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//! Module for API context management.
//!
//! This module defines traits and structs that can be used to manage
//! contextual data related to a request, as it is passed through a series of
//! hyper services.
//!
//! See the `context_tests` module below for examples of how to use.
use crate::auth::{AuthData, Authorization};
use crate::XSpanIdString;
use hyper::{service::Service, Request, Response};
use std::future::Future;
use std::pin::Pin;
/// Defines methods for accessing, modifying, adding and removing the data stored
/// in a context. Used to specify the requirements that a hyper service makes on
/// a generic context type that it receives with a request, e.g.
///
/// ```rust
/// # use futures::future::ok;
/// # use std::future::Future;
/// # use std::marker::PhantomData;
/// # use std::pin::Pin;
/// # use std::task::{Context, Poll};
/// # use swagger::context::*;
/// #
/// # struct MyItem;
/// # fn do_something_with_my_item(item: &MyItem) {}
/// #
/// struct MyService<C> {
/// marker: PhantomData<C>,
/// }
///
/// impl<C> hyper::service::Service<(hyper::Request<hyper::Body>, C)> for MyService<C>
/// where C: Has<MyItem> + Send + 'static
/// {
/// type Response = hyper::Response<hyper::Body>;
/// type Error = std::io::Error;
/// type Future = Pin<Box<dyn Future<Output=Result<Self::Response, Self::Error>>>>;
///
/// fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
/// Poll::Ready(Ok(()))
/// }
///
/// fn call(&mut self, req : (hyper::Request<hyper::Body>, C)) -> Self::Future {
/// let (_, context) = req;
/// do_something_with_my_item(Has::<MyItem>::get(&context));
/// Box::pin(ok(hyper::Response::new(hyper::Body::empty())))
/// }
/// }
/// ```
pub trait Has<T> {
/// Get an immutable reference to the value.
fn get(&self) -> &T;
/// Get a mutable reference to the value.
fn get_mut(&mut self) -> &mut T;
/// Set the value.
fn set(&mut self, value: T);
}
/// Defines a method for permanently extracting a value, changing the resulting
/// type. Used to specify that a hyper service consumes some data from the context,
/// making it unavailable to later layers, e.g.
///
/// ```rust
/// # use futures::future::{Future, ok};
/// # use std::task::{Context, Poll};
/// # use std::marker::PhantomData;
/// # use swagger::context::*;
/// #
/// struct MyItem1;
/// struct MyItem2;
/// struct MyItem3;
///
/// struct MiddlewareService<T, C> {
/// inner: T,
/// marker: PhantomData<C>,
/// }
///
/// impl<T, C, D, E> hyper::service::Service<(hyper::Request<hyper::Body>, C)> for MiddlewareService<T, C>
/// where
/// C: Pop<MyItem1, Result=D> + Send + 'static,
/// D: Pop<MyItem2, Result=E>,
/// E: Pop<MyItem3>,
/// E::Result: Send + 'static,
/// T: hyper::service::Service<(hyper::Request<hyper::Body>, E::Result)>
/// {
/// type Response = T::Response;
/// type Error = T::Error;
/// type Future = T::Future;
///
/// fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
/// self.inner.poll_ready(cx)
/// }
///
/// fn call(&mut self, req : (hyper::Request<hyper::Body>, C)) -> Self::Future {
/// let (request, context) = req;
///
/// // type annotations optional, included for illustrative purposes
/// let (_, context): (MyItem1, D) = context.pop();
/// let (_, context): (MyItem2, E) = context.pop();
/// let (_, context): (MyItem3, E::Result) = context.pop();
///
/// self.inner.call((request, context))
/// }
/// }
pub trait Pop<T> {
/// The type that remains after the value has been popped.
type Result;
/// Extracts a value.
fn pop(self) -> (T, Self::Result);
}
/// Defines a method for inserting a value, changing the resulting
/// type. Used to specify that a hyper service adds some data from the context,
/// making it available to later layers, e.g.
///
/// ```rust
/// # use swagger::context::*;
/// # use std::marker::PhantomData;
/// # use std::task::{Context, Poll};
/// #
/// struct MyItem1;
/// struct MyItem2;
/// struct MyItem3;
///
/// struct MiddlewareService<T, C> {
/// inner: T,
/// marker: PhantomData<C>,
/// }
///
/// impl<T, C, D, E> hyper::service::Service<(hyper::Request<hyper::Body>, C)> for MiddlewareService<T, C>
/// where
/// C: Push<MyItem1, Result=D> + Send + 'static,
/// D: Push<MyItem2, Result=E>,
/// E: Push<MyItem3>,
/// E::Result: Send + 'static,
/// T: hyper::service::Service<(hyper::Request<hyper::Body>, E::Result)>
/// {
/// type Response = T::Response;
/// type Error = T::Error;
/// type Future = T::Future;
///
/// fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
/// self.inner.poll_ready(cx)
/// }
///
/// fn call(&mut self, req : (hyper::Request<hyper::Body>, C)) -> Self::Future {
/// let (request, context) = req;
/// let context = context
/// .push(MyItem1{})
/// .push(MyItem2{})
/// .push(MyItem3{});
/// self.inner.call((request, context))
/// }
/// }
pub trait Push<T> {
/// The type that results from adding an item.
type Result;
/// Inserts a value.
fn push(self, value: T) -> Self::Result;
}
/// Defines a struct that can be used to build up contexts recursively by
/// adding one item to the context at a time, and a unit struct representing an
/// empty context. The first argument is the name of the newly defined context struct
/// that is used to add an item to the context, the second argument is the name of
/// the empty context struct, and subsequent arguments are the types
/// that can be stored in contexts built using these struct.
///
/// A cons list built using the generated context type will implement Has<T> and Pop<T>
/// for each type T that appears in the list, provided that the list only
/// contains the types that were passed to the macro invocation after the context
/// type name.
///
/// All list types constructed using the generated types will implement `Push<T>`
/// for all types `T` that appear in the list passed to the macro invocation.
///
/// E.g.
///
/// ```edition2018
/// #[derive(Default)]
/// struct MyType1;
/// #[derive(Default)]
/// struct MyType2;
/// #[derive(Default)]
/// struct MyType3;
/// #[derive(Default)]
/// struct MyType4;
///
/// swagger::new_context_type!(MyContext, MyEmpContext, MyType1, MyType2, MyType3);
///
/// fn use_has_my_type_1<T: swagger::Has<MyType1>> (_: &T) {}
/// fn use_has_my_type_2<T: swagger::Has<MyType2>> (_: &T) {}
/// fn use_has_my_type_3<T: swagger::Has<MyType3>> (_: &T) {}
/// fn use_has_my_type_4<T: swagger::Has<MyType4>> (_: &T) {}
///
/// // Will implement `Has<MyType1>` and `Has<MyType2>` because these appear
/// // in the type, and were passed to `new_context_type!`. Will not implement
/// // `Has<MyType3>` even though it was passed to `new_context_type!`, because
/// // it is not included in the type.
/// type ExampleContext = MyContext<MyType1, MyContext<MyType2, MyEmpContext>>;
///
/// // Will not implement `Has<MyType4>` even though it appears in the type,
/// // because `MyType4` was not passed to `new_context_type!`.
/// type BadContext = MyContext<MyType1, MyContext<MyType4, MyEmpContext>>;
///
/// fn main() {
/// # use swagger::Push as _;
/// let context : ExampleContext =
/// MyEmpContext::default()
/// .push(MyType2{})
/// .push(MyType1{});
///
/// use_has_my_type_1(&context);
/// use_has_my_type_2(&context);
/// // use_has_my_type_3(&context); // will fail
///
/// // Will fail because `MyType4`// was not passed to `new_context_type!`
/// // let context = MyEmpContext::default().push(MyType4{});
///
/// let bad_context: BadContext = BadContext::default();
/// // use_has_my_type_4(&bad_context); // will fail
/// }
/// ```
///
/// See the `context_tests` module for more usage examples.
#[macro_export]
macro_rules! new_context_type {
($context_name:ident, $empty_context_name:ident, $($types:ty),+ ) => {
/// Wrapper type for building up contexts recursively, adding one item
/// to the context at a time.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct $context_name<T, C> {
head: T,
tail: C,
}
/// Unit struct representing an empty context with no data in it.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct $empty_context_name;
// implement `Push<T>` on the empty context type for each type `T` that
// was passed to the macro
$(
impl $crate::Push<$types> for $empty_context_name {
type Result = $context_name<$types, Self>;
fn push(self, item: $types) -> Self::Result {
$context_name{head: item, tail: Self::default()}
}
}
// implement `Has<T>` for a list where `T` is the type of the head
impl<C> $crate::Has<$types> for $context_name<$types, C> {
fn set(&mut self, item: $types) {
self.head = item;
}
fn get(&self) -> &$types {
&self.head
}
fn get_mut(&mut self) -> &mut $types {
&mut self.head
}
}
// implement `Pop<T>` for a list where `T` is the type of the head
impl<C> $crate::Pop<$types> for $context_name<$types, C> {
type Result = C;
fn pop(self) -> ($types, Self::Result) {
(self.head, self.tail)
}
}
// implement `Push<U>` for non-empty lists, for each type `U` that was passed
// to the macro
impl<C, T> $crate::Push<$types> for $context_name<T, C> {
type Result = $context_name<$types, Self>;
fn push(self, item: $types) -> Self::Result {
$context_name{head: item, tail: self}
}
}
)+
// Add implementations of `Has<T>` and `Pop<T>` when `T` is any type stored in
// the list, not just the head.
$crate::new_context_type!(impl extend_has $context_name, $empty_context_name, $($types),+);
};
// "HELPER" MACRO CASE - NOT FOR EXTERNAL USE
// takes a type `Type1` ($head) and a non-empty list of types `Types` ($tail). First calls
// another helper macro to define the following impls, for each `Type2` in `Types`:
// ```
// impl<C: Has<Type1> Has<Type1> for $context_name<Type2, C> {...}
// impl<C: Has<Type2> Has<Type2> for $context_name<Type1, C> {...}
// impl<C: Pop<Type1> Pop<Type1> for $context_name<Type2, C> {...}
// impl<C: Pop<Type2> Pop<Type2> for $context_name<Type1, C> {...}
// ```
// then calls itself again with the rest of the list. The end result is to define the above
// impls for all distinct pairs of types in the original list.
(impl extend_has $context_name:ident, $empty_context_name:ident, $head:ty, $($tail:ty),+ ) => {
$crate::new_context_type!(
impl extend_has_helper
$context_name,
$empty_context_name,
$head,
$($tail),+
);
$crate::new_context_type!(impl extend_has $context_name, $empty_context_name, $($tail),+);
};
// "HELPER" MACRO CASE - NOT FOR EXTERNAL USE
// base case of the preceding helper macro - was passed an empty list of types, so
// we don't need to do anything.
(impl extend_has $context_name:ident, $empty_context_name:ident, $head:ty) => {};
// "HELPER" MACRO CASE - NOT FOR EXTERNAL USE
// takes a type `Type1` ($type) and a non-empty list of types `Types` ($types). For
// each `Type2` in `Types`, defines the following impls:
// ```
// impl<C: Has<Type1> Has<Type1> for $context_name<Type2, C> {...}
// impl<C: Has<Type2> Has<Type2> for $context_name<Type1, C> {...}
// impl<C: Pop<Type1> Pop<Type1> for $context_name<Type2, C> {...}
// impl<C: Pop<Type2> Pop<Type2> for $context_name<Type1, C> {...}
// ```
//
(impl extend_has_helper
$context_name:ident,
$empty_context_name:ident,
$type:ty,
$($types:ty),+
) => {
$(
impl<C: $crate::Has<$type>> $crate::Has<$type> for $context_name<$types, C> {
fn set(&mut self, item: $type) {
self.tail.set(item);
}
fn get(&self) -> &$type {
self.tail.get()
}
fn get_mut(&mut self) -> &mut $type {
self.tail.get_mut()
}
}
impl<C: $crate::Has<$types>> $crate::Has<$types> for $context_name<$type, C> {
fn set(&mut self, item: $types) {
self.tail.set(item);
}
fn get(&self) -> &$types {
self.tail.get()
}
fn get_mut(&mut self) -> &mut $types {
self.tail.get_mut()
}
}
impl<C> $crate::Pop<$type> for $context_name<$types, C> where C: $crate::Pop<$type> {
type Result = $context_name<$types, C::Result>;
fn pop(self) -> ($type, Self::Result) {
let (value, tail) = self.tail.pop();
(value, $context_name{ head: self.head, tail})
}
}
impl<C> $crate::Pop<$types> for $context_name<$type, C> where C: $crate::Pop<$types> {
type Result = $context_name<$type, C::Result>;
fn pop(self) -> ($types, Self::Result) {
let (value, tail) = self.tail.pop();
(value, $context_name{ head: self.head, tail})
}
}
)+
};
}
// Create a default context type to export.
new_context_type!(
ContextBuilder,
EmptyContext,
XSpanIdString,
Option<AuthData>,
Option<Authorization>
);
/// Macro for easily defining context types. The first argument should be a
/// context type created with `new_context_type!` and subsequent arguments are the
/// types to be stored in the context, with the outermost first.
///
/// ```rust
/// # #[macro_use] extern crate swagger;
/// # use swagger::{Has, Pop, Push};
///
/// # struct Type1;
/// # struct Type2;
/// # struct Type3;
///
/// # new_context_type!(MyContext, MyEmptyContext, Type1, Type2, Type3);
///
/// // the following two types are identical
/// type ExampleContext1 = make_context_ty!(MyContext, MyEmptyContext, Type1, Type2, Type3);
/// type ExampleContext2 = MyContext<Type1, MyContext<Type2, MyContext<Type3, MyEmptyContext>>>;
///
/// // e.g. this wouldn't compile if they were different types
/// fn do_nothing(input: ExampleContext1) -> ExampleContext2 {
/// input
/// }
/// ```
#[macro_export]
macro_rules! make_context_ty {
($context_name:ident, $empty_context_name:ident, $type:ty $(, $types:ty)* $(,)* ) => {
$context_name<$type, $crate::make_context_ty!($context_name, $empty_context_name, $($types),*)>
};
($context_name:ident, $empty_context_name:ident $(,)* ) => {
$empty_context_name
};
}
/// Macro for easily defining context values. The first argument should be a
/// context type created with `new_context_type!` and subsequent arguments are the
/// values to be stored in the context, with the outermost first.
///
/// ```rust
/// # #[macro_use] extern crate swagger;
/// # use swagger::{Has, Pop, Push};
///
/// # #[derive(PartialEq, Eq, Debug)]
/// # struct Type1;
/// # #[derive(PartialEq, Eq, Debug)]
/// # struct Type2;
/// # #[derive(PartialEq, Eq, Debug)]
/// # struct Type3;
///
/// # new_context_type!(MyContext, MyEmptyContext, Type1, Type2, Type3);
///
/// fn main() {
/// // the following are equivalent
/// let context1 = make_context!(MyContext, MyEmptyContext, Type1 {}, Type2 {}, Type3 {});
/// let context2 = MyEmptyContext::default()
/// .push(Type3{})
/// .push(Type2{})
/// .push(Type1{});
///
/// assert_eq!(context1, context2);
/// }
/// ```
#[macro_export]
macro_rules! make_context {
($context_name:ident, $empty_context_name:ident, $value:expr $(, $values:expr)* $(,)*) => {
$crate::make_context!($context_name, $empty_context_name, $($values),*).push($value)
};
($context_name:ident, $empty_context_name:ident $(,)* ) => {
$empty_context_name::default()
};
}
/// Context wrapper, to bind an API with a context.
#[derive(Debug)]
pub struct ContextWrapper<T, C> {
api: T,
context: C,
}
impl<T, C> ContextWrapper<T, C> {
/// Create a new ContextWrapper, binding the API and context.
pub fn new(api: T, context: C) -> Self {
Self { api, context }
}
/// Borrows the API.
pub fn api(&self) -> &T {
&self.api
}
/// Borrows the context.
pub fn context(&self) -> &C {
&self.context
}
}
impl<T: Clone, C: Clone> Clone for ContextWrapper<T, C> {
fn clone(&self) -> Self {
ContextWrapper {
api: self.api.clone(),
context: self.context.clone(),
}
}
}
/// Trait designed to ensure consistency in context used by swagger middlewares
///
/// ```rust
/// # use swagger::context::*;
/// # use std::marker::PhantomData;
/// # use std::task::{Context, Poll};
/// # use swagger::auth::{AuthData, Authorization};
/// # use swagger::XSpanIdString;
///
/// struct ExampleMiddleware<T, C> {
/// inner: T,
/// marker: PhantomData<C>,
/// }
///
/// impl<T, C> hyper::service::Service<(hyper::Request<hyper::Body>, C)> for ExampleMiddleware<T, C>
/// where
/// T: SwaggerService<hyper::Body, hyper::Body, C>,
/// C: Has<Option<AuthData>> +
/// Has<Option<Authorization>> +
/// Has<XSpanIdString> +
/// Clone +
/// Send +
/// 'static,
/// {
/// type Response = T::Response;
/// type Error = T::Error;
/// type Future = T::Future;
///
/// fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
/// self.inner.poll_ready(cx)
/// }
///
/// fn call(&mut self, req: (hyper::Request<hyper::Body>, C)) -> Self::Future {
/// self.inner.call(req)
/// }
/// }
/// ```
pub trait SwaggerService<RequestBody, ResponseBody, Context>:
Clone
+ Service<
(Request<RequestBody>, Context),
Response = Response<ResponseBody>,
Error = hyper::Error,
Future = Pin<Box<dyn Future<Output = Result<Response<ResponseBody>, hyper::Error>>>>,
>
where
Context: Has<Option<AuthData>>
+ Has<Option<Authorization>>
+ Has<XSpanIdString>
+ Clone
+ 'static
+ Send,
{
}
impl<ReqB, ResB, Context, T> SwaggerService<ReqB, ResB, Context> for T
where
T: Clone
+ Service<
(Request<ReqB>, Context),
Response = Response<ResB>,
Error = hyper::Error,
Future = Pin<Box<dyn Future<Output = Result<Response<ResB>, hyper::Error>>>>,
>,
Context: Has<Option<AuthData>>
+ Has<Option<Authorization>>
+ Has<XSpanIdString>
+ Clone
+ 'static
+ Send,
{
}
#[cfg(test)]
mod context_tests {
use super::Has;
use super::*;
struct ContextItem1 {
val: u32,
}
struct ContextItem2;
struct ContextItem3;
// all the hyper service layers you will be using, and what requirements
// their contexts types have. Use the `new_context_type!` macro to create
// a context type and empty context type that are capable of containing all the
// types that your hyper services require.
new_context_type!(
MyContext,
MyEmptyContext,
ContextItem1,
ContextItem2,
ContextItem3
);
#[test]
fn send_request() {
let t = MyEmptyContext::default();
let t = t.push(ContextItem1 { val: 1 });
let t = t.push(ContextItem2);
{
let v: &ContextItem1 = t.get();
assert_eq!(v.val, 1);
}
let (_, mut t): (ContextItem2, _) = t.pop();
{
let v: &mut ContextItem1 = t.get_mut();
v.val = 4;
}
{
let v: &ContextItem1 = t.get();
assert_eq!(v.val, 4);
}
}
}