Transition types

setup.cfg

@@ -116,6 +116,7 @@ install_requires =
     typing_extensions>=4
     py_ecc @ git+https://github.com/petertdavies/py_ecc.git@127184f4c57b1812da959586d0fe8f43bb1a2389
     ethereum-types>=0.2.1,<0.3
+    ethereum-rlp>=0.1.2,<0.2
 
 [options.package_data]
 ethereum =

src/ethereum/arrow_glacier/blocks.py

@@ -9,11 +9,16 @@
 chain.
 """
 from dataclasses import dataclass
-from typing import Tuple, Union
+from typing import Annotated, Optional, Tuple, Union
 
+from ethereum_rlp import rlp
 from ethereum_types.bytes import Bytes, Bytes8, Bytes32
 from ethereum_types.frozen import slotted_freezable
 from ethereum_types.numeric import U256, Uint
+from typing_extensions import TypeAlias
+
+from ethereum.exceptions import InvalidBlock
+from ethereum.london import blocks as previous_blocks
 
 from ..crypto.hash import Hash32
 from .fork_types import Address, Bloom, Root
@@ -45,6 +50,49 @@ class Header:
     base_fee_per_gas: Uint
 
 
+AnyHeader: TypeAlias = Union[previous_blocks.AnyHeader, Header]
+"""
+Represents all headers that may have appeared in the blockchain before or in
+the current fork.
+"""
+
+
+def decode_header(raw_header: rlp.Simple) -> AnyHeader:
+    """
+    Convert `raw_header` from raw sequences and bytes to a structured block
+    header.
+
+    Checks `raw_header` against this fork's `FORK_CRITERIA`, and if it belongs
+    to this fork, decodes it accordingly. If not, this function forwards to the
+    preceding fork where the process is repeated.
+    """
+    from . import FORK_CRITERIA
+
+    # First, ensure that `raw_header` is not `bytes` (and is therefore a
+    # sequence.)
+    if isinstance(raw_header, bytes):
+        raise InvalidBlock("header is bytes, expected sequence")
+
+    # Next, extract the block number and timestamp (which are always at index 8
+    # and 11 respectively.)
+    raw_number = raw_header[8]
+    if not isinstance(raw_number, bytes):
+        raise InvalidBlock("header number is sequence, expected bytes")
+    number = Uint.from_be_bytes(raw_number)
+
+    raw_timestamp = raw_header[11]
+    if not isinstance(raw_timestamp, bytes):
+        raise InvalidBlock("header timestamp is sequence, expected bytes")
+    timestamp = U256.from_be_bytes(raw_timestamp)
+
+    # Finally, check if this header belongs to this fork.
+    if FORK_CRITERIA.check(number, timestamp):
+        return rlp.deserialize_to(Header, raw_header)
+
+    # If it doesn't, forward to the preceding fork.
+    return previous_blocks.decode_header(raw_header)
+
+
 @slotted_freezable
 @dataclass
 class Block:
@@ -54,7 +102,14 @@ class Block:
 
     header: Header
     transactions: Tuple[Union[Bytes, LegacyTransaction], ...]
-    ommers: Tuple[Header, ...]
+    ommers: Tuple[Annotated[AnyHeader, rlp.With(decode_header)], ...]
+
+
+AnyBlock: TypeAlias = Union[previous_blocks.AnyBlock, Block]
+"""
+Represents all blocks that may have appeared in the blockchain before or in the
+current fork.
+"""
 
 
 @slotted_freezable
@@ -80,3 +135,13 @@ class Receipt:
     cumulative_gas_used: Uint
     bloom: Bloom
     logs: Tuple[Log, ...]
+
+
+def header_base_fee_per_gas(header: AnyHeader) -> Optional[Uint]:
+    """
+    Returns the `base_fee_per_gas` of the given header, or `None` for headers
+    without that field.
+    """
+    if isinstance(header, Header):
+        return header.base_fee_per_gas
+    return previous_blocks.header_base_fee_per_gas(header)