schema_utils.py

# Copyright 2022 The PyGlove Authors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Utilities for handling schema for symbolic classes."""

import types
from typing import Any, Dict, List, Optional, Sequence, Tuple, Union

from pyglove.core import object_utils
from pyglove.core import typing as pg_typing
from pyglove.core.symbolic import base
from pyglove.core.symbolic import flags


def augment_schema(
    schema: pg_typing.Schema,
    fields: List[
        Union[
            pg_typing.Field,
            Tuple[Union[str, pg_typing.KeySpec], pg_typing.ValueSpec, str],
            Tuple[Union[str, pg_typing.KeySpec], pg_typing.ValueSpec, str, Any],
        ]
    ],
    extend: bool = True,
    *,
    init_arg_list: Optional[Sequence[str]] = None,
    metadata: Optional[Dict[str, Any]] = None,
    description: Optional[str] = None,
) -> pg_typing.Schema:
  """Gets the augmented schema from class with extra fields and metadata.

  Args:
    schema: The original schema.
    fields: A list of `pg.typing.Field` or equivalent tuple representation as
      (<key>, <value-spec>, [description], [metadata-objects]). `key` should be
      a string. `value-spec` should be pg_typing.ValueSpec classes or
      equivalent, e.g. primitive values which will be converted to ValueSpec
      implementation according to its type and used as its default value.
      `description` is optional only when field overrides a field from its
      parent class. `metadata-objects` is an optional list of any type, which
      can be used to generate code according to the schema.
    extend: If True, extend existing schema using `fields`. Otherwise replace
      existing schema with a new schema created from `fields`.
    init_arg_list: An optional sequence of strings as the positional argument
      list for `__init__`. This is helpful when symbolic attributes are
      inherited from base classes or the user want to change its order. If not
      provided, the `init_arg_list` will be automatically generated from
      symbolic attributes defined from ``pg.members`` in their declaration
      order, from the base classes to the subclass.
    metadata: Optional dict of user objects as class-level metadata which will
      be attached to class schema.
    description: An optional description to set.

  Returns:
    The augmented schema (new copy).
  """
  metadata = metadata or {}
  if init_arg_list is None:
    init_arg_list = metadata.get('init_arg_list', None)
  metadata = object_utils.merge([schema.metadata, metadata])

  # NOTE(daiyip): Consider to inherit `init_arg_list` from the parent when
  # there is no new field.
  metadata['init_arg_list'] = init_arg_list

  return formalize_schema(
      pg_typing.create_schema(
          fields=fields,
          name=schema.name,
          base_schema_list=[schema] if extend else [],
          description=description or schema.description,
          allow_nonconst_keys=True,
          metadata=metadata,
      )
  )


def update_schema(
    cls,
    fields: List[
        Union[
            pg_typing.Field,
            Tuple[Union[str, pg_typing.KeySpec], pg_typing.ValueSpec, str],
            Tuple[Union[str, pg_typing.KeySpec], pg_typing.ValueSpec, str, Any],
        ]
    ],
    extend: bool = True,
    *,
    init_arg_list: Optional[Sequence[str]] = None,
    metadata: Optional[Dict[str, Any]] = None,
    description: Optional[str] = None,
    serialization_key: Optional[str] = None,
    additional_keys: Optional[List[str]] = None,
    add_to_registry: bool = True,
) -> None:
  """Updates the schema for a ``pg.Object`` subclass.

  This function allows the user to update the symbolic fields associated
  with a symbolic class. It was intended to support meta-programming
  scenarios in which symbolic fields are dynamically generated.

  Example::

    class A(pg.Object):
      pass

    # Add symbolic field 'x' to class A.
    pg.symbolic.update_schema(A, [
      ('x', schema.Int())
    ])

    # B inherits the symbolic field 'x' from A.
    class B(A):
      pass

    # Wipe out the symbolic field 'x' from B.
    pg.symbolic.update_schema(B, [], extend=False)

  See also: :func:`pyglove.members`, :func:`pyglove.functor` and
  :func:`pyglove.symbolize`.

  Args:
    cls: A symbolic Object subclass.
    fields: A list of `pg.typing.Field` or equivalent tuple representation as
      (<key>, <value-spec>, [description], [metadata-objects]). `key` should be
      a string. `value-spec` should be pg_typing.ValueSpec classes or
      equivalent, e.g. primitive values which will be converted to ValueSpec
      implementation according to its type and used as its default value.
      `description` is optional only when field overrides a field from its
      parent class. `metadata-objects` is an optional list of any type, which
      can be used to generate code according to the schema.
    extend: If True, extend existing schema using `fields`. Otherwise replace
      existing schema with a new schema created from `fields`.
    init_arg_list: An optional sequence of strings as the positional argument
      list for `__init__`. This is helpful when symbolic attributes are
      inherited from base classes or the user want to change its order. If not
      provided, the `init_arg_list` will be automatically generated from
      symbolic attributes defined from ``pg.members`` in their declaration
      order, from the base classes to the subclass.
    metadata: Optional dict of user objects as class-level metadata which will
      be attached to class schema.
    description: An optional description to set.
    serialization_key: An optional string to be used as the serialization key
      for the class during `sym_jsonify`. If None, `cls.__type_name__` will be
      used. This is introduced for scenarios when we want to relocate a class,
      before the downstream can recognize the new location, we need the class to
      serialize it using previous key.
    additional_keys: An optional list of strings as additional keys to
      deserialize an object of the registered class. This can be useful when we
      need to relocate or rename the registered class while being able to load
      existing serialized JSON values.
    add_to_registry: If True, the newly created functor class will be added to
      the registry for deserialization.
  """
  cls.apply_schema(
      augment_schema(
          cls.__schema__,
          fields=fields,
          extend=extend,
          init_arg_list=init_arg_list,
          metadata=metadata,
          description=description,
      )
  )

  if add_to_registry:
    cls.register_for_deserialization(serialization_key, additional_keys)


def callable_schema(
    func: types.FunctionType,
    args: Optional[
        List[
            Union[
                Tuple[Tuple[str, pg_typing.KeySpec], pg_typing.ValueSpec, str],
                Tuple[
                    Tuple[str, pg_typing.KeySpec], pg_typing.ValueSpec, str, Any
                ],
            ]
        ]
    ] = None,  # pylint: disable=bad-continuation
    returns: Optional[pg_typing.ValueSpec] = None,
    *,
    auto_typing: bool = True,
    auto_doc: bool = True,
    remove_self: bool = False,
) -> pg_typing.Schema:
  """Returns the schema from the signature of a callable."""
  args_docstr = None
  description = None
  if auto_doc:
    docstr = object_utils.docstr(func)
    if docstr:
      args_docstr = docstr.args
      description = schema_description_from_docstr(docstr)

  signature = pg_typing.get_signature(func, auto_typing=auto_typing)
  arg_fields = pg_typing.get_arg_fields(signature, args, args_docstr)

  if returns is not None and pg_typing.MISSING_VALUE != returns.default:
    raise ValueError('return value spec should not have default value.')
  returns = returns or signature.return_value

  if remove_self and arg_fields and arg_fields[0].key == 'self':
    arg_fields.pop(0)

  # Generate init_arg_list from signature.
  init_arg_list = [arg.name for arg in signature.args]
  if signature.varargs:
    init_arg_list.append(f'*{signature.varargs.name}')

  # Decide schema name.
  module_name = getattr(func, '__module__', None)
  func_name = func.__qualname__
  schema_name = f'{module_name}.{func_name}' if module_name else func_name

  return formalize_schema(
      pg_typing.create_schema(
          fields=arg_fields,
          name=schema_name,
          metadata={
              'init_arg_list': init_arg_list,
              'varargs_name': getattr(signature.varargs, 'name', None),
              'varkw_name': getattr(signature.varkw, 'name', None),
              'returns': returns,
          },
          description=description,
          allow_nonconst_keys=True,
      )
  )


def validate_init_arg_list(
    init_arg_list: List[str], cls_schema: pg_typing.Schema) -> None:
  """Validate init arg list."""
  for i, arg in enumerate(init_arg_list):
    is_vararg = False
    if i == len(init_arg_list) - 1 and arg.startswith('*'):
      arg = arg[1:]
      is_vararg = True
    field = cls_schema.get_field(arg)
    if field is None:
      raise TypeError(
          f'Argument {arg!r} from `init_arg_list` is not defined as a '
          f'symbolic field. init_arg_list={init_arg_list!r}.')
    if is_vararg and not isinstance(field.value, pg_typing.List):
      raise TypeError(
          f'Variable positional argument {arg!r} should be declared with '
          f'`pg.typing.List(...)`. Encountered {field.value!r}.')


def auto_init_arg_list(cls):
  """Generate the init_arg_list metadata from an pg.Object subclass."""
  # Inherit from the first non-empty base if they have the same signature.
  # This allows to bypass interface-only bases.
  init_arg_list = None
  for base_cls in cls.__bases__:
    schema = getattr(base_cls, '__schema__', None)
    if isinstance(schema, pg_typing.Schema):
      if list(schema.keys()) == list(cls.__schema__.keys()):
        init_arg_list = base_cls.init_arg_list
      else:
        break
  if init_arg_list is None:
    # Automatically generate from the field definitions in their
    # declaration order from base classes to subclasses.
    init_arg_list = [
        str(key)
        for key in cls.__schema__.fields.keys()
        if isinstance(key, pg_typing.ConstStrKey)
    ]
  return init_arg_list


def formalize_schema(schema: pg_typing.Schema) -> pg_typing.Schema:  # pylint: disable=redefined-outer-name
  """Formalize default values in the schema."""

  def _formalize_field(path: object_utils.KeyPath, node: Any) -> bool:
    """Formalize field."""
    if isinstance(node, pg_typing.Field):
      field = node
      if (not flags.is_empty_field_description_allowed()
          and not field.description):
        raise ValueError(
            f'Field description must not be empty (path={path}).')

      field.value.set_default(
          field.apply(
              field.default_value,
              allow_partial=True,
              transform_fn=base.symbolic_transform_fn(allow_partial=True)),
          use_default_apply=False)
      if isinstance(field.value, pg_typing.Dict):
        if field.value.schema is not None:
          field.value.schema.set_name(f'{schema.name}.{path.path}')
          object_utils.traverse(field.value.schema.fields, _formalize_field,
                                None, path)
      elif isinstance(field.value, pg_typing.List):
        _formalize_field(object_utils.KeyPath(0, path), field.value.element)
      elif isinstance(field.value, pg_typing.Tuple):
        for i, elem in enumerate(field.value.elements):
          _formalize_field(object_utils.KeyPath(i, path), elem)
      elif isinstance(field.value, pg_typing.Union):
        for i, c in enumerate(field.value.candidates):
          _formalize_field(
              object_utils.KeyPath(i, path),
              pg_typing.Field(field.key, c, 'Union sub-type.'))
    return True

  object_utils.traverse(schema.fields, _formalize_field)
  return schema


def schema_description_from_docstr(
    docstr: Optional[object_utils.DocStr],
    include_long_description: bool = False) -> Optional[str]:
  """Gets schema description from DocStr."""
  if docstr is None:
    return None
  description = docstr.short_description or ''
  if include_long_description:
    if docstr.blank_after_short_description:
      description += '\n'
    if docstr.long_description:
      description += '\n' + docstr.long_description
  return description.rstrip('\n')