flowstate 0.8.1

Workflow runtime powered by finite state machines.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97

#[cfg(feature = "async")]
use crate::{AsyncContext, middleware::AsyncWorkflowMiddleware};
use crate::{
    Context,
    middleware::{WorkflowMetadata, WorkflowMiddleware, identity::IdentityMiddleware},
};

pub struct MiddlewareStack<Inner, Outer> {
    inner: Inner,
    outer: Outer,
}

impl<Inner, Outer> WorkflowMiddleware for MiddlewareStack<Inner, Outer>
where
    Inner: WorkflowMiddleware,
    Outer: WorkflowMiddleware,
{
    fn wrap_workflow<'workflow, Result>(
        &self,
        metadata: &'workflow WorkflowMetadata<'workflow>,
        ctx: &Context,
        next: impl FnOnce() -> Result,
    ) -> impl FnOnce() -> Result {
        self.outer
            .wrap_workflow(metadata, ctx, self.inner.wrap_workflow(metadata, ctx, next))
    }

    fn wrap_state<'state, Transition>(
        &self,
        metadata: &'state super::WorkflowStateMetadata<'state>,
        ctx: &Context,
        next: impl FnOnce() -> Transition,
    ) -> impl FnOnce() -> Transition {
        self.outer
            .wrap_state(metadata, ctx, self.inner.wrap_state(metadata, ctx, next))
    }
}

#[cfg(feature = "async")]
impl<Inner, Outer> AsyncWorkflowMiddleware for MiddlewareStack<Inner, Outer>
where
    Inner: AsyncWorkflowMiddleware,
    Outer: AsyncWorkflowMiddleware,
{
    fn wrap_workflow<'workflow, Result: Send + 'workflow>(
        &self,
        metadata: &'workflow WorkflowMetadata<'workflow>,
        ctx: &AsyncContext,
        fut: impl Future<Output = Result> + Send + 'workflow,
    ) -> impl Future<Output = Result> + Send + 'workflow {
        self.outer
            .wrap_workflow(metadata, ctx, self.inner.wrap_workflow(metadata, ctx, fut))
    }

    fn wrap_state<'state, Transition: Send + 'state>(
        &self,
        metadata: &'state super::WorkflowStateMetadata<'state>,
        ctx: &AsyncContext,
        fut: impl Future<Output = Transition> + Send + 'state,
    ) -> impl Future<Output = Transition> + Send + 'state {
        self.outer
            .wrap_state(metadata, ctx, self.inner.wrap_state(metadata, ctx, fut))
    }
}

pub struct MiddlewareStackBuilder<Stack>(Stack);

impl MiddlewareStackBuilder<IdentityMiddleware> {
    pub fn new() -> Self {
        Self::default()
    }
}

impl Default for MiddlewareStackBuilder<IdentityMiddleware> {
    fn default() -> Self {
        Self(Default::default())
    }
}

impl<Stack> MiddlewareStackBuilder<Stack> {
    /// Adds a new layer to the middleware stack.
    ///
    /// Layers are executed in the order they are added.
    pub fn layer<Middleware>(
        self,
        middleware: Middleware,
    ) -> MiddlewareStackBuilder<MiddlewareStack<Middleware, Stack>> {
        MiddlewareStackBuilder(MiddlewareStack {
            inner: middleware,
            outer: self.0,
        })
    }

    pub fn build(self) -> Stack {
        self.0
    }
}