| 173 | |
| 174 | |
| 175 | class Header: |
| 176 | def __init__(self, s=None, charset=None, |
| 177 | maxlinelen=None, header_name=None, |
| 178 | continuation_ws=' ', errors='strict'): |
| 179 | """Create a MIME-compliant header that can contain many character sets. |
| 180 | |
| 181 | Optional s is the initial header value. If None, the initial header |
| 182 | value is not set. You can later append to the header with .append() |
| 183 | method calls. s may be a byte string or a Unicode string, but see the |
| 184 | .append() documentation for semantics. |
| 185 | |
| 186 | Optional charset serves two purposes: it has the same meaning as the |
| 187 | charset argument to the .append() method. It also sets the default |
| 188 | character set for all subsequent .append() calls that omit the charset |
| 189 | argument. If charset is not provided in the constructor, the us-ascii |
| 190 | charset is used both as s's initial charset and as the default for |
| 191 | subsequent .append() calls. |
| 192 | |
| 193 | The maximum line length can be specified explicitly via maxlinelen. For |
| 194 | splitting the first line to a shorter value (to account for the field |
| 195 | header which isn't included in s, e.g. `Subject') pass in the name of |
| 196 | the field in header_name. The default maxlinelen is 78 as recommended |
| 197 | by RFC 2822. |
| 198 | |
| 199 | continuation_ws must be RFC 2822 compliant folding whitespace (usually |
| 200 | either a space or a hard tab) which will be prepended to continuation |
| 201 | lines. |
| 202 | |
| 203 | errors is passed through to the .append() call. |
| 204 | """ |
| 205 | if charset is None: |
| 206 | charset = USASCII |
| 207 | elif not isinstance(charset, Charset): |
| 208 | charset = Charset(charset) |
| 209 | self._charset = charset |
| 210 | self._continuation_ws = continuation_ws |
| 211 | self._chunks = [] |
| 212 | if s is not None: |
| 213 | self.append(s, charset, errors) |
| 214 | if maxlinelen is None: |
| 215 | maxlinelen = MAXLINELEN |
| 216 | self._maxlinelen = maxlinelen |
| 217 | if header_name is None: |
| 218 | self._headerlen = 0 |
| 219 | else: |
| 220 | # Take the separating colon and space into account. |
| 221 | self._headerlen = len(header_name) + 2 |
| 222 | |
| 223 | def __str__(self): |
| 224 | """Return the string value of the header.""" |
| 225 | self._normalize() |
| 226 | uchunks = [] |
| 227 | lastcs = None |
| 228 | lastspace = None |
| 229 | for string, charset in self._chunks: |
| 230 | # We must preserve spaces between encoded and non-encoded word |
| 231 | # boundaries, which means for us we need to add a space when we go |
| 232 | # from a charset to None/us-ascii, or from None/us-ascii to a |