Derive Macro boulder::BuildableWithPersianRug

source · [−]

#[derive(BuildableWithPersianRug)]
{
    // Attributes available to this derive:
    #[boulder]
}

Available on crate feature persian-rug only.

Expand description

Derive the BuildableWithPersianRug trait for a type, creating a suitable BuilderWithPersianRug.

This is only implemented for structs with named fields; there is no implementation for either enums or structs with unnamed fields. All fields will be default constructed in the absence of other instructions. You can customise the construction process for your type by using the boulder attribute on its fields, as follows:

#[boulder(default=Foo)] The default value for this field is Foo, where an arbitrary well-formed Rust expression can be used in place of Foo.
#[boulder(default_with_persian_rug=|context| {(Foo, context)})] The default value for this field is derived from the context alone, via a lambda or function which receives the context, and must return it.
#[boulder(buildable)] The type for this field implements Buildable itself, so new values should be constructed using T::builder().build().
#[boulder(buildable_with_persian_rug)] The type for this field implements BuildableWithPersianRug itself, so new values should be constructed using T::builder().build(context).
#[boulder(buildable(a=5, b=10))] The type for this field implements Buildable, and new instances should be customised from the default by setting a=5 and b=10 where a and b are member names, and 5 and 10 can be replaced by arbitrary well-formed Rust expressions.
#[boulder(buildable_with_persian_rug(a=5, b=10))] The type for this field implements BuildableWithPersianRug, and new instances should be customised from the default by setting a=5 and b=10 where a and b are member names, and 5 and 10 can be replaced by arbitrary well-formed Rust expressions.
#[boulder(sequence=3)] This field is assumed to be a collection type (a type which can be the target of collect()). Generate 3 items and initialize a new collection from them, where 3 can be replaced by an arbitrary well-formed Rust expression. The generation mechanism will be taken from any generator specification (generator or generatable) if one is given; otherwise it will be from the builder specification (default or buildable, as described above) if one is given; otherwise the items will be default initialized.
#[boulder(sequence_with_persian_rug=|context| {(f(context), context)}] This field is assumed to be a collection type (a type which can be the target of collect()). Generate a number of items dependent on the context, and initialize a new collection from them, where f(context) can be replaced by an arbitrary well-formed Rust expression. The generation mechanism will be taken from any generator specification (generator, generatable, generator_with_persian_rug or generatable_with_persian_rug) if one is given; otherwise it will be from the builder specification (default, buildable, default_with_persian_rug or buildable_with_persian_rug as described above) if one is given; otherwise the items will be default initialized.

Example:

use boulder::{BuildableWithPersianRug, GeneratableWithPersianRug, BuilderWithPersianRug};
use persian_rug::{contextual, persian_rug, Context, Proxy};

#[contextual(Rug)]
#[derive(BuildableWithPersianRug)]
#[boulder(persian_rug(context=Rug))]
struct Foo {
  // This field will be default-initialized (a=0)
  a: i32,
  // This field will be initialized from the number of Bars currently in the context
  #[boulder(default_with_persian_rug=|context| (context.get_iter::<Bar>().count().try_into().unwrap(), context))]
  b: i32,
}

#[contextual(Rug)]
#[derive(BuildableWithPersianRug)]
#[boulder(persian_rug(context=Rug))]
struct Bar {
  // This field will be initialized as Foo::builder().build()
  #[boulder(buildable_with_persian_rug)]
  f1: Proxy<Foo>,
  // This field will be initialized as Foo::builder().a(1).build()
  #[boulder(buildable_with_persian_rug(a=1))]
  f2: Proxy<Foo>,
  // This field will be initialized with as many items as there are
  // pre-existing Foos of Foo::builder().build()
  #[boulder(buildable_with_persian_rug, sequence_with_persian_rug=|context| (context.get_proxy_iter::<Foo>().count(), context))]
  f3: Vec<Proxy<Foo>>,
}

#[persian_rug]
struct Rug(#[table] Foo, #[table] Bar);

let mut r = Rug(Default::default(), Default::default());
let (foo, _) = Proxy::<Foo>::builder().build(&mut r);
assert_eq!(r.get(&foo).a, 0);
assert_eq!(r.get(&foo).b, 0);

let (bar, _) = Proxy::<Bar>::builder().build(&mut r);
assert_eq!(r.get(&r.get(&bar).f1).a, 0);
assert_eq!(r.get(&r.get(&bar).f1).b, 0);
assert_eq!(r.get(&r.get(&bar).f2).a, 1);
assert_eq!(r.get(&r.get(&bar).f2).b, 0);
assert_eq!(r.get(&bar).f3.len(), 3);
assert_eq!(r.get(&r.get(&bar).f3[0]).a, 0);
assert_eq!(r.get(&r.get(&bar).f3[0]).b, 0);
assert_eq!(r.get(&r.get(&bar).f3[1]).a, 0);
assert_eq!(r.get(&r.get(&bar).f3[1]).b, 0);
assert_eq!(r.get(&r.get(&bar).f3[2]).a, 0);
assert_eq!(r.get(&r.get(&bar).f3[2]).b, 0);

let (foo, _) = Proxy::<Foo>::builder().build(&mut r);
assert_eq!(r.get(&foo).a, 0);
assert_eq!(r.get(&foo).b, 1);

let (bar, _) = Proxy::<Bar>::builder().build(&mut r);
assert_eq!(r.get(&r.get(&bar).f1).a, 0);
assert_eq!(r.get(&r.get(&bar).f1).b, 1);
assert_eq!(r.get(&r.get(&bar).f2).a, 1);
assert_eq!(r.get(&r.get(&bar).f2).b, 1);
assert_eq!(r.get(&bar).f3.len(), 9);
assert_eq!(r.get(&r.get(&bar).f3[0]).a, 0);
assert_eq!(r.get(&r.get(&bar).f3[0]).b, 1);
assert_eq!(r.get(&r.get(&bar).f3[1]).a, 0);
assert_eq!(r.get(&r.get(&bar).f3[1]).b, 1);
assert_eq!(r.get(&r.get(&bar).f3[2]).a, 0);
assert_eq!(r.get(&r.get(&bar).f3[2]).b, 1);
assert_eq!(r.get(&r.get(&bar).f3[8]).a, 0);
assert_eq!(r.get(&r.get(&bar).f3[8]).b, 1);