sbepp::message_traits< T > Class Template Reference

Provides various traits/attributes of a <message> element. More...

Public Types
template<typename Byte >
using	value_type = MessageType<Byte>
	Representation type.
using	schema_tag = SchemaTag
	Schema tag.

Static Public Member Functions
static constexpr const char *	name () noexcept
	Returns name attribute.
static constexpr const char *	description () noexcept
	Returns description attribute.
static constexpr message_id_t	id () noexcept
	Returns id attribute.
static constexpr block_length_t	block_length () noexcept
	Returns blockLength attribute.
static constexpr const char *	semantic_type () noexcept
	Returns semanticType attribute.
static constexpr version_t	since_version () noexcept
	Returns addedSince attribute.
static constexpr version_t	deprecated () noexcept
	Returns deprecated attribute. Available only if provided in schema.
static constexpr std::size_t	size_bytes (...) noexcept
	Returns number of bytes required to represent the message in given configuration.

Detailed Description

template<typename T>
class sbepp::message_traits< T >

Provides various traits/attributes of a <message> element.

For example: sbepp::message_traits<market_schema::schema::messages::msg1>::name();

Template Parameters

T	message tag

Member Typedef Documentation

value_type

template<typename T >

template<typename Byte >

using sbepp::message_traits< T >::value_type = MessageType<Byte>

Representation type.

Template Parameters

Byte

byte type

Member Function Documentation

size_bytes()

template<typename T >

static constexpr std::size_t sbepp::message_traits< T >::size_bytes ( ... )

staticconstexprnoexcept

Returns number of bytes required to represent the message in given configuration.

Parameters

...	parameter list depends on the message structure

Returns

size in bytes

Parameter list is built as follows:

• for each <group> within the message, in a top-to-bottom order, there will be a parameter in form of NumInGroupType <group_path>_num_in_group[_<n>] where <group_path> is built like <parent_group_path>_<child_group_name>. Optional _<n> part is added to disambiguate names that otherwise would be the same. This parameter represents the total number of group entries (even if they are spread across multiple enclosing group entries).
• if there exists a <data> member on any level within the message, there will be additional std::size_t total_data_size parameter at the end of parameter list, representing the total payload size from all the <data> elements within the message.

Here's the example with different cases:

<!-- size_bytes() -->
<sbe:message>
    <!-- only fields... -->
</sbe:message>
 
<!-- size_bytes(std::uint32_t group_num_in_group) -->
<sbe:message>
    <group name="group">
        <!-- only fields... -->
    </group>
</sbe:message>
 
<!-- size_bytes(
        std::uint32_t group_1_num_in_group,
        std::uint32_t group_2_num_in_group) -->
<sbe:message>
    <group name="group_1">
        <!-- only fields... -->
    </group>
    <group name="group_2">
        <!-- only fields... -->
    </group>
</sbe:message>
 
<!-- size_bytes(
        std::uint32_t group_1_num_in_group,
        std::uint32_t group_1_group_2_num_in_group,
        std::uint32_t group_3_num_in_group) -->
<sbe:message>
    <group name="group_1">
        <group name="group_2">
            <!-- only fields... -->
        </group>
    </group>
    <group name="group_3">
        <!-- only fields... -->
    </group>
</sbe:message>
 
<!-- size_bytes(
    std::uint32_t group_num_in_group,
    std::size_t total_data_size) -->
<sbe:message>
    <group name="group">
        <data name="data_1"/>
    </group>
    <data name="data_2"/>
</sbe:message>

For usage example, see Estimating buffer size to encode a message.

Warning

This function provides correct results only for the current schema version.

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

• sbepp.hpp