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
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169

use crate::Value;
use std::cmp::Ordering;
use std::collections::BTreeMap;
use std::ops::{Deref, DerefMut};

/// We'd like to avoid allocating when resolving struct fields,
/// so this is the borrowed version of Value.
/// It's a bit involved to make this work; more details can be
/// found in the excellent guide here:
/// <https://github.com/sunshowers/borrow-complex-key-example/blob/master/src/lib.rs>
#[derive(Copy, Clone, Debug, PartialEq, Hash, Eq, Ord, PartialOrd)]
pub enum BorrowedKey<'a> {
    Value(&'a Value),
    Str(&'a str),
}

pub trait ObjectKeyTrait {
    fn key<'k>(&'k self) -> BorrowedKey<'k>;
}

impl ObjectKeyTrait for Value {
    fn key<'k>(&'k self) -> BorrowedKey<'k> {
        match self {
            Value::String(s) => BorrowedKey::Str(s.as_str()),
            v => BorrowedKey::Value(v),
        }
    }
}

impl<'a> ObjectKeyTrait for BorrowedKey<'a> {
    fn key<'k>(&'k self) -> BorrowedKey<'k> {
        *self
    }
}

impl<'a> std::borrow::Borrow<dyn ObjectKeyTrait + 'a> for Value {
    fn borrow(&self) -> &(dyn ObjectKeyTrait + 'a) {
        self
    }
}

impl<'a> PartialEq for (dyn ObjectKeyTrait + 'a) {
    fn eq(&self, other: &Self) -> bool {
        self.key().eq(&other.key())
    }
}

impl<'a> Eq for (dyn ObjectKeyTrait + 'a) {}

impl<'a> PartialOrd for (dyn ObjectKeyTrait + 'a) {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        self.key().partial_cmp(&other.key())
    }
}

impl<'a> Ord for (dyn ObjectKeyTrait + 'a) {
    fn cmp(&self, other: &Self) -> Ordering {
        self.key().cmp(&other.key())
    }
}

impl<'a> std::hash::Hash for (dyn ObjectKeyTrait + 'a) {
    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
        self.key().hash(state)
    }
}

#[derive(Clone, Default, PartialEq, Eq, Hash)]
pub struct Object {
    inner: BTreeMap<Value, Value>,
}

impl Object {
    pub fn get_by_str(&self, field_name: &str) -> Option<&Value> {
        self.inner
            .get(&BorrowedKey::Str(field_name) as &dyn ObjectKeyTrait)
    }
}

impl std::fmt::Debug for Object {
    fn fmt(&self, fmt: &mut std::fmt::Formatter) -> std::fmt::Result {
        self.inner.fmt(fmt)
    }
}

impl Ord for Object {
    fn cmp(&self, other: &Self) -> Ordering {
        let self_ptr = self as *const Self;
        let other_ptr = other as *const Self;
        self_ptr.cmp(&other_ptr)
    }
}

impl PartialOrd for Object {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl Drop for Object {
    fn drop(&mut self) {
        for (_, child) in std::mem::take(&mut self.inner) {
            crate::drop::safely(child);
        }
    }
}

impl From<BTreeMap<Value, Value>> for Object {
    fn from(inner: BTreeMap<Value, Value>) -> Self {
        Self { inner }
    }
}

impl Deref for Object {
    type Target = BTreeMap<Value, Value>;

    fn deref(&self) -> &Self::Target {
        &self.inner
    }
}

impl DerefMut for Object {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.inner
    }
}

fn take(object: Object) -> BTreeMap<Value, Value> {
    let object = core::mem::ManuallyDrop::new(object);
    unsafe { core::ptr::read(&object.inner) }
}

impl IntoIterator for Object {
    type Item = (Value, Value);
    type IntoIter = <BTreeMap<Value, Value> as IntoIterator>::IntoIter;

    fn into_iter(self) -> Self::IntoIter {
        take(self).into_iter()
    }
}

impl<'a> IntoIterator for &'a Object {
    type Item = (&'a Value, &'a Value);
    type IntoIter = <&'a BTreeMap<Value, Value> as IntoIterator>::IntoIter;

    fn into_iter(self) -> Self::IntoIter {
        self.iter()
    }
}

impl<'a> IntoIterator for &'a mut Object {
    type Item = (&'a Value, &'a mut Value);
    type IntoIter = <&'a mut BTreeMap<Value, Value> as IntoIterator>::IntoIter;

    fn into_iter(self) -> Self::IntoIter {
        self.iter_mut()
    }
}

impl FromIterator<(Value, Value)> for Object {
    fn from_iter<I>(iter: I) -> Self
    where
        I: IntoIterator<Item = (Value, Value)>,
    {
        Object {
            inner: BTreeMap::from_iter(iter),
        }
    }
}