fix: support fixed-size array dimensions in signature parser (#278)

The Lark grammar only handled dynamic arrays (`[]`) but rejected fixed-size arrays (`[N]`), causing lint failures on valid Solidity types like `address[11]` and `uint256[5][5]`.

Made-with: Cursor

Author: Maroutis

src/erc7730/common/abi.py

@@ -22,7 +22,7 @@
             named_param: type identifier?
             named_tuple:  tuple array* identifier?
 
-            array: "[]"
+            array: "[]" | "[" /[0-9]+/ "]"
             identifier: /[a-zA-Z$_][a-zA-Z0-9$_]*/
             type: identifier array*
 
@@ -61,8 +61,8 @@ def named_tuple(self, ast: Any) -> Component:
 
         # Separate arrays from name
         # Arrays are "[]", name is anything else
-        arrays = [elem for elem in ast[1:] if elem == "[]"]
-        names = [elem for elem in ast[1:] if elem != "[]"]
+        arrays = [elem for elem in ast[1:] if isinstance(elem, str) and elem.startswith("[")]
+        names = [elem for elem in ast[1:] if not (isinstance(elem, str) and elem.startswith("["))]
 
         # Build type with array suffixes
         type_str = "tuple" + "".join(arrays)
@@ -73,6 +73,8 @@ def named_tuple(self, ast: Any) -> Component:
         return Component(name=name, type=type_str, components=components)
 
     def array(self, ast: Any) -> str:
+        if ast:
+            return f"[{ast[0]}]"
         return "[]"
 
     def identifier(self, ast: Any) -> str:

tests/common/test_abi.py

@@ -67,6 +67,31 @@
             "mixed(bytes32[][] data, (address a,uint256 b)[][] _tuples, string name)",
             "mixed(bytes32[][],(address,uint256)[][],string)",
         ),
+        # fixed-size arrays
+        (
+            "exchange(address[11] _route, uint256[5][5] _swap_params, uint256 _amount, uint256 _min_dy)",
+            "exchange(address[11],uint256[5][5],uint256,uint256)",
+        ),
+        # fixed-size array single dimension
+        (
+            "foo(uint256[3] values)",
+            "foo(uint256[3])",
+        ),
+        # mixed fixed and dynamic arrays
+        (
+            "bar(address[5] addrs, uint256[] amounts, bytes32[2][] pairs)",
+            "bar(address[5],uint256[],bytes32[2][])",
+        ),
+        # fixed-size array of tuples
+        (
+            "baz((uint256,address)[3] items)",
+            "baz((uint256,address)[3])",
+        ),
+        # higher-dimensional fixed-size arrays
+        (
+            "multi(uint256[2][3][4] cube)",
+            "multi(uint256[2][3][4])",
+        ),
     ],
 )
 def test_reduce_signature(signature: str, expected: str) -> None: