Fix stale variable names and comments

At some stage, it appears, we have changed from using a `HashMap` to a
`BTreeMap` but the variable names and comments still refer to hash map.
Note also that these comments are "what" comments (as opposed to "why"
comments) so they are not adding an value anyways.

Fix stale code by doing:

- Remove the "what" comments.
- Rename local variables from `hash_map` to plain old `map`

Author: heap-coder

src/psbt/finalizer.rs

@@ -36,18 +36,16 @@ fn construct_tap_witness(
 ) -> Result<Vec<Vec<u8>>, InputError> {
     // When miniscript tries to finalize the PSBT, it doesn't have the full descriptor (which contained a pkh() fragment)
     // and instead resorts to parsing the raw script sig, which is translated into a "expr_raw_pkh" internally.
-    let mut hash_map: BTreeMap<hash160::Hash, bitcoin::key::XOnlyPublicKey> = BTreeMap::new();
+    let mut map: BTreeMap<hash160::Hash, bitcoin::key::XOnlyPublicKey> = BTreeMap::new();
     let psbt_inputs = &sat.psbt.inputs;
     for psbt_input in psbt_inputs {
         // We need to satisfy or dissatisfy any given key. `tap_key_origin` is the only field of PSBT Input which consist of
         // all the keys added on a descriptor and thus we get keys from it.
         let public_keys = psbt_input.tap_key_origins.keys();
         for key in public_keys {
             let bitcoin_key = *key;
-            // Convert PubKeyHash into Hash::hash160
             let hash = bitcoin_key.to_pubkeyhash(SigType::Schnorr);
-            // Insert pair in HashMap
-            hash_map.insert(hash, bitcoin_key);
+            map.insert(hash, bitcoin_key);
         }
     }
     assert!(spk.is_v1_p2tr());
@@ -72,7 +70,7 @@ fn construct_tap_witness(
                 script,
                 &ExtParams::allow_all(),
             ) {
-                Ok(ms) => ms.substitute_raw_pkh(&hash_map),
+                Ok(ms) => ms.substitute_raw_pkh(&map),
                 Err(..) => continue, // try another script
             };
             let mut wit = if allow_mall {
@@ -142,19 +140,15 @@ pub(super) fn prevouts(psbt: &Psbt) -> Result<Vec<&bitcoin::TxOut>, super::Error
 // we want to move the script is probably already created
 // and we want to satisfy it in any way possible.
 fn get_descriptor(psbt: &Psbt, index: usize) -> Result<Descriptor<PublicKey>, InputError> {
-    // Create a HashMap <Hash(Pk),Pk>
-    let mut hash_map: BTreeMap<hash160::Hash, PublicKey> = BTreeMap::new();
+    let mut map: BTreeMap<hash160::Hash, PublicKey> = BTreeMap::new();
     let psbt_inputs = &psbt.inputs;
     for psbt_input in psbt_inputs {
         // Use BIP32 Derviation to get set of all possible keys.
         let public_keys = psbt_input.bip32_derivation.keys();
         for key in public_keys {
-            // Convert bitcoin::secp256k1::PublicKey into just bitcoin::PublicKey
             let bitcoin_key = bitcoin::PublicKey::new(*key);
-            // Convert PubKeyHash into Hash::hash160
             let hash = bitcoin_key.pubkey_hash().to_raw_hash();
-            // Insert pair in HashMap
-            hash_map.insert(hash, bitcoin_key);
+            map.insert(hash, bitcoin_key);
         }
     }
 
@@ -214,7 +208,7 @@ fn get_descriptor(psbt: &Psbt, index: usize) -> Result<Descriptor<PublicKey>, In
                 witness_script,
                 &ExtParams::allow_all(),
             )?;
-            Ok(Descriptor::new_wsh(ms.substitute_raw_pkh(&hash_map))?)
+            Ok(Descriptor::new_wsh(ms.substitute_raw_pkh(&map))?)
         } else {
             Err(InputError::MissingWitnessScript)
         }
@@ -241,7 +235,7 @@ fn get_descriptor(psbt: &Psbt, index: usize) -> Result<Descriptor<PublicKey>, In
                             witness_script,
                             &ExtParams::allow_all(),
                         )?;
-                        Ok(Descriptor::new_sh_wsh(ms.substitute_raw_pkh(&hash_map))?)
+                        Ok(Descriptor::new_sh_wsh(ms.substitute_raw_pkh(&map))?)
                     } else {
                         Err(InputError::MissingWitnessScript)
                     }
@@ -285,7 +279,7 @@ fn get_descriptor(psbt: &Psbt, index: usize) -> Result<Descriptor<PublicKey>, In
             &script_pubkey,
             &ExtParams::allow_all(),
         )?;
-        Ok(Descriptor::new_bare(ms.substitute_raw_pkh(&hash_map))?)
+        Ok(Descriptor::new_bare(ms.substitute_raw_pkh(&map))?)
     }
 }