cuprate_epee_encoding/macros.rs
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pub use bytes;
pub use paste::paste;
/// Macro to derive [`EpeeObject`](crate::EpeeObject) for structs.
///
/// ### Basic Usage:
///
/// ```rust
/// // mod visibility is here because of Rust visibility weirdness, you shouldn't need this unless defined in a function.
/// // see: <https://github.com/rust-lang/rust/issues/64079>
/// mod visibility {
///
/// use cuprate_epee_encoding::epee_object;
///
/// struct Example {
/// a: u8
/// }
///
/// epee_object!(
/// Example,
/// a: u8,
/// );
/// }
/// ```
///
/// ### Advanced Usage:
///
/// ```rust
/// // mod visibility is here because of Rust visibility weirdness, you shouldn't need this unless defined in a function.
/// // see: <https://github.com/rust-lang/rust/issues/64079>
/// mod visibility {
///
/// use cuprate_epee_encoding::epee_object;
///
/// struct Example {
/// a: u8,
/// b: u8,
/// c: u8,
/// d: u8,
/// e_f: Example2
/// }
///
/// struct Example2 {
/// e: u8
/// }
///
/// epee_object!(
/// Example2,
/// e: u8,
/// );
///
/// epee_object!(
/// Example,
/// // `("ALT-NAME")` changes the name of the field in the encoded data.
/// a("A"): u8,
/// // `= VALUE` sets a default value that this field will be set to if not in the data
/// // when encoding this field will be skipped if equal to the default.
/// b: u8 = 0,
/// // `as ALT-TYPE` encodes the data using the alt type, the alt type must impl Into<Type> and From<&Type>
/// c: u8 as u8,
/// // `=> read_fn, write_fn, should_write_fn,` allows you to specify alt field encoding functions.
/// // for the required args see the default functions, which are used here:
/// d: u8 => cuprate_epee_encoding::read_epee_value, cuprate_epee_encoding::write_field, <u8 as cuprate_epee_encoding::EpeeValue>::should_write,
/// // `!flatten` can be used on fields which are epee objects, and it flattens the fields of that object into this object.
/// // So for this example `e_f` will not appear in the data but e will.
/// // You can't use the other options with this.
/// !flatten: e_f: Example2,
/// );
/// }
/// ```
///
///
#[macro_export]
macro_rules! epee_object {
// ------------------------------------------------------------------------ internal_try_right_then_left
// All this does is return the second (right) arg if present otherwise the left is returned.
(
@internal_try_right_then_left
$a:expr, $b:expr
) => {
$b
};
(
@internal_try_right_then_left
$a:expr,
) => {
$a
};
// ------------------------------------------------------------------------ internal_field_name
// Returns the alt_name if present otherwise stringifies the field ident.
(
@internal_field_name
$field: tt, $alt_name: tt
) => {
$alt_name
};
(
@internal_field_name
$field: ident,
) => {
stringify!($field)
};
// ------------------------------------------------------------------------ internal_field_type
// All this does is return the second (right) arg if present otherwise the left is returned.
(
@internal_field_type
$ty:ty, $ty_as:ty
) => {
$ty_as
};
(
@internal_field_type
$ty:ty,
) => {
$ty
};
// ------------------------------------------------------------------------ Entry Point
(
$obj:ident,
$($field: ident $(($alt_name: literal))?: $ty:ty $(as $ty_as:ty )? $(= $default:expr)? $(=> $read_fn:expr, $write_fn:expr, $should_write_fn:expr)?, )*
$(!flatten: $flat_field: ident: $flat_ty:ty ,)*
) => {
cuprate_epee_encoding::macros::paste!(
#[allow(non_snake_case)]
mod [<__epee_builder_ $obj>] {
use super::*;
#[derive(Default)]
pub struct [<__Builder $obj>] {
$($field: Option<cuprate_epee_encoding::epee_object!(@internal_field_type $ty, $($ty_as)?)>,)*
$($flat_field: <$flat_ty as cuprate_epee_encoding::EpeeObject>::Builder,)*
}
impl cuprate_epee_encoding::EpeeObjectBuilder<$obj> for [<__Builder $obj>] {
fn add_field<B: cuprate_epee_encoding::macros::bytes::Buf>(&mut self, name: &str, b: &mut B) -> cuprate_epee_encoding::error::Result<bool> {
match name {
$(cuprate_epee_encoding::epee_object!(@internal_field_name $field, $($alt_name)?) => {
if core::mem::replace(&mut self.$field, Some(
cuprate_epee_encoding::epee_object!(@internal_try_right_then_left cuprate_epee_encoding::read_epee_value(b)?, $($read_fn(b)?)?)
)).is_some() {
Err(cuprate_epee_encoding::error::Error::Value(format!("Duplicate field in data: {}", cuprate_epee_encoding::epee_object!(@internal_field_name$field, $($alt_name)?))))?;
}
Ok(true)
},)*
_ => {
$(if self.$flat_field.add_field(name, b)? {
return Ok(true);
})*
Ok(false)
}
}
}
fn finish(self) -> cuprate_epee_encoding::error::Result<$obj> {
Ok(
$obj {
$(
$field: {
let epee_default_value = cuprate_epee_encoding::epee_object!(@internal_try_right_then_left cuprate_epee_encoding::EpeeValue::epee_default_value(), $({
let _ = $should_write_fn;
None
})?);
self.$field
$(.or(Some($default)))?
.or(epee_default_value)
$(.map(<$ty_as>::into))?
.ok_or(cuprate_epee_encoding::error::Error::Value(format!("Missing field in data: {}", cuprate_epee_encoding::epee_object!(@internal_field_name$field, $($alt_name)?))))?
},
)*
$(
$flat_field: self.$flat_field.finish()?,
)*
}
)
}
}
}
impl cuprate_epee_encoding::EpeeObject for $obj {
type Builder = [<__epee_builder_ $obj>]::[<__Builder $obj>];
fn number_of_fields(&self) -> u64 {
let mut fields = 0;
$(
let field = cuprate_epee_encoding::epee_object!(@internal_try_right_then_left &self.$field, $(<&$ty_as>::from(&self.$field))? );
if $((field) != &$default &&)? cuprate_epee_encoding::epee_object!(@internal_try_right_then_left cuprate_epee_encoding::EpeeValue::should_write, $($should_write_fn)?)(field )
{
fields += 1;
}
)*
$(
fields += self.$flat_field.number_of_fields();
)*
fields
}
fn write_fields<B: cuprate_epee_encoding::macros::bytes::BufMut>(self, w: &mut B) -> cuprate_epee_encoding::error::Result<()> {
$(
let field = cuprate_epee_encoding::epee_object!(@internal_try_right_then_left self.$field, $(<$ty_as>::from(self.$field))? );
if $(field != $default &&)? cuprate_epee_encoding::epee_object!(@internal_try_right_then_left cuprate_epee_encoding::EpeeValue::should_write, $($should_write_fn)?)(&field )
{
cuprate_epee_encoding::epee_object!(@internal_try_right_then_left cuprate_epee_encoding::write_field, $($write_fn)?)((field), cuprate_epee_encoding::epee_object!(@internal_field_name$field, $($alt_name)?), w)?;
}
)*
$(
self.$flat_field.write_fields(w)?;
)*
Ok(())
}
}
);
};
}