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
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130

//! Delay resolving a `TCRef` until a given dependency is resolved.

use async_hash::Hash;
use std::collections::HashSet;
use std::fmt;

use async_trait::async_trait;
use destream::{de, en};
use log::debug;
use safecast::{Match, TryCastFrom, TryCastInto};
use sha2::digest::{Digest, Output};

use tc_error::*;
use tcgeneric::{Id, Instance, PathSegment, TCPathBuf};

use crate::route::Public;
use crate::scalar::{Scalar, Scope};
use crate::state::{State, ToState};
use crate::txn::Txn;

use super::Refer;

/// Struct to delay resolving another reference(s) until some preliminary reference is resolved.
#[derive(Clone, Eq, PartialEq)]
pub struct After {
    when: Scalar,
    then: Scalar,
}

#[async_trait]
impl Refer for After {
    fn dereference_self(self, path: &TCPathBuf) -> Self {
        Self {
            when: self.when.dereference_self(path),
            then: self.then.dereference_self(path),
        }
    }

    fn is_conditional(&self) -> bool {
        self.then.is_conditional()
    }

    fn is_inter_service_write(&self, cluster_path: &[PathSegment]) -> bool {
        self.when.is_inter_service_write(cluster_path)
            || self.then.is_inter_service_write(cluster_path)
    }

    fn reference_self(self, path: &TCPathBuf) -> Self {
        Self {
            when: self.when.reference_self(path),
            then: self.then.reference_self(path),
        }
    }

    fn requires(&self, deps: &mut HashSet<Id>) {
        self.when.requires(deps);
        self.then.requires(deps);
    }

    async fn resolve<'a, T: ToState + Instance + Public>(
        self,
        context: &'a Scope<'a, T>,
        txn: &'a Txn,
    ) -> TCResult<State> {
        debug!("After::resolve {} from context ()", self);
        if self.when.is_conditional() {
            return Err(TCError::bad_request(
                "After does not allow a conditional clause",
                self.when,
            ));
        }

        self.when.resolve(context, txn).await?;
        self.then.resolve(context, txn).await
    }
}

impl<'a, D: Digest> Hash<D> for &'a After {
    fn hash(self) -> Output<D> {
        Hash::<D>::hash((&self.when, &self.then))
    }
}

impl TryCastFrom<Scalar> for After {
    fn can_cast_from(scalar: &Scalar) -> bool {
        scalar.matches::<(Scalar, Scalar)>()
    }

    fn opt_cast_from(scalar: Scalar) -> Option<Self> {
        scalar
            .opt_cast_into()
            .map(|(when, then)| Self { when, then })
    }
}

#[async_trait]
impl de::FromStream for After {
    type Context = ();

    async fn from_stream<D: de::Decoder>(context: (), decoder: &mut D) -> Result<Self, D::Error> {
        let (when, then) =
            <(Scalar, Scalar) as de::FromStream>::from_stream(context, decoder).await?;

        Ok(Self { when, then })
    }
}

impl<'en> en::IntoStream<'en> for After {
    fn into_stream<E: en::Encoder<'en>>(self, encoder: E) -> Result<E::Ok, E::Error> {
        (self.when, self.then).into_stream(encoder)
    }
}

impl<'en> en::ToStream<'en> for After {
    fn to_stream<E: en::Encoder<'en>>(&'en self, encoder: E) -> Result<E::Ok, E::Error> {
        en::IntoStream::into_stream((&self.when, &self.then), encoder)
    }
}

impl fmt::Debug for After {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "after {:?} then {:?}", self.when, self.then)
    }
}

impl fmt::Display for After {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "after {} then {}", self.when, self.then)
    }
}