Macro structural::FP

macro_rules! FP {
    ($ident:ident) => { ... };
    (0) => { ... };
    (1) => { ... };
    (2) => { ... };
    (3) => { ... };
    (4) => { ... };
    (5) => { ... };
    (6) => { ... };
    (7) => { ... };
    (8) => { ... };
    (9) => { ... };
    (_) => { ... };
    ($lit:literal) => { ... };
    ($($everything:tt)*) => { ... };
}

Constructs a field path type for use as a generic parameter.

Input

This takes the same input as the fp macro, getting the type of that field path.

Examples

This demonstrates how one can bound types by the accessor traits in a where clause.

use structural::{GetField,StructuralExt,FP,fp,make_struct};

greet_entity(&make_struct!{ name: "Bob" });

fn greet_entity<This,S>(entity:&This)
where
    This:GetField<FP!(name),Ty=S>,
    S:AsRef<str>,
{
    println!("Hello, {}!",entity.field_(fp!(name)).as_ref() );
    println!("Goodbye, {}!",entity.field_(fp!("name")).as_ref() );

    // The two `fp!` invocations  below are equivalent.
    //
    // Quotes allow for arbitrary identifiers,
    // useful for non-ascii identifiers before they are supported by Rust.
    //
    assert_eq!( entity.field_(fp!(name)).as_ref(), "Bob" );
    assert_eq!( entity.field_(fp!("name")).as_ref(), "Bob" );
}

Example

use structural::{GetField,StructuralExt,FP,fp,make_struct};

let struc=make_struct!{
    name: "Bob",
    huh: "John",
};

greet_entity(&struc,&(99,999,999));

type Path_0=FP!(0);
type Path_huh=FP!(huh);
type Path_name=FP!("name"); // Equivalent to FP!(name)

fn greet_entity<This,S,Tup>(entity:&This, tuple:&Tup)
where
    This: GetField<FP!(name), Ty= S> + GetField<Path_huh, Ty= &'static str>,
    Tup : GetField<Path_0,Ty=u64>,
    S:AsRef<str>,
{
    assert_eq!( entity.field_(fp!(name)).as_ref(), "Bob" );
    assert_eq!( entity.field_(fp!("name")).as_ref(), "Bob" );
    assert_eq!( entity.field_(Path_name::NEW).as_ref(), "Bob" );

    assert_eq!( entity.field_(fp!(huh)), &"John" );
    assert_eq!( entity.field_(fp!("huh")), &"John" );
    assert_eq!( entity.field_(Path_huh::NEW), &"John" );

    assert_eq!( tuple.field_(fp!(0)), &99 );
    assert_eq!( tuple.field_(Path_0::NEW), &99 );
}