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

use super::{Null, Value, ValueRef};
use Result;

/// `ToSqlOutput` represents the possible output types for implementors of the `ToSql` trait.
#[derive(Clone,Debug,PartialEq)]
pub enum ToSqlOutput<'a> {
    /// A borrowed SQLite-representable value.
    Borrowed(ValueRef<'a>),

    /// An owned SQLite-representable value.
    Owned(Value),

    /// A BLOB of the given length that is filled with zeroes.
    #[cfg(feature = "blob")]
    ZeroBlob(i32),
}

impl<'a, T: ?Sized> From<&'a T> for ToSqlOutput<'a>
    where &'a T: Into<ValueRef<'a>>
{
    fn from(t: &'a T) -> Self {
        ToSqlOutput::Borrowed(t.into())
    }
}

impl<'a, T: Into<Value>> From<T> for ToSqlOutput<'a> {
    fn from(t: T) -> Self {
        ToSqlOutput::Owned(t.into())
    }
}

impl<'a> ToSql for ToSqlOutput<'a> {
    fn to_sql(&self) -> Result<ToSqlOutput> {
        Ok(match *self {
            ToSqlOutput::Borrowed(v) => ToSqlOutput::Borrowed(v),
            ToSqlOutput::Owned(ref v) => ToSqlOutput::Borrowed(ValueRef::from(v)),

            #[cfg(feature = "blob")]
            ToSqlOutput::ZeroBlob(i) => ToSqlOutput::ZeroBlob(i),
        })
    }
}

/// A trait for types that can be converted into SQLite values.
pub trait ToSql {
    fn to_sql(&self) -> Result<ToSqlOutput>;
}

// We should be able to use a generic impl like this:
//
// impl<T: Copy> ToSql for T where T: Into<Value> {
//     fn to_sql(&self) -> Result<ToSqlOutput> {
//         Ok(ToSqlOutput::from((*self).into()))
//     }
// }
//
// instead of the following macro, but this runs afoul of
// https://github.com/rust-lang/rust/issues/30191 and reports conflicting
// implementations even when there aren't any.

macro_rules! to_sql_self(
    ($t:ty) => (
        impl ToSql for $t {
            fn to_sql(&self) -> Result<ToSqlOutput> {
                Ok(ToSqlOutput::from(*self))
            }
        }
    )
);

to_sql_self!(Null);
to_sql_self!(bool);
to_sql_self!(i8);
to_sql_self!(i16);
to_sql_self!(i32);
to_sql_self!(i64);
to_sql_self!(u8);
to_sql_self!(u16);
to_sql_self!(u32);
to_sql_self!(f64);

impl<'a, T: ?Sized> ToSql for &'a T
    where &'a T: Into<ToSqlOutput<'a>>
{
    fn to_sql(&self) -> Result<ToSqlOutput> {
        Ok(ToSqlOutput::from((*self).into()))
    }
}

impl ToSql for String {
    fn to_sql(&self) -> Result<ToSqlOutput> {
        Ok(ToSqlOutput::from(self.as_str()))
    }
}

impl ToSql for Vec<u8> {
    fn to_sql(&self) -> Result<ToSqlOutput> {
        Ok(ToSqlOutput::from(self.as_slice()))
    }
}

impl ToSql for Value {
    fn to_sql(&self) -> Result<ToSqlOutput> {
        Ok(ToSqlOutput::from(self))
    }
}

impl<T: ToSql> ToSql for Option<T> {
    fn to_sql(&self) -> Result<ToSqlOutput> {
        match *self {
            None => Ok(ToSqlOutput::from(Null)),
            Some(ref t) => t.to_sql(),
        }
    }
}

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

    fn is_to_sql<T: ToSql>() {}

    #[test]
    fn test_integral_types() {
        is_to_sql::<i8>();
        is_to_sql::<i16>();
        is_to_sql::<i32>();
        is_to_sql::<i64>();
        is_to_sql::<u8>();
        is_to_sql::<u16>();
        is_to_sql::<u32>();
    }
}