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"""Generic utilities"""
import re
# The below is adapted from an answer to
# https://stackoverflow.com/questions/66822945
# by Andrius at https://stackoverflow.com/a/66869159/1017546
# Reproduced under the CC-BY-SA 3.0 licence.
ODD_REPEAT_PATTERN = r"((?<!{c}){c}({c}{c})*(?!{c}))"
EVEN_REPEAT_PATTERN = r"(?<!{c})({c}{c})+(?!{c})"
SPECIFIER_PATTERN = r"[^(]*[diouxXeEfFgGcs]" # TODO: handle r
def __to_new_format(fmt: str, named=True):
def to_named_fmt(fmt):
pattern = rf"{odd_perc_pattern}\((.*?)\)({SPECIFIER_PATTERN})"
match = re.search(pattern, fmt)
while match:
# Only care about placeholder group here.
__, __, placeholder, specifier = match.groups()
fmt = fmt.replace(
f"%({placeholder}){specifier}", f"{{{placeholder}:{specifier}}}"
)
match = re.search(pattern, fmt)
return fmt
def to_pos_fmt(fmt):
even_perc_pattern = EVEN_REPEAT_PATTERN.format(c="%")
pattern = rf"{even_perc_pattern}s"
# When positional placeholder has even amount of percents, it
# will be treated as not having enough arguments passed.
if re.search(pattern, fmt):
raise TypeError("not all arguments converted during string formatting")
return re.sub(
rf"%({SPECIFIER_PATTERN})",
lambda sub_match: f"{{:{sub_match.group(1)}}}",
fmt,
)
odd_perc_pattern = ODD_REPEAT_PATTERN.format(c="%")
# Escape `{` and `}`, because new formatting uses it.
fmt = fmt.replace("{", "{{").replace("}", "}}")
fmt = to_named_fmt(fmt) if named else to_pos_fmt(fmt)
# If we find odd number of occurring percentage symbols, it means
# those were not escaped and we can't finish conversion.
if re.search(odd_perc_pattern, fmt):
raise ValueError("incomplete format")
return fmt.replace("%%", "%")
def to_new_named_format(fmt: str) -> str:
"""Convert old style named formatting to new style formatting.
For example: '%(x)s - %%%(y)s' -> '{x} - %{y}'
Args:
fmt: old style formatting to convert.
Returns:
new style formatting.
"""
return __to_new_format(fmt, named=True)
def to_new_pos_format(fmt: str) -> str:
"""Convert old style positional formatting to new style formatting.
For example: '%s - %%%s' -> '{} - %{}'
Args:
fmt: old style formatting to convert.
Returns:
new style formatting.
"""
return __to_new_format(fmt, named=False)
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