.. Copyright (c) 2017-2026 Juancarlo Añez (apalala@gmail.com) .. SPDX-License-Identifier: BSD-4-Clause .. include:: links.rst .. highlight:: none Parser Configuration -------------------- |TatSu| has many configuration options. They are all defined in ``tatsu.config.ParserConfig``. With the introduction of ``ParserConfig`` there's no need to declare every configuration parameter as an optional named argument in entry points and internal methods. The defaults set in ``ParserConfig`` are suitable for most cases, and they are easy to override. Entry points still accept configuration options as named keyword arguments, but those are gathered in ``**settings`` (aka ``**kwargs``) argument for a``ParserConfig`` to validate when called. .. code:: python @dataclass class ParserConfig: name: str | None = 'Test' filename: str = '' start: str | None = None semantics: type | None = None comment_recovery: bool = False # warning: not implemented memoization: bool = True perlinememos: float = DEFAULT_MEMOS_PER_LINE colorize: bool = True # INFO: requires the colorama library trace: bool = False trace_filename: bool = False trace_length: int = 72 trace_separator: str = C_DERIVE grammar: str | None = None left_recursion: bool = True comments: str | None = None eol_comments: str | None = None keywords: set[str] = field(default_factory=set) ignorecase: bool | None = False namechars: str = '' nameguard: bool | None = None # implied by namechars whitespace: str | None = undefined parseinfo: bool = False Entry points and internal methods in |TatSu| have an optional ``config: ParserConfig | None = None`` argument. .. code:: Python def parse( grammar, input, start=None, name=None, semantics=None, asmodel=False, config: ParserConfig | None = None, **settings, ): If no ``ParserConfig`` is passed, a default one is created. Configuration attributes may be overridden by relevant arguments in ``**settings``. These are different ways to apply a configuration setting: .. code:: Python config = tatsu.config.ParserConfig() config.left_recursion = False ast = tatsu.parse(grammar, text, config=config) config = tatsu.config.ParserConfig(left_recursion=False) ast = tatsu.parse(grammar, text, config=config) ast = tatsu.parse(grammar, text, left_recursion=False) name ~~~~ .. code:: Python name: str | None = 'Test' The name of the grammar. It's used in generated Python parsers and may be used in error reporting. filename ~~~~~~~~ .. code:: Python filename: str = '' The file name from which the grammar was read. It may be used in error reporting. start ~~~~~ .. code:: Python start: str | None = None The name of the rule on which to start parsing. It may be used to invoke only a specific part of the parser. .. code:: Python ast = parse(grammar, '(2+2)*2', start='expression') semantics ~~~~~~~~~ .. code:: Python semantics: type | None = None The class implementing parser semantics. See other sections of the documentation for meaning, implementation and default and generated semantic classes and objects. memoization ~~~~~~~~~~~ .. code:: Python memoization: bool = True Enable or disable memoization in the parser. Only specific input languages require this to be ``False``. Note that parsing times cease t o be linear when memoization is disabled. perlinememos ~~~~~~~~~~~~~ Sets a ``(perlinememos * linecount)`` bound on the total number of memoization entries that are allowed. colorize ~~~~~~~~ .. code:: Python colorize: bool = True Colorize trace output. Colorization requires that the ``colorama`` library is available. trace ~~~~~ .. code:: Python trace: bool = False Produce a trace of the parsing process. See the `Traces `_ section for more information. trace_filename ~~~~~~~~~~~~~~ .. code:: Python trace_filename: bool = False Include the input text's filename in trace output. trace_length ~~~~~~~~~~~~ .. code:: Python trace_length: int = 72 The max width of a line in a trace. trace_separator ~~~~~~~~~~~~~~~ .. code:: Python trace_separator: str = C_DERIVE The separator to use between lines in a trace. grammar ~~~~~~~ .. code:: Python grammar: str | None = None An alias for the `name <#name>`_ option. left_recursion ~~~~~~~~~~~~~~ .. code:: Python left_recursion: bool = True Enable or disable left recursion in analysis and parsing. comments ~~~~~~~~ .. code:: Python comments: str | None = None A regular expression describing comments in the input. Comments are skipped during parsing. eol_comments ~~~~~~~~~~~~ .. code:: Python eol_comments: str | None = None A regular expression describing end-of-line comments in the input. Comments are skipped during parsing. keywords ~~~~~~~~ .. code:: Python keywords: set[str] = field(default_factory=set) The list of keywords in the input language. See `Reserved Words and Keywords `_ for more information. ignorecase ~~~~~~~~~~ .. code:: Python ignorecase: bool | None = False namechars ~~~~~~~~~ .. code:: Python namechars: str = '' Additional characters that can be part of an identifier (for example ``namechars='$@'``'). nameguard ~~~~~~~~~ .. code:: Python nameguard: bool = False # implied by namechars When set to ``True``, avoids matching tokens when the next character in the input sequence is alphanumeric or a ``@@namechar``. Defaults to ``False``. See `token expression `_ for an explanation. whitespace ~~~~~~~~~~ .. code:: Python whitespace: str | None = undefined Provides a regular expression for the whitespace to be ignored by the parser. See the `@@whitespace `_ section for more information. parseinfo ~~~~~~~~~ .. code:: Python parseinfo: bool = False When ``parseinfo==True``, a ``parseinfo`` entry is added to `AST`_ nodes that are dict-like. The entry provides information about what was parsed and where. See `Abstract Syntax Trees `_ for more information. .. code:: Python class ParseInfo(NamedTuple): cursor: Cursor rule: str pos: int endpos: int line: int endline: int alerts: list[Alert] = [] # noqa: RUF012