tc_scalar/reference/
after.rs

1//! Delay resolving a `TCRef` until a given dependency is resolved.
2
3use std::collections::HashSet;
4use std::fmt;
5
6use async_hash::{Digest, Hash, Output};
7use async_trait::async_trait;
8use destream::{de, en};
9use get_size::GetSize;
10use get_size_derive::*;
11use log::debug;
12use safecast::{Match, TryCastFrom, TryCastInto};
13
14use tc_error::*;
15use tc_transact::public::{Public, StateInstance, ToState};
16use tc_value::Value;
17use tcgeneric::{Id, Instance, Map, PathSegment, TCPathBuf};
18
19use crate::{OpDef, Scalar, Scope};
20
21use super::Refer;
22
23/// Struct to delay resolving another reference(s) until some preliminary reference is resolved.
24#[derive(Clone, Eq, PartialEq, GetSize)]
25pub struct After {
26    when: Scalar,
27    then: Scalar,
28}
29
30#[async_trait]
31impl<State> Refer<State> for After
32where
33    State: StateInstance + Refer<State> + From<Scalar>,
34    State::Closure: From<(Map<State>, OpDef)> + TryCastFrom<State>,
35    Map<State>: TryFrom<State, Error = TCError>,
36    Value: TryFrom<State, Error = TCError> + TryCastFrom<State>,
37    bool: TryCastFrom<State>,
38{
39    fn dereference_self(self, path: &TCPathBuf) -> Self {
40        Self {
41            when: self.when.dereference_self(path),
42            then: self.then.dereference_self(path),
43        }
44    }
45
46    fn is_conditional(&self) -> bool {
47        self.then.is_conditional()
48    }
49
50    fn is_inter_service_write(&self, cluster_path: &[PathSegment]) -> bool {
51        self.when.is_inter_service_write(cluster_path)
52            || self.then.is_inter_service_write(cluster_path)
53    }
54
55    fn is_ref(&self) -> bool {
56        true
57    }
58
59    fn reference_self(self, path: &TCPathBuf) -> Self {
60        Self {
61            when: self.when.reference_self(path),
62            then: self.then.reference_self(path),
63        }
64    }
65
66    fn requires(&self, deps: &mut HashSet<Id>) {
67        self.when.requires(deps);
68        self.then.requires(deps);
69    }
70
71    async fn resolve<'a, T: ToState<State> + Public<State> + Instance>(
72        self,
73        context: &'a Scope<'a, State, T>,
74        txn: &'a State::Txn,
75    ) -> TCResult<State> {
76        debug!("After::resolve {:?} from context ()", self);
77        if self.when.is_conditional() {
78            return Err(bad_request!(
79                "After does not allow a conditional clause {:?}",
80                self.when,
81            ));
82        }
83
84        self.when.resolve(context, txn).await?;
85        self.then.resolve(context, txn).await
86    }
87}
88
89impl<'a, D: Digest> Hash<D> for &'a After {
90    fn hash(self) -> Output<D> {
91        Hash::<D>::hash((&self.when, &self.then))
92    }
93}
94
95impl TryCastFrom<Scalar> for After {
96    fn can_cast_from(scalar: &Scalar) -> bool {
97        scalar.matches::<(Scalar, Scalar)>()
98    }
99
100    fn opt_cast_from(scalar: Scalar) -> Option<Self> {
101        scalar
102            .opt_cast_into()
103            .map(|(when, then)| Self { when, then })
104    }
105}
106
107#[async_trait]
108impl de::FromStream for After {
109    type Context = ();
110
111    async fn from_stream<D: de::Decoder>(context: (), decoder: &mut D) -> Result<Self, D::Error> {
112        let (when, then) =
113            <(Scalar, Scalar) as de::FromStream>::from_stream(context, decoder).await?;
114
115        Ok(Self { when, then })
116    }
117}
118
119impl<'en> en::IntoStream<'en> for After {
120    fn into_stream<E: en::Encoder<'en>>(self, encoder: E) -> Result<E::Ok, E::Error> {
121        (self.when, self.then).into_stream(encoder)
122    }
123}
124
125impl<'en> en::ToStream<'en> for After {
126    fn to_stream<E: en::Encoder<'en>>(&'en self, encoder: E) -> Result<E::Ok, E::Error> {
127        en::IntoStream::into_stream((&self.when, &self.then), encoder)
128    }
129}
130
131impl fmt::Debug for After {
132    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
133        write!(f, "after {:?} then {:?}", self.when, self.then)
134    }
135}
tc_scalar/reference/after.rs

tc_scalar/reference/
after.rs
