state helper: rm useless get_justifications_map (leanEthereum#179)

Author: tcoratger

src/lean_spec/subspecs/containers/state/helpers.py

@@ -9,43 +9,6 @@
 from lean_spec.types import Boolean, Bytes32
 
 
-def get_justifications_map(
-    justifications_roots: JustificationRoots,
-    justifications_validators: JustificationValidators,
-    validator_count: int,
-) -> Dict[Bytes32, List[Boolean]]:
-    """
-    Reconstruct the justifications map from the state's flat data structures.
-
-    Parameters
-    ----------
-    justifications_roots : JustificationRoots
-        The block roots in alphabetical order.
-    justifications_validators : JustificationValidators
-        The list of validator justifications for each block root concatenated in the same order
-        as the list of block roots.
-    validator_count : int
-        The number of validators in the state.
-
-    Returns:
-    -------
-    Dict[Bytes32, List[Boolean]]
-        A mapping from a block root to the list of validator justifications for that root.
-    """
-    # No justified roots means no justifications to reconstruct.
-    if not justifications_roots:
-        return {}
-
-    # Extract the flattened validator justifications.
-    flat_justifications = list(justifications_validators)
-
-    # Reconstruct the map: each root gets its corresponding justification slice.
-    return {
-        root: flat_justifications[i * validator_count : (i + 1) * validator_count]
-        for i, root in enumerate(justifications_roots)
-    }
-
-
 def flatten_justifications_map(
     justifications_map: Dict[Bytes32, List[Boolean]], validator_count: int
 ) -> tuple[JustificationRoots, JustificationValidators]:

src/lean_spec/subspecs/containers/state/state.py

@@ -22,7 +22,7 @@
 from ..checkpoint import Checkpoint
 from ..config import Config
 from ..slot import Slot
-from .helpers import flatten_justifications_map, get_justifications_map
+from .helpers import flatten_justifications_map
 from .types import (
     HistoricalBlockHashes,
     JustificationRoots,
@@ -337,12 +337,35 @@ def process_attestations(
         State
             A new state with updated justification/finalization.
         """
-        # Get justifications, justified slots and historical block hashes are already up to
-        # date as per the processing in process_block_header
-        justifications = get_justifications_map(
-            justifications_roots=self.justifications_roots,
-            justifications_validators=self.justifications_validators,
-            validator_count=self.validators.count,
+        # NOTE:
+        # The state already contains three pieces of data:
+        #   1. A list of block roots that have received justification votes.
+        #   2. A long sequence of boolean entries representing all validator votes,
+        #      flattened into a single list.
+        #   3. The total number of validators.
+        #
+        # The flattened vote list is organized so that votes from all validators for
+        # each block root appear together, and those groups are simply placed back-to-back.
+        #
+        # To work with attestations, we must rebuild the intuitive structure:
+        #   “for each block root, here is the list of validator votes for it”.
+        #
+        # Reconstructing this is done by cutting the long vote list into consecutive
+        # segments, where:
+        #   - each segment corresponds to one block root,
+        #   - each segment has length equal to the number of validators,
+        #   - and the ordering of block roots is preserved.
+        flat_justifications = list(self.justifications_validators)
+
+        justifications = (
+            {
+                root: flat_justifications[
+                    i * self.validators.count : (i + 1) * self.validators.count
+                ]
+                for i, root in enumerate(self.justifications_roots)
+            }
+            if self.justifications_roots
+            else {}
         )
 
         # Track state changes to be applied at the end