Document static, make anyint standard

2025-04-11 16:39:02 +02:00
parent c403fa89a1
commit ba771836fb
3 changed files with 112 additions and 10 deletions
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+
+# Static Serialization
+
+The `gmserialization` and `gmser_chain_objects` modules implement the
+static serialization support used in the Gajumaru blockchain.
+
+The purpose is to produce fully deterministic serialization, in order
+to maintain predictable hashing.
+
+Example:
+
+```erlang
+%% deterministic canonical serialization.
+-spec serialize_to_binary(signed_tx()) -> binary_signed_tx().
+serialize_to_binary(#signed_tx{tx = Tx, signatures = Sigs}) ->
+    gmser_chain_objects:serialize(
+      ?SIG_TX_TYPE,
+      ?SIG_TX_VSN,
+      serialization_template(?SIG_TX_VSN),
+      [ {signatures, lists:sort(Sigs)}
+      , {transaction, aetx:serialize_to_binary(Tx)}
+      ]).
+
+-spec deserialize_from_binary(binary()) -> signed_tx().
+deserialize_from_binary(SignedTxBin) when is_binary(SignedTxBin) ->
+    [ {signatures, Sigs}
+    , {transaction, TxBin}
+    ] = gmser_chain_objects:deserialize(
+          ?SIG_TX_TYPE,
+          ?SIG_TX_VSN,
+          serialization_template(?SIG_TX_VSN),
+          SignedTxBin),
+    assert_sigs_size(Sigs),
+    #signed_tx{ tx = aetx:deserialize_from_binary(TxBin)
+              , signatures = Sigs
+              }.
+
+serialization_template(?SIG_TX_VSN) ->
+    [ {signatures, [binary]}
+    , {transaction, binary}
+    ].
+```
+
+The terms that can be encoded using these templates are given by
+this type in `gmserialization.erl`:
+
+```erlang
+-type encodable_term() :: non_neg_integer()
+                        | binary()
+                        | boolean()
+                        | [encodable_term()] %% Of any length
+                        | #{atom() => encodable_term()}
+                        | tuple()  %% Any arity, containing encodable_term().
+                        | gmser_id:id().
+```
+
+The template 'language' is defined by these types:
+
+```erlang
+-type template() :: [{field_name(), type()}].
+-type field_name() :: atom().
+-type type() :: 'int'
+              | 'bool'
+              | 'binary'
+              | 'id'     %% As defined in aec_id.erl
+              | [type()] %% Length one in the type. This means a list of any length.
+              | #{items := [{field_name(), type()}]} %% Record with named fields
+                                                     %% represented as a map.
+                                                     %% Encoded as a list in the given
+                                                     %% order.
+              | tuple(). %% Any arity, containing type(). This means a static size array.
+```
+
+The `gmser_chain_objects.erl` module specifies a serialization code for each
+object that can go on-chain. E.g.:
+
+```erlang
+tag(signed_tx) -> 11;
+...
+rev_tag(11) -> signed_tx;
+```
+
+The `tag` and `vsn` are laid out in the beginning of the serialized object.