Source code for simvx.core.scene_io.source._source_ast

"""The stdlib backend for the source layer: `ast` for structure, `tokenize` for trivia.

Two foundation modules sit under everything else here. :mod:`spans` is the only
module in the engine allowed to know that CPython reports column offsets in utf-8
bytes; it converts every position the parser hands out into a `str` index and
resolves the spans an editor needs to splice. :mod:`trivia` makes one `tokenize`
pass and says what lies between the statements: the comments, the blank lines,
the indentation and the semicolons.

Everything above them deals in spans and text. No module here mutates a tree,
because there is no tree to mutate: the document's only state is the author's
text, and an edit is a splice followed by a re-parse.
"""

from __future__ import annotations

from .. import SourceBackend, SourceDocument
from .document import AstDocument, parse_document, parse_one_expression

__all__ = ["BACKEND", "AstBackend", "AstDocument"]




class AstBackend(SourceBackend):
    """Reads and edits through CPython's own parser, and splices the text itself."""

    __slots__ = ()



    @property
    def name(self) -> str:
        return "ast"




    def parse(self, text: str) -> SourceDocument:
        return parse_document(text)




    def parse_expression(self, text: str) -> None:
        parse_one_expression(text)




#: The instance :func:`simvx.core.scene_io.source.get_backend` resolves.
BACKEND = AstBackend()