Add timelock related methods on Transaction and TxIn

Now we have the two `timelock` types we can implement a few methods on
`Transaction` and `TxIn` that may be useful to users of the library.

src/blockdata/transaction.rs

@@ -40,7 +40,7 @@ use crate::blockdata::witness::Witness;
 use crate::consensus::{encode, Decodable, Encodable};
 use crate::consensus::encode::MAX_VEC_SIZE;
 use crate::hash_types::{Sighash, Txid, Wtxid};
-use crate::VarInt;
+use crate::{timelock, VarInt};
 
 #[cfg(doc)]
 use crate::util::sighash::SchnorrSighashType;
@@ -208,6 +208,13 @@ pub struct TxIn {
     pub witness: Witness
 }
 
+impl TxIn {
+    /// Returns sequence number as a relative timelock.
+    pub fn relative_lock_time(&self) -> timelock::Rel {
+        timelock::Rel::from(self.sequence)
+    }
+}
+
 impl Default for TxIn {
     fn default() -> TxIn {
         TxIn {
@@ -609,6 +616,19 @@ impl Transaction {
     pub fn is_explicitly_rbf(&self) -> bool {
         self.input.iter().any(|input| input.sequence < (0xffffffff - 1))
     }
+
+    /// Returns the nLockTime as an absolute timelock.
+    pub fn absolute_lock_time(&self) -> timelock::Abs {
+        timelock::Abs::from(self.lock_time)
+    }
+
+    /// Returns `true` if this transactions nLockTime should be ignored.
+    pub fn ignore_lock_time(&self) -> bool {
+        if self.lock_time == 0 {
+            return true;
+        }
+        self.input.iter().all(|input| input.sequence == 0xffffffff)
+    }
 }
 
 impl_consensus_encoding!(TxOut, value, script_pubkey);