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# Copyright 2009 Canonical Ltd. This software is licensed under the
# GNU Affero General Public License version 3 (see the file LICENSE).
"""Translation-related formatting functions."""
__metaclass__ = type
__all__ = [
'contract_rosetta_escapes',
'convert_newlines_to_web_form',
'count_lines',
'expand_rosetta_escapes',
'parse_cformat_string',
'text_to_html',
]
from math import ceil
import re
from xml.sax.saxutils import escape as xml_escape
from canonical.launchpad import helpers
from lp.translations.interfaces.translations import TranslationConstants
class UnrecognisedCFormatString(ValueError):
"""Exception: C-style format string fails to parse."""
def contract_rosetta_escapes(text):
"""Replace Rosetta escape sequences with the real characters."""
return helpers.text_replaced(text, {'[tab]': '\t',
r'\[tab]': '[tab]',
'[nbsp]': u'\u00a0',
r'\[nbsp]': '[nbsp]',
'[nnbsp]': u'\u202f',
r'\[nnbsp]': '[nnbsp]'})
def expand_rosetta_escapes(unicode_text):
"""Replace characters needing a Rosetta escape sequences."""
escapes = {u'\t': TranslationConstants.TAB_CHAR,
u'[tab]': TranslationConstants.TAB_CHAR_ESCAPED,
u'\u00a0': TranslationConstants.NO_BREAK_SPACE_CHAR,
u'[nbsp]': TranslationConstants.NO_BREAK_SPACE_CHAR_ESCAPED,
u'\u202f': TranslationConstants.NARROW_NO_BREAK_SPACE_CHAR,
u'[nnbsp]':
TranslationConstants.NARROW_NO_BREAK_SPACE_CHAR_ESCAPED}
return helpers.text_replaced(unicode_text, escapes)
def text_to_html(text, flags, space=TranslationConstants.SPACE_CHAR,
newline=TranslationConstants.NEWLINE_CHAR):
"""Convert a unicode text to a HTML representation."""
if text is None:
return None
lines = []
# Replace leading and trailing spaces on each line with special markup.
if u'\r\n' in text:
newline_chars = u'\r\n'
elif u'\r' in text:
newline_chars = u'\r'
else:
newline_chars = u'\n'
for line in xml_escape(text).split(newline_chars):
# Pattern:
# - group 1: zero or more spaces: leading whitespace
# - group 2: zero or more groups of (zero or
# more spaces followed by one or more non-spaces): maximal string
# which doesn't begin or end with whitespace
# - group 3: zero or more spaces: trailing whitespace
match = re.match(u'^( *)((?: *[^ ]+)*)( *)$', line)
if match:
lines.append(
space * len(match.group(1)) +
match.group(2) +
space * len(match.group(3)))
else:
raise AssertionError(
"A regular expression that should always match didn't.")
if 'c-format' in flags:
# Replace c-format sequences with marked-up versions. If there is a
# problem parsing the c-format sequences on a particular line, that
# line is left unformatted.
for i in range(len(lines)):
formatted_line = ''
try:
segments = parse_cformat_string(lines[i])
except UnrecognisedCFormatString:
continue
for segment in segments:
type, content = segment
if type == 'interpolation':
formatted_line += (u'<code>%s</code>' % content)
elif type == 'string':
formatted_line += content
lines[i] = formatted_line
return expand_rosetta_escapes(newline.join(lines))
def convert_newlines_to_web_form(unicode_text):
"""Convert Unicode string to CR/LF line endings as used in web forms.
Any style of line endings is accepted: MacOS-style CR, MS-DOS-style
CR/LF, or rest-of-world-style LF.
"""
if unicode_text is None:
return None
assert isinstance(unicode_text, unicode), (
"The given text must be unicode instead of %s" % type(unicode_text))
if unicode_text is None:
return None
elif u'\r\n' in unicode_text:
# The text is already using the windows newline chars
return unicode_text
elif u'\n' in unicode_text:
return helpers.text_replaced(unicode_text, {u'\n': u'\r\n'})
else:
return helpers.text_replaced(unicode_text, {u'\r': u'\r\n'})
def count_lines(text):
"""Count the number of physical lines in a string.
This is always at least as large as the number of logical lines in a
string.
"""
if text is None:
return 0
CHARACTERS_PER_LINE = 60
count = 0
for line in text.split(u'\n'):
if len(line) == 0:
count += 1
else:
count += int(ceil(float(len(line)) / CHARACTERS_PER_LINE))
return count
def parse_cformat_string(string):
"""Parse C-style format string into sequence of segments.
The result is a sequence of tuples (type, content), where ``type`` is
either "string" (for a plain piece of string) or "interpolation" (for a
printf()-style substitution). The other part of the tuple, ``content``,
will be the part of the input string that makes up the given element, so
either plain text or a printf substitution such as ``%s`` or ``%.3d``.
As in printf(), the double parenthesis (%%) is taken as plain text.
"""
# The sequence '%%' is not counted as an interpolation. Perhaps splitting
# into 'special' and 'non-special' sequences would be better.
# This function works on the basis that s can be one of three things: an
# empty string, a string beginning with a sequence containing no
# interpolations, or a string beginning with an interpolation.
segments = []
end = string
plain_re = re.compile('(%%|[^%])+')
interpolation_re = re.compile('%[^diouxXeEfFgGcspmn]*[diouxXeEfFgGcspmn]')
while end:
# Check for a interpolation-less prefix.
match = plain_re.match(end)
if match:
segment = match.group(0)
segments.append(('string', segment))
end = end[len(segment):]
continue
# Check for an interpolation sequence at the beginning.
match = interpolation_re.match(end)
if match:
segment = match.group(0)
segments.append(('interpolation', segment))
end = end[len(segment):]
continue
# Give up.
raise UnrecognisedCFormatString(string)
return segments
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