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Convert encoder/decoder constructors to const
Public commit record
68/100 · Adequate
What the developer wrote
Authored by Mitchell Bagot
Convert encoder/decoder constructors to const
Using const functions allows the compiler to make certain optimisations
by precomputing some values during compilation, instead of at runtime.
Convert all constructors in the consensus_encoding crate to const, with
the following exceptions:
SliceEncoder::without_length_prefix - This needs to call T::encoder,
which would require making the Encodable trait use a const fn.
CompactSizeEncoder::new - Requires various ArrayVec functions to be
const, which requires a cascade of const functions elsewhere.
✓ Descriptive subject✓ Names a concrete action or component✓ Provides detailed explanatory context
What changed, and why it matters
This commit is a routine performance and ergonomics improvement. It changes several Rust constructor functions from regular functions to 'const' functions, which lets the compiler precompute some values at compile time rather than runtime. There is no change to security behavior, no bug fix, and no vulnerability patch.
Recommended action
No security action required. Treat as a normal optimization/refactoring commit.
Security signals we found
No strong security signals were identified.
Evidence from the diff
The patch converts public constructors in the consensus_encoding crate to pub const fn, enabling compile-time evaluation. It touches ByteVecDecoder, VecDecoder, ArrayDecoder, Decoder2/3/4/6, CompactSizeDecoder, BytesEncoder, ArrayEncoder, and Encoder2/3/4/6 constructors. The only functional change is replacing CompactSizeDecoder::default() with CompactSizeDecoder::new() inside ByteVecDecoder::new, which is semantically equivalent. No logic, bounds checking, error handling, or API contracts are altered.
Changed components
consensus_encoding/src/decode/decoders.rsconsensus_encoding/src/encode/encoders.rsInspect captured patch +15 / −15
diff --git a/consensus_encoding/src/decode/decoders.rs b/consensus_encoding/src/decode/decoders.rs
index 502696bb..5eadeafc 100644
--- a/consensus_encoding/src/decode/decoders.rs
+++ b/consensus_encoding/src/decode/decoders.rs
@@ -32,9 +32,9 @@ pub struct ByteVecDecoder {
#[cfg(feature = "alloc")]
impl ByteVecDecoder {
/// Constructs a new byte decoder.
- pub fn new() -> Self {
+ pub const fn new() -> Self {
Self {
- prefix_decoder: Some(CompactSizeDecoder::default()),
+ prefix_decoder: Some(CompactSizeDecoder::new()),
buffer: Vec::new(),
bytes_expected: 0,
bytes_written: 0,
@@ -116,7 +116,7 @@ pub struct VecDecoder<T: Decodable> {
#[cfg(feature = "alloc")]
impl<T: Decodable> VecDecoder<T> {
/// Constructs a new byte decoder.
- pub fn new() -> Self {
+ pub const fn new() -> Self {
Self {
prefix_decoder: Some(CompactSizeDecoder::new()),
length: 0,
@@ -235,7 +235,7 @@ pub struct ArrayDecoder<const N: usize> {
impl<const N: usize> ArrayDecoder<N> {
/// Constructs a new array decoder that expects exactly N bytes.
- pub fn new() -> Self { Self { buffer: [0; N], bytes_written: 0 } }
+ pub const fn new() -> Self { Self { buffer: [0; N], bytes_written: 0 } }
}
impl<const N: usize> Default for ArrayDecoder<N> {
@@ -299,7 +299,7 @@ where
B: Decoder,
{
/// Constructs a new composite decoder.
- pub fn new(first: A, second: B) -> Self { Self { state: Decoder2State::First(first, second) } }
+ pub const fn new(first: A, second: B) -> Self { Self { state: Decoder2State::First(first, second) } }
}
impl<A, B> Decoder for Decoder2<A, B>
@@ -392,7 +392,7 @@ where
C: Decoder,
{
/// Constructs a new composite decoder.
- pub fn new(dec_1: A, dec_2: B, dec_3: C) -> Self {
+ pub const fn new(dec_1: A, dec_2: B, dec_3: C) -> Self {
Self { inner: Decoder2::new(Decoder2::new(dec_1, dec_2), dec_3) }
}
}
@@ -450,7 +450,7 @@ where
D: Decoder,
{
/// Constructs a new composite decoder.
- pub fn new(dec_1: A, dec_2: B, dec_3: C, dec_4: D) -> Self {
+ pub const fn new(dec_1: A, dec_2: B, dec_3: C, dec_4: D) -> Self {
Self { inner: Decoder2::new(Decoder2::new(dec_1, dec_2), Decoder2::new(dec_3, dec_4)) }
}
}
@@ -516,7 +516,7 @@ where
F: Decoder,
{
/// Constructs a new composite decoder.
- pub fn new(dec_1: A, dec_2: B, dec_3: C, dec_4: D, dec_5: E, dec_6: F) -> Self {
+ pub const fn new(dec_1: A, dec_2: B, dec_3: C, dec_4: D, dec_5: E, dec_6: F) -> Self {
Self {
inner: Decoder2::new(
Decoder3::new(dec_1, dec_2, dec_3),
@@ -579,7 +579,7 @@ pub struct CompactSizeDecoder {
impl CompactSizeDecoder {
/// Constructs a new compact size decoder.
- pub fn new() -> Self { Self { buf: internals::array_vec::ArrayVec::new() } }
+ pub const fn new() -> Self { Self { buf: internals::array_vec::ArrayVec::new() } }
}
impl Default for CompactSizeDecoder {
diff --git a/consensus_encoding/src/encode/encoders.rs b/consensus_encoding/src/encode/encoders.rs
index fc6a271e..0aac982a 100644
--- a/consensus_encoding/src/encode/encoders.rs
+++ b/consensus_encoding/src/encode/encoders.rs
@@ -26,7 +26,7 @@ pub struct BytesEncoder<'sl> {
impl<'sl> BytesEncoder<'sl> {
/// Constructs a byte encoder which encodes the given byte slice, with no length prefix.
- pub fn without_length_prefix(sl: &'sl [u8]) -> Self { Self { sl: Some(sl) } }
+ pub const fn without_length_prefix(sl: &'sl [u8]) -> Self { Self { sl: Some(sl) } }
}
impl Encoder for BytesEncoder<'_> {
@@ -45,7 +45,7 @@ pub struct ArrayEncoder<const N: usize> {
impl<const N: usize> ArrayEncoder<N> {
/// Constructs an encoder which encodes the array with no length prefix.
- pub fn without_length_prefix(arr: [u8; N]) -> Self { Self { arr: Some(arr) } }
+ pub const fn without_length_prefix(arr: [u8; N]) -> Self { Self { arr: Some(arr) } }
}
impl<const N: usize> Encoder for ArrayEncoder<N> {
@@ -124,7 +124,7 @@ pub struct Encoder2<A, B> {
impl<A, B> Encoder2<A, B> {
/// Constructs a new composite encoder.
- pub fn new(enc_1: A, enc_2: B) -> Self { Self { enc_idx: 0, enc_1, enc_2 } }
+ pub const fn new(enc_1: A, enc_2: B) -> Self { Self { enc_idx: 0, enc_1, enc_2 } }
}
impl<A: Encoder, B: Encoder> Encoder for Encoder2<A, B> {
@@ -162,7 +162,7 @@ pub struct Encoder3<A, B, C> {
impl<A, B, C> Encoder3<A, B, C> {
/// Constructs a new composite encoder.
- pub fn new(enc_1: A, enc_2: B, enc_3: C) -> Self {
+ pub const fn new(enc_1: A, enc_2: B, enc_3: C) -> Self {
Self { inner: Encoder2::new(Encoder2::new(enc_1, enc_2), enc_3) }
}
}
@@ -181,7 +181,7 @@ pub struct Encoder4<A, B, C, D> {
impl<A, B, C, D> Encoder4<A, B, C, D> {
/// Constructs a new composite encoder.
- pub fn new(enc_1: A, enc_2: B, enc_3: C, enc_4: D) -> Self {
+ pub const fn new(enc_1: A, enc_2: B, enc_3: C, enc_4: D) -> Self {
Self { inner: Encoder2::new(Encoder2::new(enc_1, enc_2), Encoder2::new(enc_3, enc_4)) }
}
}
@@ -200,7 +200,7 @@ pub struct Encoder6<A, B, C, D, E, F> {
impl<A, B, C, D, E, F> Encoder6<A, B, C, D, E, F> {
/// Constructs a new composite encoder.
- pub fn new(enc_1: A, enc_2: B, enc_3: C, enc_4: D, enc_5: E, enc_6: F) -> Self {
+ pub const fn new(enc_1: A, enc_2: B, enc_3: C, enc_4: D, enc_5: E, enc_6: F) -> Self {
Self {
inner: Encoder2::new(
Encoder3::new(enc_1, enc_2, enc_3),
Risk score
Our methodology →Why this scored 15/100
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