path: root/dammit.py

"""Beautiful Soup bonus library: Unicode, Dammit

This class forces XML data into a standard format (usually to UTF-8 or
Unicode).  It is heavily based on code from Mark Pilgrim's Universal
Feed Parser. It does not rewrite the XML or HTML to reflect a new
encoding; that's Beautiful Soup's job.
"""

import codecs
import re
import types

# Autodetects character encodings.
# Download from http://chardet.feedparser.org/
try:
    import chardet
#    import chardet.constants
#    chardet.constants._debug = 1
except ImportError:
    chardet = None

# cjkcodecs and iconv_codec make Python know about more character encodings.
# Both are available from http://cjkpython.i18n.org/
# They're built in if you use Python 2.4.
try:
    import cjkcodecs.aliases
except ImportError:
    pass
try:
    import iconv_codec
except ImportError:
    pass


class UnicodeDammit:
    """A class for detecting the encoding of a *ML document and
    converting it to a Unicode string. If the source encoding is
    windows-1252, can replace MS smart quotes with their HTML or XML
    equivalents."""

    # This dictionary maps commonly seen values for "charset" in HTML
    # meta tags to the corresponding Python codec names. It only covers
    # values that aren't in Python's aliases and can't be determined
    # by the heuristics in find_codec.
    CHARSET_ALIASES = { "macintosh" : "mac-roman",
                        "x-sjis" : "shift-jis" }

    def __init__(self, markup, overrideEncodings=[],
                 smartQuotesTo='xml', isHTML=False):
        self.declaredHTMLEncoding = None
        self.markup, documentEncoding, sniffedEncoding = \
                     self._detectEncoding(markup, isHTML)
        self.smartQuotesTo = smartQuotesTo
        self.triedEncodings = []
        if markup == '' or isinstance(markup, unicode):
            self.originalEncoding = None
            self.unicode = unicode(markup)
            return

        u = None
        for proposedEncoding in overrideEncodings:
            u = self._convertFrom(proposedEncoding)
            if u: break
        if not u:
            for proposedEncoding in (documentEncoding, sniffedEncoding):
                u = self._convertFrom(proposedEncoding)
                if u: break

        # If no luck and we have auto-detection library, try that:
        if not u and chardet and not isinstance(self.markup, unicode):
            u = self._convertFrom(chardet.detect(self.markup)['encoding'])

        # As a last resort, try utf-8 and windows-1252:
        if not u:
            for proposed_encoding in ("utf-8", "windows-1252"):
                u = self._convertFrom(proposed_encoding)
                if u: break

        self.unicode = u
        if not u: self.originalEncoding = None

    def _subMSChar(self, match):
        """Changes a MS smart quote character to an XML or HTML
        entity."""
        orig = match.group(1)
        sub = self.MS_CHARS.get(orig)
        if type(sub) == types.TupleType:
            if self.smartQuotesTo == 'xml':
                sub = '&#x'.encode() + sub[1].encode() + ';'.encode()
            else:
                sub = '&'.encode() + sub[0].encode() + ';'.encode()
        else:
            sub = sub.encode()
        return sub

    def _convertFrom(self, proposed):
        proposed = self.find_codec(proposed)
        if not proposed or proposed in self.triedEncodings:
            return None
        self.triedEncodings.append(proposed)
        markup = self.markup

        # Convert smart quotes to HTML if coming from an encoding
        # that might have them.
        if self.smartQuotesTo and proposed.lower() in("windows-1252",
                                                      "iso-8859-1",
                                                      "iso-8859-2"):
            smart_quotes_re = "([\x80-\x9f])"
            smart_quotes_compiled = re.compile(smart_quotes_re)
            markup = smart_quotes_compiled.sub(self._subMSChar, markup)

        try:
            # print "Trying to convert document to %s" % proposed
            u = self._toUnicode(markup, proposed)
            self.markup = u
            self.originalEncoding = proposed
        except Exception, e:
            # print "That didn't work!"
            # print e
            return None
        #print "Correct encoding: %s" % proposed
        return self.markup

    def _toUnicode(self, data, encoding):
        '''Given a string and its encoding, decodes the string into Unicode.
        %encoding is a string recognized by encodings.aliases'''

        # strip Byte Order Mark (if present)
        if (len(data) >= 4) and (data[:2] == '\xfe\xff') \
               and (data[2:4] != '\x00\x00'):
            encoding = 'utf-16be'
            data = data[2:]
        elif (len(data) >= 4) and (data[:2] == '\xff\xfe') \
                 and (data[2:4] != '\x00\x00'):
            encoding = 'utf-16le'
            data = data[2:]
        elif data[:3] == '\xef\xbb\xbf':
            encoding = 'utf-8'
            data = data[3:]
        elif data[:4] == '\x00\x00\xfe\xff':
            encoding = 'utf-32be'
            data = data[4:]
        elif data[:4] == '\xff\xfe\x00\x00':
            encoding = 'utf-32le'
            data = data[4:]
        newdata = unicode(data, encoding)
        return newdata

    def _detectEncoding(self, xml_data, isHTML=False):
        """Given a document, tries to detect its XML encoding."""
        xml_encoding = sniffed_xml_encoding = None
        try:
            if xml_data[:4] == '\x4c\x6f\xa7\x94':
                # EBCDIC
                xml_data = self._ebcdic_to_ascii(xml_data)
            elif xml_data[:4] == '\x00\x3c\x00\x3f':
                # UTF-16BE
                sniffed_xml_encoding = 'utf-16be'
                xml_data = unicode(xml_data, 'utf-16be').encode('utf-8')
            elif (len(xml_data) >= 4) and (xml_data[:2] == '\xfe\xff') \
                     and (xml_data[2:4] != '\x00\x00'):
                # UTF-16BE with BOM
                sniffed_xml_encoding = 'utf-16be'
                xml_data = unicode(xml_data[2:], 'utf-16be').encode('utf-8')
            elif xml_data[:4] == '\x3c\x00\x3f\x00':
                # UTF-16LE
                sniffed_xml_encoding = 'utf-16le'
                xml_data = unicode(xml_data, 'utf-16le').encode('utf-8')
            elif (len(xml_data) >= 4) and (xml_data[:2] == '\xff\xfe') and \
                     (xml_data[2:4] != '\x00\x00'):
                # UTF-16LE with BOM
                sniffed_xml_encoding = 'utf-16le'
                xml_data = unicode(xml_data[2:], 'utf-16le').encode('utf-8')
            elif xml_data[:4] == '\x00\x00\x00\x3c':
                # UTF-32BE
                sniffed_xml_encoding = 'utf-32be'
                xml_data = unicode(xml_data, 'utf-32be').encode('utf-8')
            elif xml_data[:4] == '\x3c\x00\x00\x00':
                # UTF-32LE
                sniffed_xml_encoding = 'utf-32le'
                xml_data = unicode(xml_data, 'utf-32le').encode('utf-8')
            elif xml_data[:4] == '\x00\x00\xfe\xff':
                # UTF-32BE with BOM
                sniffed_xml_encoding = 'utf-32be'
                xml_data = unicode(xml_data[4:], 'utf-32be').encode('utf-8')
            elif xml_data[:4] == '\xff\xfe\x00\x00':
                # UTF-32LE with BOM
                sniffed_xml_encoding = 'utf-32le'
                xml_data = unicode(xml_data[4:], 'utf-32le').encode('utf-8')
            elif xml_data[:3] == '\xef\xbb\xbf':
                # UTF-8 with BOM
                sniffed_xml_encoding = 'utf-8'
                xml_data = unicode(xml_data[3:], 'utf-8').encode('utf-8')
            else:
                sniffed_xml_encoding = 'ascii'
                pass
        except:
            xml_encoding_match = None
        xml_encoding_re = '^<\?.*encoding=[\'"](.*?)[\'"].*\?>'.encode()
        xml_encoding_match = re.compile(xml_encoding_re).match(xml_data)
        if not xml_encoding_match and isHTML:
            meta_re = '<\s*meta[^>]+charset=([^>]*?)[;\'">]'.encode()
            regexp = re.compile(meta_re, re.I)
            xml_encoding_match = regexp.search(xml_data)
        if xml_encoding_match is not None:
            xml_encoding = xml_encoding_match.groups()[0].decode(
                'ascii').lower()
            if isHTML:
                self.declaredHTMLEncoding = xml_encoding
            if sniffed_xml_encoding and \
               (xml_encoding in ('iso-10646-ucs-2', 'ucs-2', 'csunicode',
                                 'iso-10646-ucs-4', 'ucs-4', 'csucs4',
                                 'utf-16', 'utf-32', 'utf_16', 'utf_32',
                                 'utf16', 'u16')):
                xml_encoding = sniffed_xml_encoding
        return xml_data, xml_encoding, sniffed_xml_encoding


    def find_codec(self, charset):
        return self._codec(self.CHARSET_ALIASES.get(charset, charset)) \
               or (charset and self._codec(charset.replace("-", ""))) \
               or (charset and self._codec(charset.replace("-", "_"))) \
               or charset

    def _codec(self, charset):
        if not charset: return charset
        codec = None
        try:
            codecs.lookup(charset)
            codec = charset
        except (LookupError, ValueError):
            pass
        return codec

    EBCDIC_TO_ASCII_MAP = None
    def _ebcdic_to_ascii(self, s):
        c = self.__class__
        if not c.EBCDIC_TO_ASCII_MAP:
            emap = (0,1,2,3,156,9,134,127,151,141,142,11,12,13,14,15,
                    16,17,18,19,157,133,8,135,24,25,146,143,28,29,30,31,
                    128,129,130,131,132,10,23,27,136,137,138,139,140,5,6,7,
                    144,145,22,147,148,149,150,4,152,153,154,155,20,21,158,26,
                    32,160,161,162,163,164,165,166,167,168,91,46,60,40,43,33,
                    38,169,170,171,172,173,174,175,176,177,93,36,42,41,59,94,
                    45,47,178,179,180,181,182,183,184,185,124,44,37,95,62,63,
                    186,187,188,189,190,191,192,193,194,96,58,35,64,39,61,34,
                    195,97,98,99,100,101,102,103,104,105,196,197,198,199,200,
                    201,202,106,107,108,109,110,111,112,113,114,203,204,205,
                    206,207,208,209,126,115,116,117,118,119,120,121,122,210,
                    211,212,213,214,215,216,217,218,219,220,221,222,223,224,
                    225,226,227,228,229,230,231,123,65,66,67,68,69,70,71,72,
                    73,232,233,234,235,236,237,125,74,75,76,77,78,79,80,81,
                    82,238,239,240,241,242,243,92,159,83,84,85,86,87,88,89,
                    90,244,245,246,247,248,249,48,49,50,51,52,53,54,55,56,57,
                    250,251,252,253,254,255)
            import string
            c.EBCDIC_TO_ASCII_MAP = string.maketrans( \
            ''.join(map(chr, range(256))), ''.join(map(chr, emap)))
        return s.translate(c.EBCDIC_TO_ASCII_MAP)

    MS_CHARS = { '\x80' : ('euro', '20AC'),
                 '\x81' : ' ',
                 '\x82' : ('sbquo', '201A'),
                 '\x83' : ('fnof', '192'),
                 '\x84' : ('bdquo', '201E'),
                 '\x85' : ('hellip', '2026'),
                 '\x86' : ('dagger', '2020'),
                 '\x87' : ('Dagger', '2021'),
                 '\x88' : ('circ', '2C6'),
                 '\x89' : ('permil', '2030'),
                 '\x8A' : ('Scaron', '160'),
                 '\x8B' : ('lsaquo', '2039'),
                 '\x8C' : ('OElig', '152'),
                 '\x8D' : '?',
                 '\x8E' : ('#x17D', '17D'),
                 '\x8F' : '?',
                 '\x90' : '?',
                 '\x91' : ('lsquo', '2018'),
                 '\x92' : ('rsquo', '2019'),
                 '\x93' : ('ldquo', '201C'),
                 '\x94' : ('rdquo', '201D'),
                 '\x95' : ('bull', '2022'),
                 '\x96' : ('ndash', '2013'),
                 '\x97' : ('mdash', '2014'),
                 '\x98' : ('tilde', '2DC'),
                 '\x99' : ('trade', '2122'),
                 '\x9a' : ('scaron', '161'),
                 '\x9b' : ('rsaquo', '203A'),
                 '\x9c' : ('oelig', '153'),
                 '\x9d' : '?',
                 '\x9e' : ('#x17E', '17E'),
                 '\x9f' : ('Yuml', ''),}