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use std::num::{NonZero, TryFromIntError};
pub enum Value<'a> {
Int(i64),
Float(f64),
Text(&'a str),
Blob(&'a [u8]),
Null,
}
// this is an owned trait to get around some problems with blanket implementations
pub trait FromSql: Sized {
type Error: std::error::Error;
fn try_from_sql(value: Value<'_>) -> Result<Self, Self::Error>;
}
#[derive(Debug, thiserror::Error)]
#[error("invalid type")]
pub struct InvalidTypeError;
#[derive(Debug, thiserror::Error)]
pub enum FromSqlIntError {
#[error(transparent)]
InvalidType(#[from] InvalidTypeError),
#[error(transparent)]
TryFromInt(#[from] TryFromIntError),
}
impl FromSql for i64 {
type Error = FromSqlIntError;
fn try_from_sql(value: Value<'_>) -> Result<Self, Self::Error> {
if let Value::Int(i) = value {
Ok(i)
} else {
Err(InvalidTypeError.into())
}
}
}
impl FromSql for NonZero<i64> {
type Error = FromSqlIntError;
fn try_from_sql(value: Value) -> Result<Self, Self::Error> {
let i: i64 = FromSql::try_from_sql(value)?;
Ok(i.try_into()?)
}
}
macro_rules! int_impl {
($($source:ty),+) => {$(
impl FromSql for $source {
type Error = FromSqlIntError;
fn try_from_sql(value: Value<'_>) -> Result<Self, Self::Error> {
let i: i64 = FromSql::try_from_sql(value)?;
Ok(i.try_into()?)
}
}
impl FromSql for NonZero<$source> {
type Error = FromSqlIntError;
fn try_from_sql(value: Value<'_>) -> Result<Self, Self::Error> {
let i: NonZero<i64> = FromSql::try_from_sql(value)?;
Ok(i.try_into()?)
}
}
)*}
}
int_impl!(i8, i16, i32, u8, u16, u32, u64);
impl<'a, T: FromSql> FromSql for Option<T> {
type Error = T::Error;
fn try_from_sql(value: Value<'_>) -> Result<Self, Self::Error> {
if let Value::Null = value {
Ok(None)
} else {
FromSql::try_from_sql(value).map(Some)
}
}
}
|