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Rename marker structs for Bitfield

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This commit is contained in:
Paul Hauner 2019-07-11 12:40:37 +10:00
parent 5e1a2ebf25
commit 2c1afcc2d6
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2 changed files with 66 additions and 44 deletions
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98
eth2/utils/ssz_types/src/bitfield.rs
View File

@ -5,43 +5,61 @@ use serde_hex::{encode as hex_encode, PrefixedHexVisitor};
use ssz::{Decode, Encode};
use typenum::Unsigned;
/// A marker trait applied to `BitList` and `BitVector` that defines the behaviour of a `Bitfield`.
/// A marker trait applied to `Variable` and `Fixed` that defines the behaviour of a `Bitfield`.
pub trait BitfieldBehaviour: Clone {}
/// A marker struct used to declare SSZ `BitList` behaviour on a `Bitfield`.
/// A marker struct used to declare SSZ `Variable` behaviour on a `Bitfield`.
///
/// See the [`Bitfield`](struct.Bitfield.html) docs for usage.
#[derive(Clone, PartialEq, Debug)]
pub struct BitList<N> {
pub struct Variable<N> {
_phantom: PhantomData<N>,
}
/// A marker struct used to declare SSZ `BitVector` behaviour on a `Bitfield`.
/// A marker struct used to declare SSZ `Fixed` behaviour on a `Bitfield`.
///
/// See the [`Bitfield`](struct.Bitfield.html) docs for usage.
#[derive(Clone, PartialEq, Debug)]
pub struct BitVector<N> {
pub struct Fixed<N> {
_phantom: PhantomData<N>,
}
impl<N: Unsigned + Clone> BitfieldBehaviour for BitList<N> {}
impl<N: Unsigned + Clone> BitfieldBehaviour for BitVector<N> {}
impl<N: Unsigned + Clone> BitfieldBehaviour for Variable<N> {}
impl<N: Unsigned + Clone> BitfieldBehaviour for Fixed<N> {}
/// A heap-allocated, ordered, fixed-length, collection of `bool` values. Must be used with the `BitList` or
/// `BitVector` marker structs.
/// A heap-allocated, ordered, variable-length collection of `bool` values, limited to `N` bits.
pub type BitList<N> = Bitfield<Variable<N>>;
/// A heap-allocated, ordered, fixed-length collection of `bool` values, with `N` bits.
///
/// See [Bitfield](struct.Bitfield.html) documentation.
pub type BitVector<N> = Bitfield<Fixed<N>>;
/// A heap-allocated, ordered, fixed-length, collection of `bool` values. Use of
/// [`BitList`](type.BitList.html) or [`BitVector`](type.BitVector.html) type aliases is preferred
/// over direct use of this struct.
///
/// The `T` type parameter is used to define length behaviour with the `Variable` or `Fixed` marker
/// structs.
///
/// The length of the Bitfield is set at instantiation (i.e., runtime, not compile time). However,
/// use with a `BitList` sets a type-level (i.e., compile-time) maximum length and `BitVector`
/// use with a `Variable` sets a type-level (i.e., compile-time) maximum length and `Fixed`
/// provides a type-level fixed length.
///
/// ## Example
///
/// The example uses the following crate-level type aliases:
///
/// - `BitList<N>` is an alias for `Bitfield<Variable<N>>`
/// - `BitVector<N>` is an alias for `Bitfield<Fixed<N>>`
///
/// ```
/// use ssz_types::{Bitfield, BitVector, BitList, typenum};
/// use ssz_types::{BitVector, BitList, typenum};
///
/// // `BitList` has a type-level maximum length. The length of the list is specified at runtime
/// // and it must be less than or equal to `N`. After instantiation, `BitList` cannot grow or
/// // shrink.
/// type BitList8 = Bitfield<BitList<typenum::U8>>;
/// type BitList8 = BitList<typenum::U8>;
///
/// // Creating a `BitList` with a larger-than-`N` capacity returns `None`.
/// assert!(BitList8::with_capacity(9).is_none());
@ -52,7 +70,7 @@ impl<N: Unsigned + Clone> BitfieldBehaviour for BitVector<N> {}
///
/// // `BitVector` has a type-level fixed length. Unlike `BitList`, it cannot be instantiated with a custom length
/// // or grow/shrink.
/// type BitVector8 = Bitfield<BitVector<typenum::U8>>;
/// type BitVector8 = BitVector<typenum::U8>;
///
/// let mut bitvector = BitVector8::new();
/// assert_eq!(bitvector.len(), 8); // `BitVector` length is fixed at the type-level.
@ -73,7 +91,7 @@ pub struct Bitfield<T> {
_phantom: PhantomData<T>,
}
impl<N: Unsigned + Clone> Bitfield<BitList<N>> {
impl<N: Unsigned + Clone> Bitfield<Variable<N>> {
/// Instantiate with capacity for `num_bits` boolean values. The length cannot be grown or
/// shrunk after instantiation.
///
@ -104,11 +122,11 @@ impl<N: Unsigned + Clone> Bitfield<BitList<N>> {
///
/// ## Example
/// ```
/// use ssz_types::{Bitfield, typenum};
/// use ssz_types::{BitList, typenum};
///
/// type BitList = Bitfield<ssz_types::BitList<typenum::U8>>;
/// type BitList8 = BitList<typenum::U8>;
///
/// let b = BitList::with_capacity(4).unwrap();
/// let b = BitList8::with_capacity(4).unwrap();
///
/// assert_eq!(b.into_bytes(), vec![0b0001_0000]);
/// ```
@ -120,7 +138,7 @@ impl<N: Unsigned + Clone> Bitfield<BitList<N>> {
bytes.insert(0, 0);
}
let mut bitfield: Bitfield<BitList<N>> = Bitfield::from_raw_bytes(bytes, len + 1)
let mut bitfield: Bitfield<Variable<N>> = Bitfield::from_raw_bytes(bytes, len + 1)
.expect("Bitfield capacity has been confirmed earlier.");
bitfield.set(len, true).expect("Bitfield index must exist.");
@ -132,7 +150,7 @@ impl<N: Unsigned + Clone> Bitfield<BitList<N>> {
///
/// Returns `None` if `bytes` are not a valid encoding.
pub fn from_bytes(bytes: Vec<u8>) -> Option<Self> {
let mut initial_bitfield: Bitfield<BitList<N>> = {
let mut initial_bitfield: Bitfield<Variable<N>> = {
let num_bits = bytes.len() * 8;
Bitfield::from_raw_bytes(bytes, num_bits)
.expect("Must have adequate bytes for bit count.")
@ -158,7 +176,7 @@ impl<N: Unsigned + Clone> Bitfield<BitList<N>> {
}
}
impl<N: Unsigned + Clone> Bitfield<BitVector<N>> {
impl<N: Unsigned + Clone> Bitfield<Fixed<N>> {
/// Instantiate a new `Bitfield` with a fixed-length of `N` bits.
///
/// All bits are initialized to `false`.
@ -181,11 +199,11 @@ impl<N: Unsigned + Clone> Bitfield<BitVector<N>> {
///
/// ## Example
/// ```
/// use ssz_types::{Bitfield, typenum};
/// use ssz_types::{BitVector, typenum};
///
/// type BitVector = Bitfield<ssz_types::BitVector<typenum::U4>>;
/// type BitVector4 = BitVector<typenum::U4>;
///
/// assert_eq!(BitVector::new().into_bytes(), vec![0b0000_0000]);
/// assert_eq!(BitVector4::new().into_bytes(), vec![0b0000_0000]);
/// ```
pub fn into_bytes(self) -> Vec<u8> {
self.into_raw_bytes()
@ -200,7 +218,7 @@ impl<N: Unsigned + Clone> Bitfield<BitVector<N>> {
}
}
impl<N: Unsigned + Clone> Default for Bitfield<BitVector<N>> {
impl<N: Unsigned + Clone> Default for Bitfield<Fixed<N>> {
fn default() -> Self {
Self::new()
}
@ -437,7 +455,7 @@ impl<'a, T: BitfieldBehaviour> Iterator for BitIter<'a, T> {
}
}
impl<N: Unsigned + Clone> Encode for Bitfield<BitList<N>> {
impl<N: Unsigned + Clone> Encode for Bitfield<Variable<N>> {
fn is_ssz_fixed_len() -> bool {
false
}
@ -447,18 +465,18 @@ impl<N: Unsigned + Clone> Encode for Bitfield<BitList<N>> {
}
}
impl<N: Unsigned + Clone> Decode for Bitfield<BitList<N>> {
impl<N: Unsigned + Clone> Decode for Bitfield<Variable<N>> {
fn is_ssz_fixed_len() -> bool {
false
}
fn from_ssz_bytes(bytes: &[u8]) -> Result<Self, ssz::DecodeError> {
Self::from_bytes(bytes.to_vec())
.ok_or_else(|| ssz::DecodeError::BytesInvalid("BitList failed to decode".to_string()))
.ok_or_else(|| ssz::DecodeError::BytesInvalid("Variable failed to decode".to_string()))
}
}
impl<N: Unsigned + Clone> Encode for Bitfield<BitVector<N>> {
impl<N: Unsigned + Clone> Encode for Bitfield<Fixed<N>> {
fn is_ssz_fixed_len() -> bool {
true
}
@ -472,18 +490,18 @@ impl<N: Unsigned + Clone> Encode for Bitfield<BitVector<N>> {
}
}
impl<N: Unsigned + Clone> Decode for Bitfield<BitVector<N>> {
impl<N: Unsigned + Clone> Decode for Bitfield<Fixed<N>> {
fn is_ssz_fixed_len() -> bool {
false
}
fn from_ssz_bytes(bytes: &[u8]) -> Result<Self, ssz::DecodeError> {
Self::from_bytes(bytes.to_vec())
.ok_or_else(|| ssz::DecodeError::BytesInvalid("BitVector failed to decode".to_string()))
.ok_or_else(|| ssz::DecodeError::BytesInvalid("Fixed failed to decode".to_string()))
}
}
impl<N: Unsigned + Clone> Serialize for Bitfield<BitList<N>> {
impl<N: Unsigned + Clone> Serialize for Bitfield<Variable<N>> {
/// Serde serialization is compliant with the Ethereum YAML test format.
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
@ -493,7 +511,7 @@ impl<N: Unsigned + Clone> Serialize for Bitfield<BitList<N>> {
}
}
impl<'de, N: Unsigned + Clone> Deserialize<'de> for Bitfield<BitList<N>> {
impl<'de, N: Unsigned + Clone> Deserialize<'de> for Bitfield<Variable<N>> {
/// Serde serialization is compliant with the Ethereum YAML test format.
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where
@ -508,7 +526,7 @@ impl<'de, N: Unsigned + Clone> Deserialize<'de> for Bitfield<BitList<N>> {
}
}
impl<N: Unsigned + Clone> Serialize for Bitfield<BitVector<N>> {
impl<N: Unsigned + Clone> Serialize for Bitfield<Fixed<N>> {
/// Serde serialization is compliant with the Ethereum YAML test format.
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
@ -518,7 +536,7 @@ impl<N: Unsigned + Clone> Serialize for Bitfield<BitVector<N>> {
}
}
impl<'de, N: Unsigned + Clone> Deserialize<'de> for Bitfield<BitVector<N>> {
impl<'de, N: Unsigned + Clone> Deserialize<'de> for Bitfield<Fixed<N>> {
/// Serde serialization is compliant with the Ethereum YAML test format.
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where
@ -533,7 +551,7 @@ impl<'de, N: Unsigned + Clone> Deserialize<'de> for Bitfield<BitVector<N>> {
}
}
impl<N: Unsigned + Clone> tree_hash::TreeHash for Bitfield<BitList<N>> {
impl<N: Unsigned + Clone> tree_hash::TreeHash for Bitfield<Variable<N>> {
fn tree_hash_type() -> tree_hash::TreeHashType {
tree_hash::TreeHashType::List
}
@ -552,7 +570,7 @@ impl<N: Unsigned + Clone> tree_hash::TreeHash for Bitfield<BitList<N>> {
}
}
impl<N: Unsigned + Clone> tree_hash::TreeHash for Bitfield<BitVector<N>> {
impl<N: Unsigned + Clone> tree_hash::TreeHash for Bitfield<Fixed<N>> {
fn tree_hash_type() -> tree_hash::TreeHashType {
// TODO: move this to be a vector.
tree_hash::TreeHashType::List
@ -573,7 +591,7 @@ impl<N: Unsigned + Clone> tree_hash::TreeHash for Bitfield<BitVector<N>> {
}
}
impl<N: Unsigned + Clone> cached_tree_hash::CachedTreeHash for Bitfield<BitList<N>> {
impl<N: Unsigned + Clone> cached_tree_hash::CachedTreeHash for Bitfield<Variable<N>> {
fn new_tree_hash_cache(
&self,
depth: usize,
@ -619,7 +637,7 @@ impl<N: Unsigned + Clone> cached_tree_hash::CachedTreeHash for Bitfield<BitList<
}
}
impl<N: Unsigned + Clone> cached_tree_hash::CachedTreeHash for Bitfield<BitVector<N>> {
impl<N: Unsigned + Clone> cached_tree_hash::CachedTreeHash for Bitfield<Fixed<N>> {
fn new_tree_hash_cache(
&self,
depth: usize,
@ -653,8 +671,8 @@ impl<N: Unsigned + Clone> cached_tree_hash::CachedTreeHash for Bitfield<BitVecto
#[cfg(test)]
mod bitvector {
use super::*;
use crate::BitVector;
pub type BitVector<N> = crate::Bitfield<crate::BitVector<N>>;
pub type BitVector0 = BitVector<typenum::U0>;
pub type BitVector1 = BitVector<typenum::U1>;
pub type BitVector4 = BitVector<typenum::U4>;
@ -753,8 +771,8 @@ mod bitvector {
#[cfg(test)]
mod bitlist {
use super::*;
use crate::BitList;
pub type BitList<N> = super::Bitfield<crate::BitList<N>>;
pub type BitList0 = BitList<typenum::U0>;
pub type BitList1 = BitList<typenum::U1>;
pub type BitList8 = BitList<typenum::U8>;

12
eth2/utils/ssz_types/src/lib.rs
View File

@ -2,8 +2,8 @@
//!
//! - `FixedVector`: A heap-allocated list with a size that is fixed at compile time.
//! - `VariableList`: A heap-allocated list that cannot grow past a type-level maximum length.
//! - `Bitfield<BitList>`: A heap-allocated bitfield that with a type-level _maximum_ length.
//! - `Bitfield<VariableList>`: A heap-allocated bitfield that with a type-level _fixed__ length.
//! - `BitList`: A heap-allocated bitfield that with a type-level _maximum_ length.
//! - `BitVector`: A heap-allocated bitfield that with a type-level _fixed__ length.
//!
//! These structs are required as SSZ serialization and Merklization rely upon type-level lengths
//! for padding and verification.
@ -13,8 +13,8 @@
//! use ssz_types::*;
//!
//! pub struct Example {
//! bit_vector: Bitfield<BitVector<typenum::U8>>,
//! bit_list: Bitfield<BitList<typenum::U8>>,
//! bit_vector: BitVector<typenum::U8>,
//! bit_list: BitList<typenum::U8>,
//! variable_list: VariableList<u64, typenum::U8>,
//! fixed_vector: FixedVector<u64, typenum::U8>,
//! }
@ -43,6 +43,10 @@ pub use fixed_vector::FixedVector;
pub use typenum;
pub use variable_list::VariableList;
pub mod length {
pub use crate::bitfield::{Fixed, Variable};
}
/// Returned when an item encounters an error.
#[derive(PartialEq, Debug)]
pub enum Error {