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use serde_reflection::{ContainerFormat, Error, Format, FormatHolder, Result};
pub fn lint_bcs_format(format: &ContainerFormat) -> Result<()> {
if is_empty_container(format) {
return Err(Error::Custom("Please avoid 0-sized containers".into()));
}
format.visit(&mut |f| {
use Format::*;
match f {
F32 | F64 | Char => Err(Error::Custom(format!("BCS does not support type {:?}", f))),
Seq(inner) => match inner.as_ref() {
U8 => Err(Error::Custom(
"Please use `#[serde(with = \"serde_bytes\")` on `Vec<u8>` objects.".into(),
)),
e if is_empty(e) => Err(Error::Custom(format!(
"Sequences with empty content are not allowed: {:?}",
f
))),
_ => Ok(()),
},
Map { key, value } => {
if is_empty(key) && is_empty(value) {
Err(Error::Custom(format!(
"Maps with empty keys and values are not allowed: {:?}",
f
)))
} else {
Ok(())
}
}
_ => Ok(()),
}
})
}
fn is_empty(format: &Format) -> bool {
use Format::*;
match format {
Unit => true,
TupleArray { content, size } => *size == 0 || is_empty(content.as_ref()),
Tuple(formats) => formats.iter().all(is_empty),
_ => false,
}
}
fn is_empty_container(format: &ContainerFormat) -> bool {
use ContainerFormat::*;
match format {
UnitStruct => true,
NewTypeStruct(inner) => is_empty(inner.as_ref()),
TupleStruct(formats) => formats.iter().all(is_empty),
Struct(formats) => formats.iter().map(|named| &named.value).all(is_empty),
Enum(_) => false,
}
}