def parse_format_method_string(format_string):
"""
Parses a PEP 3101 format string, returning a tuple of
(keys, num_args, manual_pos_arg),
where keys is the set of mapping keys in the format string, num_args
is the number of arguments required by the format string and
manual_pos_arg is the number of arguments passed with the position.
"""
keys = []
num_args = 0
manual_pos_arg = set()
for name in collect_string_fields(format_string):
if name and str(name).isdigit():
manual_pos_arg.add(str(name))
elif name:
keyname, fielditerator = split_format_field_names(name)
if isinstance(keyname, numbers.Number):
# In Python 2 it will return long which will lead
# to different output between 2 and 3
manual_pos_arg.add(str(keyname))
keyname = int(keyname)
try:
keys.append((keyname, list(fielditerator)))
except ValueError:
raise utils.IncompleteFormatString()
else:
num_args += 1
return keys, num_args, len(manual_pos_arg)
def collect_string_fields(format_string):
""" Given a format string, return an iterator
of all the valid format fields. It handles nested fields
as well.
"""
formatter = string.Formatter()
try:
parseiterator = formatter.parse(format_string)
for result in parseiterator:
if all(item is None for item in result[1:]):
# not a replacement format
continue
name = result[1]
nested = result[2]
yield name
if nested:
for field in collect_string_fields(nested):
yield field
except ValueError as exc:
# Probably the format string is invalid.
if exc.args[0].startswith("cannot switch from manual"):
# On Jython, parsing a string with both manual
# and automatic positions will fail with a ValueError,
# while on CPython it will simply return the fields,
# the validation being done in the interpreter (?).
# We're just returning two mixed fields in order
# to trigger the format-combined-specification check.
yield ""
yield "1"
return
raise utils.IncompleteFormatString(format_string)
def collect_string_fields(format_string):
""" Given a format string, return an iterator
of all the valid format fields. It handles nested fields
as well.
"""
formatter = string.Formatter()
try:
parseiterator = formatter.parse(format_string)
for result in parseiterator:
if all(item is None for item in result[1:]):
# not a replacement format
continue
name = result[1]
nested = result[2]
yield name
if nested:
for field in collect_string_fields(nested):
yield field
except ValueError:
# probably the format string is invalid
# should we check the argument of the ValueError?
raise utils.IncompleteFormatString(format_string)
def split_format_field_names(format_string):
try:
return _string.formatter_field_name_split(format_string)
except ValueError:
raise utils.IncompleteFormatString()
