Source code for django.utils.text
import gzip
import re
import secrets
import unicodedata
from gzip import GzipFile
from gzip import compress as gzip_compress
from io import BytesIO
from django.core.exceptions import SuspiciousFileOperation
from django.utils.functional import SimpleLazyObject, keep_lazy_text, lazy
from django.utils.regex_helper import _lazy_re_compile
from django.utils.translation import gettext as _
from django.utils.translation import gettext_lazy, pgettext
@keep_lazy_text
def capfirst(x):
"""Capitalize the first letter of a string."""
if not x:
return x
if not isinstance(x, str):
x = str(x)
return x[0].upper() + x[1:]
# ----- Begin security-related performance workaround -----
# We used to have, below
#
# re_words = _lazy_re_compile(r"<[^>]+?>|([^<>\s]+)", re.S)
#
# But it was shown that this regex, in the way we use it here, has some
# catastrophic edge-case performance features. Namely, when it is applied to
# text with only open brackets "<<<...". The class below provides the services
# and correct answers for the use cases, but in these edge cases does it much
# faster.
re_notag = _lazy_re_compile(r"([^<>\s]+)", re.S)
re_prt = _lazy_re_compile(r"<|([^<>\s]+)", re.S)
class WordsRegex:
@staticmethod
def search(text, pos):
# Look for "<" or a non-tag word.
partial = re_prt.search(text, pos)
if partial is None or partial[1] is not None:
return partial
# "<" was found, look for a closing ">".
end = text.find(">", partial.end(0))
if end < 0:
# ">" cannot be found, look for a word.
return re_notag.search(text, pos + 1)
else:
# "<" followed by a ">" was found -- fake a match.
end += 1
return FakeMatch(text[partial.start(0) : end], end)
class FakeMatch:
__slots__ = ["_text", "_end"]
def end(self, group=0):
assert group == 0, "This specific object takes only group=0"
return self._end
def __getitem__(self, group):
if group == 1:
return None
assert group == 0, "This specific object takes only group in {0,1}"
return self._text
def __init__(self, text, end):
self._text, self._end = text, end
# ----- End security-related performance workaround -----
# Set up regular expressions.
re_words = WordsRegex
re_chars = _lazy_re_compile(r"<[^>]+?>|(.)", re.S)
re_tag = _lazy_re_compile(r"<(/)?(\S+?)(?:(\s*/)|\s.*?)?>", re.S)
re_newlines = _lazy_re_compile(r"\r\n|\r") # Used in normalize_newlines
re_camel_case = _lazy_re_compile(r"(((?<=[a-z])[A-Z])|([A-Z](?![A-Z]|$)))")
@keep_lazy_text
def wrap(text, width):
"""
A word-wrap function that preserves existing line breaks. Expects that
existing line breaks are posix newlines.
Preserve all white space except added line breaks consume the space on
which they break the line.
Don't wrap long words, thus the output text may have lines longer than
``width``.
"""
def _generator():
for line in text.splitlines(True): # True keeps trailing linebreaks
max_width = min((line.endswith("\n") and width + 1 or width), width)
while len(line) > max_width:
space = line[: max_width + 1].rfind(" ") + 1
if space == 0:
space = line.find(" ") + 1
if space == 0:
yield line
line = ""
break
yield "%s\n" % line[: space - 1]
line = line[space:]
max_width = min((line.endswith("\n") and width + 1 or width), width)
if line:
yield line
return "".join(_generator())
def add_truncation_text(text, truncate=None):
if truncate is None:
truncate = pgettext(
"String to return when truncating text", "%(truncated_text)s…"
)
if "%(truncated_text)s" in truncate:
return truncate % {"truncated_text": text}
# The truncation text didn't contain the %(truncated_text)s string
# replacement argument so just append it to the text.
if text.endswith(truncate):
# But don't append the truncation text if the current text already ends
# in this.
return text
return f"{text}{truncate}"
class Truncator(SimpleLazyObject):
"""
An object used to truncate text, either by characters or words.
When truncating HTML text (either chars or words), input will be limited to
at most `MAX_LENGTH_HTML` characters.
"""
# 5 million characters are approximately 4000 text pages or 3 web pages.
MAX_LENGTH_HTML = 5_000_000
def __init__(self, text):
super().__init__(lambda: str(text))
def chars(self, num, truncate=None, html=False):
"""
Return the text truncated to be no longer than the specified number
of characters.
`truncate` specifies what should be used to notify that the string has
been truncated, defaulting to a translatable string of an ellipsis.
"""
self._setup()
length = int(num)
text = unicodedata.normalize("NFC", self._wrapped)
# Calculate the length to truncate to (max length - end_text length)
truncate_len = length
for char in add_truncation_text("", truncate):
if not unicodedata.combining(char):
truncate_len -= 1
if truncate_len == 0:
break
if html:
return self._truncate_html(length, truncate, text, truncate_len, False)
return self._text_chars(length, truncate, text, truncate_len)
def _text_chars(self, length, truncate, text, truncate_len):
"""Truncate a string after a certain number of chars."""
s_len = 0
end_index = None
for i, char in enumerate(text):
if unicodedata.combining(char):
# Don't consider combining characters
# as adding to the string length
continue
s_len += 1
if end_index is None and s_len > truncate_len:
end_index = i
if s_len > length:
# Return the truncated string
return add_truncation_text(text[: end_index or 0], truncate)
# Return the original string since no truncation was necessary
return text
def words(self, num, truncate=None, html=False):
"""
Truncate a string after a certain number of words. `truncate` specifies
what should be used to notify that the string has been truncated,
defaulting to ellipsis.
"""
self._setup()
length = int(num)
if html:
return self._truncate_html(length, truncate, self._wrapped, length, True)
return self._text_words(length, truncate)
def _text_words(self, length, truncate):
"""
Truncate a string after a certain number of words.
Strip newlines in the string.
"""
words = self._wrapped.split()
if len(words) > length:
words = words[:length]
return add_truncation_text(" ".join(words), truncate)
return " ".join(words)
def _truncate_html(self, length, truncate, text, truncate_len, words):
"""
Truncate HTML to a certain number of chars (not counting tags and
comments), or, if words is True, then to a certain number of words.
Close opened tags if they were correctly closed in the given HTML.
Preserve newlines in the HTML.
"""
if words and length <= 0:
return ""
size_limited = False
if len(text) > self.MAX_LENGTH_HTML:
text = text[: self.MAX_LENGTH_HTML]
size_limited = True
html4_singlets = (
"br",
"col",
"link",
"base",
"img",
"param",
"area",
"hr",
"input",
)
# Count non-HTML chars/words and keep note of open tags
pos = 0
end_text_pos = 0
current_len = 0
open_tags = []
regex = re_words if words else re_chars
while current_len <= length:
m = regex.search(text, pos)
if not m:
# Checked through whole string
break
pos = m.end(0)
if m[1]:
# It's an actual non-HTML word or char
current_len += 1
if current_len == truncate_len:
end_text_pos = pos
continue
# Check for tag
tag = re_tag.match(m[0])
if not tag or current_len >= truncate_len:
# Don't worry about non tags or tags after our truncate point
continue
closing_tag, tagname, self_closing = tag.groups()
# Element names are always case-insensitive
tagname = tagname.lower()
if self_closing or tagname in html4_singlets:
pass
elif closing_tag:
# Check for match in open tags list
try:
i = open_tags.index(tagname)
except ValueError:
pass
else:
# SGML: An end tag closes, back to the matching start tag,
# all unclosed intervening start tags with omitted end tags
open_tags = open_tags[i + 1 :]
else:
# Add it to the start of the open tags list
open_tags.insert(0, tagname)
truncate_text = add_truncation_text("", truncate)
if current_len <= length:
if size_limited and truncate_text:
text += truncate_text
return text
out = text[:end_text_pos]
if truncate_text:
out += truncate_text
# Close any tags still open
for tag in open_tags:
out += "</%s>" % tag
# Return string
return out
@keep_lazy_text
def get_valid_filename(name):
"""
Return the given string converted to a string that can be used for a clean
filename. Remove leading and trailing spaces; convert other spaces to
underscores; and remove anything that is not an alphanumeric, dash,
underscore, or dot.
>>> get_valid_filename("john's portrait in 2004.jpg")
'johns_portrait_in_2004.jpg'
"""
s = str(name).strip().replace(" ", "_")
s = re.sub(r"(?u)[^-\w.]", "", s)
if s in {"", ".", ".."}:
raise SuspiciousFileOperation("Could not derive file name from '%s'" % name)
return s
@keep_lazy_text
def get_text_list(list_, last_word=gettext_lazy("or")):
"""
>>> get_text_list(['a', 'b', 'c', 'd'])
'a, b, c or d'
>>> get_text_list(['a', 'b', 'c'], 'and')
'a, b and c'
>>> get_text_list(['a', 'b'], 'and')
'a and b'
>>> get_text_list(['a'])
'a'
>>> get_text_list([])
''
"""
if not list_:
return ""
if len(list_) == 1:
return str(list_[0])
return "%s %s %s" % (
# Translators: This string is used as a separator between list elements
_(", ").join(str(i) for i in list_[:-1]),
str(last_word),
str(list_[-1]),
)
@keep_lazy_text
def normalize_newlines(text):
"""Normalize CRLF and CR newlines to just LF."""
return re_newlines.sub("\n", str(text))
@keep_lazy_text
def phone2numeric(phone):
"""Convert a phone number with letters into its numeric equivalent."""
char2number = {
"a": "2",
"b": "2",
"c": "2",
"d": "3",
"e": "3",
"f": "3",
"g": "4",
"h": "4",
"i": "4",
"j": "5",
"k": "5",
"l": "5",
"m": "6",
"n": "6",
"o": "6",
"p": "7",
"q": "7",
"r": "7",
"s": "7",
"t": "8",
"u": "8",
"v": "8",
"w": "9",
"x": "9",
"y": "9",
"z": "9",
}
return "".join(char2number.get(c, c) for c in phone.lower())
def _get_random_filename(max_random_bytes):
return b"a" * secrets.randbelow(max_random_bytes)
def compress_string(s, *, max_random_bytes=None):
compressed_data = gzip_compress(s, compresslevel=6, mtime=0)
if not max_random_bytes:
return compressed_data
compressed_view = memoryview(compressed_data)
header = bytearray(compressed_view[:10])
header[3] = gzip.FNAME
filename = _get_random_filename(max_random_bytes) + b"\x00"
return bytes(header) + filename + compressed_view[10:]
class StreamingBuffer(BytesIO):
def read(self):
ret = self.getvalue()
self.seek(0)
self.truncate()
return ret
# Like compress_string, but for iterators of strings.
def compress_sequence(sequence, *, max_random_bytes=None):
buf = StreamingBuffer()
filename = _get_random_filename(max_random_bytes) if max_random_bytes else None
with GzipFile(
filename=filename, mode="wb", compresslevel=6, fileobj=buf, mtime=0
) as zfile:
# Output headers...
yield buf.read()
for item in sequence:
zfile.write(item)
data = buf.read()
if data:
yield data
yield buf.read()
# Expression to match some_token and some_token="with spaces" (and similarly
# for single-quoted strings).
smart_split_re = _lazy_re_compile(
r"""
((?:
[^\s'"]*
(?:
(?:"(?:[^"\\]|\\.)*" | '(?:[^'\\]|\\.)*')
[^\s'"]*
)+
) | \S+)
""",
re.VERBOSE,
)
def smart_split(text):
r"""
Generator that splits a string by spaces, leaving quoted phrases together.
Supports both single and double quotes, and supports escaping quotes with
backslashes. In the output, strings will keep their initial and trailing
quote marks and escaped quotes will remain escaped (the results can then
be further processed with unescape_string_literal()).
>>> list(smart_split(r'This is "a person\'s" test.'))
['This', 'is', '"a person\\\'s"', 'test.']
>>> list(smart_split(r"Another 'person\'s' test."))
['Another', "'person\\'s'", 'test.']
>>> list(smart_split(r'A "\"funky\" style" test.'))
['A', '"\\"funky\\" style"', 'test.']
"""
for bit in smart_split_re.finditer(str(text)):
yield bit[0]
@keep_lazy_text
def unescape_string_literal(s):
r"""
Convert quoted string literals to unquoted strings with escaped quotes and
backslashes unquoted::
>>> unescape_string_literal('"abc"')
'abc'
>>> unescape_string_literal("'abc'")
'abc'
>>> unescape_string_literal('"a \"bc\""')
'a "bc"'
>>> unescape_string_literal("'\'ab\' c'")
"'ab' c"
"""
if not s or s[0] not in "\"'" or s[-1] != s[0]:
raise ValueError("Not a string literal: %r" % s)
quote = s[0]
return s[1:-1].replace(r"\%s" % quote, quote).replace(r"\\", "\\")
[docs]
@keep_lazy_text
def slugify(value, allow_unicode=False):
"""
Convert to ASCII if 'allow_unicode' is False. Convert spaces or repeated
dashes to single dashes. Remove characters that aren't alphanumerics,
underscores, or hyphens. Convert to lowercase. Also strip leading and
trailing whitespace, dashes, and underscores.
"""
value = str(value)
if allow_unicode:
value = unicodedata.normalize("NFKC", value)
else:
value = (
unicodedata.normalize("NFKD", value)
.encode("ascii", "ignore")
.decode("ascii")
)
value = re.sub(r"[^\w\s-]", "", value.lower())
return re.sub(r"[-\s]+", "-", value).strip("-_")
def camel_case_to_spaces(value):
"""
Split CamelCase and convert to lowercase. Strip surrounding whitespace.
"""
return re_camel_case.sub(r" \1", value).strip().lower()
def _format_lazy(format_string, *args, **kwargs):
"""
Apply str.format() on 'format_string' where format_string, args,
and/or kwargs might be lazy.
"""
return format_string.format(*args, **kwargs)
format_lazy = lazy(_format_lazy, str)
