Remove explicit_script from DescriptorTrait

In preparation for removing the `DescriptorTrait` remove the
`explicit_script` trait method. Implement the same logic on `Descriptor`
directly but call through to `inner_script` or `script_pubkey` for each
descriptor as required.

Author: tcharding

examples/parse.rs

@@ -17,7 +17,7 @@
 use std::str::FromStr;
 
 use miniscript::descriptor::DescriptorType;
-use miniscript::{Descriptor, DescriptorTrait};
+use miniscript::Descriptor;
 
 fn main() {
     let desc = miniscript::Descriptor::<bitcoin::PublicKey>::from_str(

src/descriptor/bare.rs

@@ -75,7 +75,6 @@ impl<Pk: MiniscriptKey + ToPublicKey> Bare<Pk> {
     }
 
     /// Obtain the underlying miniscript for this descriptor
-    /// Non failing verion of [`DescriptorTrait::explicit_script`] for this descriptor
     pub fn inner_script(&self) -> Script {
         self.script_pubkey()
     }
@@ -138,13 +137,6 @@ where
 }
 
 impl<Pk: MiniscriptKey> DescriptorTrait<Pk> for Bare<Pk> {
-    fn explicit_script(&self) -> Result<Script, Error>
-    where
-        Pk: ToPublicKey,
-    {
-        Ok(self.inner_script())
-    }
-
     fn get_satisfaction<S>(&self, satisfier: S) -> Result<(Vec<Vec<u8>>, Script), Error>
     where
         Pk: ToPublicKey,
@@ -248,7 +240,6 @@ impl<Pk: MiniscriptKey + ToPublicKey> Pkh<Pk> {
     }
 
     /// Obtain the underlying miniscript for this descriptor
-    /// Non failing verion of [`DescriptorTrait::explicit_script`] for this descriptor
     pub fn inner_script(&self) -> Script {
         self.script_pubkey()
     }
@@ -319,13 +310,6 @@ where
 }
 
 impl<Pk: MiniscriptKey> DescriptorTrait<Pk> for Pkh<Pk> {
-    fn explicit_script(&self) -> Result<Script, Error>
-    where
-        Pk: ToPublicKey,
-    {
-        Ok(self.inner_script())
-    }
-
     fn get_satisfaction<S>(&self, satisfier: S) -> Result<(Vec<Vec<u8>>, Script), Error>
     where
         Pk: ToPublicKey,

src/descriptor/mod.rs

@@ -76,15 +76,6 @@ pub type KeyMap = HashMap<DescriptorPublicKey, DescriptorSecretKey>;
 // because of traits cannot know underlying generic of Self.
 // Thus, we must implement additional trait for translate function
 pub trait DescriptorTrait<Pk: MiniscriptKey> {
-    /// Computes the "witness script" of the descriptor, i.e. the underlying
-    /// script before any hashing is done. For `Bare`, `Pkh` and `Wpkh` this
-    /// is the scriptPubkey; for `ShWpkh` and `Sh` this is the redeemScript;
-    /// for the others it is the witness script.
-    /// For `Tr` descriptors, this will error as there is no underlying script
-    fn explicit_script(&self) -> Result<Script, Error>
-    where
-        Pk: ToPublicKey;
-
     /// Returns satisfying non-malleable witness and scriptSig with minimum weight to spend an
     /// output controlled by the given descriptor if it possible to
     /// construct one using the satisfier S.
@@ -429,6 +420,23 @@ impl<Pk: MiniscriptKey + ToPublicKey> Descriptor<Pk> {
             Descriptor::Tr(_) => Script::new(),
         }
     }
+
+    /// Computes the the underlying script before any hashing is done. For
+    /// `Bare`, `Pkh` and `Wpkh` this is the scriptPubkey; for `ShWpkh` and `Sh`
+    /// this is the redeemScript; for the others it is the witness script.
+    ///
+    /// # Errors
+    /// If the descriptor is a taproot descriptor.
+    pub fn explicit_script(&self) -> Result<Script, Error> {
+        match *self {
+            Descriptor::Bare(ref bare) => Ok(bare.script_pubkey()),
+            Descriptor::Pkh(ref pkh) => Ok(pkh.script_pubkey()),
+            Descriptor::Wpkh(ref wpkh) => Ok(wpkh.script_pubkey()),
+            Descriptor::Wsh(ref wsh) => Ok(wsh.inner_script()),
+            Descriptor::Sh(ref sh) => Ok(sh.inner_script()),
+            Descriptor::Tr(_) => Err(Error::TrNoScriptCode),
+        }
+    }
 }
 
 impl<P, Q> TranslatePk<P, Q> for Descriptor<P>
@@ -462,26 +470,6 @@ where
 }
 
 impl<Pk: MiniscriptKey> DescriptorTrait<Pk> for Descriptor<Pk> {
-    /// Computes the "witness script" of the descriptor, i.e. the underlying
-    /// script before any hashing is done. For `Bare`, `Pkh` and `Wpkh` this
-    /// is the scriptPubkey; for `ShWpkh` and `Sh` this is the redeemScript;
-    /// for the others it is the witness script.
-    /// Errors:
-    /// - When the descriptor is Tr
-    fn explicit_script(&self) -> Result<Script, Error>
-    where
-        Pk: ToPublicKey,
-    {
-        match *self {
-            Descriptor::Bare(ref bare) => bare.explicit_script(),
-            Descriptor::Pkh(ref pkh) => pkh.explicit_script(),
-            Descriptor::Wpkh(ref wpkh) => wpkh.explicit_script(),
-            Descriptor::Wsh(ref wsh) => wsh.explicit_script(),
-            Descriptor::Sh(ref sh) => sh.explicit_script(),
-            Descriptor::Tr(ref tr) => tr.explicit_script(),
-        }
-    }
-
     /// Returns satisfying non-malleable witness and scriptSig to spend an
     /// output controlled by the given descriptor if it possible to
     /// construct one using the satisfier S.

src/descriptor/segwitv0.rs

@@ -100,7 +100,6 @@ impl<Pk: MiniscriptKey + ToPublicKey> Wsh<Pk> {
     }
 
     /// Obtain the underlying miniscript for this descriptor
-    /// Non failing verion of [`DescriptorTrait::explicit_script`] for this descriptor
     pub fn inner_script(&self) -> Script {
         match self.inner {
             WshInner::SortedMulti(ref smv) => smv.encode(),
@@ -196,13 +195,6 @@ where
 }
 
 impl<Pk: MiniscriptKey> DescriptorTrait<Pk> for Wsh<Pk> {
-    fn explicit_script(&self) -> Result<Script, Error>
-    where
-        Pk: ToPublicKey,
-    {
-        Ok(self.inner_script())
-    }
-
     fn get_satisfaction<S>(&self, satisfier: S) -> Result<(Vec<Vec<u8>>, Script), Error>
     where
         Pk: ToPublicKey,
@@ -355,7 +347,6 @@ impl<Pk: MiniscriptKey + ToPublicKey> Wpkh<Pk> {
     }
 
     /// Obtain the underlying miniscript for this descriptor
-    /// Non failing verion of [`DescriptorTrait::explicit_script`] for this descriptor
     pub fn inner_script(&self) -> Script {
         self.script_pubkey()
     }
@@ -431,13 +422,6 @@ where
 }
 
 impl<Pk: MiniscriptKey> DescriptorTrait<Pk> for Wpkh<Pk> {
-    fn explicit_script(&self) -> Result<Script, Error>
-    where
-        Pk: ToPublicKey,
-    {
-        Ok(self.inner_script())
-    }
-
     fn get_satisfaction<S>(&self, satisfier: S) -> Result<(Vec<Vec<u8>>, Script), Error>
     where
         Pk: ToPublicKey,

src/descriptor/sh.rs

@@ -249,7 +249,6 @@ impl<Pk: MiniscriptKey + ToPublicKey> Sh<Pk> {
     }
 
     /// Obtain the underlying miniscript for this descriptor
-    /// Non failing verion of [`DescriptorTrait::explicit_script`] for this descriptor
     pub fn inner_script(&self) -> Script {
         match self.inner {
             ShInner::Wsh(ref wsh) => wsh.inner_script(),
@@ -301,13 +300,6 @@ impl<Pk: MiniscriptKey + ToPublicKey> Sh<Pk> {
 }
 
 impl<Pk: MiniscriptKey> DescriptorTrait<Pk> for Sh<Pk> {
-    fn explicit_script(&self) -> Result<Script, Error>
-    where
-        Pk: ToPublicKey,
-    {
-        Ok(self.inner_script())
-    }
-
     fn get_satisfaction<S>(&self, satisfier: S) -> Result<(Vec<Vec<u8>>, Script), Error>
     where
         Pk: ToPublicKey,

src/descriptor/tr.rs

@@ -554,13 +554,6 @@ impl<Pk: MiniscriptKey> Liftable<Pk> for Tr<Pk> {
 }
 
 impl<Pk: MiniscriptKey> DescriptorTrait<Pk> for Tr<Pk> {
-    fn explicit_script(&self) -> Result<Script, Error>
-    where
-        Pk: ToPublicKey,
-    {
-        Err(Error::TrNoScriptCode)
-    }
-
     fn get_satisfaction<S>(&self, satisfier: S) -> Result<(Vec<Vec<u8>>, Script), Error>
     where
         Pk: ToPublicKey,

src/psbt/mod.rs

@@ -1152,7 +1152,6 @@ mod tests {
     use bitcoin::{OutPoint, TxIn, TxOut, XOnlyPublicKey};
 
     use super::*;
-    use crate::descriptor::DescriptorTrait;
     use crate::Miniscript;
 
     #[test]