deer: implement Deserialize for tuples (#2418)

* feat: glue helper trait `TupleExt` * feat: take code from #1875 and fix * test: array impl * fix: miri
hashintel · Apr 28, 2023 · 078f55f · 078f55f
1 parent 7ef3167
commit 078f55f
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diff --git a/libs/deer/Cargo.toml b/libs/deer/Cargo.toml
@@ -27,6 +27,7 @@ similar-asserts = { version = "1.4.2", features = ['serde'] }
 deer-desert = { path = "./desert", features = ['pretty'] }
 proptest = "1.1.0"
 paste = "1.0.12"
+seq-macro = "0.3.3"
 
 [build-dependencies]
 rustc_version = "0.4.0"

diff --git a/libs/deer/src/ext.rs b/libs/deer/src/ext.rs
@@ -0,0 +1,69 @@
+//! Temporary helper trait for folding reports until [#2377](https://github.com/hashintel/hash/discussions/2377)
+//! is resolved and implemented.
+
+use error_stack::{Context, Report};
+
+pub(crate) trait TupleExt {
+    type Context: Context;
+    type Ok;
+
+    fn fold_reports(self) -> Result<Self::Ok, Report<Self::Context>>;
+}
+
+#[rustfmt::skip]
+macro_rules! all_the_tuples {
+    ($name:ident) => {
+        $name!([T1], T2);
+        $name!([T1, T2], T3);
+        $name!([T1, T2, T3], T4);
+        $name!([T1, T2, T3, T4], T5);
+        $name!([T1, T2, T3, T4, T5], T6);
+        $name!([T1, T2, T3, T4, T5, T6], T7);
+        $name!([T1, T2, T3, T4, T5, T6, T7], T8);
+        $name!([T1, T2, T3, T4, T5, T6, T7, T8], T9);
+        $name!([T1, T2, T3, T4, T5, T6, T7, T8, T9], T10);
+        $name!([T1, T2, T3, T4, T5, T6, T7, T8, T9, T10], T11);
+        $name!([T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11], T12);
+        $name!([T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12], T13);
+        $name!([T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13], T14);
+        $name!([T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14], T15);
+        $name!([T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15], T16);
+    };
+}
+
+impl<T1, C: Context> TupleExt for (Result<T1, Report<C>>,) {
+    type Context = C;
+    type Ok = (T1,);
+
+    fn fold_reports(self) -> Result<Self::Ok, Report<Self::Context>> {
+        self.0.map(|value| (value,))
+    }
+}
+
+macro_rules! impl_tuple_ext {
+    ([$($elem:ident),*], $other:ident) => {
+        #[allow(non_snake_case)]
+        impl<C: Context $(, $elem)*, $other> TupleExt for ($(Result<$elem, Report<C>>, )* Result<$other, Report<C>>) {
+            type Context = C;
+            type Ok = ($($elem ,)* $other);
+
+            fn fold_reports(self) -> Result<Self::Ok, Report<Self::Context>> {
+                let ( $($elem ,)* $other ) = self;
+
+                let lhs = ( $($elem ,)* ).fold_reports();
+
+                match (lhs, $other) {
+                    (Ok(( $($elem ,)* )), Ok(rhs)) => Ok(($($elem ,)* rhs)),
+                    (Ok(_), Err(err)) | (Err(err), Ok(_)) => Err(err),
+                    (Err(mut lhs), Err(rhs)) => {
+                        lhs.extend_one(rhs);
+
+                        Err(lhs)
+                    }
+                }
+            }
+        }
+    };
+}
+
+all_the_tuples!(impl_tuple_ext);
diff --git a/libs/deer/src/impls/core.rs b/libs/deer/src/impls/core.rs
@@ -13,4 +13,5 @@ mod result;
 mod string;
 mod sync;
 mod time;
+mod tuples;
 mod unit;
diff --git a/libs/deer/src/impls/core/tuples.rs b/libs/deer/src/impls/core/tuples.rs
@@ -0,0 +1,115 @@
+use core::marker::PhantomData;
+
+use error_stack::{Report, Result, ResultExt};
+
+use crate::{
+    error::{
+        ArrayLengthError, DeserializeError, ExpectedLength, Location, ReceivedLength, Variant,
+        VisitorError,
+    },
+    ext::TupleExt,
+    ArrayAccess, Deserialize, Deserializer, Document, Reflection, Schema, Visitor,
+};
+
+#[rustfmt::skip]
+macro_rules! all_the_tuples {
+    ($name:ident) => {
+        $name!( 1, V01, R01; T1);
+        $name!( 2, V02, R02; T1, T2);
+        $name!( 3, V03, R03; T1, T2, T3);
+        $name!( 4, V04, R04; T1, T2, T3, T4);
+        $name!( 5, V05, R05; T1, T2, T3, T4, T5);
+        $name!( 6, V06, R06; T1, T2, T3, T4, T5, T6);
+        $name!( 7, V07, R07; T1, T2, T3, T4, T5, T6, T7);
+        $name!( 8, V08, R08; T1, T2, T3, T4, T5, T6, T7, T8);
+        $name!( 9, V09, R09; T1, T2, T3, T4, T5, T6, T7, T8, T9);
+        $name!(10, V10, R10; T1, T2, T3, T4, T5, T6, T7, T8, T9, T10);
+        $name!(11, V11, R11; T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11);
+        $name!(12, V12, R12; T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12);
+        $name!(13, V13, R13; T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13);
+        $name!(14, V14, R14; T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14);
+        $name!(15, V15, R15; T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15);
+        $name!(16, V16, R16; T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16);
+    };
+}
+
+macro_rules! impl_tuple {
+    ($(#[$meta:meta])* $expected:literal, $visitor:ident, $reflection:ident; $($elem:ident),*) => {
+        pub struct $reflection<$($elem: ?Sized,)*>($(PhantomData<fn() -> *const $elem>,)*);
+
+        impl<$($elem,)*> Reflection for $reflection<$($elem,)*>
+        where
+            $($elem: Reflection + ?Sized),*
+        {
+            fn schema(doc: &mut Document) -> Schema {
+                Schema::new("array")
+                    .with("prefixItems", [$(doc.add::<$elem>()),*])
+                    .with("items", false)
+            }
+        }
+
+
+        // we do not use &'de as the return type, as that would mean that `Deserialize<'de>`
+        // must be `'de`, which we cannot guarantee
+        struct $visitor<$($elem,)*>(PhantomData<fn() -> *const ( $($elem ,)* )>);
+
+
+        #[automatically_derived]
+        impl<'de, $($elem,)*> Visitor<'de> for $visitor<$($elem,)*>
+        where
+            $($elem: Deserialize<'de>),*
+        {
+            type Value = ($($elem,)*);
+
+            fn expecting(&self) -> Document {
+                Self::Value::reflection()
+            }
+
+            #[allow(non_snake_case)]
+            fn visit_array<T>(self, mut v: T) -> Result<Self::Value, VisitorError>
+            where
+                T: ArrayAccess<'de>,
+            {
+                v.set_bounded($expected).change_context(VisitorError)?;
+
+                let mut length = 0;
+
+                $(
+                let $elem = match v.next() {
+                    None => {
+                        return Err(Report::new(ArrayLengthError.into_error())
+                            .attach(ExpectedLength::new($expected))
+                            .attach(ReceivedLength::new(length))
+                            .change_context(VisitorError));
+                    }
+                    Some(value) => value.attach(Location::Tuple(length)),
+                };
+
+                length += 1;
+                )*
+
+                let value = ($($elem,)*).fold_reports();
+
+                (value, v.end())
+                    .fold_reports()
+                    .map(|(value, _)| value)
+                    .change_context(VisitorError)
+            }
+        }
+
+        $(#[$meta])*
+        impl<'de, $($elem,)*> Deserialize<'de> for ($($elem,)*)
+        where
+            $($elem: Deserialize<'de>),*
+        {
+            type Reflection = $reflection<$($elem::Reflection),*>;
+
+            fn deserialize<D: Deserializer<'de>>(de: D) -> Result<Self, DeserializeError> {
+                de.deserialize_array($visitor::<$($elem,)*>(PhantomData))
+                            .change_context(DeserializeError)
+            }
+        }
+    };
+}
+
+all_the_tuples!(impl_tuple);
diff --git a/libs/deer/src/lib.rs b/libs/deer/src/lib.rs
@@ -38,6 +38,7 @@ pub mod error;
 mod impls;
 #[macro_use]
 mod macros;
+mod ext;
 mod number;
 pub mod schema;
 pub mod value;

diff --git a/libs/deer/tests/test_impls_core_tuples.rs b/libs/deer/tests/test_impls_core_tuples.rs
@@ -0,0 +1,105 @@
+use deer::Deserialize;
+use deer_desert::{assert_tokens, assert_tokens_error, error, Token};
+use proptest::prelude::*;
+use seq_macro::seq;
+use serde_json::json;
+
+#[rustfmt::skip]
+macro_rules! all_the_tuples {
+    ($name:ident) => {
+        $name!( 1, u8);
+        $name!( 2, u8, u16);
+        $name!( 3, u8, u16, u32);
+        $name!( 4, u8, u16, u32, u64);
+        $name!( 5, u8, u16, u32, u64, f32);
+        $name!( 6, u8, u16, u32, u64, f32, f64);
+        $name!( 7, u8, u16, u32, u64, f32, f64, i8);
+        $name!( 8, u8, u16, u32, u64, f32, f64, i8, i16);
+        $name!( 9, u8, u16, u32, u64, f32, f64, i8, i16, i32);
+
+        // Tuples larger than 9 elements are not supported by proptest, but because the
+        // code generated for each variant is pretty much the same we can assume that those are
+        // also ok. In the future we might want to test them with a more sophisticated macro.
+        // $name!(10, u8, u16, u32, u64, f32, f64, i8, i16, i32, i64);
+        // $name!(11, u8, u16, u32, u64, f32, f64, i8, i16, i32, i64, u8);
+        // $name!(12, u8, u16, u32, u64, f32, f64, i8, i16, i32, i64, u8, u16);
+        // $name!(13, u8, u16, u32, u64, f32, f64, i8, i16, i32, i64, u8, u16, u32);
+        // $name!(14, u8, u16, u32, u64, f32, f64, i8, i16, i32, i64, u8, u16, u32, u64);
+        // $name!(15, u8, u16, u32, u64, f32, f64, i8, i16, i32, i64, u8, u16, u32, u64, f32);
+        // $name!(16, u8, u16, u32, u64, f32, f64, i8, i16, i32, i64, u8, u16, u32, u64, f32, f64);
+    };
+}
+
+macro_rules! impl_test_case {
+    ($length:literal, $($types:ty),*) => {
+        paste::paste! {
+            #[cfg(not(miri))]
+            proptest! {
+                #[test]
+                fn [< tuple $length _ok >](value in any::<($($types,)*)>()) {
+                    seq!(N in 0..$length {
+                        let stream = [
+                            Token::Array {length: Some($length)},
+                            #(Token::Number(value.N.into()),)*
+                            Token::ArrayEnd,
+                        ];
+                    });
+
+                    assert_tokens(&value, &stream);
+                }
+            }
+        }
+    };
+}
+
+all_the_tuples!(impl_test_case);
+
+#[test]
+fn tuple_insufficient_length_err() {
+    assert_tokens_error::<(u8, u16)>(
+        &error!([{
+            ns: "deer",
+            id: ["value", "missing"],
+            properties: {
+                "expected": u16::reflection(),
+                "location": [{"type": "tuple", "value": 1}]
+            }
+        }]),
+        &[
+            Token::Array { length: Some(1) },
+            Token::Number(12.into()),
+            Token::ArrayEnd,
+        ],
+    );
+}
+
+#[test]
+fn tuple_too_many_items_err() {
+    assert_tokens_error::<(u8, u16)>(
+        &error!([{
+            ns: "deer",
+            id: ["array", "length"],
+            properties: {
+                "expected": 2,
+                "received": 3,
+                "location": []
+            }
+        }]),
+        &[
+            Token::Array { length: Some(3) },
+            Token::Number(12.into()),
+            Token::Number(13.into()),
+            Token::Number(14.into()),
+            Token::ArrayEnd,
+        ],
+    );
+}
+
+#[test]
+fn tuple_fallback_to_default_ok() {
+    assert_tokens(&(Some(12u8), None::<u16>), &[
+        Token::Array { length: Some(1) },
+        Token::Number(12.into()),
+        Token::ArrayEnd,
+    ]);
+}