#![allow(clippy::needless_range_loop)]
use super::try_make_table_array;
use serde::de;
pub fn deserialize_table_array<'de, D, T, const ROW: usize, const COL: usize>(
deserializer: D,
) -> Result<[[T; COL]; ROW], D::Error>
where
D: de::Deserializer<'de>,
T: de::Deserialize<'de> + Default,
{
deserializer.deserialize_tuple(ROW * COL, TableArrayVisitor::<T, ROW, COL>::default())
}
#[derive(Default)]
struct TableArrayVisitor<T, const ROW: usize, const COL: usize> {
_marker: core::marker::PhantomData<T>,
}
impl<'de, T, const ROW: usize, const COL: usize> de::Visitor<'de> for TableArrayVisitor<T, ROW, COL>
where
T: de::Deserialize<'de> + Default,
{
type Value = [[T; COL]; ROW];
fn expecting(&self, formatter: &mut core::fmt::Formatter) -> core::fmt::Result {
write!(formatter, "an array of size {}", ROW * COL)
}
fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>
where
A: de::SeqAccess<'de>,
{
let table = try_make_table_array(|row, col| {
if let Some(x) = seq.next_element::<T>()? {
Ok(x)
} else {
Err(de::Error::invalid_length(row * COL + col, &self))
}
})?;
if seq.next_element::<T>()?.is_some() {
Err(de::Error::invalid_length((ROW * COL) + 1, &self))
} else {
Ok(table)
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use serde::Deserialize;
#[derive(Debug, Default, PartialEq, Eq, Deserialize)]
struct ComplexObj {
field1: u8,
field2: String,
field3: bool,
}
#[derive(Debug, PartialEq, Eq, Deserialize)]
struct TestTableArray<T: Default, const ROW: usize, const COL: usize>(
#[serde(
bound(deserialize = "T: Deserialize<'de>"),
deserialize_with = "deserialize_table_array"
)]
[[T; COL]; ROW],
);
#[test]
fn deserialize_table_array_should_fail_if_not_enough_elements() {
let s = "[1,2,3,4,5,6,7]";
let res: serde_json::Result<TestTableArray<usize, 2, 4>> = serde_json::from_str(s);
assert!(res.is_err());
}
#[test]
fn deserialize_table_array_should_fail_if_too_many_elements() {
let s = "[1,2,3,4,5,6,7,8,9]";
let res: serde_json::Result<TestTableArray<usize, 2, 4>> = serde_json::from_str(s);
assert!(res.is_err());
}
#[test]
fn deserialize_table_array_should_correctly_deserialize() {
let s = "[1,2,3,4,5,6,7,8]";
let arr: TestTableArray<usize, 2, 4> = serde_json::from_str(s).unwrap();
assert_eq!(arr, TestTableArray([[1, 2, 3, 4], [5, 6, 7, 8]]));
}
#[test]
fn deserialize_table_array_should_support_complex_generic_types() {
let s = concat!(
"[",
r#"{"field1":1,"field2":"hello","field3":false}"#,
",",
r#"{"field1":2,"field2":"world","field3":true}"#,
"]",
);
let arr: TestTableArray<ComplexObj, 2, 1> = serde_json::from_str(s).unwrap();
assert_eq!(
arr,
TestTableArray([
[ComplexObj {
field1: 1,
field2: "hello".to_string(),
field3: false,
}],
[ComplexObj {
field1: 2,
field2: "world".to_string(),
field3: true,
}],
])
);
}
}