fake_fastnumbers.py 文件源码

def fast_float(x, key=lambda x: x, nan=None,
               uni=unicodedata.numeric, nan_inf=nan_inf):
    """\
    Convert a string to a float quickly, return input as-is if not possible.
    We don't need to accept all input that the real fast_int accepts because
    the input will be controlled by the splitting algorithm.
    """
    if x[0] in '0123456789+-.' or x.lstrip()[:3] in nan_inf:
        try:
            x = float(x)
            return nan if nan is not None and x != x else x
        except ValueError:
            try:
                return uni(x, key(x)) if len(x) == 1 else key(x)
            except TypeError:  # pragma: no cover
                return key(x)
    else:
        try:
            return uni(x, key(x)) if len(x) == 1 else key(x)
        except TypeError:  # pragma: no cover
            return key(x)