Merge rust-bitcoin/rust-bitcoin#3150: Create a macro that implements `to_hex` for types that have `core::fmt::LowerHex` implemented

30bb93c676 Implement impl_to_hex_from_lower_hex macro for types that implement fmt::LowerHex (Shing Him Ng)

Pull request description:

  Created a macro that implements `to_hex` for types that currently have `core::fmt::LowerHex` and called it on types that have `core::fmt::LowerHex` implemented. I put the macro in the `internals` crate since there are types across the whole project that can potentially use this.

  Resolves #2869

ACKs for top commit:
  Kixunil:
    ACK 30bb93c676
  apoelstra:
    ACK 30bb93c676 successfully ran local tests

Tree-SHA512: d3ebc7b5c0c23f1a8f8eef4379c1b475e8c23845e18ce514cb1e98eb63fc4f215e6bc4425f97c7303053df13374ef931ae9d9373badd7ca1975a55b0d00d0e40

bitcoin/src/blockdata/script/mod.rs

@@ -65,6 +65,7 @@ use core::fmt;
 use core::ops::{Deref, DerefMut};
 
 use hashes::{hash160, sha256};
+use internals::impl_to_hex_from_lower_hex;
 use io::{BufRead, Write};
 
 use crate::consensus::{encode, Decodable, Encodable};
@@ -459,11 +460,13 @@ impl fmt::LowerHex for Script {
         fmt::LowerHex::fmt(&self.as_bytes().as_hex(), f)
     }
 }
+impl_to_hex_from_lower_hex!(Script, |script: &Script| script.len() * 2);
 
 impl fmt::LowerHex for ScriptBuf {
     #[inline]
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::LowerHex::fmt(self.as_script(), f) }
 }
+impl_to_hex_from_lower_hex!(ScriptBuf, |script_buf: &ScriptBuf| script_buf.len() * 2);
 
 impl fmt::UpperHex for Script {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {

bitcoin/src/crypto/ecdsa.rs

@@ -8,7 +8,7 @@ use core::str::FromStr;
 use core::{fmt, iter};
 
 use hex::FromHex;
-use internals::write_err;
+use internals::{impl_to_hex_from_lower_hex, write_err};
 use io::Write;
 
 use crate::prelude::{DisplayHex, Vec};
@@ -174,6 +174,7 @@ impl fmt::LowerHex for SerializedSignature {
         fmt::LowerHex::fmt(&(**self).as_hex(), f)
     }
 }
+impl_to_hex_from_lower_hex!(SerializedSignature, |signature: &SerializedSignature| signature.len * 2);
 
 impl fmt::UpperHex for SerializedSignature {
     #[inline]

bitcoin/src/crypto/key.rs

@@ -12,7 +12,7 @@ use core::str::FromStr;
 use hashes::hash160;
 use hex::{FromHex, HexToArrayError};
 use internals::array_vec::ArrayVec;
-use internals::write_err;
+use internals::{impl_to_hex_from_lower_hex, write_err};
 use io::{Read, Write};
 
 use crate::crypto::ecdsa;
@@ -705,6 +705,8 @@ pub struct TweakedPublicKey(XOnlyPublicKey);
 impl fmt::LowerHex for TweakedPublicKey {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::LowerHex::fmt(&self.0, f) }
 }
+// Allocate for serialized size
+impl_to_hex_from_lower_hex!(TweakedPublicKey, |_| constants::SCHNORR_PUBLIC_KEY_SIZE * 2);
 
 impl fmt::Display for TweakedPublicKey {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Display::fmt(&self.0, f) }

bitcoin/src/p2p/mod.rs

@@ -22,9 +22,8 @@ pub mod message_network;
 
 use core::str::FromStr;
 use core::{fmt, ops};
-
 use hex::FromHex;
-use internals::{debug_from_display, write_err};
+use internals::{debug_from_display, impl_to_hex_from_lower_hex, write_err};
 use io::{BufRead, Write};
 
 use crate::consensus::encode::{self, Decodable, Encodable};
@@ -123,6 +122,7 @@ impl ServiceFlags {
 impl fmt::LowerHex for ServiceFlags {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::LowerHex::fmt(&self.0, f) }
 }
+impl_to_hex_from_lower_hex!(ServiceFlags, |service_flags: &ServiceFlags| 16 - service_flags.0.leading_zeros() as usize / 4);
 
 impl fmt::UpperHex for ServiceFlags {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::UpperHex::fmt(&self.0, f) }
@@ -290,6 +290,7 @@ impl fmt::LowerHex for Magic {
         Ok(())
     }
 }
+impl_to_hex_from_lower_hex!(Magic, |_| 8);
 
 impl fmt::UpperHex for Magic {
     fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {

bitcoin/src/pow.rs

@@ -7,7 +7,7 @@
 
 use core::ops::{Add, Div, Mul, Not, Rem, Shl, Shr, Sub};
 use core::{cmp, fmt};
-
+use internals::impl_to_hex_from_lower_hex;
 use io::{BufRead, Write};
 #[cfg(all(test, mutate))]
 use mutagen::mutate;
@@ -108,6 +108,7 @@ impl Work {
     pub fn log2(self) -> f64 { self.0.to_f64().log2() }
 }
 do_impl!(Work);
+impl_to_hex_from_lower_hex!(Work, |_| 64);
 
 impl Add for Work {
     type Output = Work;
@@ -333,6 +334,7 @@ impl Target {
     pub fn max_transition_threshold_unchecked(&self) -> Self { Self(self.0 << 2) }
 }
 do_impl!(Target);
+impl_to_hex_from_lower_hex!(Target, |_| 64);
 
 define_extension_trait! {
     /// Extension functionality for the [`CompactTarget`] type.

bitcoin/src/taproot/mod.rs

@@ -12,7 +12,7 @@ use core::fmt;
 use core::iter::FusedIterator;
 
 use hashes::{hash_newtype, sha256t, sha256t_tag, HashEngine};
-use internals::write_err;
+use internals::{impl_to_hex_from_lower_hex, write_err};
 use io::Write;
 use secp256k1::{Scalar, Secp256k1};
 
@@ -1221,6 +1221,7 @@ impl fmt::LowerHex for FutureLeafVersion {
     #[inline]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::LowerHex::fmt(&self.0, f) }
 }
+impl_to_hex_from_lower_hex!(FutureLeafVersion, |_| 2);
 
 impl fmt::UpperHex for FutureLeafVersion {
     #[inline]
@@ -1277,6 +1278,7 @@ impl fmt::LowerHex for LeafVersion {
         fmt::LowerHex::fmt(&self.to_consensus(), f)
     }
 }
+impl_to_hex_from_lower_hex!(LeafVersion, |_| 2);
 
 impl fmt::UpperHex for LeafVersion {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

internals/src/macros.rs

@@ -204,3 +204,30 @@ macro_rules! impl_from_infallible {
         }
     }
 }
+
+/// Implements `to_hex` for functions that have implemented [`core::fmt::LowerHex`]
+#[macro_export]
+#[cfg(feature = "alloc")]
+macro_rules! impl_to_hex_from_lower_hex {
+    ($t:ident, $hex_len_fn:expr) => {
+        impl $t {
+            /// Gets the hex representation of this type
+            pub fn to_hex(&self) -> alloc::string::String {
+                use core::fmt::Write;
+
+                let mut hex_string = alloc::string::String::with_capacity($hex_len_fn(self));
+                write!(&mut hex_string, "{:x}", self).expect("writing to string shouldn't fail");
+
+                hex_string
+            }
+        }
+    };
+}
+
+#[macro_export]
+#[cfg(not(feature = "alloc"))]
+macro_rules! impl_to_hex_from_lower_hex {
+    ($t:ident, $hex_len_fn:expr) => {
+
+    };
+}

primitives/src/lib.rs

@@ -47,5 +47,5 @@ pub use self::{pow::CompactTarget, sequence::Sequence};
 #[allow(unused_imports)]
 mod prelude {
     #[cfg(feature = "alloc")]
-    pub use alloc::string::ToString;
+    pub use alloc::string::{String, ToString};
 }

primitives/src/pow.rs

@@ -3,6 +3,7 @@
 //! Proof-of-work related integer types.
 
 use core::fmt;
+use internals::impl_to_hex_from_lower_hex;
 
 /// Encoding of 256-bit target as 32-bit float.
 ///
@@ -34,6 +35,7 @@ impl fmt::LowerHex for CompactTarget {
     #[inline]
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::LowerHex::fmt(&self.0, f) }
 }
+impl_to_hex_from_lower_hex!(CompactTarget, |compact_target: &CompactTarget| 8 - compact_target.0.leading_zeros() as usize / 4);
 
 impl fmt::UpperHex for CompactTarget {
     #[inline]

primitives/src/sequence.rs

@@ -16,14 +16,13 @@
 //! [BIP-125]: <https://github.com/bitcoin/bips/blob/master/bip-0125.mediawiki>
 
 use core::fmt;
-
+use internals::impl_to_hex_from_lower_hex;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 #[cfg(feature = "alloc")]
 use units::locktime::relative::TimeOverflowError;
 #[cfg(feature = "alloc")]
 use units::parse::{self, PrefixedHexError, UnprefixedHexError};
-
 #[cfg(feature = "alloc")]
 use crate::locktime::relative;
 
@@ -220,6 +219,7 @@ impl fmt::Display for Sequence {
 impl fmt::LowerHex for Sequence {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::LowerHex::fmt(&self.0, f) }
 }
+impl_to_hex_from_lower_hex!(Sequence, |sequence: &Sequence| 8 - sequence.0.leading_zeros() as usize / 4);
 
 impl fmt::UpperHex for Sequence {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::UpperHex::fmt(&self.0, f) }