fonttools/Lib/ufoLib/filenames.py

"""
User name to file name conversion.
This was taken form the UFO 3 spec.
"""

illegalCharacters = "\" * + / : < > ? [ \ ] | \0".split(" ")
illegalCharacters += [chr(i) for i in range(1, 32)]
illegalCharacters += [chr(0x7F)]
reservedFileNames = "CON PRN AUX CLOCK$ NUL A:-Z: COM1".lower().split(" ")
reservedFileNames += "LPT1 LPT2 LPT3 COM2 COM3 COM4".lower().split(" ")
maxFileNameLength = 255

def userNameToFileName(userName, existing=[], prefix="", suffix=""):
    """
    existing should be a case-insensitive list
    of all existing file names.

    >>> userNameToFileName(u"a")
    u'a'
    >>> userNameToFileName(u"A")
    u'A_'
    >>> userNameToFileName(u"AE")
    u'A_E_'
    >>> userNameToFileName(u"Ae")
    u'A_e'
    >>> userNameToFileName(u"ae")
    u'ae'
    >>> userNameToFileName(u"aE")
    u'aE_'
    >>> userNameToFileName(u"a.alt")
    u'a.alt'
    >>> userNameToFileName(u"A.alt")
    u'A_.alt'
    >>> userNameToFileName(u"A.Alt")
    u'A_.A_lt'
    >>> userNameToFileName(u"A.aLt")
    u'A_.aL_t'
    >>> userNameToFileName(u"A.alT")
    u'A_.alT_'
    >>> userNameToFileName(u"T_H")
    u'T__H_'
    >>> userNameToFileName(u"T_h")
    u'T__h'
    >>> userNameToFileName(u"t_h")
    u't_h'
    >>> userNameToFileName(u"F_F_I")
    u'F__F__I_'
    >>> userNameToFileName(u"f_f_i")
    u'f_f_i'
    >>> userNameToFileName(u"Aacute_V.swash")
    u'A_acute_V_.swash'
    >>> userNameToFileName(u".notdef")
    u'_notdef'
    >>> userNameToFileName(u"con")
    u'_con'
    >>> userNameToFileName(u"CON")
    u'C_O_N_'
    >>> userNameToFileName(u"con.alt")
    u'_con.alt'
    >>> userNameToFileName(u"alt.con")
    u'alt._con'
    """
    # the incoming name must be a unicode string
    assert isinstance(userName, unicode), "The value for userName must be a unicode 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

def handleClash1(userName, existing=[], prefix="", suffix=""):
    """
    existing should be a case-insensitive list
    of all existing file names.

    >>> 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'

    >>> e = list(existing)
    >>> e.append(prefix + "aaaaa" + "1".zfill(15) + suffix)
    >>> handleClash1(userName="A" * 5, existing=e,
    ...     prefix=prefix, suffix=suffix)
    '00000.AAAAA000000000000002.0000000000'

    >>> e = list(existing)
    >>> e.append(prefix + "AAAAA" + "2".zfill(15) + suffix)
    >>> handleClash1(userName="A" * 5, existing=e,
    ...     prefix=prefix, suffix=suffix)
    '00000.AAAAA000000000000001.0000000000'
    """
    # 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

def handleClash2(existing=[], prefix="", suffix=""):
    """
    existing should be a case-insensitive list
    of all existing file names.

    >>> 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'

    >>> e = list(existing)
    >>> e.remove(prefix + "1" + suffix)
    >>> handleClash2(existing=e, prefix=prefix, suffix=suffix)
    '00000.1.0000000000'

    >>> e = list(existing)
    >>> e.remove(prefix + "2" + suffix)
    >>> handleClash2(existing=e, prefix=prefix, suffix=suffix)
    '00000.2.0000000000'
    """
    # 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()