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//! A procedural macro which creates a "staged" builder for a type.
//!
//! Staged (also known as telescopic) builders are a style of infallible builders; code will not compile if any required
//! fields are not set. Specifically, the builder advances in order through a sequence of "stage" types, each
//! corresponding to a required field of the struct. The final stage has setters for all optional fields and the final
//! `.build()` method.
//!
//! See the documentation for [`#[staged_builder]`](staged_builder) for more details.
//!
//! # Examples
//!
//! ```
//! use staged_builder::staged_builder;
//!
//! #[staged_builder]
//! struct Person {
//! #[builder(into)]
//! name: String,
//! age: u32,
//! #[builder(list(item(type = Person)))]
//! parents: Vec<Person>,
//! }
//!
//! # fn main() {
//! let person = Person::builder()
//! .name("John Doe")
//! .age(25)
//! .build();
//! # }
//! ```
#![cfg_attr(not(doc), no_std)]
// Not part of the public API.
#[doc(hidden)]
pub use staged_builder_internals::__StagedBuilderInternalDerive;
#[doc(inline)]
pub use staged_builder_internals::staged_builder;
// Not part of the public API.
#[doc(hidden)]
pub mod __private {
pub use core::convert::{From, Into};
pub use core::default::Default;
pub use core::iter::{Extend, FromIterator, IntoIterator, Iterator};
pub use core::result::Result;
#[inline]
pub fn call_hack<T, R>(f: impl FnOnce(T) -> R, v: T) -> R {
f(v)
}
}
/// A trait for types which validate their state before construction finishes.
///
/// The generated builder will call this method if the `#[builder(validate)]` attribute is placed at the struct level.
pub trait Validate {
/// The error returned for an invalid value.
type Error;
/// Validates the state of `self`.
fn validate(&self) -> Result<(), Self::Error>;
}
/// An example type using [`#[staged_builder]`](staged_builder).
#[cfg(doc)]
#[staged_builder]
#[builder(crate = crate)]
pub struct ExamplePerson {
#[builder(into)]
pub name: String,
pub age: u32,
#[builder(list(item(type = ExamplePerson)))]
pub parents: Vec<ExamplePerson>,
}