Merge #414: Improve timelock code

b084010 Use terse functional programming terms (Tobin C. Harding)
6f3303d Improve docs on TimelockInfo (Tobin C. Harding)
b2f6ef0 Add unit test for combine_threshold (Tobin C. Harding)
a36f608 Be uniform in spelling of timelock (Tobin C. Harding)
51de643 Rename comibine methods (Tobin C. Harding)
ef6803f Use > 1 instead of >= 2 (Tobin C. Harding)
d1fdbaa Use LOCKTIME_THRESHOLD same as bitcoin core (Tobin C. Harding)

Pull request description:

  Done while working on a [timelock module](rust-bitcoin/rust-bitcoin#994). This is all the initial patches (except one) from #408 (which is a PR displaying usage of the new timelock module).

  Note, does _not_ do the 'make `TimelockInfo` fields pub crate' change - I was unsure if this was correct.

Top commit has no ACKs.

Tree-SHA512: aa54e2d884f7cb1fb5dcb2d828ada29830ac4a7a09b04797e6e2fb448df476cbb31345841735e6cf4d5b7b1f6783781859778805fffef708f259fe780c6ba677

src/interpreter/mod.rs

@@ -485,12 +485,12 @@ pub enum SatisfiedConstraint {
         preimage: [u8; 32],
     },
     ///Relative Timelock for CSV.
-    RelativeTimeLock {
+    RelativeTimelock {
         /// The value of RelativeTimelock
         time: u32,
     },
     ///Absolute Timelock for CLTV.
-    AbsoluteTimeLock {
+    AbsoluteTimelock {
         /// The value of Absolute timelock
         time: u32,
     },
@@ -1197,7 +1197,7 @@ mod tests {
         let after_satisfied: Result<Vec<SatisfiedConstraint>, Error> = constraints.collect();
         assert_eq!(
             after_satisfied.unwrap(),
-            vec![SatisfiedConstraint::AbsoluteTimeLock { time: 1000 }]
+            vec![SatisfiedConstraint::AbsoluteTimelock { time: 1000 }]
         );
 
         //Check Older
@@ -1207,7 +1207,7 @@ mod tests {
         let older_satisfied: Result<Vec<SatisfiedConstraint>, Error> = constraints.collect();
         assert_eq!(
             older_satisfied.unwrap(),
-            vec![SatisfiedConstraint::RelativeTimeLock { time: 1000 }]
+            vec![SatisfiedConstraint::RelativeTimelock { time: 1000 }]
         );
 
         //Check Sha256

src/interpreter/stack.rs

@@ -235,7 +235,7 @@ impl<'txin> Stack<'txin> {
     ) -> Option<Result<SatisfiedConstraint, Error>> {
         if age >= *n {
             self.push(Element::Satisfied);
-            Some(Ok(SatisfiedConstraint::AbsoluteTimeLock { time: *n }))
+            Some(Ok(SatisfiedConstraint::AbsoluteTimelock { time: *n }))
         } else {
             Some(Err(Error::AbsoluteLocktimeNotMet(*n)))
         }
@@ -254,7 +254,7 @@ impl<'txin> Stack<'txin> {
     ) -> Option<Result<SatisfiedConstraint, Error>> {
         if height >= *n {
             self.push(Element::Satisfied);
-            Some(Ok(SatisfiedConstraint::RelativeTimeLock { time: *n }))
+            Some(Ok(SatisfiedConstraint::RelativeTimelock { time: *n }))
         } else {
             Some(Err(Error::RelativeLocktimeNotMet(*n)))
         }

src/miniscript/analyzable.rs

@@ -41,7 +41,7 @@ pub enum AnalysisError {
     /// Miniscript contains at least one path that exceeds resource limits
     BranchExceedResouceLimits,
     /// Contains a combination of heightlock and timelock
-    HeightTimeLockCombination,
+    HeightTimelockCombination,
     /// Malleable script
     Malleable,
 }
@@ -58,7 +58,7 @@ impl fmt::Display for AnalysisError {
             AnalysisError::BranchExceedResouceLimits => {
                 f.write_str("At least one spend path exceeds the resource limits(stack depth/satisfaction size..)")
             }
-            AnalysisError::HeightTimeLockCombination => {
+            AnalysisError::HeightTimelockCombination => {
                 f.write_str("Contains a combination of heightlock and timelock")
             }
             AnalysisError::Malleable => f.write_str("Miniscript is malleable")
@@ -128,7 +128,7 @@ impl<Pk: MiniscriptKey, Ctx: ScriptContext> Miniscript<Pk, Ctx> {
         } else if self.has_repeated_keys() {
             Err(AnalysisError::RepeatedPubkeys)
         } else if self.has_mixed_timelocks() {
-            Err(AnalysisError::HeightTimeLockCombination)
+            Err(AnalysisError::HeightTimelockCombination)
         } else {
             Ok(())
         }

src/miniscript/limits.rs

@@ -17,7 +17,7 @@ pub const MAX_STANDARD_P2WSH_SCRIPT_SIZE: usize = 3600;
 /// The Threshold for deciding whether `nLockTime` is interpreted as
 /// time or height.
 // https://github.com/bitcoin/bitcoin/blob/9ccaee1d5e2e4b79b0a7c29aadb41b97e4741332/src/script/script.h#L39
-pub const HEIGHT_TIME_THRESHOLD: u32 = 500_000_000;
+pub const LOCKTIME_THRESHOLD: u32 = 500_000_000;
 
 /// Bit flag for deciding whether sequence number is
 /// interpreted as height or time

src/miniscript/satisfy.rs

@@ -28,7 +28,7 @@ use bitcoin::secp256k1::XOnlyPublicKey;
 use bitcoin::util::taproot::{ControlBlock, LeafVersion, TapLeafHash};
 
 use crate::miniscript::limits::{
-    HEIGHT_TIME_THRESHOLD, SEQUENCE_LOCKTIME_DISABLE_FLAG, SEQUENCE_LOCKTIME_TYPE_FLAG,
+    LOCKTIME_THRESHOLD, SEQUENCE_LOCKTIME_DISABLE_FLAG, SEQUENCE_LOCKTIME_TYPE_FLAG,
 };
 use crate::util::witness_size;
 use crate::{Miniscript, MiniscriptKey, ScriptContext, Terminal, ToPublicKey};
@@ -155,7 +155,7 @@ pub struct After(pub u32);
 impl<Pk: MiniscriptKey + ToPublicKey> Satisfier<Pk> for After {
     fn check_after(&self, n: u32) -> bool {
         // if n > self.0; we will be returning false anyways
-        if n < HEIGHT_TIME_THRESHOLD && self.0 >= HEIGHT_TIME_THRESHOLD {
+        if n < LOCKTIME_THRESHOLD && self.0 >= LOCKTIME_THRESHOLD {
             false
         } else {
             n <= self.0