Source code for bpc_utils.context

"""BPC conversion context."""

import abc
import unicodedata

import parso.tree

from .misc import UUID4Generator
from .typing import TYPE_CHECKING, TypeVar, final

    from .misc import Config
    from .typing import Callable, Final, Linesep, Optional, Tuple

BaseContextType = TypeVar('BaseContextType', bound='BaseContext')

[docs]class BaseContext(abc.ABC): """Abstract base class for general conversion context.""" def __init__(self, node: 'parso.tree.NodeOrLeaf', config: 'Config', *, indent_level: int = 0, raw: bool = False) -> None: """Initialize BaseContext. Args: node: parso AST config (:class:`~bpc_utils.Config`): conversion configurations indent_level: current indentation level raw: raw processing flag """ #: Internal configurations. self.config = config # type: Final[Config] #: Indentation sequence. self._indentation = config.indentation # type: Final[str] # type: ignore[attr-defined] #: Final[:data:`~bpc_utils.Linesep`]: Line separator. self._linesep = config.linesep # type: Final[Linesep] # type: ignore[attr-defined] #: :pep:`8` compliant conversion flag. self._pep8 = config.pep8 # type: Final[bool] # type: ignore[attr-defined] #: Root node given by the ``node`` parameter. self._root = node # type: Final[parso.tree.NodeOrLeaf] #: Current indentation level. self._indent_level = indent_level # type: Final[int] #: UUID generator. self._uuid_gen = UUID4Generator(dash=False) # type: Final[UUID4Generator] #: Code before insertion point. self._prefix = '' # type: str #: Code after insertion point. self._suffix = '' # type: str #: Final converted result. self._buffer = '' # type: str #: Flag to indicate whether buffer is now :attr:`self._prefix <bpc_utils.BaseContext._prefix>`. self._prefix_or_suffix = True # type: bool #: Preceding node with the target expression, i.e. the *insertion point*. self._node_before_expr = None # type: Optional[parso.tree.NodeOrLeaf] self._walk(node) # traverse children if raw: self._buffer = self._prefix + self._suffix else: self._concat() # generate final result
[docs] @final def __iadd__(self: BaseContextType, code: str) -> BaseContextType: """Support of the ``+=`` operator. If :attr:`self._prefix_or_suffix <bpc_utils.BaseContext._prefix_or_suffix>` is :data:`True`, then the ``code`` will be appended to :attr:`self._prefix <bpc_utils.BaseContext._prefix>`; else it will be appended to :attr:`self._suffix <bpc_utils.BaseContext._suffix>`. Args: code: code string Returns: BaseContext: self """ if self._prefix_or_suffix: self._prefix += code else: self._suffix += code return self
[docs] @final def __str__(self) -> str: """Returns a *stripped* version of :attr:`self._buffer <bpc_utils.BaseContext._buffer>`.""" return self._buffer.strip()
@final @property def string(self) -> str: """Returns conversion buffer (:attr:`self._buffer <bpc_utils.BaseContext._buffer>`).""" return self._buffer
[docs] @final def _walk(self, node: 'parso.tree.NodeOrLeaf') -> None: """Start traversing the AST module. The method traverses through all *children* of ``node``. It first checks if such child has the target expression. If so, it will toggle :attr:`self._prefix_or_suffix <bpc_utils.BaseContext._prefix_or_suffix>` (set to :data:`False`) and save the last previous child as :attr:`self._node_before_expr <bpc_utils.BaseContext._node_before_expr>`. Then it processes the child with :meth:`self._process <bpc_utils.BaseContext._process>`. Args: node: parso AST """ # process node if isinstance(node, parso.tree.BaseNode): last_node = None for child in node.children: if self._prefix_or_suffix and self.has_expr(child): self._prefix_or_suffix = False self._node_before_expr = last_node self._process(child) last_node = child return # preserve leaf node as is by default self += node.get_code()
[docs] @final def _process(self, node: 'parso.tree.NodeOrLeaf') -> None: """Recursively process parso AST. All processing methods for a specific ``node`` type are defined as ``_process_{type}``. This method first checks if such processing method exists. If so, it will call such method on the ``node``; otherwise it will traverse through all *children* of ``node``, and perform the same logic on each child. Args: node: parso AST """ func_name = '_process_%s' % node.type if hasattr(self, func_name): func = getattr(self, func_name) # type: Callable[[parso.tree.NodeOrLeaf], None] func(node) return # process node if isinstance(node, parso.tree.BaseNode): for child in node.children: self._process(child) return # preserve leaf node as is by default self += node.get_code()
[docs] @abc.abstractmethod def _concat(self) -> None: """Concatenate final string.""" raise NotImplementedError # pragma: no cover
[docs] @abc.abstractmethod def has_expr(self, node: 'parso.tree.NodeOrLeaf') -> bool: """Check if node has the target expression. Args: node: parso AST Returns: whether ``node`` has the target expression """ raise NotImplementedError # pragma: no cover
[docs] @final @staticmethod def split_comments(code: str, linesep: 'Linesep') -> 'Tuple[str, str]': """Separates prefixing comments from code. This method separates *prefixing* comments and *suffixing* code. It is rather useful when inserting code might break `shebang`_ and encoding cookies (:pep:`263`), etc. .. _shebang: Args: code: the code to split comments linesep (:data:`~bpc_utils.Linesep`): line separator Returns: a tuple of *prefix comments* and *suffix code* """ prefix = '' suffix = '' prefix_or_suffix = True for line in code.split(linesep): if prefix_or_suffix: if line.strip().startswith('#'): prefix += line + linesep continue prefix_or_suffix = False suffix += line + linesep if prefix_or_suffix: prefix = prefix[:-len(linesep)] # 3.9+ str.removesuffix else: suffix = suffix[:-len(linesep)] return prefix, suffix
[docs] @final @staticmethod def missing_newlines(prefix: str, suffix: str, expected: int, linesep: 'Linesep') -> int: """Count missing blank lines for code insertion given surrounding code. Args: prefix: preceding source code suffix: succeeding source code expected: number of expected blank lines linesep (:data:`~bpc_utils.Linesep`): line separator Returns: number of blank lines to add """ current = 0 # count trailing newlines in `prefix` if prefix: for line in reversed(prefix.split(linesep)): # pragma: no branch if line.strip(): break current += 1 if current > 0: # keep a trailing newline in `prefix` current -= 1 # count leading newlines in `suffix` if suffix: for line in suffix.split(linesep): # pragma: no branch if line.strip(): break current += 1 missing = expected - current return max(missing, 0)
[docs] @final @staticmethod def extract_whitespaces(code: str) -> 'Tuple[str, str]': """Extract preceding and succeeding whitespaces from the code given. Args: code: the code to extract whitespaces Returns: a tuple of *preceding* and *succeeding* whitespaces in ``code`` """ # get preceding whitespaces prefix = '' for char in code: if char not in ' \t\n\r\f': break prefix += char # get succeeding whitespaces suffix = '' for char in reversed(code): if char not in ' \t\n\r\f': break suffix += char return prefix, suffix[::-1]
[docs] @final @staticmethod def normalize(name: str) -> str: """Normalize variable names. This method normalizes variable names as described in `Python documentation about identifiers`_ and :pep:`3131`. Args: name: variable name as it appears in the source code Returns: normalized variable name .. _Python documentation about identifiers: """ return unicodedata.normalize('NFKC', name)
[docs] @final @classmethod def mangle(cls, cls_name: str, var_name: str) -> str: """Mangle variable names. This method mangles variable names as described in `Python documentation about mangling`_ and further normalizes the mangled variable name through :meth:`~bpc_utils.BaseContext.normalize`. Args: cls_name: class name var_name: variable name Returns: mangled and normalized variable name .. _Python documentation about mangling: """ # should only perform mangling if variable name begins with two or more underscores # and does not end in two or more underscores if not var_name.startswith('__') or var_name.endswith('__'): name = var_name else: # perform mangling, remove leading underscores from the class name when inserting class_name_stripped = cls_name.lstrip('_') if class_name_stripped: name = '_%(cls)s%(var)s' % {'cls': class_name_stripped, 'var': var_name} else: # if the class name consists only of underscores, do not mangle name = var_name return cls.normalize(name)
__all__ = ['BaseContext']