71 lines
2.3 KiB
Rust
71 lines
2.3 KiB
Rust
//! Field guards
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use crate::{Context, FieldResult};
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use serde::export::PhantomData;
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/// Field guard
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///
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/// Guard is a pre-condition for a field that is resolved if `Ok(())` is returned, otherwise an error is returned.
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///
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/// This trait is defined through the [`async-trait`](https://crates.io/crates/async-trait) macro.
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#[async_trait::async_trait]
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pub trait Guard {
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/// Check whether the guard will allow access to the field.
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async fn check(&self, ctx: &Context<'_>) -> FieldResult<()>;
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}
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/// An extension trait for `Guard`.
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pub trait GuardExt: Guard + Sized {
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/// Merge the two guards.
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fn and<R: Guard>(self, other: R) -> And<Self, R> {
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And(self, other)
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}
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}
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impl<T: Guard> GuardExt for T {}
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/// Guard for [`GuardExt::and`](trait.GuardExt.html#method.and).
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pub struct And<A: Guard, B: Guard>(A, B);
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#[async_trait::async_trait]
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impl<A: Guard + Send + Sync, B: Guard + Send + Sync> Guard for And<A, B> {
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async fn check(&self, ctx: &Context<'_>) -> FieldResult<()> {
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self.0.check(ctx).await?;
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self.1.check(ctx).await
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}
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}
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/// Field post guard
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///
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/// This is a post-condition for a field that is resolved if `Ok(()` is returned, otherwise an error is returned.
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///
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/// This trait is defined through the [`async-trait`](https://crates.io/crates/async-trait) macro.
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#[async_trait::async_trait]
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pub trait PostGuard<T: Send + Sync> {
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/// Check whether to allow the result of the field through.
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async fn check(&self, ctx: &Context<'_>, result: &T) -> FieldResult<()>;
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}
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/// An extension trait for `PostGuard<T>`
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pub trait PostGuardExt<T: Send + Sync>: PostGuard<T> + Sized {
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/// Merge the two guards.
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fn and<R: PostGuard<T>>(self, other: R) -> PostAnd<T, Self, R> {
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PostAnd(self, other, PhantomData)
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}
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}
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impl<T: PostGuard<R>, R: Send + Sync> PostGuardExt<R> for T {}
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/// PostGuard for [`PostGuardExt<T>::and`](trait.PostGuardExt.html#method.and).
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pub struct PostAnd<T: Send + Sync, A: PostGuard<T>, B: PostGuard<T>>(A, B, PhantomData<T>);
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#[async_trait::async_trait]
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impl<T: Send + Sync, A: PostGuard<T> + Send + Sync, B: PostGuard<T> + Send + Sync> PostGuard<T>
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for PostAnd<T, A, B>
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{
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async fn check(&self, ctx: &Context<'_>, result: &T) -> FieldResult<()> {
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self.0.check(ctx, result).await?;
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self.1.check(ctx, result).await
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}
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}
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