feat: add decode_calldata to ABI functions

boa/contracts/abi/abi_contract.py

@@ -4,6 +4,7 @@
 from warnings import warn
 
 from eth.abc import ComputationAPI
+from sortedcontainers import SortedDict
 from vyper.semantics.analysis.base import FunctionVisibility, StateMutability
 from vyper.utils import method_id
 
@@ -105,6 +106,16 @@ def prepare_calldata(self, *args, **kwargs) -> bytes:
             return encoded_args
         return self.method_id + encoded_args
 
+    def decode_calldata(self, calldata: bytes) -> tuple:
+        """Decode the calldata for the function call."""
+        calldata_method_id = calldata[:4]
+        if calldata_method_id != self.method_id:
+            raise ValueError(
+                f"The calldata 0x{calldata_method_id.hex()} does not match "
+                f"the method_id 0x{self.method_id.hex()}"
+            )
+        return abi_decode(self.signature, calldata[4:])
+
     def _merge_kwargs(self, *args, **kwargs) -> list:
         """Merge positional and keyword arguments into a single list."""
         if len(kwargs) + len(args) != self.argument_count:
@@ -166,11 +177,15 @@ def create(
         return ABIOverload(functions)
 
     def __init__(self, functions: list[ABIFunction]):
-        self.functions = functions
+        self.functions = SortedDict([(f.method_id, f) for f in functions])
 
     @cached_property
     def name(self) -> str | None:
-        return self.functions[0].name
+        """
+        Gets the name of the overloaded function.
+        Note that all overloads have the same name by definition.
+        """
+        return next(iter(self.functions.values())).name
 
     def prepare_calldata(self, *args, disambiguate_signature=None, **kwargs) -> bytes:
         """Prepare the calldata for the function that matches the given arguments."""
@@ -179,6 +194,12 @@ def prepare_calldata(self, *args, disambiguate_signature=None, **kwargs) -> byte
         )
         return function.prepare_calldata(*args, **kwargs)
 
+    def decode_calldata(self, calldata: bytes) -> tuple:
+        """Decode the calldata for the function that matches the given arguments."""
+        calldata_method_id = calldata[:4]
+        function = self.functions[calldata_method_id]
+        return function.decode_calldata(calldata)
+
     def __call__(
         self,
         *args,
@@ -201,12 +222,12 @@ def _pick_overload(
         self, *args, disambiguate_signature=None, **kwargs
     ) -> ABIFunction:
         """Pick the function that matches the given arguments."""
+        fns = self.functions.values()
+
         if disambiguate_signature is None:
-            matches = [f for f in self.functions if f.is_encodable(*args, **kwargs)]
+            matches = [f for f in fns if f.is_encodable(*args, **kwargs)]
         else:
-            matches = [
-                f for f in self.functions if disambiguate_signature == f.full_signature
-            ]
+            matches = [f for f in fns if disambiguate_signature == f.full_signature]
             assert len(matches) <= 1, "ABI signature must be unique"
 
         assert self.name, "Constructor does not have a name."

tests/unitary/contracts/abi/test_abi.py

@@ -203,7 +203,7 @@ def test(n: uint256) -> uint256:
     assert re.match(r"^ +\(unknown method id .*\.0x29e99f07\)$", error)
 
 
-def test_prepare_calldata():
+def test_calldata():
     code = """
 @external
 def overloaded(n: uint256 = 0) -> uint256:
@@ -215,9 +215,10 @@ def argumented(n: uint256) -> uint256:
 """
     abi_contract, _ = load_via_abi(code)
     assert abi_contract.overloaded.prepare_calldata() == b"\x07\x8e\xec\xb4"
-    assert (
-        abi_contract.argumented.prepare_calldata(0) == b"\xedu\x96\x8d" + b"\x00" * 32
-    )
+    assert abi_contract.overloaded.decode_calldata(b"\x07\x8e\xec\xb4") == ()
+    argumented_calldata = b"\xedu\x96\x8d" + b"\x00" * 32
+    assert abi_contract.argumented.prepare_calldata(0) == argumented_calldata
+    assert abi_contract.argumented.decode_calldata(argumented_calldata) == (0,)
     assert len(abi_contract.abi) == 3
     assert abi_contract.deployer.abi == abi_contract.abi