# Django 5.2 documentation

# Source code for django.utils.text

    import gzip
    import re
    import secrets
    import textwrap
    import unicodedata
    from collections import deque
    from gzip import GzipFile
    from gzip import compress as gzip_compress
    from html import escape
    from html.parser import HTMLParser
    from io import BytesIO

    from django.core.exceptions import SuspiciousFileOperation
    from django.utils.functional import (
        SimpleLazyObject,
        cached_property,
        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:]

    # Set up regular expressions
    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``.
        """

        wrapper = textwrap.TextWrapper(
            width=width,
            break_long_words=False,
            break_on_hyphens=False,
        )
        result = []
        for line in text.splitlines(True):
            result.extend(wrapper.wrap(line))
        return "\n".join(result)

    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}"

    def calculate_truncate_chars_length(length, replacement):
        truncate_len = length
        for char in add_truncation_text("", replacement):
            if not unicodedata.combining(char):
                truncate_len -= 1
                if truncate_len == 0:
                    break
        return truncate_len

    class TruncateHTMLParser(HTMLParser):
        class TruncationCompleted(Exception):
            pass

        def __init__(self, *, length, replacement, convert_charrefs=True):
            super().__init__(convert_charrefs=convert_charrefs)
            self.tags = deque()
            self.output = ""
            self.remaining = length
            self.replacement = replacement

        @cached_property
        def void_elements(self):
            from django.utils.html import VOID_ELEMENTS

            return VOID_ELEMENTS

        def handle_startendtag(self, tag, attrs):
            self.handle_starttag(tag, attrs)
            if tag not in self.void_elements:
                self.handle_endtag(tag)

        def handle_starttag(self, tag, attrs):
            self.output += self.get_starttag_text()
            if tag not in self.void_elements:
                self.tags.appendleft(tag)

        def handle_endtag(self, tag):
            if tag not in self.void_elements:
                self.output += f"</{tag}>"
                try:
                    self.tags.remove(tag)
                except ValueError:
                    pass

        def handle_data(self, data):
            data, output = self.process(data)
            data_len = len(data)
            if self.remaining < data_len:
                self.remaining = 0
                self.output += add_truncation_text(output, self.replacement)
                raise self.TruncationCompleted
            self.remaining -= data_len
            self.output += output

        def feed(self, data):
            try:
                super().feed(data)
            except self.TruncationCompleted:
                self.output += "".join([f"</{tag}>" for tag in self.tags])
                self.tags.clear()
                self.reset()
            else:
                # No data was handled.
                self.reset()

    class TruncateCharsHTMLParser(TruncateHTMLParser):
        def __init__(self, *, length, replacement, convert_charrefs=True):
            self.length = length
            self.processed_chars = 0
            super().__init__(
                length=calculate_truncate_chars_length(length, replacement),
                replacement=replacement,
                convert_charrefs=convert_charrefs,
            )

        def process(self, data):
            self.processed_chars += len(data)
            if (self.processed_chars == self.length) and (
                len(self.output) + len(data) == len(self.rawdata)
            ):
                self.output += data
                raise self.TruncationCompleted
            output = escape("".join(data[: self.remaining]))
            return data, output

    class TruncateWordsHTMLParser(TruncateHTMLParser):
        def process(self, data):
            data = re.split(r"(?<=\S)\s+(?=\S)", data)
            output = escape(" ".join(data[: self.remaining]))
            return data, output

    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)
            if length <= 0:
                return ""
            text = unicodedata.normalize("NFC", self._wrapped)

            if html:
                parser = TruncateCharsHTMLParser(length=length, replacement=truncate)
                parser.feed(text)
                parser.close()
                return parser.output
            return self._text_chars(length, truncate, text)

        def _text_chars(self, length, truncate, text):
            """Truncate a string after a certain number of chars."""
            truncate_len = calculate_truncate_chars_length(length, truncate)
            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 length <= 0:
                return ""
            if html:
                parser = TruncateWordsHTMLParser(length=length, replacement=truncate)
                parser.feed(self._wrapped)
                parser.close()
                return parser.output
            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)

    @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"\\", "\\")

    @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)