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Felipe Gasper
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CBOR::Free - Fast CBOR for everyone


    $cbor = CBOR::Free::encode( $scalar_or_ar_or_hr );

    $thing = CBOR::Free::decode( $cbor )

    my $tagged = CBOR::Free::tag( 1, '2019-01-02T00:01:02Z' );

Also see CBOR::Free::Decoder for an object-oriented interface to the decoder.


This library implements CBOR via XS under a license that permits commercial usage with no “strings attached”.


This distribution is an experimental effort. Its interface is still subject to change. If you decide to use CBOR::Free in your project, please always check the changelog before upgrading.


$cbor = encode( $DATA, %OPTS )

Encodes a data structure or non-reference scalar to CBOR. The encoder recognizes and encodes integers, floats, byte and character strings, array and hash references, CBOR::Free::Tagged instances, Types::Serialiser booleans, and undef (encoded as null).

The encoder currently does not handle any other blessed references.

%OPTS may be:

  • canonical - A boolean that makes the function output CBOR in canonical form.

Notes on mapping Perl to CBOR:

  • The internal state of a defined Perl scalar (e.g., whether it’s an integer, float, byte string, or character string) determines its CBOR encoding.

  • Types::Serialiser booleans are encoded as CBOR booleans. Perl undef is encoded as CBOR null. (NB: No Perl value encodes as CBOR undefined.)

  • Scalar references are encoded via CBOR’s “indirection” tag.

  • Instances of CBOR::Free::Tagged are encoded as tagged values.

An error is thrown on excess recursion or an unrecognized object.

$data = decode( $CBOR )

Decodes a data structure from CBOR. Errors are thrown to indicate invalid CBOR. A warning is thrown if $CBOR is longer than is needed for $data.

Notes on mapping CBOR to Perl:

  • CBOR text strings become Perl character strings. CBOR binary strings become Perl byte strings. (This may become configurable later.)

    Note that invalid UTF-8 in a CBOR text string is considered invalid input and will thus prompt a thrown exception.

  • The only map keys that decode() accepts are integers and strings. An exception is thrown if the decoder finds anything else as a map key.

  • CBOR booleans become the corresponding Types::Serialiser values. Both CBOR null and undefined become Perl undef.

  • CBOR’s “indirection” tag is interpreted as a scalar reference.

  • This function does not interpret any other tags. If you need to decode other tags, look at CBOR::Free::Decoder. Any unhandled tags that this function sees prompt a warning but are otherwise ignored.

$obj = tag( $NUMBER, $DATA )

Tags an item for encoding so that its CBOR encoding will preserve the tag number. (Include $obj, not $DATA, in the data structure that encode() receives.)


CBOR::Free::true() and CBOR::Free::false() are defined as convenience aliases for the equivalent Types::Serialiser functions. (Note that there are no equivalent scalar aliases.)


Floating-point numbers are encoded in CBOR as IEEE 754 half-, single-, or double-precision. If your Perl is compiled to use “long double” floating-point numbers, you may see rounding errors when converting to/from CBOR. If that’s a problem for you, append an empty string to your floating-point numbers, which will cause CBOR::Free to encode them as strings.


CBOR handles up to 64-bit positive and negative integers. Most Perls nowadays can handle 64-bit integers, but if yours can’t then you’ll get an exception whenever trying to parse an integer that can’t be represented with 32 bits. This means:

  • Anything greater than 0xffff_ffff (4,294,967,295)

  • Anything less than -0x8000_0000 (2,147,483,648)

Note that even 64-bit Perls can’t parse negatives that are less than -0x8000_0000_0000_0000 (-9,223,372,036,854,775,808); these also prompt an exception since Perl can’t handle them. (It would be possible to load Math::BigInt to handle these; if that’s desirable for you, file a feature request.)


Most errors are represented via instances of subclasses of CBOR::Free::X, which subclasses X::Tiny::Base.


CBOR::Free is pretty snappy. I find that it keeps pace with or surpasses CBOR::XS, Cpanel::JSON::XS, JSON::XS, Sereal, and Data::MessagePack.

It’s also quite light. Its only “heavy” dependency is Types::Serialiser, which is only loaded when you actually need it. This keeps memory usage low for when, e.g., you’re using CBOR for IPC between Perl processes and have no need for true booleans.


Gasper Software Consulting (FELIPE)


This code is licensed under the same license as Perl itself.


CBOR::PP is a pure-Perl CBOR library.

CBOR::XS is an older CBOR module on CPAN. It’s got more bells and whistles, so check it out if CBOR::Free lacks a feature you’d like. Note that its maintainer has abandoned support for Perl versions from 5.22 onward, though, and its GPL license limits its usefulness in commercial perlcc applications.