EQ2EMu/EQ2/source/depends/boost_1_72_0/libs/metaparse/example/constexpr_parser

Parsers parsing "a* b* a*" and counting the appearance of the characters.
This parser is implemented in three different ways:
- One built with Metaparse
- One implemented using constexpr functions
- One built with Metaparse but parsing a subexpression with a constexpr parser:
- a* at the beginning is parsed using a Metaparse parser
- b* is parsed using a constexpr function
- a* at the end is parsed using a Mataparse parser again

This example demonstrates how Metaparse can be combined with parsers using
constexpr functions.