<QtCborCommon>

The <QtCborCommon> header contains definitions common to both the streaming classes (QCborStreamReader and QCborStreamWriter) and to QCborValue. More...

Classes

class QCborError

Types

enum QCborKnownTags { DateTimeString, UnixTime_t, PositiveBignum, NegativeBignum, ..., Signature }
enum QCborSimpleType { False, True, Null, Undefined }
enum QCborTag { }

Classes

class QCborError

The QCborError class holds the error condition found while parsing or validating a CBOR stream.

Note: All functions in this class are reentrant.

This class was introduced in Qt 5.12.

See also QCborStreamReader, QCborValue, and QCborParserError.

Type Documentation

enum QCborKnownTags

This enum contains a list of CBOR tags, known at the time of the Qt implementation. This list is not meant to be complete and contains only tags that are either backed by an RFC or specifically used by the Qt implementation.

The authoritative list is maintained by IANA in the CBOR tag registry.

ConstantValueDescription
DateTimeString0A date and time string, formatted according to RFC 3339, as refined by RFC 4287. It is the same format as Qt::ISODate and Qt::ISODateWithMs.
UnixTime_t1A numerical representation of seconds elapsed since 1970-01-01T00:00Z.
PositiveBignum2A positive number of arbitrary length, encoded as a byte array in network byte order. For example, the number 264 is represented by a byte array containing the byte value 0x01 followed by 8 zero bytes.
NegativeBignum3A negative number of arbirary length, encoded as the absolute value of that number, minus one. For example, a byte array containing byte value 0x02 followed by 8 zero bytes represents the number -265 - 1.
Decimal4A decimal fraction, encoded as an array of two integers: the first is the exponent of the power of 10, the second the integral mantissa. The value 273.15 would be encoded as array [-2, 27315].
Bigfloat5Similar to Decimal, but the exponent is a power of 2 instead.
COSE_Encrypt016An Encrypt0 map as specified by RFC 8152 (CBOR Object Signing and Encryption).
COSE_Mac017A Mac0 map as specified by RFC 8152 (CBOR Object Signing and Encryption).
COSE_Sign118A Sign1 map as specified by RFC 8152 (CBOR Object Signing and Encryption).
ExpectedBase64url21Indicates that the byte array should be encoded using Base64url if the stream is converted to JSON.
ExpectedBase6422Indicates that the byte array should be encoded using Base64 if the stream is converted to JSON.
ExpectedBase1623Indicates that the byte array should be encoded using Base16 (hex) if the stream is converted to JSON.
EncodedCbor24Indicates that the byte array contains a CBOR stream.
Url32Indicates that the string contains a URL.
Base64url33Indicates that the string contains data encoded using Base64url.
Base6434Indicates that the string contains data encoded using Base64.
RegularExpression35Indicates that the string contains a Perl-Compatible Regular Expression pattern.
MimeMessage36Indicates that the string contains a MIME message (according to https://tools.ietf.org/html/rfc2045){RFC 2045}.
Uuid37Indicates that the byte array contains a UUID.
COSE_Encrypt96An Encrypt map as specified by RFC 8152 (CBOR Object Signing and Encryption).
COSE_Mac97A Mac map as specified by RFC 8152 (CBOR Object Signing and Encryption).
COSE_Sign98A Sign map as specified by RFC 8152 (CBOR Object Signing and Encryption).
Signature55799No change in interpretation; this tag can be used as the outermost tag in a CBOR stream as the file header.

The following tags are interpreted by QCborValue during decoding and will produce objects with extended Qt types, and it will use those tags when encoding the same extended types.

ConstantValueDescription
DateTimeString0QDateTime
UnixTime_t1QDateTime (only in decoding)
Url32QUrl
Uuid37QUuid

Additionally, if a QCborValue containing a QByteArray is tagged using one of ExpectedBase64url, ExpectedBase64 or ExpectedBase16, QCborValue will use the expected encoding when converting to JSON (see QCborValue::toJsonValue).

See also QCborTag, QCborStreamWriter::append(QCborTag), QCborStreamReader::isTag(), QCborStreamReader::toTag(), QCborValue::isTag(), and QCborValue::tag().

enum QCborSimpleType

This enum contains the possible "Simple Types" for CBOR. Simple Types range from 0 to 255 and are types that carry no further value.

The following values are currently known:

ConstantValueDescription
False?A "false" boolean.
True?A "true" boolean.
Null?Absence of value (null).
Undefined?Missing or deleted value, usually an error.

Qt CBOR API supports encoding and decoding any Simple Type, whether one of those above or any other value.

Applications should only use further values if a corresponding specification has been published, otherwise interpretation and validation by the remote may fail. Values 24 to 31 are reserved and must not be used.

The current authoritative list is maintained by IANA in the Simple Values registry.

See also QCborStreamWriter::append(QCborSimpleType), QCborStreamReader::isSimpleType(), QCborStreamReader::toSimpleType(), QCborValue::isSimpleType(), and QCborValue::toSimpleType().

enum QCborTag

This enum contains no enumeration and is used only to provide type-safe access to a CBOR tag.

CBOR tags are 64-bit numbers that are attached to generic CBOR types to provide further semantic meaning. QCborTag may be constructed from an enumeration found in QCborKnownTags or directly by providing the numeric representation.

For example, the following creates a QCborValue containing a byte array tagged with a tag 2.

   QCborValue(QCborTag(2), QByteArray("\x01\0\0\0\0\0\0\0\0", 9));

See also QCborKnownTags, QCborStreamWriter::append(QCborTag), QCborStreamReader::isTag(), QCborStreamReader::toTag(), QCborValue::isTag(), and QCborValue::tag().

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