ot::Appender class

The `Appender` class acts as a wrapper over either a `Message` or a data buffer and provides different flavors of `Append()` method. Helps in construction of message content where the destination can be either a `Message` or a buffer.

Syntax

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Summary

Declaration

from appender.hpp:53

class Appender { public: enum Type : uint8_t { kMessage, kBuffer, }; explicit Appender(Message &aMessage); Appender(uint8_t *aBuffer, uint16_t aSize); Type GetType(void) const { return mType; } Error AppendBytes(const void *aBuffer, uint16_t aLength); template <typename ObjectType> Error Append(const ObjectType &aObject) { static_assert(!TypeTraits::IsPointer<ObjectType>::kValue, "ObjectType must not be a pointer"); return AppendBytes(&aObject, sizeof(ObjectType)); } uint16_t GetAppendedLength(void) const; Message &GetMessage(void) const { return *mShared.mMessage.mMessage; } uint8_t *GetBufferStart(void) const { return AsNonConst(mShared.mFrameBuilder.GetBytes()); } void GetAsData(Data<kWithUint16Length> &aData) const; private: Type mType; union { struct { Message *mMessage; uint16_t mStartOffset; } mMessage; FrameBuilder mFrameBuilder; } mShared; };

Fields

Field

Declared as

ot::Appender::mType

Type

ot::Appender::mShared

union { struct { Message *mMessage; uint16_t mStartOffset; } mMessage; FrameBuilder mFrameBuilder; }

Methods

GetType() const

Indicates the `Appender` type (whether appending to a `Message` or data buffer).

AppendBytes()

Appends bytes to the `Appender` object.

Append()

GetAppendedLength() const

Returns the number of bytes appended so far using `Appender` methods. Can be used independent of the `Type` of `Appender`.

GetMessage() const

Returns the `Message` associated with `Appender`. MUST be used when `GetType() == kMessage`. Otherwise its behavior is undefined.

GetBufferStart() const

Returns a pointer to the start of the data buffer associated with `Appender`. MUST be used when `GetType() == kBuffer`. Otherwise its behavior is undefined.

GetAsData() const

Gets the data buffer associated with `Appender` as a `Data`. MUST be used when `GetType() == kBuffer`. Otherwise its behavior is undefined. @pram[out] aData A reference to a `Data` to output the data buffer.