1. Epic GamesDeveloper
  3. FCbFieldView

FCbFieldView

An atom of data in the compact binary format.

Unreal Engine C++ API Reference > Runtime > Core > Serialization

Inheritance Hierarchy

References

   
Module Core
Header /Engine/Source/Runtime/Core/Public/Serialization/CompactBinary.h
Include #include "Serialization/CompactBinary.h"

Syntax

class FCbFieldView

Remarks

An atom of data in the compact binary format.

Accessing the value of a field is always a safe operation, even if accessed as the wrong type. An invalid access will return a default value for the requested type, and set an error code on the field that can be checked with GetLastError and HasLastError. A valid access will clear an error from a previous invalid access.

A field is encoded in one or more bytes, depending on its type and the type of object or array that contains it. A field of an object or array which is non-uniform encodes its field type in the first byte, and includes the HasFieldName flag for a field in an object. The field name is encoded in a variable-length unsigned integer of its size in bytes, for named fields, followed by that many bytes of the UTF-8 encoding of the name with no null terminator. The remainder of the field is the value which is described in the field type enum. Every field must be uniquely addressable when encoded, which means a zero-byte field is not permitted, and only arises in a uniform array of fields with no value, where the answer is to encode as a non-uniform array.

This type only provides a view into memory and does not perform any memory management itself. Use FCbField to hold a reference to the underlying memory when necessary.

Constructors

  Type Name Description
Public function constexpr Construct a field with no name and no value.
Public function  

FCbFieldView ( const FCbValue& Value
)

 Construct a field from a value, without access to the name.
Public function  

FCbFieldView ( const void* Data,
ECbFieldType Type
)

 Construct a field from a pointer to its data and an optional externally-provided type.

Functions

  Type Name Description
Public function Const void

AppendHash ( FIoHashBuilder& Builder
)

 Append the hash of the field, including the type and name.
Public function FCbArrayView Access the field as an array. Defaults to an empty array on error.
Public function FIoHash

AsAttachment ( const FIoHash& Default
)

 Access the field as a hash referencing an attachment. Returns the provided default on error.
Public function FIoHash

AsBinaryAttachment ( const FIoHash& Default
)

 Access the field as a hash referencing a binary attachment. Returns the provided default on error.
Public function FMemoryView Access the field as binary. Returns the provided default on error.
Public function bool

AsBool ( bool bDefault
)

 Access the field as a bool. Returns the provided default on error.
Public function FMemoryView Access the field as a custom sub-type with a string identifier.
Public function FMemoryView

AsCustom ( uint64 Id,
FMemoryView Default
)

 Access the field as a custom sub-type with an integer identifier.
Public function FCbCustomById Access the field as a custom sub-type with an integer identifier.
Public function FCbCustomByName Access the field as a custom sub-type with a string identifier.
Public function FDateTime Access the field as a date/time. Returns a date/time at the epoch on error.
Public function FDateTime

AsDateTime ( FDateTime Default
)

 Access the field as a date/time. Returns the provided default on error.
Public function int64

AsDateTimeTicks ( int64 Default
)

 Access the field as a date/time tick count. Returns the provided default on error.
Public function double

AsDouble ( double Default
)

 Access the field as a double. Returns the provided default on error.
Public function float

AsFloat ( float Default
)

 Access the field as a float. Returns the provided default on error.
Public function FIoHash

AsHash ( const FIoHash& Default
)

 Access the field as a hash. Returns the provided default on error.
Public function int16

AsInt16 ( int16 Default
)

 Access the field as an int16. Returns the provided default on error.
Public function int32

AsInt32 ( int32 Default
)

 Access the field as an int32. Returns the provided default on error.
Public function int64

AsInt64 ( int64 Default
)

 Access the field as an int64. Returns the provided default on error.
Public function int8

AsInt8 ( int8 Default
)

 Access the field as an int8. Returns the provided default on error.
Public function FIoHash

AsObjectAttachment ( const FIoHash& Default
)

 Access the field as a hash referencing an object attachment. Returns the provided default on error.
Public function FCbObjectId

AsObjectId ( const FCbObjectId& Default
)

 Access the field as an object identifier. Returns the provided default on error.
Public function FCbObjectView Access the field as an object. Defaults to an empty object on error.
Protected function void

Assign ( const void* InData,
const ECbFieldType InType
)

 Assign a field from a pointer to its data and an optional externally-provided type.
Public function FUtf8StringView Access the field as a string. Returns the provided default on error.
Public function FTimespan

AsTimeSpan ( FTimespan Default
)

 Access the field as a timespan. Returns the provided default on error.
Public function FTimespan Access the field as a timespan. Returns an empty timespan on error.
Public function int64

AsTimeSpanTicks ( int64 Default
)

 Access the field as a timespan tick count. Returns the provided default on error.
Public function uint16

AsUInt16 ( uint16 Default
)

 Access the field as a uint16. Returns the provided default on error.
Public function uint32

AsUInt32 ( uint32 Default
)

 Access the field as a uint32. Returns the provided default on error.
Public function uint64

AsUInt64 ( uint64 Default
)

 Access the field as a uint64. Returns the provided default on error.
Public function uint8

AsUInt8 ( uint8 Default
)

 Access the field as a uint8. Returns the provided default on error.
Public function FGuid

AsUuid ( const FGuid& Default
)

 Access the field as a UUID. Returns the provided default on error.
Public function FGuid

AsUuid ()

 Access the field as a UUID. Returns a nil UUID on error.
Public function Const FCbFieldViewIterator

begin ()

 DO NOT USE DIRECTLY. These functions enable range-based for loop support.
Public function Const void

CopyTo ( FArchive& Ar
)

 Copy the field into an archive, including its type and name.
Public function Const void Copy the field into a buffer of exactly GetSize() bytes, including the type and name.
Public function Const FCbFieldViewIterator Create an iterator for the fields of an array or object, otherwise an empty iterator.
Public function Const FCbIteratorSentinel

end ()

  
Public function Const bool

Equals ( const FCbFieldView& Other
)

 Whether this field is identical to the other field.
Public function Const ECbFieldError The type of error that occurred on the last field access, or None.
Public function Const FIoHash

GetHash ()

 Calculate the hash of the field, including the type and name.
Public function Const FUtf8StringView

GetName ()

 Returns the name of the field if it has a name, otherwise an empty view.
Public function Const uint64

GetSize ()

 Returns the size of the field in bytes, including the type and name.
Protected function Const ECbFieldType

GetType ()

 Returns the type of the field excluding flags.
Protected function Const ECbFieldType Returns the type of the field including flags.
Public function Const FCbValue Returns the value for unchecked access. Prefer the typed accessors below.
Protected function Const const void * Returns the start of the value.
Protected function Const const void * Returns the end of the value.
Protected function Const uint64 Returns the size of the value in bytes, which is the field excluding the type and name.
Protected function Const FMemoryView Returns a view of the value, which excludes the type and name.
Protected function Const FMemoryView

GetView ()

 Returns a view of the field, including the type and name when present.
Protected function Const FMemoryView Returns a view of the name and value, which excludes the type.
Public function Const bool Whether the last field access encountered an error.
Public function Const bool

HasName ()

 True if the field has a name.
Public function Const bool Whether the field has a value.
Public function Const bool

IsArray ()

  
Public function Const bool  
Public function Const bool  
Public function Const bool  
Public function Const bool

IsBool ()

  
Public function Const bool  
Public function Const bool  
Public function Const bool  
Public function Const bool

IsFloat ()

 Whether the field is a float, or integer that supports implicit conversion.
Public function Const bool

IsHash ()

  
Public function Const bool Whether the field is an integer of unspecified range and sign.
Public function Const bool

IsNull ()

  
Public function Const bool  
Public function Const bool  
Public function Const bool  
Public function Const bool  
Public function Const bool  
Public function Const bool

IsUuid ()

  
Public function Const void Invoke the visitor for every attachment in the field.
Public function Const FCbFieldView Returns a copy of the field with the name removed.
Public function Const bool

TryGetView ( FMemoryView& OutView
)

 Try to get a view of the field as it would be serialized, such as by CopyTo.

Operators

  Type Name Description
Public function Const constexpr Whether the field has a value.
Public function Const FCbFieldView Find a field of an object by case-sensitive name comparison, otherwise a field with no value.

Ask questions and help your peers Developer Forums

Write your own tutorials or read those from others Learning Library

On this page