units: Implement constructor for decoders

So the decoders can be used by downstream add constructors for them
all. Also implement `Default` for the decoder types.

Author: tcharding

units/src/amount/unsigned.rs

@@ -582,6 +582,17 @@ impl encoding::Encodable for Amount {
 #[cfg(feature = "encoding")]
 pub struct AmountDecoder(encoding::ArrayDecoder<8>);
 
+#[cfg(feature = "encoding")]
+impl AmountDecoder {
+    /// Constructs a new [`Amount`] decoder.
+    pub fn new() -> Self { Self(encoding::ArrayDecoder::new()) }
+}
+
+#[cfg(feature = "encoding")]
+impl Default for AmountDecoder {
+    fn default() -> Self { Self::new() }
+}
+
 #[cfg(feature = "encoding")]
 impl encoding::Decoder for AmountDecoder {
     type Output = Amount;

units/src/block.rs

@@ -165,6 +165,17 @@ impl encoding::Encodable for BlockHeight {
 #[cfg(feature = "encoding")]
 pub struct BlockHeightDecoder(encoding::ArrayDecoder<4>);
 
+#[cfg(feature = "encoding")]
+impl Default for BlockHeightDecoder {
+    fn default() -> Self { Self::new() }
+}
+
+#[cfg(feature = "encoding")]
+impl BlockHeightDecoder {
+    /// Constructs a new [`BlockHeight`] decoder.
+    pub fn new() -> Self { Self(encoding::ArrayDecoder::new()) }
+}
+
 #[cfg(feature = "encoding")]
 impl encoding::Decoder for BlockHeightDecoder {
     type Output = BlockHeight;

units/src/locktime/absolute/mod.rs

@@ -423,6 +423,17 @@ impl encoding::Encodable for LockTime {
 #[cfg(feature = "encoding")]
 pub struct LockTimeDecoder(encoding::ArrayDecoder<4>);
 
+#[cfg(feature = "encoding")]
+impl LockTimeDecoder {
+    /// Constructs a new [`LockTime`] decoder.
+    pub fn new() -> Self { Self(encoding::ArrayDecoder::new()) }
+}
+
+#[cfg(feature = "encoding")]
+impl Default for LockTimeDecoder {
+    fn default() -> Self { Self::new() }
+}
+
 #[cfg(feature = "encoding")]
 impl encoding::Decoder for LockTimeDecoder {
     type Output = LockTime;

units/src/sequence.rs

@@ -288,6 +288,17 @@ impl encoding::Encodable for Sequence {
 #[cfg(feature = "encoding")]
 pub struct SequenceDecoder(encoding::ArrayDecoder<4>);
 
+#[cfg(feature = "encoding")]
+impl Default for SequenceDecoder {
+    fn default() -> Self { Self::new() }
+}
+
+#[cfg(feature = "encoding")]
+impl SequenceDecoder {
+    /// Constructs a new [`Sequence`] decoder.
+    pub fn new() -> Self { Self(encoding::ArrayDecoder::new()) }
+}
+
 #[cfg(feature = "encoding")]
 impl encoding::Decoder for SequenceDecoder {
     type Output = Sequence;

units/src/time.rs

@@ -98,6 +98,17 @@ impl encoding::Encodable for BlockTime {
 #[cfg(feature = "encoding")]
 pub struct BlockTimeDecoder(encoding::ArrayDecoder<4>);
 
+#[cfg(feature = "encoding")]
+impl Default for BlockTimeDecoder {
+    fn default() -> Self { Self::new() }
+}
+
+#[cfg(feature = "encoding")]
+impl BlockTimeDecoder {
+    /// Constructs a new [`BlockTime`] decoder.
+    pub fn new() -> Self { Self(encoding::ArrayDecoder::new()) }
+}
+
 #[cfg(feature = "encoding")]
 impl encoding::Decoder for BlockTimeDecoder {
     type Output = BlockTime;