# Provides various useful routines
from __future__ import annotations
import collections, collections.abc
import sys
if sys.version_info >= (3, 10):
from types import NoneType
else:
NoneType = type(None)
from dataclasses import dataclass, make_dataclass
from typing import Optional, Tuple, Union, List, Any, Dict, Callable, Sequence
import functools
import abc
import apsw
try:
from keyword import iskeyword as _iskeyword
except ImportError:
# From https://docs.python.org/3/reference/lexical_analysis.html#keywords
_keywords = set("""
False await else import pass
None break except in raise
True class finally is return
and continue for lambda try
as def from nonlocal while
assert del global not with
async elif if or yield
""".split())
def _iskeyword(s: str) -> bool:
return s in _keywords
[docs]class DataClassRowFactory:
"""Returns each row as a :mod:`dataclass <dataclasses>`, accessible by column name.
To use set an instance as :attr:`Connection.rowtrace
<apsw.Connection.rowtrace>` to affect all :class:`cursors
<apsw.Cursor>`, or on a specific cursor::
connection.rowtrace = apsw.ext.DataClassRowFactory()
for row in connection.execute("SELECT title, sum(orders) AS total, ..."):
# You can now access by name
print (row.title, row.total)
# you can get the underlying description
print (row.__description__)
You can use as many instances of this class as you want, each across as many
:class:`connections <apsw.Connection>` as you want.
:param rename: Column names could be duplicated, or not
valid in Python (eg a column named `continue`).
If `rename` is True, then invalid/duplicate names are replaced
with `_` and their position starting at zero. For example `title,
total, title, continue` would become `title, total, _2, _3`. If
`rename` is False then problem column names will result in
:exc:`TypeError` raised by :func:`dataclasses.make_dataclass`
:param dataclass_kwargs: Additional parameters when creating the dataclass
as described in :func:`dataclasses.dataclass`. For example you may
want `frozen = True` to make the dataclass read-only, or `slots = True`
to reduce memory consumption.
"""
def __init__(self, *, rename: bool = True, dataclass_kwargs: Optional[Dict[str, Any]] = None):
self.dataclass_kwargs = dataclass_kwargs or {}
self.rename = rename
[docs] @functools.lru_cache(maxsize=16)
def get_dataclass(self, description: Tuple[Tuple[str, str], ...]) -> Tuple[Any, Tuple[str, ...]]:
"""Returns dataclass and tuple of (potentially renamed) column names
The dataclass is what is returned for each row with that
:meth:`description <apsw.Cursor.getdescription>`
This method caches it results.
"""
names = [d[0] for d in description]
if self.rename:
new_names: List[str] = []
for i, n in enumerate(names):
if n.isidentifier() and not _iskeyword(n) and n not in new_names:
new_names.append(n)
else:
new_names.append(f"_{ i }")
names = new_names
types = [self.get_type(d[1]) for d in description]
kwargs = self.dataclass_kwargs.copy()
if "namespace" not in kwargs:
kwargs["namespace"] = {}
kwargs["namespace"]["__description__"] = description
# some magic to make the reported classnames different
suffix = (".%06X" % hash(repr(description)))[:7]
return make_dataclass(f"{ self.__class__.__name__ }{ suffix }", zip(names, types), **kwargs), tuple(names)
[docs] def get_type(self, t: Optional[str]) -> Any:
"""Returns the `type hint <https://docs.python.org/3/library/typing.html>`__ to use in the dataclass based on the type in the :meth:`description <apsw.Cursor.getdescription>`
`SQLite's affinity rules <https://www.sqlite.org/datatype3.html#affname>`__ are followed.
The values have no effect on how your program runs, but can be used by tools like
mypy. Column information like whether `null` is allowed is not present, so
this is just a hint.
"""
if not t:
return Any
# From 3.1 https://www.sqlite.org/datatype3.html
t = t.upper()
if "INT" in t:
return int
if "CHAR" in t or "CLOB" in t or "TEXT" in t:
return str
if "BLOB" in t:
return bytes
if "REAL" in t or "FLOA" in t or "DOUB" in t:
return float
return Union[float, int]
[docs] def __call__(self, cursor: apsw.Cursor, row: apsw.SQLiteValues) -> Any:
"""What the row tracer calls
This :meth:`looks up <get_dataclass>` the dataclass and column
names, and then returns an instance of the dataclass.
"""
dc, column_names = self.get_dataclass(cursor.getdescription())
return dc(**dict(zip(column_names, row)))
[docs]class SQLiteTypeAdapter(abc.ABC):
"""A metaclass to indicate conversion to SQLite types is supported
This is one way to indicate your type supports conversion to a
value supported by SQLite. You can either inherit from this class,
or call the register method::
apsw.ext.SQLiteTypeAdapter.register(YourClassHere)
Doing either is entirely sufficient and there is no need to
register with :class:`TypesConverterCursorFactory`
"""
[docs] @abc.abstractmethod
def to_sqlite_value(self) -> apsw.SQLiteValue:
"Return a SQLite compatible value for this object"
raise NotImplementedError
[docs]class TypesConverterCursorFactory:
"""Provides cursors that can convert objects into one of the types supported by SQLite. or back from SQLite
:param metaclass: Which metaclass to consider as conversion capable
"""
def __init__(self, abstract_base_class: abc.ABCMeta = SQLiteTypeAdapter):
self.abstract_base_class = abstract_base_class
# to sqlite value
self.adapters: Dict[type, Callable[[Any], apsw.SQLiteValue]] = {}
# from sqlite value
self.converters: Dict[str, Callable[[apsw.SQLiteValue], Any]] = {}
[docs] def register_adapter(self, klass: type, callable: Callable[[Any], apsw.SQLiteValue]) -> None:
"""Registers a callable that converts from `klass` to one of the supported SQLite types"""
self.adapters[klass] = callable
[docs] def register_converter(self, name: str, callable: Callable[[apsw.SQLiteValue], Any]) -> None:
"""Registers a callable that converts from a SQLite value"""
self.converters[name] = callable
[docs] def __call__(self, connection: apsw.Connection) -> TypeConverterCursor:
"Returns a new :class:`cursor <apsw.Cursor>` for the `connection`"
return TypesConverterCursorFactory.TypeConverterCursor(connection, self)
[docs] def adapt_value(self, value: Any) -> apsw.SQLiteValue:
"Returns SQLite representation of `value`"
if isinstance(value, (int, bytes, str, NoneType, float)):
return value
if isinstance(value, self.abstract_base_class):
return value.to_sqlite_value()
adapter = self.adapters.get(type(value))
if not adapter:
raise TypeError(f"No adapter registered for type { type(value) }")
return adapter(value)
[docs] def convert_value(self, schematype: str, value: apsw.SQLiteValue) -> Any:
"Returns Python object from schema type and SQLite value"
converter = self.converters.get(schematype)
if not converter:
return value
return converter(value)
[docs] def wrap_bindings(self, bindings: Optional[apsw.Bindings]) -> Optional[apsw.Bindings]:
"Wraps bindings that are supplied to underlying execute"
if bindings is None:
return None
if isinstance(bindings, (dict, collections.abc.Mapping)):
return TypesConverterCursorFactory.DictAdapter(self, bindings)
# turn into a list since PySequence_Fast does that anyway
return [self.adapt_value(v) for v in bindings]
[docs] def wrap_sequence_bindings(self, sequenceofbindings: Sequence[apsw.Bindings]):
for binding in sequenceofbindings:
yield self.wrap_bindings(binding)
[docs] class DictAdapter(collections.abc.Mapping):
"Used to wrap dictionaries supplied as bindings"
def __init__(self, factory: TypesConverterCursorFactory, data: collections.abc.Mapping[str, apsw.SQLiteValue]):
self.data = data
self.factory = factory
def __getitem__(self, key: str) -> apsw.SQLiteValue:
return self.factory.adapt_value(self.data[key])
def __iter__(self):
"Required by mapping, but not used"
raise NotImplementedError
def __len__(self):
"Required by mapping, but not used"
raise NotImplementedError
[docs] class TypeConverterCursor(apsw.Cursor):
"Cursor used to do conversions"
def __init__(self, connection: apsw.Connection, factory: TypesConverterCursorFactory):
super().__init__(connection)
self.factory = factory
self.rowtrace = self._rowtracer
def _rowtracer(self, cursor: apsw.Cursor, values: apsw.SQLiteValues) -> Tuple[Any, ...]:
return tuple(self.factory.convert_value(d[1], v) for d, v in zip(cursor.getdescription(), values))
[docs] def execute(self,
statements: str,
bindings: Optional[apsw.Bindings] = None,
*,
can_cache: bool = True,
prepare_flags: int = 0) -> apsw.Cursor:
"""Executes the statements doing conversions on supplied and returned values
See :meth:`apsw.Cursor.execute` for parameter details"""
return super().execute(statements,
self.factory.wrap_bindings(bindings),
can_cache=can_cache,
prepare_flags=prepare_flags)
[docs] def executemany(self,
statements: str,
sequenceofbindings: Sequence[apsw.Bindings],
*,
can_cache: bool = True,
prepare_flags: int = 0) -> apsw.Cursor:
"""Executes the statements against each item in sequenceofbindings, doing conversions on supplied and returned values
See :meth:`apsw.Cursor.executemany` for parameter details"""
return super().executemany(statements,
self.factory.wrap_sequence_bindings(sequenceofbindings),
can_cache=can_cache,
prepare_flags=prepare_flags)
[docs]def query_info(db: apsw.Connection,
query: str,
bindings: Optional[apsw.Bindings] = None,
*,
prepare_flags: int = 0,
actions: bool = False,
expanded_sql: bool = False,
explain: bool = False,
explain_query_plan: bool = False) -> QueryDetails:
"""Returns information about the query, but does not run it.
Set the various parameters to `True` if you also want the
actions, expanded_sql, explain, query_plan etc filled in.
"""
res: dict[str, Any] = {"actions": None, "query_plan": None, "explain": None}
def tracer(cursor: apsw.Cursor, first_query: str, bindings: Optional[apsw.Bindings]):
nonlocal res
res.update({
"first_query": first_query,
"query": query,
"bindings": bindings,
"is_explain": cursor.is_explain,
"is_readonly": cursor.is_readonly,
"description": cursor.getdescription(),
"description_full": None,
})
if hasattr(cursor, "description_full"):
res["description_full"] = cursor.description_full
assert query == first_query or query.startswith(first_query)
res["query_remaining"] = query[len(first_query):] if len(query) > len(first_query) else None
res["expanded_sql"] = cursor.expanded_sql if expanded_sql else None
return False
actions_taken = []
def auther(code, third, fourth, dbname, trigview):
a = {"action": code, "action_name": apsw.mapping_authorizer_function[code]}
if dbname:
a["database_name"] = dbname
if trigview:
a["trigger_or_view"] = trigview
# this block corresponds to the table at https://sqlite.org/c3ref/c_alter_table.html
for op, thirdname, fourthname in (
(apsw.SQLITE_CREATE_INDEX, "index_name", "table_name"),
(apsw.SQLITE_CREATE_TABLE, "table_name", None),
(apsw.SQLITE_CREATE_TEMP_INDEX, "index_name", "table_name"),
(apsw.SQLITE_CREATE_TEMP_TABLE, "table_name", None),
(apsw.SQLITE_CREATE_TEMP_TRIGGER, "trigger_name", "table_name"),
(apsw.SQLITE_CREATE_TEMP_VIEW, "view_name", None),
(apsw.SQLITE_CREATE_TRIGGER, "trigger_name", "table_name"),
(apsw.SQLITE_CREATE_VIEW, "view_name", None),
(apsw.SQLITE_DELETE, "table_name", None),
(apsw.SQLITE_DROP_INDEX, "index_name", "table_name"),
(apsw.SQLITE_DROP_TABLE, "table_name", None),
(apsw.SQLITE_DROP_TEMP_INDEX, "index_name", "table_name"),
(apsw.SQLITE_DROP_TEMP_TABLE, "table_name", None),
(apsw.SQLITE_DROP_TEMP_TRIGGER, "trigger_name", "table_name"),
(apsw.SQLITE_DROP_TEMP_VIEW, "view_name", None),
(apsw.SQLITE_DROP_TRIGGER, "trigger_name", "table_name"),
(apsw.SQLITE_DROP_VIEW, "view_name", None),
(apsw.SQLITE_INSERT, "table_name", None),
(apsw.SQLITE_PRAGMA, "pragma_name", "pragma_value"),
(apsw.SQLITE_READ, "table_name", "column_name"),
(apsw.SQLITE_SELECT, None, None),
(apsw.SQLITE_TRANSACTION, "operation", None),
(apsw.SQLITE_UPDATE, "table_name", "column_name"),
(apsw.SQLITE_ATTACH, "file_name", None),
(apsw.SQLITE_DETACH, "database_name", None),
(apsw.SQLITE_ALTER_TABLE, "database_name", "table_name"),
(apsw.SQLITE_REINDEX, "index_name", None),
(apsw.SQLITE_ANALYZE, "table_name", None),
(apsw.SQLITE_CREATE_VTABLE, "table_name", "module_name"),
(apsw.SQLITE_DROP_VTABLE, "table_name", "module_name"),
(apsw.SQLITE_FUNCTION, None, "function_name"),
(apsw.SQLITE_SAVEPOINT, "operation", None),
(apsw.SQLITE_RECURSIVE, None, None),
):
if code == op:
if thirdname is not None:
a[thirdname] = third
if fourthname is not None:
a[fourthname] = fourth
break
else:
raise ValueError(f"Unknown authorizer code { code }")
actions_taken.append(QueryAction(**a))
return apsw.SQLITE_OK
cur = db.cursor()
cur.exectrace = tracer
if actions:
orig_authorizer = db.authorizer
db.authorizer = auther
try:
cur.execute(query, bindings, can_cache=False, prepare_flags=prepare_flags)
except apsw.ExecTraceAbort:
pass
finally:
if actions:
db.authorizer = orig_authorizer
cur.exectrace = None
if actions:
res["actions"] = actions_taken
if explain and not res["is_explain"]:
vdbe = []
for row in cur.execute("EXPLAIN " + res["first_query"], bindings):
vdbe.append(
VDBEInstruction(**dict((v[0][0], v[1]) for v in zip(cur.getdescription(), row) if v[1] is not None)))
res["explain"] = vdbe
if explain_query_plan and not res["is_explain"]:
subn = "sub"
byid = {0: {"detail": "QUERY PLAN"}}
for row in cur.execute("EXPLAIN QUERY PLAN " + res["first_query"], bindings):
node = dict((v[0][0], v[1]) for v in zip(cur.getdescription(), row) if v[0][0] != "notused")
assert len(node) == 3 # catch changes in returned format
parent = byid[node["parent"]]
if subn not in parent:
parent[subn] = [node]
else:
parent[subn].append(node)
byid[node["id"]] = node
def flatten(node):
res = {"detail": node["detail"]}
if subn in node:
res[subn] = [QueryPlan(**flatten(child)) for child in node[subn]]
return res
res["query_plan"] = QueryPlan(**flatten(byid[0]))
return QueryDetails(**res)
[docs]@dataclass
class QueryDetails:
"A :mod:`dataclass <dataclasses>` that provides detailed information about a query, returned by :func:`query_info`"
query: str
"Original query provided"
bindings: Optional[apsw.Bindings]
"Bindings provided"
first_query: str
"The first statement present in query"
query_remaining: Optional[str]
"Query text after the first one if multiple were in query, else None"
is_explain: int
":attr:`Cursor.is_explain <apsw.Cursor.is_explain>`"
is_readonly: bool
":attr:`Cursor.is_readonly <apsw.Cursor.is_readonly>`"
description: Tuple[Tuple[str, str], ...]
":meth:`Cursor.getdescription <apsw.Cursor.getdescription>`"
description_full: Optional[Tuple[Tuple[str, str, str, str, str], ...]]
":attr:`Cursor.description_full <apsw.Cursor.description_full>`"
expanded_sql: Optional[str]
":attr:`Cursor.expanded_sql <apsw.Cursor.expanded_sql>`"
actions: Optional[List[QueryAction]]
"""A list of the actions taken by the query, as discovered via
:attr:`Connection.authorizer <apsw.Connection.authorizer>`"""
explain: Optional[List[VDBEInstruction]]
"""A list of instructions of the `internal code <https://sqlite.org/opcode.html>`__
used by SQLite to execute the query"""
query_plan: Optional[QueryPlan]
"""The steps taken against tables and indices `described here <https://sqlite.org/eqp.html>`__"""
[docs]@dataclass
class QueryAction:
"""A :mod:`dataclass <dataclasses>` that provides information about one action taken by a query
Depending on the action, only a subset of the fields will have non-None values"""
action: int
"""`Authorizer code <https://sqlite.org/c3ref/c_alter_table.html>`__ (also present
in :attr:`apsw.mapping_authorizer_function`)"""
action_name: str
"""The string corresponding to the action. For example `action` could be `21` in which
case `action_name` will be `SQLITE_SELECT`"""
column_name: Optional[str] = None
database_name: Optional[str] = None
"eg `main`, `temp`, the name in `ATTACH <https://sqlite.org/lang_attach.html>`__"
file_name: Optional[str] = None
function_name: Optional[str] = None
module_name: Optional[str] = None
operation: Optional[str] = None
pragma_name: Optional[str] = None
pragma_value: Optional[str] = None
table_name: Optional[str] = None
trigger_name: Optional[str] = None
trigger_or_view: Optional[str] = None
"""This action is happening due to a trigger or view, and not
directly expressed in the query itself"""
view_name: Optional[str] = None
[docs]@dataclass
class QueryPlan:
"A :mod:`dataclass <dataclasses>` for one step of a query plan"
detail: str
"Description of this step"
sub: Optional[List[QueryPlan]] = None
"Steps that run within this one"
[docs]@dataclass
class VDBEInstruction:
"A :mod:`dataclass <dataclasses>` representing one instruction and its parameters"
addr: int
"Address of this opcode. It will be the target of goto, loops etc"
opcode: str
"The instruction"
comment: Optional[str] = None
"Additional human readable information"
p1: Optional[int] = None
"First opcode parameter"
p2: Optional[int] = None
"Second opcode parameter"
p3: Optional[int] = None
"Third opcode parameter"
p4: Optional[int] = None
"Fourth opcode parameter"
p5: Optional[int] = None
"Fifth opcode parameter"