Add a macro to implement serialization of enums using TLVs

diff --git a/lightning/src/util/ser_macros.rs b/lightning/src/util/ser_macros.rs
index 45435ecdd64ac5f5f579e168b011896831550709..44bd9ec49729fc1ecb4351c00e086beaf07d9df1 100644 (file)
--- a/lightning/src/util/ser_macros.rs
+++ b/lightning/src/util/ser_macros.rs
@@ -325,26 +325,26 @@ macro_rules! read_tlv_fields {
 // `Self { ,,vecfield: vecfield }` which is obviously incorrect. Instead, we have to match here to
 // detect at least one empty field set and skip the potentially-extra comma.
 macro_rules! _init_tlv_based_struct {
-       ({}, {$($field: ident),*}, {$($vecfield: ident),*}) => {
-               Ok(Self {
+       ($($type: ident)::*, {}, {$($field: ident),*}, {$($vecfield: ident),*}) => {
+               Ok($($type)::* {
                        $($field),*,
                        $($vecfield: $vecfield.unwrap().0),*
                })
        };
-       ({$($reqfield: ident),*}, {}, {$($vecfield: ident),*}) => {
-               Ok(Self {
+       ($($type: ident)::*, {$($reqfield: ident),*}, {}, {$($vecfield: ident),*}) => {
+               Ok($($type)::* {
                        $($reqfield: $reqfield.0.unwrap()),*,
                        $($vecfield: $vecfield.unwrap().0),*
                })
        };
-       ({$($reqfield: ident),*}, {$($field: ident),*}, {}) => {
-               Ok(Self {
+       ($($type: ident)::*, {$($reqfield: ident),*}, {$($field: ident),*}, {}) => {
+               Ok($($type)::* {
                        $($reqfield: $reqfield.0.unwrap()),*,
                        $($field),*
                })
        };
-       ({$($reqfield: ident),*}, {$($field: ident),*}, {$($vecfield: ident),*}) => {
-               Ok(Self {
+       ($($type: ident)::*, {$($reqfield: ident),*}, {$($field: ident),*}, {$($vecfield: ident),*}) => {
+               Ok($($type)::* {
                        $($reqfield: $reqfield.0.unwrap()),*,
                        $($field),*,
                        $($vecfield: $vecfield.unwrap().0),*
@@ -433,7 +433,88 @@ macro_rules! impl_writeable_tlv_based {
                                }, {
                                        $(($vectype, $vecfield)),*
                                });
-                               _init_tlv_based_struct!({$($reqfield),*}, {$($field),*}, {$($vecfield),*})
+                               _init_tlv_based_struct!($st, {$($reqfield),*}, {$($field),*}, {$($vecfield),*})
+                       }
+               }
+       }
+}
+
+/// Implement Readable and Writeable for an enum, with struct variants stored as TLVs and tuple
+/// variants stored directly.
+/// The format is, for example
+/// impl_writeable_tlv_based_enum!(EnumName,
+///   (0, StructVariantA) => {(0, variant_field)}, {(1, variant_optional_field)}, {},
+///   (1, StructVariantB) => {(0, variant_field_a), (1, variant_field_b)}, {}, {(2, variant_vec_field)};
+///   (2, TupleVariantA), (3, TupleVariantB),
+/// );
+/// The type is written as a single byte, followed by any variant data.
+/// Attempts to read an unknown type byte result in DecodeError::UnknownRequiredFeature.
+macro_rules! impl_writeable_tlv_based_enum {
+       ($st: ident, $(($variant_id: expr, $variant_name: ident) =>
+               {$(($reqtype: expr, $reqfield: ident)),* $(,)*},
+               {$(($type: expr, $field: ident)),* $(,)*},
+               {$(($vectype: expr, $vecfield: ident)),* $(,)*}
+       ),* $(,)*;
+       $(($tuple_variant_id: expr, $tuple_variant_name: ident)),*  $(,)*) => {
+               impl ::util::ser::Writeable for $st {
+                       fn write<W: ::util::ser::Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
+                               match self {
+                                       $($st::$variant_name { $(ref $reqfield),* $(ref $field),*, $(ref $vecfield),* } => {
+                                               let id: u8 = $variant_id;
+                                               id.write(writer)?;
+                                               _write_tlv_fields!(writer, {
+                                                       $(($reqtype, $reqfield)),*
+                                               }, {
+                                                       $(($type, $field)),*
+                                               }, {
+                                                       $(($vectype, Some(::util::ser::VecWriteWrapper(&$vecfield)))),*
+                                               });
+                                       }),*
+                                       $($st::$tuple_variant_name (ref field) => {
+                                               let id: u8 = $tuple_variant_id;
+                                               id.write(writer)?;
+                                               field.write(writer)?;
+                                       }),*
+                               }
+                               Ok(())
+                       }
+               }
+
+               impl ::util::ser::Readable for $st {
+                       fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, ::ln::msgs::DecodeError> {
+                               let id: u8 = ::util::ser::Readable::read(reader)?;
+                               match id {
+                                       $($variant_id => {
+                                               // Because read_tlv_fields creates a labeled loop, we cannot call it twice
+                                               // in the same function body. Instead, we define a closure and call it.
+                                               let f = || {
+                                                       $(
+                                                               let mut $reqfield = ::util::ser::OptionDeserWrapper(None);
+                                                       )*
+                                                       $(
+                                                               let mut $field = None;
+                                                       )*
+                                                       $(
+                                                               let mut $vecfield = Some(::util::ser::VecReadWrapper(Vec::new()));
+                                                       )*
+                                                       _read_tlv_fields!(reader, {
+                                                               $(($reqtype, $reqfield)),*
+                                                       }, {
+                                                               $(($type, $field)),*
+                                                       }, {
+                                                               $(($vectype, $vecfield)),*
+                                                       });
+                                                       _init_tlv_based_struct!($st::$variant_name, {$($reqfield),*}, {$($field),*}, {$($vecfield),*})
+                                               };
+                                               f()
+                                       }),*
+                                       $($tuple_variant_id => {
+                                               Ok($st::$tuple_variant_name(Readable::read(reader)?))
+                                       }),*
+                                       _ => {
+                                               Err(DecodeError::UnknownRequiredFeature)?
+                                       },
+                               }
                        }
                }
        }