add

ccxt/static_dependencies/starknet/serialization/_context.py

@@ -0,0 +1,142 @@
+from __future__ import annotations
+
+from abc import ABC
+from contextlib import contextmanager
+from typing import Any, Generator, Iterator, List
+
+from ._calldata_reader import (
+    CairoData,
+    CalldataReader,
+    OutOfBoundsError,
+)
+from .errors import InvalidTypeException, InvalidValueException
+
+
+class Context(ABC):
+    """
+    Holds information about context when (de)serializing data. This is needed to inform what and where went
+    wrong during processing. Every separate (de)serialization should have its own context.
+    """
+
+    _namespace_stack: List[str]
+
+    def __init__(self):
+        self._namespace_stack = []
+
+    @property
+    def current_entity(self):
+        """
+        Name of currently processed entity.
+
+        :return: transformed path.
+        """
+        return ".".join(self._namespace_stack)
+
+    @contextmanager
+    def push_entity(self, name: str) -> Generator:
+        """
+        Manager used for maintaining information about names of (de)serialized types. Wraps some errors with
+        custom errors, adding information about the context.
+
+        :param name: name of (de)serialized entity.
+        """
+        # This ensures the name will be popped if everything is ok. In case an exception is raised we want the stack to
+        # be filled to wrap the error at the end.
+        self._namespace_stack.append(name)
+        yield
+        self._namespace_stack.pop()
+
+    def ensure_valid_value(self, valid: bool, text: str):
+        if not valid:
+            raise InvalidValueException(f"{self._error_prefix}: {text}.")
+
+    def ensure_valid_type(self, value: Any, valid: bool, expected_type: str):
+        if not valid:
+            raise InvalidTypeException(
+                f"{self._error_prefix}: expected {expected_type}, "
+                f"received '{value}' of type '{type(value)}'."
+            )
+
+    @contextmanager
+    def _wrap_errors(self):
+        try:
+            yield
+        except OutOfBoundsError as err:
+            action_name = (
+                f"deserialize '{self.current_entity}'"
+                if self._namespace_stack
+                else "deserialize"
+            )
+            # This way we can precisely inform user what's wrong when reading calldata.
+            raise InvalidValueException(
+                f"Not enough data to {action_name}. "
+                f"Can't read {err.requested_size} values at position {err.position}, {err.remaining_len} available."
+            ) from err
+
+        # Those two are based on ValueError and TypeError, we have to catch them early
+        except (InvalidValueException, InvalidTypeException) as err:
+            raise err
+
+        except ValueError as err:
+            raise InvalidValueException(f"{self._error_prefix}: {err}") from err
+        except TypeError as err:
+            raise InvalidTypeException(f"{self._error_prefix}: {err}") from err
+
+    @property
+    def _error_prefix(self):
+        if not self._namespace_stack:
+            return "Error"
+        return f"Error at path '{self.current_entity}'"
+
+
+class SerializationContext(Context):
+    """
+    Context used during serialization.
+    """
+
+    # Type is iterator, because ContextManager doesn't work with pyright :|
+    # https://github.com/microsoft/pyright/issues/476
+    @classmethod
+    @contextmanager
+    def create(cls) -> Iterator[SerializationContext]:
+        context = cls()
+        with context._wrap_errors():
+            yield context
+
+
+class DeserializationContext(Context):
+    """
+    Context used during deserialization.
+    """
+
+    reader: CalldataReader
+
+    def __init__(self, calldata: CairoData):
+        """
+        Don't use default constructor. Use DeserializationContext.create context manager.
+        """
+        super().__init__()
+        self._namespace_stack = []
+        self.reader = CalldataReader(calldata)
+
+    @classmethod
+    @contextmanager
+    def create(cls, data: CairoData) -> Iterator[DeserializationContext]:
+        context = cls(data)
+        with context._wrap_errors():
+            yield context
+            context._ensure_all_values_read(len(data))
+
+    def _ensure_all_values_read(self, total_len: int):
+        values_not_used = self.reader.remaining_len
+        if values_not_used != 0:
+            # We want to output up to 3 values. It there is more they will be truncated like "0x1,0x1,0x1..."
+            max_values_to_show = 3
+            values_to_show = min(values_not_used, max_values_to_show)
+            example = ",".join(hex(v) for v in self.reader.read(values_to_show))
+            suffix = "..." if values_not_used > max_values_to_show else ""
+
+            raise InvalidValueException(
+                f"Last {values_not_used} values '{example}{suffix}' out of total {total_len} "
+                "values were not used during deserialization."
+            )