Function match_expansion 

pub fn match_expansion<EN: Fn(TokenStream, &FieldsNamed) -> (TokenStream, TokenStream), EU: Fn(TokenStream, &FieldsUnnamed) -> (TokenStream, TokenStream), U: Fn(TokenStream) -> TokenStream>(
    derive_input: &DeriveInput,
    expand_named: &EN,
    expand_unnamed: &EU,
    expand_unit: &U,
) -> TokenStream

Handles the expansion of a struct/enum into a match statement that accesses every field for procedural code generation.

Requires several Fn helpers which perform expand different structures:

• expand_named handles the expansion of a struct or enum variant with named fields (e.g. struct Foo { bar: u32 }, Foo::Bar { baz: u32 }).
• expand_unnamed handles the expansion of a struct or enum variant with unnamed fields (e.g. struct Foo(u32), Foo::Bar(u32)).
• expand_unit handles the expansion of a unit struct or enum (e.g. struct Foo;, Foo::Bar).

These helpers should themselves call generate_destructuring to generate the destructure necessary to access the fields of the value.