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# arch-tag: b1ae35f1-d91b-49f0-a1ff-e163ddd8cefd
# Copyright (C) 2004 David Allouche <david@allouche.net>
# 2005 Canonical Limited.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
"""
Internal module providing name escaping functionality.
This module implements some of public interface for the
arch_ package. But for convenience reasons the author prefers
to store this code in a file separate from ``__init__.py`` .
.. _arch: arch-module.html
This module is strictly internal and should never be used.
"""
__all__ = ['name_escape', 'name_unescape']
### Escaping Tables ###
__space_escape_table = { '\t': 'tab', '\n': 'nl', '\v': 'U+B',
'\f': 'np', '\r': 'cr', ' ': 'sp' }
def __make_name_escape_table():
table = {}
for N in range(256):
C = chr(N)
if C in __space_escape_table: val = '\\(%s)' % __space_escape_table[C]
elif N < 32 or N > 127: val = '\\(U+%X)' % N
elif C in '"\\': val = '\\'+C
else: val = C
table[C] = val
return table
__name_escape_table = __make_name_escape_table()
__space_unescape_table = {}
for k, v in __space_escape_table.items(): __space_unescape_table[v] = k
### Escaping Functions ###
def name_escape(name):
"""Escape a file name using the Arch syntax.
:arg name: unescaped file name.
:type name: str
:return: escaped file name.
:rtype: str
"""
return ''.join([__name_escape_table[C] for C in name])
def name_unescape(name):
"""Unescape a file name using the Arch syntax.
:arg name: escaped file name.
:type name: str
:return: unescaped file name.
:rtype: str
:raise errors.IllegalEscapeSequence: the syntax of ``name`` is incorrect.
"""
result = []
after_backslash = 'after_backslash'
in_brackets = 'in_brackets'
state = None
escape = None # buffer for escape sequence
for C in name:
if state is None:
if C != '\\':
result.append(C)
continue
else:
state = after_backslash
continue
elif state is after_backslash:
if C == '(':
escape = []
state = in_brackets
continue
elif C in '\\"':
state = None
result.append(C)
continue
else:
raise errors.IllegalEscapeSequence(name)
elif state is in_brackets:
if C != ')':
escape.append(C)
continue
else:
state = None
if len(escape) < 2:
raise errors.IllegalEscapeSequence(name)
escape_str = ''.join(escape)
escape = None
if escape_str[0:2] in ('U+', 'u+'):
try:
code = int(escape_str[2:], 16)
except ValueError:
raise errors.IllegalEscapeSequence(name)
if code > 255:
raise errors.IllegalEscapeSequence(name)
result.append(chr(code))
continue
else:
escape_str = escape_str.lower()
try:
result.append(__space_unescape_table[escape_str])
except KeyError:
raise errors.IllegalEscapeSequence(name)
continue
else:
raise AssertionError, "The programmer is on crack!"
if state is not None:
raise errors.IllegalEscapeSequence(name)
else:
return ''.join(result)
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