Merge BlockstreamResearch#358: Move the Jet codec and parser towards the object-safaty

bb63bff Transform Jet codec towards object safety (ivanlele)

Pull request description:

  This PR moves the `Jet::decode` method to `JetEnvironment::decode_jet`, introduces a `parse` method for jets within that environment, and updates `Jet::encode` to comply with object safety. See BlockstreamResearch#349 for details.


ACKs for top commit:
  apoelstra:
    ACK bb63bff; successfully ran local tests


Tree-SHA512: 8842ca01f071405a40385712b64b42c5b9a9fd6453325ddd8962108a6d7c59c71f2c4af3e068a5775dee06e9bb8618b6b2270bceaad23268fd2dcf354021b838

Author: apoelstra

fuzz/fuzz_targets/decode_program.rs

@@ -11,10 +11,10 @@ fn do_test(data: &[u8]) {
     let wit_iter = BitIter::new(core::iter::repeat(0));
     if let Ok(program) = RedeemNode::<Core>::decode(prog_iter, wit_iter) {
         let mut prog_reser = Vec::<u8>::new();
-        let mut wit_reser = std::io::sink();
+        let mut wit_reser = Vec::<u8>::new();
 
-        let mut prog_w = BitWriter::from(&mut prog_reser);
-        let mut wit_w = BitWriter::from(&mut wit_reser);
+        let mut prog_w = BitWriter::from(&mut prog_reser as &mut dyn std::io::Write);
+        let mut wit_w = BitWriter::from(&mut wit_reser as &mut dyn std::io::Write);
         program
             .encode(&mut prog_w, &mut wit_w)
             .expect("encoding to vector");

simplicity-sys/depend/simplicity-HEAD-revision.txt

@@ -1,2 +1,2 @@
 # This file has been automatically generated.
-d190505509f4c04b1b9193c6739515f9faa18aac
+c6ab4dd8f17838506f92f0d829c40618168817cd

src/bit_encoding/encode.rs

@@ -154,9 +154,9 @@ impl<N: node::Marker> SharingTracker<EncodeNode<'_, N>> for EncodeSharing<N> {
 /// Encode a Simplicity program to bits, without witness data.
 ///
 /// Returns the number of written bits.
-pub fn encode_program<W: io::Write, N: node::Marker>(
+pub fn encode_program<N: node::Marker>(
     program: &node::Node<N>,
-    w: &mut BitWriter<W>,
+    w: &mut BitWriter<&mut dyn io::Write>,
 ) -> io::Result<usize> {
     let iter = EncodeNode::Node(program).post_order_iter::<EncodeSharing<N>>();
 
@@ -172,9 +172,9 @@ pub fn encode_program<W: io::Write, N: node::Marker>(
 }
 
 /// Encode a node to bits.
-fn encode_node<W: io::Write, N: node::Marker>(
+fn encode_node<N: node::Marker>(
     data: PostOrderIterItem<EncodeNode<N>>,
-    w: &mut BitWriter<W>,
+    w: &mut BitWriter<&mut dyn io::Write>,
 ) -> io::Result<()> {
     // Handle Hidden nodes specially
     let node = match data.node {

src/human_encoding/named_node.rs

@@ -199,7 +199,7 @@ impl<J: Jet> NamedCommitNode<J> {
 
     /// Encode a Simplicity expression to bits without any witness data
     #[deprecated(since = "0.5.0", note = "use Self::encode_without_witness instead")]
-    pub fn encode<W: io::Write>(&self, w: &mut BitWriter<W>) -> io::Result<usize> {
+    pub fn encode(&self, w: &mut BitWriter<&mut dyn io::Write>) -> io::Result<usize> {
         let program_bits = encode::encode_program(self, w)?;
         w.flush_all()?;
         Ok(program_bits)

src/human_encoding/parse/ast.rs

@@ -495,7 +495,7 @@ fn parse_expr<J: Jet + 'static>(p: &mut Parser) -> Result<Expression<J>, ErrorSe
         Some(Token::Jet(ref name)) => {
             let jet_name = name.clone();
             p.advance();
-            let Ok(jet) = J::from_str(&jet_name[4..]) else {
+            let Ok(jet) = J::parse(&jet_name[4..]) else {
                 return Err(ErrorSet::single(position, Error::UnknownJet(jet_name)));
             };
             Ok(Expression {

src/jet/bitcoin/mod.rs

@@ -6,7 +6,6 @@ pub use environment::BitcoinEnv;
 
 use super::init::bitcoin::Bitcoin;
 use super::JetEnvironment;
-use crate::jet::Jet;
 use simplicity_sys::c_jets::frame_ffi::CFrameItem;
 
 impl JetEnvironment for BitcoinEnv {
@@ -19,7 +18,7 @@ impl JetEnvironment for BitcoinEnv {
 
     fn c_jet_ptr(
         jet: &Self::Jet,
-    ) -> &dyn Fn(&mut CFrameItem, CFrameItem, &Self::CJetEnvironment) -> bool {
-        jet.c_jet_ptr()
+    ) -> fn(&mut CFrameItem, CFrameItem, &Self::CJetEnvironment) -> bool {
+        super::init::bitcoin::c_jet_ptr(jet)
     }
 }

src/jet/core/mod.rs

@@ -2,7 +2,6 @@
 
 use super::init::core::Core;
 use super::JetEnvironment;
-use crate::jet::Jet;
 use simplicity_sys::c_jets::frame_ffi::CFrameItem;
 
 /// Type alias for the Core jet environment.
@@ -27,7 +26,7 @@ impl JetEnvironment for CoreEnv {
 
     fn c_jet_ptr(
         jet: &Self::Jet,
-    ) -> &dyn Fn(&mut CFrameItem, CFrameItem, &Self::CJetEnvironment) -> bool {
-        jet.c_jet_ptr()
+    ) -> fn(&mut CFrameItem, CFrameItem, &Self::CJetEnvironment) -> bool {
+        super::init::core::c_jet_ptr(jet)
     }
 }

src/jet/elements/mod.rs

@@ -9,7 +9,6 @@ pub use environment::{ElementsEnv, ElementsUtxo};
 
 use super::init::elements::Elements;
 use super::JetEnvironment;
-use crate::jet::Jet;
 use simplicity_sys::c_jets::frame_ffi::CFrameItem;
 use simplicity_sys::CElementsTxEnv;
 
@@ -26,7 +25,7 @@ impl JetEnvironment for ElementsTxEnv {
 
     fn c_jet_ptr(
         jet: &Self::Jet,
-    ) -> &dyn Fn(&mut CFrameItem, CFrameItem, &Self::CJetEnvironment) -> bool {
-        jet.c_jet_ptr()
+    ) -> fn(&mut CFrameItem, CFrameItem, &Self::CJetEnvironment) -> bool {
+        super::init::elements::c_jet_ptr(jet)
     }
 }

src/jet/init/bitcoin.rs

@@ -10,7 +10,6 @@ use hashes::sha256::Midstate;
 use simplicity_sys::CFrameItem;
 use std::io::Write;
 use std::{fmt, str};
-use crate::jet::bitcoin::BitcoinEnv;
 
 /// The Bitcoin jet family.
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
@@ -881,13 +880,6 @@ impl Bitcoin {
 
 impl Jet for Bitcoin {
 
-    type Environment = BitcoinEnv;
-    type CJetEnvironment = ();
-
-    fn c_jet_env(_env: &Self::Environment) -> &Self::CJetEnvironment {
-        unimplemented!("Unspecified CJetEnvironment for Bitcoin jets")
-    }
-
     fn cmr(&self) -> Cmr {
         unimplemented!("Bitcoin jet CMRs weights have not yet been implemented.")
     }
@@ -1762,7 +1754,7 @@ impl Jet for Bitcoin {
         TypeName(name)
     }
 
-    fn encode<W: Write>(&self, w: &mut BitWriter<W>) -> std::io::Result<usize> {
+    fn encode(&self, w: &mut BitWriter<&mut dyn Write>) -> std::io::Result<usize> {
         let (n, len) = match self {
             Bitcoin::Verify => (0, 3),
             Bitcoin::Low1 => (8, 6),
@@ -2197,7 +2189,7 @@ impl Jet for Bitcoin {
         w.write_bits_be(n, len)
     }
 
-    fn decode<I: Iterator<Item = u8>>(bits: &mut BitIter<I>) -> Result<Self, decode::Error> {
+    fn decode<I: Iterator<Item = u8>>(bits: &mut BitIter<I>) -> Result<Self, decode::Error> where Self: Sized {
         decode_bits!(bits, {
             0 => {
                 0 => {
@@ -4706,13 +4698,13 @@ impl Jet for Bitcoin {
         })
     }
 
-    fn c_jet_ptr(&self) -> &dyn Fn(&mut CFrameItem, CFrameItem, &Self::CJetEnvironment) -> bool {
-        unimplemented!("Bitcoin jets have not yet been implemented.")
-    }
-
     fn cost(&self) -> Cost {
         unimplemented!("Unspecified cost of Bitcoin jets")
     }
+
+    fn parse(s: &str) -> Result<Self, crate::Error> where Self: Sized {
+        str::FromStr::from_str(s)
+    }
 }
 
 impl fmt::Display for Bitcoin {
@@ -5587,3 +5579,7 @@ impl str::FromStr for Bitcoin {
         }
     }
 }
+
+pub(crate) fn c_jet_ptr(jet: &Bitcoin) -> fn(&mut CFrameItem, CFrameItem, &()) -> bool {
+        unimplemented!("Bitcoin jets have not yet been implemented.")
+}