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
170
171
172
173
174
175
176
177
178
179
180

#[cfg(feature = "numeric")]
use bigdecimal::BigDecimal;
use prost::bytes::Bytes;

use crate::{Error, Type, Value};

/// A trait for Rust types that can be converted to Cloud Spanner values.
///
/// # Types
///
/// The crate provides the following mapping between Cloud Spanner types and Rust types.
///
/// | Rust Type | Spanner Type |
/// |---|---|
/// | `bool` | [`BOOL`](https://cloud.google.com/spanner/docs/data-types#boolean_type) |
/// | `u8`, `i8`, `u16`, `i16`, `u32`, `i32`, `i64` | [`INT64`](https://cloud.google.com/spanner/docs/data-types#integer_type) |
/// | `f64` | [`FLOAT64`](https://cloud.google.com/spanner/docs/data-types#floating_point_types) |
/// | `&str`, `String` | [`STRING`](https://cloud.google.com/spanner/docs/data-types#string_type) |
/// | `&[u8]`, `Bytes` | [`BYTES`](https://cloud.google.com/spanner/docs/data-types#bytes_type) |
///
/// The following are provided when the corresponding feature is enabled:
///
/// | Feature | Rust Type | Spanner Type |
/// |---|---|---|
/// | `json` | `serde_json::Value` | [`JSON`](https://cloud.google.com/spanner/docs/data-types#json_type) |
/// | `numeric` | `bigdecimal::BigDecimal` | [`NUMERIC`](https://cloud.google.com/spanner/docs/data-types#numeric_type) |
/// | `temporal` | `chrono::DateTime<Utc>` | [`TIMESTAMP`](https://cloud.google.com/spanner/docs/data-types#timestamp_type) |
/// | `temporal` | `chrono::NaiveDate` | [`DATE`](https://cloud.google.com/spanner/docs/data-types#date_type) |
///
/// # Nullability
///
/// `ToSpanner` is implemented for `Option<T>` when `T` implements `ToSpanner`.
/// `Option<T>` represents a nullable Spanner value.
///
/// # Arrays
///
/// `ToSpanner` is implemented for `Vec<T>` when `T` implements `ToSpanner`.
/// Such values map to Spanner's [`Array`](https://cloud.google.com/spanner/docs/data-types#array_type) type.
/// Arrays may contain `null` values (i.e.: `Vec<Option<T>>`). Note that `Vec<Vec<T>>` is not allowed.
pub trait ToSpanner {
    /// Creates a new Cloud Spanner value from this value.
    fn to_spanner(&self) -> Result<Value, Error>;

    /// Returns the Cloud Spanner [Type] that this implementation produces.
    fn spanner_type() -> Type
    where
        Self: Sized;
}

impl<T> ToSpanner for Option<T>
where
    T: ToSpanner,
{
    fn to_spanner(&self) -> Result<Value, Error> {
        match self.as_ref() {
            Some(v) => v.to_spanner(),
            None => Ok(Value::Null(<T as ToSpanner>::spanner_type())),
        }
    }
    fn spanner_type() -> Type {
        <T as ToSpanner>::spanner_type()
    }
}

impl<T> ToSpanner for Vec<T>
where
    T: ToSpanner,
{
    fn to_spanner(&self) -> Result<Value, Error> {
        let values = self
            .iter()
            .map(|v| v.to_spanner())
            .collect::<Result<Vec<Value>, Error>>()?;
        Ok(Value::Array(<T as ToSpanner>::spanner_type(), values))
    }
    fn spanner_type() -> Type {
        Type::Array(Box::new(<T as ToSpanner>::spanner_type()))
    }
}

impl<T> ToSpanner for &[T]
where
    T: ToSpanner,
{
    fn to_spanner(&self) -> Result<Value, Error> {
        let values = self
            .iter()
            .map(|v| v.to_spanner())
            .collect::<Result<Vec<Value>, Error>>()?;
        Ok(Value::Array(<T as ToSpanner>::spanner_type(), values))
    }
    fn spanner_type() -> Type {
        Type::Array(Box::new(<T as ToSpanner>::spanner_type()))
    }
}

macro_rules! simple {
    ($t:ty, $v:ident, $into:path $(, $deref:tt)?) => {
        impl ToSpanner for $t {
            fn to_spanner(&self) -> Result<Value, Error> {
                Ok(Value::$v($into($($deref)? self)))
            }

            fn spanner_type() -> Type {
                Type::$v
            }
        }
    };
}

simple!(i8, Int64, i64::from, *);
simple!(u8, Int64, i64::from, *);
simple!(i16, Int64, i64::from, *);
simple!(u16, Int64, i64::from, *);
simple!(i32, Int64, i64::from, *);
simple!(u32, Int64, i64::from, *);
simple!(i64, Int64, i64::from, *);
simple!(String, String, Clone::clone);
simple!(&str, String, ToString::to_string);
#[cfg(feature = "numeric")]
simple!(BigDecimal, Numeric, Clone::clone);
simple!(Bytes, Bytes, Clone::clone);
#[cfg(feature = "json")]
simple!(serde_json::Value, Json, Clone::clone);
#[cfg(feature = "temporal")]
simple!(chrono::DateTime<chrono::Utc>, Timestamp, Clone::clone);
#[cfg(feature = "temporal")]
simple!(chrono::NaiveDate, Date, Clone::clone);

#[cfg(test)]
mod test {
    use super::*;

    macro_rules! simple_test_int64 {
        ($t:ty) => {
            assert_eq!((0 as $t).to_spanner().ok(), Some(Value::Int64(0)));
        };
        ($($t:ty),+) => {
            $(
                simple_test_int64!($t);
            )+
        };
    }

    #[test]
    fn test_to_spanner_simple_int64() {
        simple_test_int64!(i8, u8, i16, u16, i32, u32, i64);
    }

    #[test]
    fn test_to_spanner_opt() {
        let some = Some(0 as u32);
        assert_eq!(some.to_spanner().ok(), Some(Value::Int64(0)));
        let none: Option<u32> = None;
        assert_eq!(none.to_spanner().ok(), Some(Value::Null(Type::Int64)));
    }

    #[test]
    fn test_to_spanner_array() {
        let array = vec![0, 1, 2, 3, 4];
        assert_eq!(
            array.to_spanner().ok(),
            Some(Value::Array(
                Type::Int64,
                vec![
                    Value::Int64(0),
                    Value::Int64(1),
                    Value::Int64(2),
                    Value::Int64(3),
                    Value::Int64(4)
                ]
            ))
        );
        let empty: Vec<u32> = vec![];
        assert_eq!(
            empty.to_spanner().ok(),
            Some(Value::Array(Type::Int64, vec![]))
        );
    }
}