-
Notifications
You must be signed in to change notification settings - Fork 2
Expand file tree
/
Copy pathvalue.rs
More file actions
148 lines (129 loc) · 4.32 KB
/
value.rs
File metadata and controls
148 lines (129 loc) · 4.32 KB
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
141
142
143
144
145
146
147
148
//! Non-streaming translation between Serde data formats using zero-copy deserialization.
use std::borrow::Cow;
use std::fmt;
use serde::de::{self, Deserialize, Deserializer};
use serde::ser::{Serialize, SerializeMap, Serializer};
/// A deserialized value referencing borrowed data.
///
/// `Value` supports cases where an input format doesn't provide access to a [`Deserializer`] for
/// direct transcoding, and instead requires deserializing into an in-memory value.
///
/// Unlike most "Serde value" types, `Value` is explicitly optimized for use in transcoding.
/// It prefers zero-copy deserialization for byte sequences and strings, which limits the lifetime
/// of the value and the types of inputs it can deserialize from. It represents maps as `Vec`s of
/// key-value pairs, which preserves ordering but doesn't allow random access to entries.
pub(crate) enum Value<'a> {
Unit,
Bool(bool),
I8(i8),
I16(i16),
I32(i32),
I64(i64),
I128(i128),
U8(u8),
U16(u16),
U32(u32),
U64(u64),
U128(u128),
F32(f32),
F64(f64),
Char(char),
String(Cow<'a, str>),
Bytes(Cow<'a, [u8]>),
Seq(Vec<Value<'a>>),
Map(Vec<(Value<'a>, Value<'a>)>),
}
impl Serialize for Value<'_> {
fn serialize<S>(&self, s: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
match self {
Value::Unit => s.serialize_unit(),
Value::Bool(b) => s.serialize_bool(*b),
Value::I8(n) => s.serialize_i8(*n),
Value::I16(n) => s.serialize_i16(*n),
Value::I32(n) => s.serialize_i32(*n),
Value::I64(n) => s.serialize_i64(*n),
Value::I128(n) => s.serialize_i128(*n),
Value::U8(n) => s.serialize_u8(*n),
Value::U16(n) => s.serialize_u16(*n),
Value::U32(n) => s.serialize_u32(*n),
Value::U64(n) => s.serialize_u64(*n),
Value::U128(n) => s.serialize_u128(*n),
Value::F32(f) => s.serialize_f32(*f),
Value::F64(f) => s.serialize_f64(*f),
Value::Char(c) => s.serialize_char(*c),
Value::String(v) => v.serialize(s),
Value::Bytes(v) => v.serialize(s),
Value::Seq(v) => v.serialize(s),
Value::Map(m) => {
let mut s = s.serialize_map(Some(m.len()))?;
for (k, v) in m {
s.serialize_entry(k, v)?;
}
s.end()
}
}
}
}
/// Implements the simplest [`de::Visitor`] methods that shove scalars into [`Value`]s.
macro_rules! impl_value_scalar_visitors {
( $( $name:ident($($arg:ident: $ty:ty)?) => $result:expr; )* ) => {
$(fn $name<E: de::Error>(self, $($arg: $ty)?) -> Result<Self::Value, E> {
Ok($result)
})*
};
}
impl<'de: 'a, 'a> Deserialize<'de> for Value<'a> {
fn deserialize<D>(d: D) -> Result<Value<'a>, D::Error>
where
D: Deserializer<'de>,
{
struct Visitor;
impl<'a> de::Visitor<'a> for Visitor {
type Value = Value<'a>;
fn expecting(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str("any supported value")
}
impl_value_scalar_visitors! {
visit_unit() => Value::Unit;
visit_bool(v: bool) => Value::Bool(v);
visit_i8(v: i8) => Value::I8(v);
visit_i16(v: i16) => Value::I16(v);
visit_i32(v: i32) => Value::I32(v);
visit_i64(v: i64) => Value::I64(v);
visit_i128(v: i128) => Value::I128(v);
visit_u8(v: u8) => Value::U8(v);
visit_u16(v: u16) => Value::U16(v);
visit_u32(v: u32) => Value::U32(v);
visit_u64(v: u64) => Value::U64(v);
visit_u128(v: u128) => Value::U128(v);
visit_f32(v: f32) => Value::F32(v);
visit_f64(v: f64) => Value::F64(v);
visit_char(v: char) => Value::Char(v);
visit_borrowed_str(v: &'a str) => Value::String(Cow::Borrowed(v));
visit_str(v: &str) => Value::String(Cow::Owned(v.to_owned()));
visit_string(v: String) => Value::String(Cow::Owned(v));
visit_borrowed_bytes(v: &'a [u8]) => Value::Bytes(Cow::Borrowed(v));
visit_bytes(v: &[u8]) => Value::Bytes(Cow::Owned(v.to_owned()));
visit_byte_buf(v: Vec<u8>) => Value::Bytes(Cow::Owned(v));
}
fn visit_seq<A: de::SeqAccess<'a>>(self, mut seq: A) -> Result<Self::Value, A::Error> {
let mut vec = Vec::with_capacity(seq.size_hint().unwrap_or(0));
while let Some(e) = seq.next_element()? {
vec.push(e);
}
Ok(Value::Seq(vec))
}
fn visit_map<A: de::MapAccess<'a>>(self, mut map: A) -> Result<Self::Value, A::Error> {
let mut vec = Vec::with_capacity(map.size_hint().unwrap_or(0));
while let Some(entry) = map.next_entry()? {
vec.push(entry);
}
Ok(Value::Map(vec))
}
}
d.deserialize_any(Visitor)
}
}