SSZ size improvements

ssz/src/bit_list.rs

@@ -130,7 +130,7 @@ impl<'de, N: Unsigned> Deserialize<'de> for BitList<N> {
 }
 
 // `BitBox` serializes itself as a struct with multiple fields.
-impl<N> Serialize for BitList<N> {
+impl<N: Unsigned> Serialize for BitList<N> {
     fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
         let mut ssz_bytes = vec![];
         self.write_variable(&mut ssz_bytes)
@@ -139,8 +139,11 @@ impl<N> Serialize for BitList<N> {
     }
 }
 
-impl<N> SszSize for BitList<N> {
-    const SIZE: Size = Size::Variable { minimum_size: 1 };
+impl<N: Unsigned> SszSize for BitList<N> {
+    const SIZE: Size = Size::Variable {
+        minimum: 1,
+        maximum: Ok(bytes_with_delimiting_bit(N::USIZE)),
+    };
 }
 
 impl<C, N: Unsigned> SszRead<C> for BitList<N> {
@@ -151,7 +154,7 @@ impl<C, N: Unsigned> SszRead<C> for BitList<N> {
     }
 }
 
-impl<N> SszWrite for BitList<N> {
+impl<N: Unsigned> SszWrite for BitList<N> {
     fn write_variable(&self, bytes: &mut Vec<u8>) -> Result<(), WriteError> {
         let length_before = bytes.len();
         let length_after = length_before + bytes_with_delimiting_bit(self.len());

ssz/src/byte_list.rs

@@ -51,8 +51,8 @@ impl<'de, N: Unsigned> Deserialize<'de> for ByteList<N> {
     }
 }
 
-impl<N> SszSize for ByteList<N> {
-    const SIZE: Size = Size::Variable { minimum_size: 0 };
+impl<N: Unsigned> SszSize for ByteList<N> {
+    const SIZE: Size = Size::for_list(u8::SIZE, N::USIZE);
 }
 
 impl<C, N: Unsigned> SszRead<C> for ByteList<N> {
@@ -61,7 +61,7 @@ impl<C, N: Unsigned> SszRead<C> for ByteList<N> {
     }
 }
 
-impl<N> SszWrite for ByteList<N> {
+impl<N: Unsigned> SszWrite for ByteList<N> {
     fn write_variable(&self, bytes: &mut Vec<u8>) -> Result<(), WriteError> {
         self.bytes.write_variable(bytes)
     }

ssz/src/contiguous_list.rs

@@ -98,8 +98,8 @@ impl<'de, T: Deserialize<'de>, N: Unsigned> Deserialize<'de> for ContiguousList<
     }
 }
 
-impl<T: SszSize, N> SszSize for ContiguousList<T, N> {
-    const SIZE: Size = Size::Variable { minimum_size: 0 };
+impl<T: SszSize, N: Unsigned> SszSize for ContiguousList<T, N> {
+    const SIZE: Size = Size::for_list(T::SIZE, N::USIZE);
 }
 
 impl<C, T: SszRead<C>, N: Unsigned> SszRead<C> for ContiguousList<T, N> {
@@ -109,7 +109,7 @@ impl<C, T: SszRead<C>, N: Unsigned> SszRead<C> for ContiguousList<T, N> {
     }
 }
 
-impl<T: SszWrite, N> SszWrite for ContiguousList<T, N> {
+impl<T: SszWrite, N: Unsigned> SszWrite for ContiguousList<T, N> {
     fn write_variable(&self, bytes: &mut Vec<u8>) -> Result<(), WriteError> {
         shared::write_list(bytes, self)
     }

ssz/src/contiguous_vector.rs

@@ -114,7 +114,7 @@ impl<'de, T: Deserialize<'de>, N: ArrayLength<T>> Deserialize<'de> for Contiguou
 }
 
 impl<T: SszSize, N: ContiguousVectorElements<T>> SszSize for ContiguousVector<T, N> {
-    const SIZE: Size = T::SIZE.mul(N::USIZE);
+    const SIZE: Size = Size::for_vector(T::SIZE, N::USIZE);
 }
 
 impl<C, T: SszRead<C>, N: ContiguousVectorElements<T>> SszRead<C> for ContiguousVector<T, N> {

ssz/src/dynamic_list.rs

@@ -58,7 +58,7 @@ impl<T: Serialize> Serialize for DynamicList<T> {
 }
 
 impl<T: SszSize> SszSize for DynamicList<T> {
-    const SIZE: Size = Size::Variable { minimum_size: 0 };
+    const SIZE: Size = Size::for_list(T::SIZE, usize::MAX);
 }
 
 impl<T: SszReadDefault> SszRead<usize> for DynamicList<T> {

ssz/src/error.rs

@@ -5,6 +5,12 @@ use crate::{
     uint256::Uint256,
 };
 
+#[derive(Clone, Copy, PartialEq, Eq, Debug, Error)]
+pub enum SizeError {
+    #[error("maximum size does not fit in usize")]
+    MaximumSizeDoesNotFitInUsize,
+}
+
 #[derive(Clone, Copy, PartialEq, Eq, Debug, Error)]
 pub enum ReadError {
     #[error("expected fixed-size value of {expected} bytes, found {actual} bytes")]

ssz/src/lib.rs

@@ -14,7 +14,7 @@ pub use crate::{
     contiguous_list::ContiguousList,
     contiguous_vector::ContiguousVector,
     dynamic_list::DynamicList,
-    error::{IndexError, PushError, ReadError, WriteError},
+    error::{IndexError, PushError, ReadError, SizeError, WriteError},
     hc::Hc,
     merkle_tree::{mix_in_length, MerkleTree, ProofWithLength},
     persistent_list::PersistentList,

ssz/src/persistent_list.rs

@@ -235,8 +235,8 @@ impl<T: Serialize, N, B: BundleSize<T>> Serialize for PersistentList<T, N, B> {
     }
 }
 
-impl<T: SszSize, N, B> SszSize for PersistentList<T, N, B> {
-    const SIZE: Size = Size::Variable { minimum_size: 0 };
+impl<T: SszSize, N: Unsigned, B> SszSize for PersistentList<T, N, B> {
+    const SIZE: Size = Size::for_list(T::SIZE, N::USIZE);
 }
 
 impl<C, T: SszRead<C>, N: Unsigned, B: BundleSize<T>> SszRead<C> for PersistentList<T, N, B> {
@@ -246,7 +246,7 @@ impl<C, T: SszRead<C>, N: Unsigned, B: BundleSize<T>> SszRead<C> for PersistentL
     }
 }
 
-impl<T: SszWrite, N, B: BundleSize<T>> SszWrite for PersistentList<T, N, B> {
+impl<T: SszWrite, N: Unsigned, B: BundleSize<T>> SszWrite for PersistentList<T, N, B> {
     fn write_variable(&self, bytes: &mut Vec<u8>) -> Result<(), WriteError> {
         shared::write_list(bytes, self)
     }

ssz/src/persistent_vector.rs

@@ -241,7 +241,7 @@ where
 }
 
 impl<T: SszSize, N: Unsigned + NonZero, B: BundleSize<T>> SszSize for PersistentVector<T, N, B> {
-    const SIZE: Size = T::SIZE.mul(N::USIZE);
+    const SIZE: Size = Size::for_vector(T::SIZE, N::USIZE);
 }
 
 impl<C, T, N, B> SszRead<C> for PersistentVector<T, N, B>

ssz/src/porcelain.rs

@@ -72,8 +72,11 @@ pub trait SszWrite: SszSize {
                 self.write_fixed(bytes.as_mut_slice());
                 Ok(bytes)
             }
-            Size::Variable { minimum_size } => {
-                let mut bytes = Vec::with_capacity(minimum_size);
+            Size::Variable {
+                minimum,
+                maximum: _,
+            } => {
+                let mut bytes = Vec::with_capacity(minimum);
                 self.write_variable(&mut bytes)?;
                 Ok(bytes)
             }