1"""Check and assemble commands for running Graphviz ``dot``.""" 
    2 
    3import os 
    4import pathlib 
    5from typing import Final 
    6 
    7from .. import exceptions 
    8from .. import parameters 
    9 
    10__all__ = ['DOT_BINARY', 'command'] 
    11 
    12DOT_BINARY: Final = pathlib.Path('dot') 
    13 
    14 
    15def command(engine: str, format_: str, *, 
    16            renderer: str | None = None, 
    17            formatter: str | None = None, 
    18            neato_no_op: bool | int | None = None) -> list[os.PathLike[str] | str]: 
    19    """Return ``subprocess.Popen`` argument list for rendering. 
    20 
    21    See also: 
    22        Upstream documentation: 
    23        - https://www.graphviz.org/doc/info/command.html#-K 
    24        - https://www.graphviz.org/doc/info/command.html#-T 
    25        - https://www.graphviz.org/doc/info/command.html#-n 
    26    """ 
    27    if formatter is not None and renderer is None: 
    28        raise exceptions.RequiredArgumentError('formatter given without renderer') 
    29 
    30    parameters.verify_engine(engine, required=True) 
    31    parameters.verify_format(format_, required=True) 
    32    parameters.verify_renderer(renderer, required=False) 
    33    parameters.verify_formatter(formatter, required=False) 
    34 
    35    output_format = [f for f in (format_, renderer, formatter) if f is not None] 
    36    output_format_flag = ':'.join(output_format) 
    37 
    38    cmd: list[os.PathLike[str] | str] 
    39    cmd = [DOT_BINARY, f'-K{engine}', f'-T{output_format_flag}'] 
    40 
    41    if neato_no_op: 
    42        cmd.append(f'-n{neato_no_op:d}') 
    43 
    44    return cmd