Source code for fontTools.ufoLib.filenames

"""
Convert user-provided internal UFO names to spec-compliant filenames.

This module implements the algorithm for converting between a "user name" -
something that a user can choose arbitrarily inside a font editor - and a file
name suitable for use in a wide range of operating systems and filesystems.

The `UFO 3 specification <http://unifiedfontobject.org/versions/ufo3/conventions/>`_
provides an example of an algorithm for such conversion, which avoids illegal
characters, reserved file names, ambiguity between upper- and lower-case
characters, and clashes with existing files.

This code was originally copied from
`ufoLib <https://github.com/unified-font-object/ufoLib/blob/8747da7/Lib/ufoLib/filenames.py>`_
by Tal Leming and is copyright (c) 2005-2016, The RoboFab Developers:

-	Erik van Blokland
-	Tal Leming
-	Just van Rossum
"""

# Restrictions are taken mostly from
# https://docs.microsoft.com/en-gb/windows/win32/fileio/naming-a-file#naming-conventions.
#
# 1. Integer value zero, sometimes referred to as the ASCII NUL character.
# 2. Characters whose integer representations are in the range 1 to 31,
#    inclusive.
# 3. Various characters that (mostly) Windows and POSIX-y filesystems don't
#    allow, plus "(" and ")", as per the specification.
illegalCharacters = {
    "\x00",
    "\x01",
    "\x02",
    "\x03",
    "\x04",
    "\x05",
    "\x06",
    "\x07",
    "\x08",
    "\t",
    "\n",
    "\x0b",
    "\x0c",
    "\r",
    "\x0e",
    "\x0f",
    "\x10",
    "\x11",
    "\x12",
    "\x13",
    "\x14",
    "\x15",
    "\x16",
    "\x17",
    "\x18",
    "\x19",
    "\x1a",
    "\x1b",
    "\x1c",
    "\x1d",
    "\x1e",
    "\x1f",
    '"',
    "*",
    "+",
    "/",
    ":",
    "<",
    ">",
    "?",
    "[",
    "\\",
    "]",
    "(",
    ")",
    "|",
    "\x7f",
}
reservedFileNames = {
    "aux",
    "clock$",
    "com1",
    "com2",
    "com3",
    "com4",
    "com5",
    "com6",
    "com7",
    "com8",
    "com9",
    "con",
    "lpt1",
    "lpt2",
    "lpt3",
    "lpt4",
    "lpt5",
    "lpt6",
    "lpt7",
    "lpt8",
    "lpt9",
    "nul",
    "prn",
}
maxFileNameLength = 255


[docs] class NameTranslationError(Exception): pass
[docs] def userNameToFileName(userName: str, existing=(), prefix="", suffix=""): """Converts from a user name to a file name. Takes care to avoid illegal characters, reserved file names, ambiguity between upper- and lower-case characters, and clashes with existing files. Args: userName (str): The input file name. existing: A case-insensitive list of all existing file names. prefix: Prefix to be prepended to the file name. suffix: Suffix to be appended to the file name. Returns: A suitable filename. Raises: NameTranslationError: If no suitable name could be generated. Examples:: >>> userNameToFileName("a") == "a" True >>> userNameToFileName("A") == "A_" True >>> userNameToFileName("AE") == "A_E_" True >>> userNameToFileName("Ae") == "A_e" True >>> userNameToFileName("ae") == "ae" True >>> userNameToFileName("aE") == "aE_" True >>> userNameToFileName("a.alt") == "a.alt" True >>> userNameToFileName("A.alt") == "A_.alt" True >>> userNameToFileName("A.Alt") == "A_.A_lt" True >>> userNameToFileName("A.aLt") == "A_.aL_t" True >>> userNameToFileName(u"A.alT") == "A_.alT_" True >>> userNameToFileName("T_H") == "T__H_" True >>> userNameToFileName("T_h") == "T__h" True >>> userNameToFileName("t_h") == "t_h" True >>> userNameToFileName("F_F_I") == "F__F__I_" True >>> userNameToFileName("f_f_i") == "f_f_i" True >>> userNameToFileName("Aacute_V.swash") == "A_acute_V_.swash" True >>> userNameToFileName(".notdef") == "_notdef" True >>> userNameToFileName("con") == "_con" True >>> userNameToFileName("CON") == "C_O_N_" True >>> userNameToFileName("con.alt") == "_con.alt" True >>> userNameToFileName("alt.con") == "alt._con" True """ # the incoming name must be a string if not isinstance(userName, str): raise ValueError("The value for userName must be a string.") # establish the prefix and suffix lengths prefixLength = len(prefix) suffixLength = len(suffix) # replace an initial period with an _ # if no prefix is to be added if not prefix and userName[0] == ".": userName = "_" + userName[1:] # filter the user name filteredUserName = [] for character in userName: # replace illegal characters with _ if character in illegalCharacters: character = "_" # add _ to all non-lower characters elif character != character.lower(): character += "_" filteredUserName.append(character) userName = "".join(filteredUserName) # clip to 255 sliceLength = maxFileNameLength - prefixLength - suffixLength userName = userName[:sliceLength] # test for illegal files names parts = [] for part in userName.split("."): if part.lower() in reservedFileNames: part = "_" + part parts.append(part) userName = ".".join(parts) # test for clash fullName = prefix + userName + suffix if fullName.lower() in existing: fullName = handleClash1(userName, existing, prefix, suffix) # finished return fullName
[docs] def handleClash1(userName, existing=[], prefix="", suffix=""): """A helper function that resolves collisions with existing names when choosing a filename. This function attempts to append an unused integer counter to the filename. Args: userName (str): The input file name. existing: A case-insensitive list of all existing file names. prefix: Prefix to be prepended to the file name. suffix: Suffix to be appended to the file name. Returns: A suitable filename. >>> prefix = ("0" * 5) + "." >>> suffix = "." + ("0" * 10) >>> existing = ["a" * 5] >>> e = list(existing) >>> handleClash1(userName="A" * 5, existing=e, ... prefix=prefix, suffix=suffix) == ( ... '00000.AAAAA000000000000001.0000000000') True >>> e = list(existing) >>> e.append(prefix + "aaaaa" + "1".zfill(15) + suffix) >>> handleClash1(userName="A" * 5, existing=e, ... prefix=prefix, suffix=suffix) == ( ... '00000.AAAAA000000000000002.0000000000') True >>> e = list(existing) >>> e.append(prefix + "AAAAA" + "2".zfill(15) + suffix) >>> handleClash1(userName="A" * 5, existing=e, ... prefix=prefix, suffix=suffix) == ( ... '00000.AAAAA000000000000001.0000000000') True """ # if the prefix length + user name length + suffix length + 15 is at # or past the maximum length, silce 15 characters off of the user name prefixLength = len(prefix) suffixLength = len(suffix) if prefixLength + len(userName) + suffixLength + 15 > maxFileNameLength: l = prefixLength + len(userName) + suffixLength + 15 sliceLength = maxFileNameLength - l userName = userName[:sliceLength] finalName = None # try to add numbers to create a unique name counter = 1 while finalName is None: name = userName + str(counter).zfill(15) fullName = prefix + name + suffix if fullName.lower() not in existing: finalName = fullName break else: counter += 1 if counter >= 999999999999999: break # if there is a clash, go to the next fallback if finalName is None: finalName = handleClash2(existing, prefix, suffix) # finished return finalName
[docs] def handleClash2(existing=[], prefix="", suffix=""): """A helper function that resolves collisions with existing names when choosing a filename. This function is a fallback to :func:`handleClash1`. It attempts to append an unused integer counter to the filename. Args: userName (str): The input file name. existing: A case-insensitive list of all existing file names. prefix: Prefix to be prepended to the file name. suffix: Suffix to be appended to the file name. Returns: A suitable filename. Raises: NameTranslationError: If no suitable name could be generated. Examples:: >>> prefix = ("0" * 5) + "." >>> suffix = "." + ("0" * 10) >>> existing = [prefix + str(i) + suffix for i in range(100)] >>> e = list(existing) >>> handleClash2(existing=e, prefix=prefix, suffix=suffix) == ( ... '00000.100.0000000000') True >>> e = list(existing) >>> e.remove(prefix + "1" + suffix) >>> handleClash2(existing=e, prefix=prefix, suffix=suffix) == ( ... '00000.1.0000000000') True >>> e = list(existing) >>> e.remove(prefix + "2" + suffix) >>> handleClash2(existing=e, prefix=prefix, suffix=suffix) == ( ... '00000.2.0000000000') True """ # calculate the longest possible string maxLength = maxFileNameLength - len(prefix) - len(suffix) maxValue = int("9" * maxLength) # try to find a number finalName = None counter = 1 while finalName is None: fullName = prefix + str(counter) + suffix if fullName.lower() not in existing: finalName = fullName break else: counter += 1 if counter >= maxValue: break # raise an error if nothing has been found if finalName is None: raise NameTranslationError("No unique name could be found.") # finished return finalName
if __name__ == "__main__": import doctest doctest.testmod()