Copying the email package back, despite its failings.

1 files changed, 389 insertions, 0 deletions

diff --git a/Lib/email/charset.py b/Lib/email/charset.py
new file mode 100644
index 0000000..1435ee5
--- /dev/null
+++ b/Lib/email/charset.py
@@ -0,0 +1,389 @@
+# Copyright (C) 2001-2007 Python Software Foundation
+# Author: Ben Gertzfield, Barry Warsaw
+# Contact: email-sig@python.org
+
+__all__ = [
+    'Charset',
+    'add_alias',
+    'add_charset',
+    'add_codec',
+    ]
+
+import email.base64mime
+import email.quoprimime
+
+from email import errors
+from email.encoders import encode_7or8bit
+
+
+
+# Flags for types of header encodings
+QP          = 1 # Quoted-Printable
+BASE64      = 2 # Base64
+SHORTEST    = 3 # the shorter of QP and base64, but only for headers
+
+# In "=?charset?q?hello_world?=", the =?, ?q?, and ?= add up to 7
+MISC_LEN = 7
+
+DEFAULT_CHARSET = 'us-ascii'
+
+
+
+# Defaults
+CHARSETS = {
+    # input        header enc  body enc output conv
+    'iso-8859-1':  (QP,        QP,      None),
+    'iso-8859-2':  (QP,        QP,      None),
+    'iso-8859-3':  (QP,        QP,      None),
+    'iso-8859-4':  (QP,        QP,      None),
+    # iso-8859-5 is Cyrillic, and not especially used
+    # iso-8859-6 is Arabic, also not particularly used
+    # iso-8859-7 is Greek, QP will not make it readable
+    # iso-8859-8 is Hebrew, QP will not make it readable
+    'iso-8859-9':  (QP,        QP,      None),
+    'iso-8859-10': (QP,        QP,      None),
+    # iso-8859-11 is Thai, QP will not make it readable
+    'iso-8859-13': (QP,        QP,      None),
+    'iso-8859-14': (QP,        QP,      None),
+    'iso-8859-15': (QP,        QP,      None),
+    'iso-8859-16': (QP,        QP,      None),
+    'windows-1252':(QP,        QP,      None),
+    'viscii':      (QP,        QP,      None),
+    'us-ascii':    (None,      None,    None),
+    'big5':        (BASE64,    BASE64,  None),
+    'gb2312':      (BASE64,    BASE64,  None),
+    'euc-jp':      (BASE64,    None,    'iso-2022-jp'),
+    'shift_jis':   (BASE64,    None,    'iso-2022-jp'),
+    'iso-2022-jp': (BASE64,    None,    None),
+    'koi8-r':      (BASE64,    BASE64,  None),
+    'utf-8':       (SHORTEST,  BASE64, 'utf-8'),
+    }
+
+# Aliases for other commonly-used names for character sets.  Map
+# them to the real ones used in email.
+ALIASES = {
+    'latin_1': 'iso-8859-1',
+    'latin-1': 'iso-8859-1',
+    'latin_2': 'iso-8859-2',
+    'latin-2': 'iso-8859-2',
+    'latin_3': 'iso-8859-3',
+    'latin-3': 'iso-8859-3',
+    'latin_4': 'iso-8859-4',
+    'latin-4': 'iso-8859-4',
+    'latin_5': 'iso-8859-9',
+    'latin-5': 'iso-8859-9',
+    'latin_6': 'iso-8859-10',
+    'latin-6': 'iso-8859-10',
+    'latin_7': 'iso-8859-13',
+    'latin-7': 'iso-8859-13',
+    'latin_8': 'iso-8859-14',
+    'latin-8': 'iso-8859-14',
+    'latin_9': 'iso-8859-15',
+    'latin-9': 'iso-8859-15',
+    'latin_10':'iso-8859-16',
+    'latin-10':'iso-8859-16',
+    'cp949':   'ks_c_5601-1987',
+    'euc_jp':  'euc-jp',
+    'euc_kr':  'euc-kr',
+    'ascii':   'us-ascii',
+    }
+
+
+# Map charsets to their Unicode codec strings.
+CODEC_MAP = {
+    'gb2312':      'eucgb2312_cn',
+    'big5':        'big5_tw',
+    # Hack: We don't want *any* conversion for stuff marked us-ascii, as all
+    # sorts of garbage might be sent to us in the guise of 7-bit us-ascii.
+    # Let that stuff pass through without conversion to/from Unicode.
+    'us-ascii':    None,
+    }
+
+
+
+# Convenience functions for extending the above mappings
+def add_charset(charset, header_enc=None, body_enc=None, output_charset=None):
+    """Add character set properties to the global registry.
+
+    charset is the input character set, and must be the canonical name of a
+    character set.
+
+    Optional header_enc and body_enc is either Charset.QP for
+    quoted-printable, Charset.BASE64 for base64 encoding, Charset.SHORTEST for
+    the shortest of qp or base64 encoding, or None for no encoding.  SHORTEST
+    is only valid for header_enc.  It describes how message headers and
+    message bodies in the input charset are to be encoded.  Default is no
+    encoding.
+
+    Optional output_charset is the character set that the output should be
+    in.  Conversions will proceed from input charset, to Unicode, to the
+    output charset when the method Charset.convert() is called.  The default
+    is to output in the same character set as the input.
+
+    Both input_charset and output_charset must have Unicode codec entries in
+    the module's charset-to-codec mapping; use add_codec(charset, codecname)
+    to add codecs the module does not know about.  See the codecs module's
+    documentation for more information.
+    """
+    if body_enc == SHORTEST:
+        raise ValueError('SHORTEST not allowed for body_enc')
+    CHARSETS[charset] = (header_enc, body_enc, output_charset)
+
+
+def add_alias(alias, canonical):
+    """Add a character set alias.
+
+    alias is the alias name, e.g. latin-1
+    canonical is the character set's canonical name, e.g. iso-8859-1
+    """
+    ALIASES[alias] = canonical
+
+
+def add_codec(charset, codecname):
+    """Add a codec that map characters in the given charset to/from Unicode.
+
+    charset is the canonical name of a character set.  codecname is the name
+    of a Python codec, as appropriate for the second argument to the unicode()
+    built-in, or to the encode() method of a Unicode string.
+    """
+    CODEC_MAP[charset] = codecname
+
+
+
+class Charset:
+    """Map character sets to their email properties.
+
+    This class provides information about the requirements imposed on email
+    for a specific character set.  It also provides convenience routines for
+    converting between character sets, given the availability of the
+    applicable codecs.  Given a character set, it will do its best to provide
+    information on how to use that character set in an email in an
+    RFC-compliant way.
+
+    Certain character sets must be encoded with quoted-printable or base64
+    when used in email headers or bodies.  Certain character sets must be
+    converted outright, and are not allowed in email.  Instances of this
+    module expose the following information about a character set:
+
+    input_charset: The initial character set specified.  Common aliases
+                   are converted to their `official' email names (e.g. latin_1
+                   is converted to iso-8859-1).  Defaults to 7-bit us-ascii.
+
+    header_encoding: If the character set must be encoded before it can be
+                     used in an email header, this attribute will be set to
+                     Charset.QP (for quoted-printable), Charset.BASE64 (for
+                     base64 encoding), or Charset.SHORTEST for the shortest of
+                     QP or BASE64 encoding.  Otherwise, it will be None.
+
+    body_encoding: Same as header_encoding, but describes the encoding for the
+                   mail message's body, which indeed may be different than the
+                   header encoding.  Charset.SHORTEST is not allowed for
+                   body_encoding.
+
+    output_charset: Some character sets must be converted before the can be
+                    used in email headers or bodies.  If the input_charset is
+                    one of them, this attribute will contain the name of the
+                    charset output will be converted to.  Otherwise, it will
+                    be None.
+
+    input_codec: The name of the Python codec used to convert the
+                 input_charset to Unicode.  If no conversion codec is
+                 necessary, this attribute will be None.
+
+    output_codec: The name of the Python codec used to convert Unicode
+                  to the output_charset.  If no conversion codec is necessary,
+                  this attribute will have the same value as the input_codec.
+    """
+    def __init__(self, input_charset=DEFAULT_CHARSET):
+        # RFC 2046, $4.1.2 says charsets are not case sensitive.  We coerce to
+        # unicode because its .lower() is locale insensitive.  If the argument
+        # is already a unicode, we leave it at that, but ensure that the
+        # charset is ASCII, as the standard (RFC XXX) requires.
+        try:
+            if isinstance(input_charset, str):
+                input_charset.encode('ascii')
+            else:
+                input_charset = str(input_charset, 'ascii')
+        except UnicodeError:
+            raise errors.CharsetError(input_charset)
+        input_charset = input_charset.lower()
+        # Set the input charset after filtering through the aliases
+        self.input_charset = ALIASES.get(input_charset, input_charset)
+        # We can try to guess which encoding and conversion to use by the
+        # charset_map dictionary.  Try that first, but let the user override
+        # it.
+        henc, benc, conv = CHARSETS.get(self.input_charset,
+                                        (SHORTEST, BASE64, None))
+        if not conv:
+            conv = self.input_charset
+        # Set the attributes, allowing the arguments to override the default.
+        self.header_encoding = henc
+        self.body_encoding = benc
+        self.output_charset = ALIASES.get(conv, conv)
+        # Now set the codecs.  If one isn't defined for input_charset,
+        # guess and try a Unicode codec with the same name as input_codec.
+        self.input_codec = CODEC_MAP.get(self.input_charset,
+                                         self.input_charset)
+        self.output_codec = CODEC_MAP.get(self.output_charset,
+                                          self.output_charset)
+
+    def __str__(self):
+        return self.input_charset.lower()
+
+    __repr__ = __str__
+
+    def __eq__(self, other):
+        return str(self) == str(other).lower()
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def get_body_encoding(self):
+        """Return the content-transfer-encoding used for body encoding.
+
+        This is either the string `quoted-printable' or `base64' depending on
+        the encoding used, or it is a function in which case you should call
+        the function with a single argument, the Message object being
+        encoded.  The function should then set the Content-Transfer-Encoding
+        header itself to whatever is appropriate.
+
+        Returns "quoted-printable" if self.body_encoding is QP.
+        Returns "base64" if self.body_encoding is BASE64.
+        Returns "7bit" otherwise.
+        """
+        assert self.body_encoding != SHORTEST
+        if self.body_encoding == QP:
+            return 'quoted-printable'
+        elif self.body_encoding == BASE64:
+            return 'base64'
+        else:
+            return encode_7or8bit
+
+    def convert(self, s):
+        """Convert a string from the input_codec to the output_codec."""
+        if self.input_codec != self.output_codec:
+            rawbytes = bytes(ord(c) for c in s)
+            decoded = rawbytes.decode(self.input_codec)
+            encoded = decoded.encode(self.output_codec)
+            return str(encoded)
+        else:
+            return s
+
+    def to_splittable(self, s):
+        """Convert a possibly multibyte string to a safely splittable format.
+
+        Uses the input_codec to try and convert the string to Unicode, so it
+        can be safely split on character boundaries (even for multibyte
+        characters).
+
+        Returns the string as-is if it isn't known how to convert it to
+        Unicode with the input_charset.
+
+        Characters that could not be converted to Unicode will be replaced
+        with the Unicode replacement character U+FFFD.
+        """
+        if isinstance(s, str) or self.input_codec is None:
+            return s
+        try:
+            return str(s, self.input_codec, 'replace')
+        except LookupError:
+            # Input codec not installed on system, so return the original
+            # string unchanged.
+            return s
+
+    def from_splittable(self, ustr, to_output=True):
+        """Convert a splittable string back into an encoded string.
+
+        Uses the proper codec to try and convert the string from Unicode back
+        into an encoded format.  Return the string as-is if it is not Unicode,
+        or if it could not be converted from Unicode.
+
+        Characters that could not be converted from Unicode will be replaced
+        with an appropriate character (usually '?').
+
+        If to_output is True (the default), uses output_codec to convert to an
+        encoded format.  If to_output is False, uses input_codec.
+        """
+        if to_output:
+            codec = self.output_codec
+        else:
+            codec = self.input_codec
+        if not isinstance(ustr, str) or codec is None:
+            return ustr
+        try:
+            return str(ustr.encode(codec, 'replace'))
+        except LookupError:
+            # Output codec not installed
+            return ustr
+
+    def get_output_charset(self):
+        """Return the output character set.
+
+        This is self.output_charset if that is not None, otherwise it is
+        self.input_charset.
+        """
+        return self.output_charset or self.input_charset
+
+    def encoded_header_len(self, s):
+        """Return the length of the encoded header string."""
+        cset = self.get_output_charset()
+        # The len(s) of a 7bit encoding is len(s)
+        if self.header_encoding == BASE64:
+            return email.base64mime.base64_len(s) + len(cset) + MISC_LEN
+        elif self.header_encoding == QP:
+            return email.quoprimime.header_quopri_len(s) + len(cset) + MISC_LEN
+        elif self.header_encoding == SHORTEST:
+            lenb64 = email.base64mime.base64_len(s)
+            lenqp = email.quoprimime.header_quopri_len(s)
+            return min(lenb64, lenqp) + len(cset) + MISC_LEN
+        else:
+            return len(s)
+
+    def header_encode(self, string):
+        """Header-encode a string by converting it first to bytes.
+
+        :param string: A unicode string for the header.  This must be
+        encodable to bytes using the current character set's `output_codec`.
+
+        The type of encoding (base64 or quoted-printable) will be based on
+        this charset's `header_encoding`.
+        """
+        codec = self.output_codec or 'us-ascii'
+        charset = self.get_output_charset()
+        header_bytes = string.encode(codec)
+        # 7bit/8bit encodings return the string unchanged (modulo conversions)
+        if self.header_encoding == BASE64:
+            encoder = email.base64mime.header_encode
+        elif self.header_encoding == QP:
+            encoder = email.quoprimime.header_encode
+        elif self.header_encoding == SHORTEST:
+            lenb64 = email.base64mime.base64_len(header_bytes)
+            lenqp = email.quoprimime.header_quopri_len(header_bytes)
+            if lenb64 < lenqp:
+                encoder = email.base64mime.header_encode
+            else:
+                encoder = email.quoprimime.header_encode
+        else:
+            return string
+        return encoder(header_bytes, codec)
+
+    def body_encode(self, s, convert=True):
+        """Body-encode a string and convert it to output_charset.
+
+        If convert is True (the default), the string will be converted from
+        the input charset to output charset automatically.  Unlike
+        header_encode(), there are no issues with byte boundaries and
+        multibyte charsets in email bodies, so this is usually pretty safe.
+
+        The type of encoding (base64 or quoted-printable) will be based on
+        self.body_encoding.
+        """
+        if convert:
+            s = self.convert(s)
+        # 7bit/8bit encodings return the string unchanged (module conversions)
+        if self.body_encoding is BASE64:
+            return email.base64mime.body_encode(s)
+        elif self.body_encoding is QP:
+            return email.quoprimime.body_encode(s)
+        else:
+            return s