Merge pull request #28 from strict-types/phantom

Support phantom data

rust/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "strict_encoding"
-version = "2.6.1"
+version = "2.6.2"
 description = "Strict encoding: deterministic & confined binary serialization for strict types"
 keywords = ["strict-types", "gadt", "serialization", "serde", "protobuf"]
 categories = ["encoding", "parsing"]

rust/src/traits.rs

@@ -20,6 +20,7 @@
 // limitations under the License.
 
 use std::io::{BufRead, Seek};
+use std::marker::PhantomData;
 use std::{fs, io};
 
 use amplify::confinement::{Collection, Confined};
@@ -335,6 +336,14 @@ impl<T: StrictEncode> StrictEncode for &T {
     }
 }
 
+impl<T> StrictEncode for PhantomData<T> {
+    fn strict_encode<W: TypedWrite>(&self, writer: W) -> io::Result<W> { Ok(writer) }
+}
+
+impl<T> StrictDecode for PhantomData<T> {
+    fn strict_decode(_reader: &mut impl TypedRead) -> Result<Self, DecodeError> { Ok(default!()) }
+}
+
 pub trait StrictSerialize: StrictEncode {
     fn strict_serialized_len(&self) -> io::Result<usize> {
         let counter = StrictWriter::counter();

rust/src/types.rs

@@ -22,6 +22,7 @@
 use std::any;
 use std::collections::BTreeSet;
 use std::fmt::{Debug, Display};
+use std::marker::PhantomData;
 
 use crate::{FieldName, LibName, TypeName};
 
@@ -70,6 +71,10 @@ impl<T: StrictType> StrictType for &T {
     const STRICT_LIB_NAME: &'static str = T::STRICT_LIB_NAME;
 }
 
+impl<T> StrictType for PhantomData<T> {
+    const STRICT_LIB_NAME: &'static str = "";
+}
+
 pub trait StrictProduct: StrictType + StrictDumb {}
 
 pub trait StrictTuple: StrictProduct {