PDB(3) User Contributed Perl Documentation PDB(3)NAMEPalm::PDB - Parse Palm database files.
SYNOPSIS
use Palm::PDB;
use SomeHelperClass;
$pdb = new Palm::PDB;
$pdb->Load("myfile.pdb");
# Manipulate records in $pdb
$pdb->Write("myotherfile.pdb");
(Note: yes, you do want to use "Palm::PDB", even if you're dealing with
some other type of database. $pdb will be reblessed to the appropriate
type by "$pdb->Load".)
DESCRIPTION
The Palm::PDB module provides a framework for reading and writing
database files for use on PalmOS devices such as the PalmPilot. It can
read and write both Palm Database (".pdb") and Palm Resource (".prc")
files.
By itself, the PDB module is not terribly useful; it is intended to be
used in conjunction with supplemental modules for specific types of
databases, such as Palm::Raw or Palm::Memo.
The Palm::PDB module encapsulates the common work of parsing the
structure of a Palm database. The Load() function reads the file, then
passes the individual chunks (header, records, etc.) to application-
specific functions for processing. Similarly, the Write() function
calls application-specific functions to get the individual chunks, then
writes them to a file.
METHODS
new
$new = new Palm::PDB();
Creates a new PDB. $new is a reference to an anonymous hash. Some of
its elements have special significance. See Load().
RegisterPDBHandlers
&Palm::PDB::RegisterPDBHandlers("classname", typespec...);
Typically:
&Palm::PDB::RegisterPDBHandlers(__PACKAGE__,
[ "FooB", "DATA" ],
);
The $pdb->Load() method acts as a virtual constructor. When it reads
the header of a ".pdb" file, it looks up the file's creator and type in
a set of tables, and reblesses $pdb into a class capable of parsing the
application-specific parts of the file (AppInfo block, records, etc.)
RegisterPDBHandlers() adds entries to these tables; it says that any
file whose creator and/or type match any of the typespecs (there may be
several) should be reblessed into the class classname.
Note that RegisterPDBHandlers() applies only to record databases
(".pdb" files). For resource databases, see RegisterPRCHandlers().
RegisterPDBHandlers() is typically called in the import() function of a
helper class. In this case, the class is registering itself, and it is
simplest just to use "__PACKAGE__" for the package name:
package PalmFoo;
use Palm::PDB;
sub import
{
&Palm::PDB::RegisterPDBHandlers(__PACKAGE__,
[ "FooZ", "DATA" ]
);
}
A typespec can be either a string, or an anonymous array with two
elements. If it is an anonymous array, then the first element is the
file's creator; the second element is its type. If a typespec is a
string, it is equivalent to specifying that string as the database's
creator, and a wildcard as its type.
The creator and type should be either four-character strings, or the
empty string. An empty string represents a wildcard. Thus:
&Palm::PDB::RegisterPDBHandlers("MyClass",
[ "fOOf", "DATA" ],
[ "BarB", "" ],
[ "", "BazQ" ],
"Fred"
);
Class MyClass will handle:
Databases whose creator is "fOOf" and whose type is "DATA".
Databases whose creator is "BarB", of any type.
Databases with any creator whose type is "BazQ".
Databases whose creator is "Fred", of any type.
RegisterPRCHandlers
&Palm::PDB::RegisterPRCHandlers("classname", typespec...);
Typically:
&Palm::PDB::RegisterPRCHandlers(__PACKAGE__,
[ "FooZ", "CODE" ],
);
RegisterPRCHandlers() is similar to RegisterPDBHandlers(), but
specifies a class to handle resource database (".prc") files.
A class for parsing applications should begin with:
package PalmApps;
use Palm::PDB;
sub import
{
&Palm::PDB::RegisterPRCHandlers(__PACKAGE__,
[ "", "appl" ]
);
}
Load
$pdb->Load($filename);
Reads the file $filename, parses it, reblesses $pdb to the appropriate
class, and invokes appropriate methods to parse the application-
specific parts of the database (see "HELPER CLASSES").
$filename may also be an open file handle (as long as it's seekable).
This allows for manipulating databases in memory structures.
Load() uses the typespecs given to RegisterPDBHandlers() and
RegisterPRCHandlers() when deciding how to rebless $pdb. For record
databases, it uses the typespecs passed to RegisterPDBHandlers(), and
for resource databases, it uses the typespecs passed to
RegisterPRCHandlers().
Load() looks for matching typespecs in the following order, from most
to least specific:
1. A typespec that specifies both the database's creator and its type
exactly.
2. A typespec that specifies the database's type and has a wildcard
for the creator (this is rarely used).
3. A typespec that specifies the database's creator and has a wildcard
for the type.
4. A typespec that has wildcards for both the creator and type.
Thus, if the database has creator "FooZ" and type "DATA", Load() will
first look for "FooZ"/"DATA", then ""/"DATA", then "FooZ"/"", and
finally will fall back on ""/"" (the universal default).
After Load() returns, $pdb may contain the following fields:
$pdb->{"name"}
The name of the database.
$pdb->{"attributes"}{"ResDB"}
$pdb->{"attributes"}{"ReadOnly"}
$pdb->{"attributes"}{"AppInfoDirty"}
$pdb->{"attributes"}{"Backup"}
$pdb->{"attributes"}{"OKToInstallNewer"}
$pdb->{"attributes"}{"ResetAfterInstall"}
$pdb->{"attributes"}{"CopyPrevention"}
$pdb->{"attributes"}{"Stream"}
$pdb->{"attributes"}{"Hidden"}
$pdb->{"attributes"}{"LaunchableData"}
$pdb->{"attributes"}{"Recyclable"}
$pdb->{"attributes"}{"Bundle"}
$pdb->{"attributes"}{"Open"}
These are the attribute flags from the database header. Each is
true iff the corresponding flag is set.
The "LaunchableData" attribute is set on PQAs.
$pdb->{"version"}
The database's version number. An integer.
$pdb->{"ctime"}
$pdb->{"mtime"}
$pdb->{"baktime"}
The database's creation time, last modification time, and time of
last backup, in Unix "time_t" format (seconds since Jan. 1, 1970).
$pdb->{"modnum"}
The database's modification number. An integer.
$pdb->{"type"}
The database's type. A four-character string.
$pdb->{"creator"}
The database's creator. A four-character string.
$pdb->{"uniqueIDseed"}
The database's unique ID seed. An integer.
$pdb->{"2NULs"}
The two NUL bytes that appear after the record index and the
AppInfo block. Included here because every once in a long while,
they are not NULs, for some reason.
$pdb->{"appinfo"}
The AppInfo block, as returned by the $pdb->ParseAppInfoBlock()
helper method.
$pdb->{"sort"}
The sort block, as returned by the $pdb->ParseSortBlock() helper
method.
@{$pdb->{"records"}}
The list of records in the database, as returned by the
$pdb->ParseRecord() helper method. Resource databases do not have
this.
@{$pdb->{"resources"}}
The list of resources in the database, as returned by the
$pdb->ParseResource() helper method. Record databases do not have
this.
All of these fields may be set by hand, but should conform to the
format given above.
Write
$pdb->Write($filename);
Invokes methods in helper classes to get the application-specific parts
of the database, then writes the database to the file $filename.
$filename may also be an open file handle (as long as it's seekable).
This allows for manipulating databases in memory structures.
Write() uses the following helper methods:
PackAppInfoBlock()PackSortBlock()PackResource() or PackRecord()
See also "HELPER CLASSES".
new_Record
$record = Palm::PDB->new_Record();
$record = new_Record Palm::PDB;
Creates a new record, with the bare minimum needed:
$record->{'category'}
$record->{'attributes'}{'Dirty'}
$record->{'id'}
The ``Dirty'' attribute is originally set, since this function will
usually be called to create records to be added to a database.
"new_Record" does not add the new record to a PDB. For that, you want
"append_Record".
is_Dirty
$pdb->Write( $fname ) if $pdb->is_Dirty();
Returns non-zero if any of the in-memory elements of the database have
been changed. This includes changes via function calls (any call that
changes the $pdb's "last modification" time) as well as testing the
"dirty" status of attributes where possible (i.e. AppInfo, records, but
not resource entries).
append_Record
$record = $pdb->append_Record;
$record2 = $pdb->append_Record($record1);
If called without any arguments, creates a new record with
new_Record(), and appends it to $pdb.
If given a reference to a record, appends that record to
@{$pdb->{records}}.
Returns a reference to the newly-appended record.
This method updates $pdb's "last modification" time.
new_Resource
$resource = Palm::PDB->new_Resource();
$resource = new_Resource Palm::PDB;
Creates a new resource and initializes
$resource->{type}
$resource->{id}
append_Resource
$resource = $pdb->append_Resource;
$resource2 = $pdb->append_Resource($resource1);
If called without any arguments, creates a new resource with
new_Resource(), and appends it to $pdb.
If given a reference to a resource, appends that resource to
@{$pdb->{resources}}.
Returns a reference to the newly-appended resource.
This method updates $pdb's "last modification" time.
findRecordByID
$record = $pdb->findRecordByID($id);
Looks through the list of records in $pdb, and returns a reference to
the record with ID $id, or the undefined value if no such record was
found.
delete_Record
$pdb->delete_Record($record, $expunge);
Marks $record for deletion, so that it will be deleted from the
database at the next sync.
If $expunge is false or omitted, the record will be marked for deletion
with archival. If $expunge is true, the record will be marked for
deletion without archival.
This method updates $pdb's "last modification" time.
remove_Record
for (@{$pdb->{'records'}})
{
$pdb->remove_Record( $_ ) if $_->{attributes}{deleted};
}
Removes $record from the database. This differs from "delete_Record" in
that it's an actual deletion rather than just setting a flag.
This method updates $pdb's "last modification" time.
HELPER CLASSES
$pdb->Load() reblesses $pdb into a new class. This helper class is
expected to convert raw data from the database into parsed
representations of it, and vice-versa.
A helper class must have all of the methods listed below. The Palm::Raw
class is useful if you don't want to define all of the required
methods.
ParseAppInfoBlock
$appinfo = $pdb->ParseAppInfoBlock($buf);
$buf is a string of raw data. ParseAppInfoBlock() should parse this
data and return it, typically in the form of a reference to an object
or to an anonymous hash.
This method will not be called if the database does not have an AppInfo
block.
The return value from ParseAppInfoBlock() will be accessible as
$pdb->{appinfo}.
PackAppInfoBlock
$buf = $pdb->PackAppInfoBlock();
This is the converse of ParseAppInfoBlock(). It takes $pdb's AppInfo
block, $pdb->{appinfo}, and returns a string of binary data that can be
written to the database file.
ParseSortBlock
$sort = $pdb->ParseSortBlock($buf);
$buf is a string of raw data. ParseSortBlock() should parse this data
and return it, typically in the form of a reference to an object or to
an anonymous hash.
This method will not be called if the database does not have a sort
block.
The return value from ParseSortBlock() will be accessible as
$pdb->{sort}.
PackSortBlock
$buf = $pdb->PackSortBlock();
This is the converse of ParseSortBlock(). It takes $pdb's sort block,
$pdb->{sort}, and returns a string of raw data that can be written to
the database file.
ParseRecord
$record = $pdb->ParseRecord(
offset => $offset, # Record's offset in file
attributes => # Record attributes
{
expunged => bool, # True iff expunged
dirty => bool, # True iff dirty
deleted => bool, # True iff deleted
private => bool, # True iff private
archive => bool, # True iff to be archived
},
category => $category, # Record's category number
id => $id, # Record's unique ID
data => $buf, # Raw record data
);
ParseRecord() takes the arguments listed above and returns a parsed
representation of the record, typically as a reference to a record
object or anonymous hash.
The output from ParseRecord() will be appended to @{$pdb->{records}}.
The records appear in this list in the same order as they appear in the
file.
$offset argument is not normally useful, but is included for
completeness.
The fields in %$attributes are boolean values. They are true iff the
record has the corresponding flag set.
$category is an integer in the range 0-15, which indicates which
category the record belongs to. This is normally an index into a table
given at the beginning of the AppInfo block.
A typical ParseRecord() method has this general form:
sub ParseRecord
{
my $self = shift
my %record = @_;
# Parse $self->{data} and put the fields into new fields in
# $self.
delete $record{data}; # No longer useful
return \%record;
}
PackRecord
$buf = $pdb->PackRecord($record);
The converse of ParseRecord(). PackRecord() takes a record as returned
by ParseRecord() and returns a string of raw data that can be written
to the database file.
PackRecord() is never called when writing a resource database.
ParseResource
$record = $pdb->ParseResource(
type => $type, # Resource type
id => $id, # Resource ID
offset => $offset, # Resource's offset in file
data => $buf, # Raw resource data
);
ParseResource() takes the arguments listed above and returns a parsed
representation of the resource, typically as a reference to a resource
object or anonymous hash.
The output from ParseResource() will be appended to
@{$pdb->{resources}}. The resources appear in this list in the same
order as they appear in the file.
$type is a four-character string giving the resource's type.
$id is an integer that uniquely identifies the resource amongst others
of its type.
$offset is not normally useful, but is included for completeness.
PackResource
$buf = $pdb->PackResource($resource);
The converse of ParseResource(). PackResource() takes a resource as
returned by PackResource() and returns a string of raw data that can be
written to the database file.
PackResource() is never called when writing a record database.
BUGS
These functions die too easily. They should return an error code.
Database manipulation is still an arcane art.
It may be possible to parse sort blocks further.
SOURCE CONTROL
The source is in Github:
http://github.com/briandfoy/p5-Palm/tree/master
AUTHOR
Alessandro Zummo, "<a.zummo@towertech.it>"
Currently maintained by brian d foy, "<bdfoy@cpan.org>"
SEE ALSOPalm::Raw(3)Palm::Address(3)Palm::Datebook(3)Palm::Mail(3)Palm::Memo(3)Palm::ToDo(3)
Palm Database Files, in the ColdSync distribution.
The Virtual Constructor (aka Factory Method) pattern is described in
Design Patterns, by Erich Gamma et al., Addison-Wesley.
perl v5.14.0 2010-02-23 PDB(3)
