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
131
132
133
134
135
136
137
138
139
140
// SPDX-License-Identifier: CC0-1.0

//! Macros for serde trait implementations, and supporting code.
//!

/// Functions used by serde impls of all hashes.
#[cfg(feature = "serde")]
pub mod serde_details {
    use core::marker::PhantomData;
    use core::str::FromStr;
    use core::{fmt, ops, str};

    use crate::FromSliceError;
    struct HexVisitor<ValueT>(PhantomData<ValueT>);
    use serde::{de, Deserializer, Serializer};

    impl<'de, ValueT> de::Visitor<'de> for HexVisitor<ValueT>
    where
        ValueT: FromStr,
        <ValueT as FromStr>::Err: fmt::Display,
    {
        type Value = ValueT;

        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
            formatter.write_str("an ASCII hex string")
        }

        fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
        where
            E: de::Error,
        {
            if let Ok(hex) = str::from_utf8(v) {
                Self::Value::from_str(hex).map_err(E::custom)
            } else {
                return Err(E::invalid_value(de::Unexpected::Bytes(v), &self));
            }
        }

        fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
        where
            E: de::Error,
        {
            Self::Value::from_str(v).map_err(E::custom)
        }
    }

    struct BytesVisitor<ValueT>(PhantomData<ValueT>);

    impl<'de, ValueT> de::Visitor<'de> for BytesVisitor<ValueT>
    where
        ValueT: SerdeHash,
        <ValueT as FromStr>::Err: fmt::Display,
    {
        type Value = ValueT;

        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
            formatter.write_str("a bytestring")
        }

        fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
        where
            E: de::Error,
        {
            SerdeHash::from_slice_delegated(v).map_err(|_| {
                // from_slice only errors on incorrect length
                E::invalid_length(v.len(), &stringify!(N))
            })
        }
    }

    /// Default serialization/deserialization methods.
    pub trait SerdeHash
    where
        Self: Sized
            + FromStr
            + fmt::Display
            + ops::Index<usize, Output = u8>
            + ops::Index<ops::RangeFull, Output = [u8]>,
        <Self as FromStr>::Err: fmt::Display,
    {
        /// Size, in bits, of the hash.
        const N: usize;

        /// Helper function to turn a deserialized slice into the correct hash type.
        fn from_slice_delegated(sl: &[u8]) -> Result<Self, FromSliceError>;

        /// Do serde serialization.
        fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
            if s.is_human_readable() {
                s.collect_str(self)
            } else {
                s.serialize_bytes(&self[..])
            }
        }

        /// Do serde deserialization.
        fn deserialize<'de, D: Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
            if d.is_human_readable() {
                d.deserialize_str(HexVisitor::<Self>(PhantomData))
            } else {
                d.deserialize_bytes(BytesVisitor::<Self>(PhantomData))
            }
        }
    }
}

/// Implements `Serialize` and `Deserialize` for a type `$t` which
/// represents a newtype over a byte-slice over length `$len`.
#[macro_export]
#[cfg(feature = "serde")]
macro_rules! serde_impl(
    ($t:ident, $len:expr $(, $gen:ident: $gent:ident)*) => (
        impl<$($gen: $gent),*> $crate::serde_macros::serde_details::SerdeHash for $t<$($gen),*> {
            const N : usize = $len;
            fn from_slice_delegated(sl: &[u8]) -> Result<Self, $crate::FromSliceError> {
                #[allow(unused_imports)]
                use $crate::Hash as _;
                $t::from_slice(sl)
            }
        }

        impl<$($gen: $gent),*> $crate::serde::Serialize for $t<$($gen),*> {
            fn serialize<S: $crate::serde::Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
                $crate::serde_macros::serde_details::SerdeHash::serialize(self, s)
            }
        }

        impl<'de $(, $gen: $gent)*> $crate::serde::Deserialize<'de> for $t<$($gen),*> {
            fn deserialize<D: $crate::serde::Deserializer<'de>>(d: D) -> Result<$t<$($gen),*>, D::Error> {
                $crate::serde_macros::serde_details::SerdeHash::deserialize(d)
            }
        }
));

/// Does an "empty" serde implementation for the configuration without serde feature.
#[macro_export]
#[cfg(not(feature = "serde"))]
macro_rules! serde_impl(
        ($t:ident, $len:expr $(, $gen:ident: $gent:ident)*) => ()
);