
arguments. Use $_[1] if you want to update the original data
structure.
the handler also receives the item as $_
in the handler you can use the following functions:
path
the current path to an item in the data structure is built
from the hash keys to get to the item, joined with '/'.
path_matches ($exp)
$exp is a regular expression. The path is matched against that
regexp.
parent
the parent of the current item (a hashref or arrayref that
includes the item)
ancestors
the list (root first) of ancestors of the current item
item_index
if the item is an element of an array then this is the item
index in the array
item_key
if the item is a value in a hash then this is the item key in
the hash
parent_item_key
if the parent of the item is a value in a hash then this is
the associated key
data_level
the level of depth at which the item is found in the data
structure (the size of the ancestors stack)
path_level
the number of steps in the item path
is_scalar
return true if the item is a scalar (this is just !ref but
