Merge rust-bitcoin/rust-miniscript#845: various improvements/refactors of the decoder and its errors

cdb36c19b536ef8d8716dd1423e7e6b96433101e miniscript: rename parse_* functions to decode_* (Andrew Poelstra)
5fea2b3cee70f02b18f1d6fbba7b777ab329e7b1 miniscript: rename and cleanup decode::KeyParseError (Andrew Poelstra)
a57fab3ca26a20140a90b8ca66408c9246fdf9cd miniscript: replace many calls to reduce0 in decode with infallible constructors (Andrew Poelstra)
5b736bdede89b15866659c4d38383db4af4240cd miniscript: move lexer errors into their own type (Andrew Poelstra)
ceadd0d4d98bf8f7bc2a80f1727769cb9e442f9a miniscript: use byte arrays in lexer (Andrew Poelstra)

Pull request description:

  The last commit, which renames `parse_with_ext` to `decode_with_ext`, I think we should backport with deprecation to 12.x. This is a pretty uncommonly used function and is unlikely to bother anybody, but the current name is inconsistent with our general use of "parse" for strings and "decode" for scripts.


ACKs for top commit:
  sanket1729:
    ACK cdb36c19b536ef8d8716dd1423e7e6b96433101e


Tree-SHA512: 8a3563dd23e49cf9331b299e237337a3d1097c15d5fe143ec9aa3f686d681fda077f019b25f0d66fccdd9a88ec489a84e144fcbb28410a671eb113f38e0fe58d

Author: heap-coder

fuzz/fuzz_targets/roundtrip_miniscript_script.rs

@@ -8,7 +8,7 @@ fn do_test(data: &[u8]) {
     // Try round-tripping as a script
     let script = script::Script::from_bytes(data);
 
-    if let Ok(pt) = Miniscript::<miniscript::bitcoin::PublicKey, Segwitv0>::parse(script) {
+    if let Ok(pt) = Miniscript::<miniscript::bitcoin::PublicKey, Segwitv0>::decode(script) {
         let output = pt.encode();
         assert_eq!(pt.script_size(), output.len());
         assert_eq!(&output, script);

fuzz/fuzz_targets/roundtrip_miniscript_script_tap.rs

@@ -8,7 +8,7 @@ fn do_test(data: &[u8]) {
     // Try round-tripping as a script
     let script = script::Script::from_bytes(data);
 
-    if let Ok(pt) = Miniscript::<miniscript::bitcoin::key::XOnlyPublicKey, Tap>::parse(script) {
+    if let Ok(pt) = Miniscript::<miniscript::bitcoin::key::XOnlyPublicKey, Tap>::decode(script) {
         let output = pt.encode();
         assert_eq!(pt.script_size(), output.len());
         assert_eq!(&output, script);

src/interpreter/inner.rs

@@ -43,7 +43,7 @@ fn script_from_stack_elem<Ctx: ScriptContext>(
 ) -> Result<Miniscript<Ctx::Key, Ctx>, Error> {
     match *elem {
         stack::Element::Push(sl) => {
-            Miniscript::parse_with_ext(bitcoin::Script::from_bytes(sl), &ExtParams::allow_all())
+            Miniscript::decode_with_ext(bitcoin::Script::from_bytes(sl), &ExtParams::allow_all())
                 .map_err(Error::from)
         }
         stack::Element::Satisfied => Ok(Miniscript::TRUE),
@@ -327,7 +327,7 @@ pub(super) fn from_txdata<'txin>(
     } else {
         if wit_stack.is_empty() {
             // Bare script parsed in BareCtx
-            let miniscript = Miniscript::<bitcoin::PublicKey, BareCtx>::parse_with_ext(
+            let miniscript = Miniscript::<bitcoin::PublicKey, BareCtx>::decode_with_ext(
                 spk,
                 &ExtParams::allow_all(),
             )?;

src/lib.rs

@@ -131,8 +131,6 @@ mod util;
 use core::{fmt, hash, str};
 
 use bitcoin::hashes::{hash160, ripemd160, sha256, Hash};
-use bitcoin::hex::DisplayHex;
-use bitcoin::{script, Opcode};
 
 pub use crate::blanket_traits::FromStrKey;
 pub use crate::descriptor::{DefiniteDescriptorKey, Descriptor, DescriptorPublicKey};
@@ -436,15 +434,8 @@ pub trait ForEachKey<Pk: MiniscriptKey> {
 
 #[derive(Debug)]
 pub enum Error {
-    /// Opcode appeared which is not part of the script subset
-    InvalidOpcode(Opcode),
-    /// Some opcode occurred followed by `OP_VERIFY` when it had
-    /// a `VERIFY` version that should have been used instead
-    NonMinimalVerify(String),
-    /// Push was illegal in some context
-    InvalidPush(Vec<u8>),
-    /// rust-bitcoin script error
-    Script(script::Error),
+    /// Error when lexing a bitcoin Script.
+    ScriptLexer(crate::miniscript::lex::Error),
     /// rust-bitcoin address error
     AddrError(bitcoin::address::ParseError),
     /// rust-bitcoin p2sh address error
@@ -490,7 +481,7 @@ pub enum Error {
     /// Bare descriptors don't have any addresses
     BareDescriptorAddr,
     /// PubKey invalid under current context
-    PubKeyCtxError(miniscript::decode::KeyParseError, &'static str),
+    PubKeyCtxError(miniscript::decode::KeyError, &'static str),
     /// No script code for Tr descriptors
     TrNoScriptCode,
     /// At least two BIP389 key expressions in the descriptor contain tuples of
@@ -519,12 +510,7 @@ const MAX_RECURSION_DEPTH: u32 = 402;
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
-            Error::InvalidOpcode(op) => write!(f, "invalid opcode {}", op),
-            Error::NonMinimalVerify(ref tok) => write!(f, "{} VERIFY", tok),
-            Error::InvalidPush(ref push) => {
-                write!(f, "invalid push {:x}", push.as_hex())
-            },
-            Error::Script(ref e) => fmt::Display::fmt(e, f),
+            Error::ScriptLexer(ref e) => e.fmt(f),
             Error::AddrError(ref e) => fmt::Display::fmt(e, f),
             Error::AddrP2shError(ref e) => fmt::Display::fmt(e, f),
             Error::UnexpectedStart => f.write_str("unexpected start of script"),
@@ -576,10 +562,7 @@ impl std::error::Error for Error {
         use self::Error::*;
 
         match self {
-            InvalidOpcode(_)
-            | NonMinimalVerify(_)
-            | InvalidPush(_)
-            | UnexpectedStart
+            UnexpectedStart
             | Unexpected(_)
             | UnknownWrapper(_)
             | NonTopLevel(_)
@@ -593,7 +576,7 @@ impl std::error::Error for Error {
             | BareDescriptorAddr
             | TrNoScriptCode
             | MultipathDescLenMismatch => None,
-            Script(e) => Some(e),
+            ScriptLexer(e) => Some(e),
             AddrError(e) => Some(e),
             AddrP2shError(e) => Some(e),
             Secp(e) => Some(e),
@@ -614,6 +597,11 @@ impl std::error::Error for Error {
     }
 }
 
+#[doc(hidden)]
+impl From<miniscript::lex::Error> for Error {
+    fn from(e: miniscript::lex::Error) -> Error { Error::ScriptLexer(e) }
+}
+
 #[doc(hidden)]
 impl From<miniscript::types::Error> for Error {
     fn from(e: miniscript::types::Error) -> Error { Error::TypeCheck(e.to_string()) }

src/miniscript/analyzable.rs

@@ -13,7 +13,7 @@ use crate::prelude::*;
 use crate::{Miniscript, MiniscriptKey, ScriptContext, Terminal};
 
 /// Params for parsing miniscripts that either non-sane or non-specified(experimental) in the spec.
-/// Used as a parameter [`Miniscript::from_str_ext`] and [`Miniscript::parse_with_ext`].
+/// Used as a parameter [`Miniscript::from_str_ext`] and [`Miniscript::decode_with_ext`].
 ///
 /// This allows parsing miniscripts if
 /// 1. It is unsafe(does not require a digital signature to spend it)