projekt kivitendo

  unshift @INC, "modules/YAML"; # Use our own version of YAML.

  push @INC, "modules";         # Only use our own versions of modules if there's no system version.

  unshift @INC, "modules/YAML"; # Use our own version of YAML.

  push @INC, "modules";         # Only use our own versions of modules if there's no system version.

NAME

    YAML - YAML Ain't Markup Language (tm)

SYNOPSIS

        use YAML;

        # Load a YAML stream of 3 YAML documents into Perl data structures.

        my ($hashref, $arrayref, $string) = Load(<<'...');

        ---

        name: ingy

        age: old

        weight: heavy

        # I should comment that I also like pink, but don't tell anybody.

        favorite colors:

            - red

            - green

            - blue

        ---

        - Clark Evans

        - Oren Ben-Kiki

        - Ingy döt Net

        --- >

        You probably think YAML stands for "Yet Another Markup Language". It

        ain't! YAML is really a data serialization language. But if you want

        to think of it as a markup, that's OK with me. A lot of people try

        to use XML as a serialization format.

        "YAML" is catchy and fun to say. Try it. "YAML, YAML, YAML!!!"

        ...

        # Dump the Perl data structures back into YAML.

        print Dump($string, $arrayref, $hashref); 

        # YAML::Dump is used the same way you'd use Data::Dumper::Dumper

        use Data::Dumper;

        print Dumper($string, $arrayref, $hashref); 

DESCRIPTION

    The YAML.pm module implements a YAML Loader and Dumper based on the YAML

    1.0 specification. <http://www.yaml.org/spec/>

    YAML is a generic data serialization language that is optimized for

    human readability. It can be used to express the data structures of most

    modern programming languages. (Including Perl!!!)

    For information on the YAML syntax, please refer to the YAML

    specification.

WHY YAML IS COOL

    YAML is readable for people.

        It makes clear sense out of complex data structures. You should find

        that YAML is an exceptional data dumping tool. Structure is shown

        through indentation, YAML supports recursive data, and hash keys are

        sorted by default. In addition, YAML supports several styles of

        scalar formatting for different types of data.

    YAML is editable.

        YAML was designed from the ground up to be an excellent syntax for

        configuration files. Almost all programs need configuration files,

        so why invent a new syntax for each one? And why subject users to

        the complexities of XML or native Perl code?

    YAML is multilingual.

        Yes, YAML supports Unicode. But I'm actually referring to

        programming languages. YAML was designed to meet the serialization

        needs of Perl, Python, Ruby, Tcl, PHP, Javascript and Java. It was

        also designed to be interoperable between those languages. That

        means YAML serializations produced by Perl can be processed by

        Python.

    YAML is taint safe.

        Using modules like Data::Dumper for serialization is fine as long as

        you can be sure that nobody can tamper with your data files or

        transmissions. That's because you need to use Perl's "eval()"

        built-in to deserialize the data. Somebody could add a snippet of

        Perl to erase your files.

        YAML's parser does not need to eval anything.

    YAML is full featured.

        YAML can accurately serialize all of the common Perl data structures

        and deserialize them again without losing data relationships.

        Although it is not 100% perfect (no serializer is or can be

        perfect), it fares as well as the popular current modules:

        Data::Dumper, Storable, XML::Dumper and Data::Denter.

        YAML.pm also has the ability to handle code (subroutine) references

        and typeglobs. (Still experimental) These features are not found in

        Perl's other serialization modules.

    YAML is extensible.

        The YAML language has been designed to be flexible enough to solve

        it's own problems. The markup itself has 3 basic construct which

        resemble Perl's hash, array and scalar. By default, these map to

        their Perl equivalents. But each YAML node also supports a tagging

        mechanism (type system) which can cause that node to be interpreted

        in a completely different manner. That's how YAML can support object

        serialization and oddball structures like Perl's typeglob.

YAML IMPLEMENTATIONS IN PERL

    This module, YAML.pm, is really just the interface module for YAML

    modules written in Perl. The basic interface for YAML consists of two

    functions: "Dump" and "Load". The real work is done by the modules

    YAML::Dumper and YAML::Loader.

    Different YAML module distributions can be created by subclassing

    YAML.pm and YAML::Loader and YAML::Dumper. For example, YAML-Simple

    consists of YAML::Simple YAML::Dumper::Simple and YAML::Loader::Simple.

    Why would there be more than one implementation of YAML? Well, despite

    YAML's offering of being a simple data format, YAML is actually very

    deep and complex. Implementing the entirety of the YAML specification is

    a daunting task.

    For this reason I am currently working on 3 different YAML

    implementations.

    YAML

        The main YAML distribution will keeping evolving to support the

        entire YAML specification in pure Perl. This may not be the fastest

        or most stable module though. Currently, YAML.pm has lots of known

        bugs. It is mostly a great tool for dumping Perl data structures to

        a readable form.

    YAML::Lite

        The point of YAML::Lite is to strip YAML down to the 90% that people

        use most and offer that in a small, fast, stable, pure Perl form.

        YAML::Lite will simply die when it is asked to do something it

        can't.

    YAML::Syck

        "libsyck" is the C based YAML processing library used by the Ruby

        programming language (and also Python, PHP and Pugs). YAML::Syck is

        the Perl binding to "libsyck". It should be very fast, but may have

        problems of its own. It will also require C compilation.

        NOTE: Audrey Tang has actually completed this module and it works

        great and is 10 times faster than YAML.pm.

    In the future, there will likely be even more YAML modules. Remember,

    people other than Ingy are allowed to write YAML modules!

FUNCTIONAL USAGE

    YAML is completely OO under the hood. Still it exports a few useful top

    level functions so that it is dead simple to use. These functions just

    do the OO stuff for you. If you want direct access to the OO API see the

    documentation for YAML::Dumper and YAML::Loader.

  Exported Functions

    The following functions are exported by YAML.pm by default. The reason

    they are exported is so that YAML works much like Data::Dumper. If you

    don't want functions to be imported, just use YAML with an empty import

    list:

        use YAML ();

    Dump(list-of-Perl-data-structures)

        Turn Perl data into YAML. This function works very much like

        Data::Dumper::Dumper(). It takes a list of Perl data strucures and

        dumps them into a serialized form. It returns a string containing

        the YAML stream. The structures can be references or plain scalars.

    Load(string-containing-a-YAML-stream)

        Turn YAML into Perl data. This is the opposite of Dump. Just like

        Storable's thaw() function or the eval() function in relation to

        Data::Dumper. It parses a string containing a valid YAML stream into

        a list of Perl data structures.

  Exportable Functions

    These functions are not exported by default but you can request them in

    an import list like this:

        use YAML qw'freeze thaw Bless';

    freeze() and thaw()

        Aliases to Dump() and Load() for Storable fans. This will also allow

        YAML.pm to be plugged directly into modules like POE.pm, that use

        the freeze/thaw API for internal serialization.

    DumpFile(filepath, list)

        Writes the YAML stream to a file instead of just returning a string.

    LoadFile(filepath)

        Reads the YAML stream from a file instead of a string.

    Bless(perl-node, [yaml-node | class-name])

        Associate a normal Perl node, with a yaml node. A yaml node is an

        object tied to the YAML::Node class. The second argument is either a

        yaml node that you've already created or a class (package) name that

        supports a yaml_dump() function. A yaml_dump() function should take

        a perl node and return a yaml node. If no second argument is

        provided, Bless will create a yaml node. This node is not returned,

        but can be retrieved with the Blessed() function.

        Here's an example of how to use Bless. Say you have a hash

        containing three keys, but you only want to dump two of them.

        Furthermore the keys must be dumped in a certain order. Here's how

        you do that:

            use YAML qw(Dump Bless);

            $hash = {apple => 'good', banana => 'bad', cauliflower => 'ugly'};

            print Dump $hash;

            Bless($hash)->keys(['banana', 'apple']);

            print Dump $hash;

        produces:

            ---

            apple: good

            banana: bad

            cauliflower: ugly

            ---

            banana: bad

            apple: good

        Bless returns the tied part of a yaml-node, so that you can call the

        YAML::Node methods. This is the same thing that YAML::Node::ynode()

        returns. So another way to do the above example is:

            use YAML qw(Dump Bless);

            use YAML::Node;

            $hash = {apple => 'good', banana => 'bad', cauliflower => 'ugly'};

            print Dump $hash;

            Bless($hash);

            $ynode = ynode(Blessed($hash));

            $ynode->keys(['banana', 'apple']);

            print Dump $hash;

        Note that Blessing a Perl data structure does not change it anyway.

        The extra information is stored separately and looked up by the

        Blessed node's memory address.

    Blessed(perl-node)

        Returns the yaml node that a particular perl node is associated with

        (see above). Returns undef if the node is not (YAML) Blessed.

GLOBAL OPTIONS

    YAML options are set using a group of global variables in the YAML

    namespace. This is similar to how Data::Dumper works.

    For example, to change the indentation width, do something like:

        local $YAML::Indent = 3;

    The current options are:

    DumperClass

        You can override which module/class YAML uses for Dumping data.

    LoaderClass

        You can override which module/class YAML uses for Loading data.

    Indent

        This is the number of space characters to use for each indentation

        level when doing a Dump(). The default is 2.

        By the way, YAML can use any number of characters for indentation at

        any level. So if you are editing YAML by hand feel free to do it

        anyway that looks pleasing to you; just be consistent for a given

        level.

    SortKeys

        Default is 1. (true)

        Tells YAML.pm whether or not to sort hash keys when storing a

        document.

        YAML::Node objects can have their own sort order, which is usually

        what you want. To override the YAML::Node order and sort the keys

        anyway, set SortKeys to 2.

    Stringify

        Default is 0. (false)

        Objects with string overloading should honor the overloading and

        dump the stringification of themselves, rather than the actual

        object's guts.

    UseHeader

        Default is 1. (true)

        This tells YAML.pm whether to use a separator string for a Dump

        operation. This only applies to the first document in a stream.

        Subsequent documents must have a YAML header by definition.

    UseVersion

        Default is 0. (false)

        Tells YAML.pm whether to include the YAML version on the

        separator/header.

            --- %YAML:1.0

    AnchorPrefix

        Default is ''.

        Anchor names are normally numeric. YAML.pm simply starts with '1'

        and increases by one for each new anchor. This option allows you to

        specify a string to be prepended to each anchor number.

    UseCode

        Setting the UseCode option is a shortcut to set both the DumpCode

        and LoadCode options at once. Setting UseCode to '1' tells YAML.pm

        to dump Perl code references as Perl (using B::Deparse) and to load

        them back into memory using eval(). The reason this has to be an

        option is that using eval() to parse untrusted code is, well,

        untrustworthy.

    DumpCode

        Determines if and how YAML.pm should serialize Perl code references.

        By default YAML.pm will dump code references as dummy placeholders

        (much like Data::Dumper). If DumpCode is set to '1' or 'deparse',

        code references will be dumped as actual Perl code.

        DumpCode can also be set to a subroutine reference so that you can

        write your own serializing routine. YAML.pm passes you the code ref.

        You pass back the serialization (as a string) and a format

        indicator. The format indicator is a simple string like: 'deparse'

        or 'bytecode'.

    LoadCode

        LoadCode is the opposite of DumpCode. It tells YAML if and how to

        deserialize code references. When set to '1' or 'deparse' it will

        use "eval()". Since this is potentially risky, only use this option

        if you know where your YAML has been.

        LoadCode can also be set to a subroutine reference so that you can

        write your own deserializing routine. YAML.pm passes the

        serialization (as a string) and a format indicator. You pass back

        the code reference.

    UseBlock

        YAML.pm uses heuristics to guess which scalar style is best for a

        given node. Sometimes you'll want all multiline scalars to use the

        'block' style. If so, set this option to 1.

        NOTE: YAML's block style is akin to Perl's here-document.

    UseFold

        If you want to force YAML to use the 'folded' style for all

        multiline scalars, then set $UseFold to 1.

        NOTE: YAML's folded style is akin to the way HTML folds text, except

        smarter.

    UseAliases

        YAML has an alias mechanism such that any given structure in memory

        gets serialized once. Any other references to that structure are

        serialized only as alias markers. This is how YAML can serialize

        duplicate and recursive structures.

        Sometimes, when you KNOW that your data is nonrecursive in nature,

        you may want to serialize such that every node is expressed in full.

        (ie as a copy of the original). Setting $YAML::UseAliases to 0 will

        allow you to do this. This also may result in faster processing

        because the lookup overhead is by bypassed.

        THIS OPTION CAN BE DANGEROUS. *If* your data is recursive, this

        option *will* cause Dump() to run in an endless loop, chewing up

        your computers memory. You have been warned.

    CompressSeries

        Default is 1.

        Compresses the formatting of arrays of hashes:

            -

              foo: bar

            - 

              bar: foo

        becomes:

            - foo: bar

            - bar: foo

        Since this output is usually more desirable, this option is turned

        on by default.

YAML TERMINOLOGY

    YAML is a full featured data serialization language, and thus has its

    own terminology.

    It is important to remember that although YAML is heavily influenced by

    Perl and Python, it is a language in its own right, not merely just a

    representation of Perl structures.

    YAML has three constructs that are conspicuously similar to Perl's hash,

    array, and scalar. They are called mapping, sequence, and string

    respectively. By default, they do what you would expect. But each

    instance may have an explicit or implicit tag (type) that makes it

    behave differently. In this manner, YAML can be extended to represent

    Perl's Glob or Python's tuple, or Ruby's Bigint.

    stream

        A YAML stream is the full sequence of unicode characters that a YAML

        parser would read or a YAML emitter would write. A stream may

        contain one or more YAML documents separated by YAML headers.

            ---

            a: mapping

            foo: bar

            ---

            - a

            - sequence

    document

        A YAML document is an independent data structure representation

        within a stream. It is a top level node. Each document in a YAML

        stream must begin with a YAML header line. Actually the header is

        optional on the first document.

            ---

            This: top level mapping

            is:

                - a

                - YAML

                - document

    header

        A YAML header is a line that begins a YAML document. It consists of

        three dashes, possibly followed by more info. Another purpose of the

        header line is that it serves as a place to put top level tag and

        anchor information.

            --- !recursive-sequence &001

            - * 001

            - * 001

    node

        A YAML node is the representation of a particular data stucture.

        Nodes may contain other nodes. (In Perl terms, nodes are like

        scalars. Strings, arrayrefs and hashrefs. But this refers to the

        serialized format, not the in-memory structure.)

    tag This is similar to a type. It indicates how a particular YAML node

        serialization should be transferred into or out of memory. For

        instance a Foo::Bar object would use the tag 'perl/Foo::Bar':

            - !perl/Foo::Bar

                foo: 42

                bar: stool

    collection

        A collection is the generic term for a YAML data grouping. YAML has

        two types of collections: mappings and sequences. (Similar to hashes

        and arrays)

    mapping

        A mapping is a YAML collection defined by unordered key/value pairs

        with unique keys. By default YAML mappings are loaded into Perl

        hashes.

            a mapping:

                foo: bar

                two: times two is 4

    sequence

        A sequence is a YAML collection defined by an ordered list of

        elements. By default YAML sequences are loaded into Perl arrays.

            a sequence:

                - one bourbon

                - one scotch

                - one beer

    scalar

        A scalar is a YAML node that is a single value. By default YAML

        scalars are loaded into Perl scalars.

            a scalar key: a scalar value

        YAML has many styles for representing scalars. This is important

        because varying data will have varying formatting requirements to

        retain the optimum human readability.

    plain scalar

        A plain sclar is unquoted. All plain scalars are automatic

        candidates for "implicit tagging". This means that their tag may be

        determined automatically by examination. The typical uses for this

        are plain alpha strings, integers, real numbers, dates, times and

        currency.

            - a plain string

            - -42

            - 3.1415

            - 12:34

            - 123 this is an error

    single quoted scalar

        This is similar to Perl's use of single quotes. It means no escaping

        except for single quotes which are escaped by using two adjacent

        single quotes.

            - 'When I say ''\n'' I mean "backslash en"'

    double quoted scalar

        This is similar to Perl's use of double quotes. Character escaping

        can be used.

            - "This scalar\nhas two lines, and a bell -->\a"

    folded scalar

        This is a multiline scalar which begins on the next line. It is

        indicated by a single right angle bracket. It is unescaped like the

        single quoted scalar. Line folding is also performed.

            - > 

             This is a multiline scalar which begins on

             the next line. It is indicated by a single

             carat. It is unescaped like the single

             quoted scalar. Line folding is also

             performed.

    block scalar

        This final multiline form is akin to Perl's here-document except

        that (as in all YAML data) scope is indicated by indentation.

        Therefore, no ending marker is required. The data is verbatim. No

        line folding.

            - |

                QTY  DESC          PRICE  TOTAL

                ---  ----          -----  -----

                  1  Foo Fighters  $19.95 $19.95

                  2  Bar Belles    $29.95 $59.90

    parser

        A YAML processor has four stages: parse, load, dump, emit.

        A parser parses a YAML stream. YAML.pm's Load() function contains a

        parser.

    loader

        The other half of the Load() function is a loader. This takes the

        information from the parser and loads it into a Perl data structure.

    dumper

        The Dump() function consists of a dumper and an emitter. The dumper

        walks through each Perl data structure and gives info to the

        emitter.

    emitter

        The emitter takes info from the dumper and turns it into a YAML

        stream.

        NOTE: In YAML.pm the parser/loader and the dumper/emitter code are

        currently very closely tied together. In the future they may be

        broken into separate stages.

    For more information please refer to the immensely helpful YAML

    specification available at <http://www.yaml.org/spec/>.

ysh - The YAML Shell

    The YAML distribution ships with a script called 'ysh', the YAML shell.

    ysh provides a simple, interactive way to play with YAML. If you type in

    Perl code, it displays the result in YAML. If you type in YAML it turns

    it into Perl code.

    To run ysh, (assuming you installed it along with YAML.pm) simply type:

        ysh [options]

    Please read the "ysh" documentation for the full details. There are lots

    of options.

BUGS & DEFICIENCIES

    If you find a bug in YAML, please try to recreate it in the YAML Shell

    with logging turned on ('ysh -L'). When you have successfully reproduced

    the bug, please mail the LOG file to the author (ingy@cpan.org).

    WARNING: This is still *ALPHA* code. Well, most of this code has been

    around for years...

    BIGGER WARNING: YAML.pm has been slow in the making, but I am committed

    to having top notch YAML tools in the Perl world. The YAML team is close

    to finalizing the YAML 1.1 spec. This version of YAML.pm is based off of

    a very old pre 1.0 spec. In actuality there isn't a ton of difference,

    and this YAML.pm is still fairly useful. Things will get much better in

    the future.

RESOURCES

    <http://lists.sourceforge.net/lists/listinfo/yaml-core> is the mailing

    list. This is where the language is discussed and designed.

    <http://www.yaml.org> is the official YAML website.

    <http://www.yaml.org/spec/> is the YAML 1.0 specification.

    <http://yaml.kwiki.org> is the official YAML wiki.

SEE ALSO

    See YAML::Syck. Fast!

AUTHOR

    Ingy döt Net <ingy@cpan.org>

    is resonsible for YAML.pm.

    The YAML serialization language is the result of years of collaboration

    between Oren Ben-Kiki, Clark Evans and Ingy döt Net. Several others

    have added help along the way.

COPYRIGHT

    Copyright (c) 2005, 2006. Ingy döt Net. All rights reserved. Copyright

    (c) 2001, 2002, 2005. Brian Ingerson. All rights reserved.

    This program is free software; you can redistribute it and/or modify it

    under the same terms as Perl itself.

    See <http://www.perl.com/perl/misc/Artistic.html>

package YAML;

use strict; use warnings;

use YAML::Base;

use base 'YAML::Base';

use YAML::Node;         # XXX This is a temp fix for Module::Build

use 5.006001;

our $VERSION = '0.62';

our @EXPORT = qw'Dump Load';

our @EXPORT_OK = qw'freeze thaw DumpFile LoadFile Bless Blessed';

# XXX This VALUE nonsense needs to go.

use constant VALUE => "\x07YAML\x07VALUE\x07";

# YAML Object Properties

field dumper_class => 'YAML::Dumper';

field loader_class => 'YAML::Loader';

field dumper_object =>

    -init => '$self->init_action_object("dumper")';

field loader_object =>

    -init => '$self->init_action_object("loader")';

sub Dump {

    my $yaml = YAML->new;

    $yaml->dumper_class($YAML::DumperClass)

        if $YAML::DumperClass;

    return $yaml->dumper_object->dump(@_);

}

sub Load {

    my $yaml = YAML->new;

    $yaml->loader_class($YAML::LoaderClass)

        if $YAML::LoaderClass;

    return $yaml->loader_object->load(@_);

}

{

    no warnings 'once';

    # freeze/thaw is the API for Storable string serialization. Some

    # modules make use of serializing packages on if they use freeze/thaw.

    *freeze = \ &Dump;

    *thaw   = \ &Load;

}

sub DumpFile {

    my $OUT;

    my $filename = shift;

    if (ref $filename eq 'GLOB') {

        $OUT = $filename;

    }

    else {

        my $mode = '>';

        if ($filename =~ /^\s*(>{1,2})\s*(.*)$/) {

            ($mode, $filename) = ($1, $2);

        }

        open $OUT, $mode, $filename

          or YAML::Base->die('YAML_DUMP_ERR_FILE_OUTPUT', $filename, $!);

    }  

    local $/ = "\n"; # reset special to "sane"

    print $OUT Dump(@_);

}

sub LoadFile {

    my $IN;

    my $filename = shift;

    if (ref $filename eq 'GLOB') {

        $IN = $filename;

    }

    else {

        open $IN, $filename

          or YAML::Base->die('YAML_LOAD_ERR_FILE_INPUT', $filename, $!);

    }

    return Load(do { local $/; <$IN> });

}

sub init_action_object {

    my $self = shift;

    my $object_class = (shift) . '_class';

    my $module_name = $self->$object_class;

    eval "require $module_name";

    $self->die("Error in require $module_name - $@")

        if $@ and "$@" !~ /Can't locate/;

    my $object = $self->$object_class->new;

    $object->set_global_options;

    return $object;

}

my $global = {};

sub Bless {

    require YAML::Dumper::Base;

    YAML::Dumper::Base::bless($global, @_)

}

sub Blessed {

    require YAML::Dumper::Base;

    YAML::Dumper::Base::blessed($global, @_)

}

sub global_object { $global }

1;

__END__

=head1 NAME

YAML - YAML Ain't Markup Language (tm)

=head1 SYNOPSIS

    use YAML;

    # Load a YAML stream of 3 YAML documents into Perl data structures.

    my ($hashref, $arrayref, $string) = Load(<<'...');

    ---

    name: ingy

    age: old

    weight: heavy

    # I should comment that I also like pink, but don't tell anybody.

    favorite colors:

        - red

        - green

        - blue

    ---

    - Clark Evans

    - Oren Ben-Kiki

    - Ingy döt Net

    --- >

    You probably think YAML stands for "Yet Another Markup Language". It

    ain't! YAML is really a data serialization language. But if you want

    to think of it as a markup, that's OK with me. A lot of people try

    to use XML as a serialization format.

    "YAML" is catchy and fun to say. Try it. "YAML, YAML, YAML!!!"

    ...

    # Dump the Perl data structures back into YAML.

    print Dump($string, $arrayref, $hashref); 

    # YAML::Dump is used the same way you'd use Data::Dumper::Dumper

    use Data::Dumper;

    print Dumper($string, $arrayref, $hashref); 

=head1 DESCRIPTION

The YAML.pm module implements a YAML Loader and Dumper based on the YAML

1.0 specification. L<http://www.yaml.org/spec/>

YAML is a generic data serialization language that is optimized for

human readability. It can be used to express the data structures of most

modern programming languages. (Including Perl!!!)

For information on the YAML syntax, please refer to the YAML

specification.

=head1 WHY YAML IS COOL

=over 4

=item YAML is readable for people. 

It makes clear sense out of complex data structures. You should find

that YAML is an exceptional data dumping tool. Structure is shown

through indentation, YAML supports recursive data, and hash keys are

sorted by default. In addition, YAML supports several styles of scalar

formatting for different types of data.

=item YAML is editable.

YAML was designed from the ground up to be an excellent syntax for

configuration files. Almost all programs need configuration files, so

why invent a new syntax for each one? And why subject users to the

complexities of XML or native Perl code?

=item YAML is multilingual.

Yes, YAML supports Unicode. But I'm actually referring to programming

languages. YAML was designed to meet the serialization needs of Perl,

Python, Ruby, Tcl, PHP, Javascript and Java. It was also designed to be

interoperable between those languages. That means YAML serializations

produced by Perl can be processed by Python.

=item YAML is taint safe.

Using modules like Data::Dumper for serialization is fine as long as you

can be sure that nobody can tamper with your data files or

transmissions. That's because you need to use Perl's C<eval()> built-in

to deserialize the data. Somebody could add a snippet of Perl to erase

your files.

YAML's parser does not need to eval anything.

=item YAML is full featured.

YAML can accurately serialize all of the common Perl data structures and

deserialize them again without losing data relationships. Although it is

not 100% perfect (no serializer is or can be perfect), it fares as well

as the popular current modules: Data::Dumper, Storable, XML::Dumper and

Data::Denter.

YAML.pm also has the ability to handle code (subroutine) references and

typeglobs. (Still experimental) These features are not found in Perl's

other serialization modules.

=item YAML is extensible.

The YAML language has been designed to be flexible enough to solve it's

own problems. The markup itself has 3 basic construct which resemble

Perl's hash, array and scalar. By default, these map to their Perl

equivalents. But each YAML node also supports a tagging mechanism (type

system) which can cause that node to be interpreted in a completely

different manner. That's how YAML can support object serialization and

oddball structures like Perl's typeglob.

=back

=head1 YAML IMPLEMENTATIONS IN PERL

This module, YAML.pm, is really just the interface module for YAML

modules written in Perl. The basic interface for YAML consists of two

functions: C<Dump> and C<Load>. The real work is done by the modules

YAML::Dumper and YAML::Loader.

Different YAML module distributions can be created by subclassing

YAML.pm and YAML::Loader and YAML::Dumper. For example, YAML-Simple

consists of YAML::Simple YAML::Dumper::Simple and YAML::Loader::Simple.

Why would there be more than one implementation of YAML? Well, despite

YAML's offering of being a simple data format, YAML is actually very

deep and complex. Implementing the entirety of the YAML specification is

a daunting task.

For this reason I am currently working on 3 different YAML implementations.

=over

=item YAML

The main YAML distribution will keeping evolving to support the entire

YAML specification in pure Perl. This may not be the fastest or most

stable module though. Currently, YAML.pm has lots of known bugs. It is

mostly a great tool for dumping Perl data structures to a readable form.

=item YAML::Lite

The point of YAML::Lite is to strip YAML down to the 90% that people

use most and offer that in a small, fast, stable, pure Perl form.

YAML::Lite will simply die when it is asked to do something it can't.

=item YAML::Syck

C<libsyck> is the C based YAML processing library used by the Ruby

programming language (and also Python, PHP and Pugs). YAML::Syck is the

Perl binding to C<libsyck>. It should be very fast, but may have

problems of its own. It will also require C compilation.

NOTE: Audrey Tang has actually completed this module and it works great

      and is 10 times faster than YAML.pm.

=back

In the future, there will likely be even more YAML modules. Remember,

people other than Ingy are allowed to write YAML modules!

=head1 FUNCTIONAL USAGE

YAML is completely OO under the hood. Still it exports a few useful top

level functions so that it is dead simple to use. These functions just

do the OO stuff for you. If you want direct access to the OO API see the

documentation for YAML::Dumper and YAML::Loader.

=head2 Exported Functions

The following functions are exported by YAML.pm by default. The reason

they are exported is so that YAML works much like Data::Dumper. If you

don't want functions to be imported, just use YAML with an empty

import list:

    use YAML ();

=over 4

=item Dump(list-of-Perl-data-structures)

Turn Perl data into YAML. This function works very much like

Data::Dumper::Dumper(). It takes a list of Perl data strucures and

dumps them into a serialized form. It returns a string containing the

YAML stream. The structures can be references or plain scalars.

=item Load(string-containing-a-YAML-stream) 

Turn YAML into Perl data. This is the opposite of Dump. Just like

Storable's thaw() function or the eval() function in relation to

Data::Dumper. It parses a string containing a valid YAML stream into a

list of Perl data structures.

=back

=head2 Exportable Functions

These functions are not exported by default but you can request them in

an import list like this:

    use YAML qw'freeze thaw Bless';

=over 4

=item freeze() and thaw()

Aliases to Dump() and Load() for Storable fans. This will also allow

YAML.pm to be plugged directly into modules like POE.pm, that use the

freeze/thaw API for internal serialization.

=item DumpFile(filepath, list)

Writes the YAML stream to a file instead of just returning a string.

=item LoadFile(filepath)

Reads the YAML stream from a file instead of a string.

=item Bless(perl-node, [yaml-node | class-name])

Associate a normal Perl node, with a yaml node. A yaml node is an object

tied to the YAML::Node class. The second argument is either a yaml node

that you've already created or a class (package) name that supports a

yaml_dump() function. A yaml_dump() function should take a perl node and

return a yaml node. If no second argument is provided, Bless will create

a yaml node. This node is not returned, but can be retrieved with the

Blessed() function.

Here's an example of how to use Bless. Say you have a hash containing

three keys, but you only want to dump two of them. Furthermore the keys

must be dumped in a certain order. Here's how you do that:

    use YAML qw(Dump Bless);

    $hash = {apple => 'good', banana => 'bad', cauliflower => 'ugly'};

    print Dump $hash;

    Bless($hash)->keys(['banana', 'apple']);

    print Dump $hash;

produces:

    ---

    apple: good

    banana: bad

    cauliflower: ugly

    ---

    banana: bad

    apple: good

Bless returns the tied part of a yaml-node, so that you can call the

YAML::Node methods. This is the same thing that YAML::Node::ynode()

returns. So another way to do the above example is:

    use YAML qw(Dump Bless);

    use YAML::Node;

    $hash = {apple => 'good', banana => 'bad', cauliflower => 'ugly'};

    print Dump $hash;

    Bless($hash);

    $ynode = ynode(Blessed($hash));

    $ynode->keys(['banana', 'apple']);

    print Dump $hash;

Note that Blessing a Perl data structure does not change it anyway. The

extra information is stored separately and looked up by the Blessed

node's memory address.

=item Blessed(perl-node)

Returns the yaml node that a particular perl node is associated with

(see above). Returns undef if the node is not (YAML) Blessed.

=back

=head1 GLOBAL OPTIONS

YAML options are set using a group of global variables in the YAML

namespace. This is similar to how Data::Dumper works.

For example, to change the indentation width, do something like:

    local $YAML::Indent = 3;

The current options are:

=over 4

=item DumperClass

You can override which module/class YAML uses for Dumping data.

=item LoaderClass

You can override which module/class YAML uses for Loading data.

=item Indent

This is the number of space characters to use for each indentation level

when doing a Dump(). The default is 2.

By the way, YAML can use any number of characters for indentation at any

level. So if you are editing YAML by hand feel free to do it anyway that

looks pleasing to you; just be consistent for a given level.

=item SortKeys

Default is 1. (true)

Tells YAML.pm whether or not to sort hash keys when storing a document. 

YAML::Node objects can have their own sort order, which is usually what

you want. To override the YAML::Node order and sort the keys anyway, set

SortKeys to 2.

=item Stringify

Default is 0. (false)

Objects with string overloading should honor the overloading and dump the

stringification of themselves, rather than the actual object's guts.

=item UseHeader

Default is 1. (true)

This tells YAML.pm whether to use a separator string for a Dump

operation. This only applies to the first document in a stream.

Subsequent documents must have a YAML header by definition.

=item UseVersion

Default is 0. (false)

Tells YAML.pm whether to include the YAML version on the

separator/header.

    --- %YAML:1.0

=item AnchorPrefix

Default is ''.

Anchor names are normally numeric. YAML.pm simply starts with '1' and

increases by one for each new anchor. This option allows you to specify a

string to be prepended to each anchor number.

=item UseCode

Setting the UseCode option is a shortcut to set both the DumpCode and

LoadCode options at once. Setting UseCode to '1' tells YAML.pm to dump

Perl code references as Perl (using B::Deparse) and to load them back

into memory using eval(). The reason this has to be an option is that

using eval() to parse untrusted code is, well, untrustworthy.

=item DumpCode

Determines if and how YAML.pm should serialize Perl code references. By

default YAML.pm will dump code references as dummy placeholders (much

like Data::Dumper). If DumpCode is set to '1' or 'deparse', code

references will be dumped as actual Perl code.

DumpCode can also be set to a subroutine reference so that you can

write your own serializing routine. YAML.pm passes you the code ref. You

pass back the serialization (as a string) and a format indicator. The

format indicator is a simple string like: 'deparse' or 'bytecode'.

=item LoadCode

LoadCode is the opposite of DumpCode. It tells YAML if and how to

deserialize code references. When set to '1' or 'deparse' it will use

C<eval()>. Since this is potentially risky, only use this option if you

know where your YAML has been.

LoadCode can also be set to a subroutine reference so that you can write

your own deserializing routine. YAML.pm passes the serialization (as a

string) and a format indicator. You pass back the code reference.

=item UseBlock

YAML.pm uses heuristics to guess which scalar style is best for a given

node. Sometimes you'll want all multiline scalars to use the 'block'

style. If so, set this option to 1.

NOTE: YAML's block style is akin to Perl's here-document. 

=item UseFold

If you want to force YAML to use the 'folded' style for all multiline

scalars, then set $UseFold to 1.

NOTE: YAML's folded style is akin to the way HTML folds text,

      except smarter.

=item UseAliases

YAML has an alias mechanism such that any given structure in memory gets

serialized once. Any other references to that structure are serialized

only as alias markers. This is how YAML can serialize duplicate and

recursive structures.

Sometimes, when you KNOW that your data is nonrecursive in nature, you

may want to serialize such that every node is expressed in full. (ie as

a copy of the original). Setting $YAML::UseAliases to 0 will allow you

to do this. This also may result in faster processing because the lookup

overhead is by bypassed.

THIS OPTION CAN BE DANGEROUS. *If* your data is recursive, this option

*will* cause Dump() to run in an endless loop, chewing up your computers

memory. You have been warned.

=item CompressSeries

Default is 1.

Compresses the formatting of arrays of hashes:

    -

      foo: bar

    - 

      bar: foo

becomes:

    - foo: bar

    - bar: foo

Since this output is usually more desirable, this option is turned on by

default.

=back

=head1 YAML TERMINOLOGY

YAML is a full featured data serialization language, and thus has its

own terminology.

It is important to remember that although YAML is heavily influenced by

Perl and Python, it is a language in its own right, not merely just a

representation of Perl structures.

YAML has three constructs that are conspicuously similar to Perl's hash,

array, and scalar. They are called mapping, sequence, and string

respectively. By default, they do what you would expect. But each

instance may have an explicit or implicit tag (type) that makes it

behave differently. In this manner, YAML can be extended to represent

Perl's Glob or Python's tuple, or Ruby's Bigint.

=over 4

=item stream

A YAML stream is the full sequence of unicode characters that a YAML

parser would read or a YAML emitter would write. A stream may contain

one or more YAML documents separated by YAML headers.

    ---

    a: mapping

    foo: bar

    ---

    - a

    - sequence

=item document

A YAML document is an independent data structure representation within a

stream. It is a top level node. Each document in a YAML stream must

begin with a YAML header line. Actually the header is optional on the

first document.

    ---

    This: top level mapping

    is:

        - a

        - YAML

        - document

=item header

A YAML header is a line that begins a YAML document. It consists of

three dashes, possibly followed by more info. Another purpose of the

header line is that it serves as a place to put top level tag and anchor

information.

    --- !recursive-sequence &001

    - * 001

    - * 001

=item node

A YAML node is the representation of a particular data stucture. Nodes

may contain other nodes. (In Perl terms, nodes are like scalars.

Strings, arrayrefs and hashrefs. But this refers to the serialized

format, not the in-memory structure.)

=item tag

This is similar to a type. It indicates how a particular YAML node

serialization should be transferred into or out of memory. For instance

a Foo::Bar object would use the tag 'perl/Foo::Bar':

    - !perl/Foo::Bar

        foo: 42

        bar: stool

=item collection

A collection is the generic term for a YAML data grouping. YAML has two

types of collections: mappings and sequences. (Similar to hashes and arrays)

=item mapping

A mapping is a YAML collection defined by unordered key/value pairs with

unique keys. By default YAML mappings are loaded into Perl hashes.

    a mapping:

        foo: bar

        two: times two is 4

=item sequence

A sequence is a YAML collection defined by an ordered list of elements. By

default YAML sequences are loaded into Perl arrays.

    a sequence:

        - one bourbon

        - one scotch

        - one beer

=item scalar

A scalar is a YAML node that is a single value. By default YAML scalars

are loaded into Perl scalars.

    a scalar key: a scalar value

YAML has many styles for representing scalars. This is important because

varying data will have varying formatting requirements to retain the

optimum human readability.

=item plain scalar

A plain sclar is unquoted. All plain scalars are automatic candidates

for "implicit tagging". This means that their tag may be determined

automatically by examination. The typical uses for this are plain alpha

strings, integers, real numbers, dates, times and currency.

    - a plain string

    - -42

    - 3.1415

    - 12:34

    - 123 this is an error

=item single quoted scalar

This is similar to Perl's use of single quotes. It means no escaping

except for single quotes which are escaped by using two adjacent

single quotes.

    - 'When I say ''\n'' I mean "backslash en"'

=item double quoted scalar

This is similar to Perl's use of double quotes. Character escaping can

be used.

    - "This scalar\nhas two lines, and a bell -->\a"

=item folded scalar

This is a multiline scalar which begins on the next line. It is

indicated by a single right angle bracket. It is unescaped like the

single quoted scalar. Line folding is also performed.

    - > 

     This is a multiline scalar which begins on

     the next line. It is indicated by a single

     carat. It is unescaped like the single

     quoted scalar. Line folding is also

     performed.

=item block scalar

This final multiline form is akin to Perl's here-document except that

(as in all YAML data) scope is indicated by indentation. Therefore, no

ending marker is required. The data is verbatim. No line folding.

    - |

        QTY  DESC          PRICE  TOTAL

        ---  ----          -----  -----

          1  Foo Fighters  $19.95 $19.95

          2  Bar Belles    $29.95 $59.90

=item parser

A YAML processor has four stages: parse, load, dump, emit. 

A parser parses a YAML stream. YAML.pm's Load() function contains a

parser.

=item loader

The other half of the Load() function is a loader. This takes the

information from the parser and loads it into a Perl data structure.

=item dumper

The Dump() function consists of a dumper and an emitter. The dumper

walks through each Perl data structure and gives info to the emitter.

=item emitter

The emitter takes info from the dumper and turns it into a YAML stream. 

NOTE: 

In YAML.pm the parser/loader and the dumper/emitter code are currently

very closely tied together. In the future they may be broken into

separate stages.

=back

For more information please refer to the immensely helpful YAML

specification available at L<http://www.yaml.org/spec/>.

=head1 ysh - The YAML Shell

The YAML distribution ships with a script called 'ysh', the YAML shell.

ysh provides a simple, interactive way to play with YAML. If you type in

Perl code, it displays the result in YAML. If you type in YAML it turns

it into Perl code.

To run ysh, (assuming you installed it along with YAML.pm) simply type:

    ysh [options]

Please read the C<ysh> documentation for the full details. There are

lots of options.

=head1 BUGS & DEFICIENCIES

If you find a bug in YAML, please try to recreate it in the YAML Shell

with logging turned on ('ysh -L'). When you have successfully reproduced

the bug, please mail the LOG file to the author (ingy@cpan.org).

WARNING: This is still *ALPHA* code. Well, most of this code has been

around for years...

BIGGER WARNING: YAML.pm has been slow in the making, but I am committed

to having top notch YAML tools in the Perl world. The YAML team is close

to finalizing the YAML 1.1 spec. This version of YAML.pm is based off of

a very old pre 1.0 spec. In actuality there isn't a ton of difference,

and this YAML.pm is still fairly useful. Things will get much better in

the future.

=head1 RESOURCES

L<http://lists.sourceforge.net/lists/listinfo/yaml-core> is the mailing

list. This is where the language is discussed and designed.

L<http://www.yaml.org> is the official YAML website.

L<http://www.yaml.org/spec/> is the YAML 1.0 specification.

L<http://yaml.kwiki.org> is the official YAML wiki.

=head1 SEE ALSO

See YAML::Syck. Fast!

=head1 AUTHOR

Ingy döt Net <ingy@cpan.org>

is resonsible for YAML.pm.

The YAML serialization language is the result of years of collaboration

between Oren Ben-Kiki, Clark Evans and Ingy döt Net. Several others

have added help along the way.

=head1 COPYRIGHT

Copyright (c) 2005, 2006. Ingy döt Net. All rights reserved.

Copyright (c) 2001, 2002, 2005. Brian Ingerson. All rights reserved.

This program is free software; you can redistribute it and/or modify it

under the same terms as Perl itself.

See L<http://www.perl.com/perl/misc/Artistic.html>

=cut

package YAML::Base;

use strict; use warnings;

use base 'Exporter';

our @EXPORT = qw(field XXX);

sub new {

    my $class = shift;

    $class = ref($class) || $class;

    my $self = bless {}, $class;

    while (@_) {

        my $method = shift;

        $self->$method(shift);

    }

    return $self;

}

# Use lexical subs to reduce pollution of private methods by base class.

my ($_new_error, $_info, $_scalar_info, $parse_arguments, $default_as_code);

sub XXX {

    require Data::Dumper;

    CORE::die(Data::Dumper::Dumper(@_));

}

my %code = (

    sub_start =>

      "sub {\n",

    set_default =>

      "  \$_[0]->{%s} = %s\n    unless exists \$_[0]->{%s};\n",

    init =>

      "  return \$_[0]->{%s} = do { my \$self = \$_[0]; %s }\n" .

      "    unless \$#_ > 0 or defined \$_[0]->{%s};\n",

    return_if_get =>

      "  return \$_[0]->{%s} unless \$#_ > 0;\n",

    set =>

      "  \$_[0]->{%s} = \$_[1];\n",

    sub_end => 

      "  return \$_[0]->{%s};\n}\n",

);

sub field {

    my $package = caller;

    my ($args, @values) = &$parse_arguments(

        [ qw(-package -init) ],

        @_,

    );

    my ($field, $default) = @values;

    $package = $args->{-package} if defined $args->{-package};

    return if defined &{"${package}::$field"};