sqlx/sqlx-core/src/arguments.rs
2024-06-13 13:11:36 -07:00

64 lines
2.0 KiB
Rust

//! Types and traits for passing arguments to SQL queries.
use crate::database::Database;
use crate::encode::Encode;
use crate::error::BoxDynError;
use crate::types::Type;
use std::fmt::{self, Write};
/// A tuple of arguments to be sent to the database.
// This lint is designed for general collections, but `Arguments` is not meant to be as such.
#[allow(clippy::len_without_is_empty)]
pub trait Arguments<'q>: Send + Sized + Default {
type Database: Database;
/// Reserves the capacity for at least `additional` more values (of `size` total bytes) to
/// be added to the arguments without a reallocation.
fn reserve(&mut self, additional: usize, size: usize);
/// Add the value to the end of the arguments.
fn add<T>(&mut self, value: T) -> Result<(), BoxDynError>
where
T: 'q + Encode<'q, Self::Database> + Type<Self::Database>;
/// The number of arguments that were already added.
fn len(&self) -> usize;
fn format_placeholder<W: Write>(&self, writer: &mut W) -> fmt::Result {
writer.write_str("?")
}
}
pub trait IntoArguments<'q, DB: Database>: Sized + Send {
fn into_arguments(self) -> <DB as Database>::Arguments<'q>;
}
// NOTE: required due to lack of lazy normalization
#[macro_export]
macro_rules! impl_into_arguments_for_arguments {
($Arguments:path) => {
impl<'q>
$crate::arguments::IntoArguments<
'q,
<$Arguments as $crate::arguments::Arguments<'q>>::Database,
> for $Arguments
{
fn into_arguments(self) -> $Arguments {
self
}
}
};
}
/// used by the query macros to prevent supernumerary `.bind()` calls
pub struct ImmutableArguments<'q, DB: Database>(pub <DB as Database>::Arguments<'q>);
impl<'q, DB: Database> IntoArguments<'q, DB> for ImmutableArguments<'q, DB> {
fn into_arguments(self) -> <DB as Database>::Arguments<'q> {
self.0
}
}
// TODO: Impl `IntoArguments` for &[&dyn Encode]
// TODO: Impl `IntoArguments` for (impl Encode, ...) x16