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// Copyright (c) 2018-2022 Brendan Molloy <brendan@bbqsrc.net>,
// Ilya Solovyiov <ilya.solovyiov@gmail.com>,
// Kai Ren <tyranron@gmail.com>
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Helper type-level glue for [`cucumber_codegen`] crate.
use std::{convert::Infallible, future::Future};
use futures::future;
use crate::{step, Step, World};
pub use anyhow;
pub use async_trait::async_trait;
pub use cucumber_expressions::{
expand::parameters::Provider as ParametersProvider, Expression, Spanned,
};
pub use futures::future::LocalBoxFuture;
pub use inventory::{self, collect, submit};
pub use once_cell::sync::Lazy;
pub use regex::Regex;
/// [`World`] extension allowing to register steps in [`inventory`].
pub trait WorldInventory: World {
/// Struct [`submit`]ted in a [`given`] macro.
///
/// [`given`]: crate::given
type Given: inventory::Collect + StepConstructor<Self>;
/// Struct [`submit`]ted in a [`when`] macro.
///
/// [`when`]: crate::when
type When: inventory::Collect + StepConstructor<Self>;
/// Struct [`submit`]ted in a [`then`] macro.
///
/// [`then`]: crate::then
type Then: inventory::Collect + StepConstructor<Self>;
}
/// Alias for a [`fn`] returning a [`Lazy`] [`Regex`].
pub type LazyRegex = fn() -> Regex;
/// Trait for registering a [`Step`] with [`given`], [`when`] and [`then`]
/// attributes inside [`World::collection()`] method.
///
/// [`given`]: crate::given
/// [`when`]: crate::when
/// [`then`]: crate::then
pub trait StepConstructor<W> {
/// Returns an inner [`Step`] with the corresponding [`Regex`].
fn inner(&self) -> (step::Location, LazyRegex, Step<W>);
}
/// Custom parameter of a [Cucumber Expression].
///
/// Should be implemented only with via [`Parameter`] derive macro.
///
/// [`Parameter`]: macro@crate::Parameter
/// [Cucumber Expression]: https://cucumber.github.io/cucumber-expressions
pub trait Parameter {
/// [`Regex`] matching this [`Parameter`].
///
/// Shouldn't contain any capturing groups.
///
/// Validated during [`Parameter`](macro@crate::Parameter) derive macro
/// expansion.
///
/// [`Regex`]: regex::Regex
const REGEX: &'static str;
/// Name of this [`Parameter`] to be referenced by in
/// [Cucumber Expressions].
///
/// [Cucumber Expressions]: https://cucumber.github.io/cucumber-expressions
const NAME: &'static str;
}
/// Compares two strings in a `const` context.
///
/// As there is no `const impl Trait` and `l == r` calls [`Eq`], we have to use
/// a custom comparison function.
///
/// [`Eq`]: std::cmp::Eq
// TODO: Remove once `Eq` trait is allowed in a `const` context.
#[must_use]
pub const fn str_eq(l: &str, r: &str) -> bool {
if l.len() != r.len() {
return false;
}
let (l, r) = (l.as_bytes(), r.as_bytes());
let mut i = 0;
while i < l.len() {
if l[i] != r[i] {
return false;
}
i += 1;
}
true
}
/// Return-type polymorphism over `async`ness for a `#[world(init)]` attribute
/// of a [`#[derive(World)]`](macro@World) macro.
///
/// It allows to accept both sync and `async` functions as an attribute's
/// argument, by automatically wrapping sync functions in a [`future::Ready`].
///
/// ```rust
/// # use async_trait::async_trait;
/// #
/// # #[derive(Default)]
/// # struct World;
/// #
/// #[async_trait(?Send)]
/// impl cucumber::World for World {
/// type Error = anyhow::Error;
///
/// async fn new() -> Result<Self, Self::Error> {
/// use cucumber::codegen::{
/// IntoWorldResult as _, ToWorldFuture as _,
/// };
///
/// fn as_fn_ptr<T>(v: fn() -> T) -> fn() -> T {
/// v
/// }
///
/// // `#[world(init)]`'s value
/// // ⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄
/// (&as_fn_ptr(<Self as Default>::default))
/// .to_world_future() // maybe wraps into `future::Ready`
/// .await
/// .into_world_result()
/// .map_err(Into::into)
/// }
/// }
/// ```
pub trait ToWorldFuture {
/// [`Future`] returned by this [`World`] constructor.
///
/// Set to [`future::Ready`] in case construction is sync.
type Future: Future;
/// Resolves this [`Future`] for constructing a new[`World`] using
/// [autoderef-based specialization][0].
///
/// [0]: https://tinyurl.com/autoref-spec
fn to_world_future(&self) -> Self::Future;
}
impl<R: IntoWorldResult> ToWorldFuture for fn() -> R {
type Future = future::Ready<R>;
fn to_world_future(&self) -> Self::Future {
future::ready(self())
}
}
impl<Fut: Future> ToWorldFuture for &fn() -> Fut
where
Fut::Output: IntoWorldResult,
{
type Future = Fut;
fn to_world_future(&self) -> Self::Future {
self()
}
}
/// Return-type polymorphism over fallibility for a `#[world(init)]` attribute
/// of a [`#[derive(World)]`](macro@World) macro.
///
/// It allows to accept both fallible (returning [`Result`]) and infallible
/// functions as an attribute's argument, by automatically wrapping infallible
/// functions in a [`Result`]`<`[`World`]`, `[`Infallible`]`>`.
///
/// ```rust
/// # use async_trait::async_trait;
/// #
/// # #[derive(Default)]
/// # struct World;
/// #
/// #[async_trait(?Send)]
/// impl cucumber::World for World {
/// type Error = anyhow::Error;
///
/// async fn new() -> Result<Self, Self::Error> {
/// use cucumber::codegen::{
/// IntoWorldResult as _, ToWorldFuture as _,
/// };
///
/// fn as_fn_ptr<T>(v: fn() -> T) -> fn() -> T {
/// v
/// }
///
/// // `#[world(init)]`'s value
/// // ⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄⌄
/// (&as_fn_ptr(<Self as Default>::default))
/// .to_world_future()
/// .await
/// .into_world_result() // maybe wraps into `Result<_, Infallible>`
/// .map_err(Into::into)
/// }
/// }
/// ```
pub trait IntoWorldResult: Sized {
/// [`World`] type itself.
type World: World;
/// Error returned by this [`World`] constructor.
///
/// Set to [`Infallible`] in case construction is infallible.
type Error;
/// Passes [`Result`]`<`[`World`]`, Self::Error>` as is, or wraps the plain
/// [`World`] in a [`Result`]`<`[`World`]`, `[`Infallible`]`>`.
///
/// # Errors
///
/// In case the [`World`] construction errors.
fn into_world_result(self) -> Result<Self::World, Self::Error>;
}
impl<W: World> IntoWorldResult for W {
type World = Self;
type Error = Infallible;
fn into_world_result(self) -> Result<Self, Self::Error> {
Ok(self)
}
}
impl<W: World, E> IntoWorldResult for Result<W, E> {
type World = W;
type Error = E;
fn into_world_result(self) -> Self {
self
}
}