/** \brief Define VariantParser field
- This macro is a special helper to define a senf::DirectVariantParser type field. This is a
- variant field which chooses the sub-type by directly taking the value of some other field.
-
+ This macro is a special helper to define a senf::VariantParser type field.
\code
struct SomeParser : public PacketParserBase
{
# include SENF_PARSER()
SENF_PARSER_PRIVATE_FIELD( type, senf::UInt8Parser );
- SENF_PARSER_PRIVATE_VARIANT( content, type,
- (novalue( disable, senf::VoidPacketParser ))
- ( id( uint8, senf::UInt8Parser ))
- ( id( uint16, senf::UInt16Parser ))
- ( id( uint24, senf::UInt24Parser ))
- ( id( uint32, senf::UInt32Parser )) );
+ SENF_PARSER_VARIANT( content, type,
+ (novalue( disable, senf::VoidPacketParser ))
+ ( id( uint8, senf::UInt8Parser ))
+ ( id( uint16, senf::UInt16Parser ))
+ ( id( uint24, senf::UInt24Parser ))
+ ( id( uint32, senf::UInt32Parser )) );
SENF_PARSER_FINALIZE(SomeParser);
};
- \endcode
-
+ \endcode
+
The variant \c content chooses one of the sub parsers depending on the \c type field. If \c
type is 0, senf::VoidPacketParser is selected, if it is 1, senf::UInt8Parser and so on.
<tr><td>\a type</td><td>Do not provide accessor and use the 0-based type index as
key.</td></tr>
- <tr><td>\c id(\a name, \a type)</td><td>Automatically create an accessor \a name for this
- type</td></tr>
+ <tr><td>\c id(\a name, \a type)</td><td>Automatically create an accessor \a name, a test
+ function <tt>has_</tt>\a name and a function to switch to this type <tt>init_</tt>\a name
+ for this type. Identical to \c ids(\a name, <tt>has_</tt>\a name, <tt>init_</tt>\a name, \a
+ type)</td></tr>
<tr><td>\c novalue(\a name, \a type)</td><td>This is like \c id but only provides an
- initializer called \a name and no accessor</td></tr>
+ initializer called \a name and no accessor. Identical to \c ids(\c na, \c na, \a name, \a
+ type)</td></tr>
+
+ <tr><td>\c ids(\a accessorId, \a testId, \a initId, \a type)</td><td>This is again like \c
+ id but the names of the accessor, test function and init function are given
+ explicitly. Setting any of the id's to \c na will disable that function.</td></tr>
<tr><td>\c key(\a value, \a type)</td><td>Use \a value to identity this type. The type is
selected, when the \a chooser is equal to \a value</td></tr>
<tr><td>\c id(\a name, \c key(\a value, \a type))<br/>\c novalue(\a name, \c key(\a value,
- \a type))</td><td>The options may be nested in this way.</td></tr> </table>
+ \a type))</td><td>The options may be nested in this way.</td></tr>
+ </table>
+
+ Whenever an id is specified for any type, the variant itself will automatically be made
+ private so the only access to the variant from the outside is via the accessors.
- It is customary, to hide the variant parser (by defining it private) and provide
- more conveniently named accessors. In above example, these accessors are automatically
- generated using the id's given. The exact members defined are:
+ The functions defined by specifying an id are:
<table class="senf fixedcolumn">
- <tr><td>\a name \c _t</td><td>The type for this specific variant value if not \c
- novalue.</td></tr>
+ <tr><td><em>name</em><tt>_t</tt></td><td>The type for this specific variant value if not \c
+ novalue.</td></tr>
<tr><td><em>name</em><tt>_t</tt> <em>name</em>()</td><td>Return the variant value at this id
if not \c novalue.</td></tr>
currently holds this kind of value, \c false otherwise. Only if not \c novalue.</td></tr>
</table>
- If \a value keys are given, they designate the value to expect in the \a chooser field to
+ If \c key specs are given, they designate the value to expect in the \a chooser field to
select a specific variant type. If the \a chooser value does not match any key, the variant
will be initialized to the \e first type.
\param[in] types a Boost.Preprocessor style sequence of sub-parser types
\see
- senf::VariantParser \n
+ senf::VariantParser for the VariantParser API\n
\ref SENF_PARSER_PRIVATE_VARIANT()
\hideinitializer
\ingroup packetparsermacros
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