WIP: Array types and interned schema

source/postcard-schema-ng/src/impls/builtins_nostd.rs

@@ -90,7 +90,10 @@ impl<T: Schema> Schema for [T] {
 }
 
 impl<T: Schema, const N: usize> Schema for [T; N] {
-    const SCHEMA: &'static DataModelType = &DataModelType::Tuple(&[T::SCHEMA; N]);
+    const SCHEMA: &'static DataModelType = &DataModelType::Array {
+        item: T::SCHEMA,
+        count: N,
+    };
 }
 
 impl<T: Schema> Schema for Range<T> {

source/postcard-schema-ng/src/key/hash.rs

@@ -163,6 +163,18 @@ pub mod fnv1a64 {
                 state
             }
             DataModelType::Schema => hash_update(state, &[0xE5]),
+            DataModelType::Array { item, count } => {
+                let mut state = hash_update(state, &[0x2B]);
+                let mut idx = 0;
+
+                // TODO: Do we want to hash the len or something? I'm not
+                // sure how to handle this for different sizes of `usize`.
+                while idx < *count {
+                    state = hash_sdm_type(state, item);
+                    idx += 1;
+                }
+                state
+            }
         }
     }
 
@@ -333,6 +345,18 @@ pub mod fnv1a64_owned {
                 state
             }
             OwnedDataModelType::Schema => hash_update(state, &[0xE5]),
+            OwnedDataModelType::Array { item, count } => {
+                let mut state = hash_update(state, &[0x2B]);
+                let mut idx = 0;
+
+                // TODO: Do we want to hash the len or something? I'm not
+                // sure how to handle this for different sizes of `usize`.
+                while idx < *count {
+                    state = hash_sdm_type_owned(state, item);
+                    idx += 1;
+                }
+                state
+            }
         }
     }
 

source/postcard-schema-ng/src/key/mod.rs

@@ -50,7 +50,7 @@ impl core::fmt::Debug for Key {
     fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         f.write_str("Key(")?;
         for b in self.0.iter() {
-            f.write_fmt(format_args!("{} ", b))?;
+            f.write_fmt(format_args!("{b} "))?;
         }
         f.write_str(")")
     }
@@ -106,29 +106,3 @@ mod key_owned {
         }
     }
 }
-
-#[cfg(test)]
-mod test {
-    use crate::{key::Key, schema::DataModelType, Schema};
-
-    #[test]
-    fn matches_old_postcard_rpc_defn() {
-        let old = &DataModelType::Struct {
-            name: "Key",
-            data: crate::schema::Data::Newtype(&DataModelType::Tuple(&[
-                &DataModelType::U8,
-                &DataModelType::U8,
-                &DataModelType::U8,
-                &DataModelType::U8,
-                &DataModelType::U8,
-                &DataModelType::U8,
-                &DataModelType::U8,
-                &DataModelType::U8,
-            ])),
-        };
-
-        let new = <Key as Schema>::SCHEMA;
-
-        assert_eq!(old, new);
-    }
-}

source/postcard-schema-ng/src/schema/fmt.rs

@@ -39,6 +39,7 @@ pub fn is_prim(osdmty: &OwnedDataModelType) -> bool {
         OwnedDataModelType::Unit => true,
         OwnedDataModelType::Seq(_) => false,
         OwnedDataModelType::Tuple(_) => false,
+        OwnedDataModelType::Array { item, count: _ } => is_prim(item),
         OwnedDataModelType::Map { key, val } => is_prim(key) && is_prim(val),
         OwnedDataModelType::Struct { .. } => false,
         OwnedDataModelType::Enum { .. } => false,
@@ -146,6 +147,13 @@ pub fn fmt_owned_dmt_to_buf(dmt: &OwnedDataModelType, buf: &mut String, top_leve
                 *buf += "()";
             }
         }
+        OwnedDataModelType::Array { item, count } => {
+            *buf += "[";
+            fmt_owned_dmt_to_buf(item, buf, false);
+            *buf += "; ";
+            *buf += &format!("{count}");
+            *buf += "]";
+        }
         OwnedDataModelType::Map { key, val } => {
             *buf += "Map<";
             fmt_owned_dmt_to_buf(key, buf, false);
@@ -244,6 +252,9 @@ pub fn discover_tys(
                 discover_tys(v, set);
             }
         }
+        OwnedDataModelType::Array { item, count: _ } => {
+            discover_tys(item, set);
+        }
         OwnedDataModelType::Map { key, val } => {
             discover_tys(key, set);
             discover_tys(val, set);