df0::message_callbacks Struct Reference

Callback bundle used by pipeline elements to emit messages. More...

#include <message.h>

Public Member Functions
continuation	further (message_ptr msg) const
template<typename T> requires (!std::is_convertible_v<std::remove_cvref_t<T>, message_ptr> && !std::derived_from<std::remove_cvref_t<T>, message_base>)
continuation	further (T &&object) const
continuation	back (message_ptr msg) const
template<typename T> requires (!std::is_convertible_v<std::remove_cvref_t<T>, message_ptr> && !std::derived_from<std::remove_cvref_t<T>, message_base>)
continuation	back (T &&object) const
continuation	operator() (message_ptr msg) const
template<typename T> requires (!std::is_convertible_v<std::remove_cvref_t<T>, message_ptr> && !std::derived_from<std::remove_cvref_t<T>, message_base>)
continuation	operator() (T &&object) const

Public Attributes
std::function< continuation(message_ptr)>	m_further
std::function< continuation(message_ptr)>	m_back

Detailed Description

Callback bundle used by pipeline elements to emit messages.

There are two independent directions:

• further sends a message to the next element on the right.
• back sends a message back to the beginning of the fully assembled pipeline so that it can be processed by the whole pipeline again.

back is intended for embedded/nested content. For example, a document parser may discover an embedded image and call back(image_data) so that the image is processed again from the pipeline source and can reach OCR.

Note

A back-emitted message must not be pipeline::start_processing. Sending start_processing backwards is indistinguishable from the initial pipeline start and can cause infinite recursion.

Both further and back wrap raw payload types into a message<T>. Passing an already-created message_ptr forwards it without re-wrapping.

Definition at line 89 of file message.h.

Member Function Documentation

back() [1/2]

continuation df0::message_callbacks::back ( message_ptr msg ) const

inline

Definition at line 101 of file message.h.

back() [2/2]

template<typename T>
requires (!std::is_convertible_v<std::remove_cvref_t<T>, message_ptr> && !std::derived_from<std::remove_cvref_t<T>, message_base>)

continuation df0::message_callbacks::back ( T && object ) const

inline

Definition at line 106 of file message.h.

further() [1/2]

continuation df0::message_callbacks::further ( message_ptr msg ) const

inline

Definition at line 94 of file message.h.

further() [2/2]

template<typename T>
requires (!std::is_convertible_v<std::remove_cvref_t<T>, message_ptr> && !std::derived_from<std::remove_cvref_t<T>, message_base>)

continuation df0::message_callbacks::further ( T && object ) const

inline

Definition at line 99 of file message.h.

operator()() [1/2]

continuation df0::message_callbacks::operator() ( message_ptr msg ) const

inline

Definition at line 108 of file message.h.

operator()() [2/2]

template<typename T>
requires (!std::is_convertible_v<std::remove_cvref_t<T>, message_ptr> && !std::derived_from<std::remove_cvref_t<T>, message_base>)

continuation df0::message_callbacks::operator() ( T && object ) const

inline

Definition at line 113 of file message.h.

Member Data Documentation

m_back

std::function<continuation(message_ptr)> df0::message_callbacks::m_back

Definition at line 92 of file message.h.

m_further

std::function<continuation(message_ptr)> df0::message_callbacks::m_further

Definition at line 91 of file message.h.

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The documentation for this struct was generated from the following file:

• message.h