python-ox/ox/html.py

# -*- coding: utf-8 -*-
# vi:si:et:sw=4:sts=4:ts=4
# GPL 2008
import re
import string
from htmlentitydefs import name2codepoint


# Configuration for add_links() function
LEADING_PUNCTUATION  = ['(', '<', '&lt;']
TRAILING_PUNCTUATION = ['.', ',', ')', '>', '\n', '&gt;', "'", '"']

# list of possible strings used for bullets in bulleted lists
DOTS = ['&middot;', '*', '\xe2\x80\xa2', '&#149;', '&bull;', '&#8226;']

unencoded_ampersands_re = re.compile(r'&(?!(\w+|#\d+);)')
word_split_re = re.compile(r'(\s+)')
punctuation_re = re.compile('^(?P<lead>(?:%s)*)(?P<middle>.*?)(?P<trail>(?:%s)*)$' % \
    ('|'.join([re.escape(x) for x in LEADING_PUNCTUATION]),
    '|'.join([re.escape(x) for x in TRAILING_PUNCTUATION])))
simple_email_re = re.compile(r'^\S+@[a-zA-Z0-9._-]+\.[a-zA-Z0-9._-]+$')
link_target_attribute_re = re.compile(r'(<a [^>]*?)target=[^\s>]+')
html_gunk_re = re.compile(r'(?:<br clear="all">|<i><\/i>|<b><\/b>|<em><\/em>|<strong><\/strong>|<\/?smallcaps>|<\/?uppercase>)', re.IGNORECASE)
hard_coded_bullets_re = re.compile(r'((?:<p>(?:%s).*?[a-zA-Z].*?</p>\s*)+)' % '|'.join([re.escape(x) for x in DOTS]), re.DOTALL)
trailing_empty_content_re = re.compile(r'(?:<p>(?:&nbsp;|\s|<br \/>)*?</p>\s*)+\Z')
del x # Temporary variable

def escape(html):
    '''
    Returns the given HTML with ampersands, quotes and carets encoded

    >>> escape('html "test" & <brothers>')
    'html &quot;test&quot; &amp; &lt;brothers&gt;'
    '''
    if not isinstance(html, basestring):
        html = str(html)
    return html.replace('&', '&amp;').replace('<', '&lt;').replace('>', '&gt;').replace('"', '&quot;').replace("'", '&apos;')

def linebreaks(value):
    '''
    Converts newlines into <p> and <br />
    '''
    value = re.sub(r'\r\n|\r|\n', '\n', value) # normalize newlines
    paras = re.split('\n{2,}', value)
    paras = ['<p>%s</p>' % p.strip().replace('\n', '<br />') for p in paras]
    return '\n\n'.join(paras)

def strip_tags(value):
    """
    Returns the given HTML with all tags stripped
    
    >>> strip_tags('some <h2>title</h2> <script>asdfasdf</script>')
    'some title asdfasdf'
    """
    return re.sub(r'<[^>]*?>', '', value)

stripTags = strip_tags

def strip_spaces_between_tags(value):
    "Returns the given HTML with spaces between tags normalized to a single space"
    return re.sub(r'>\s+<', '> <', value)

def strip_entities(value):
    "Returns the given HTML with all entities (&something;) stripped"
    return re.sub(r'&(?:\w+|#\d);', '', value)

def fix_ampersands(value):
    "Returns the given HTML with all unencoded ampersands encoded correctly"
    return unencoded_ampersands_re.sub('&amp;', value)

def add_links(text, trim_url_limit=None, nofollow=False):
    """
    Converts any URLs in text into clickable links. Works on http://, https:// and
    www. links. Links can have trailing punctuation (periods, commas, close-parens)
    and leading punctuation (opening parens) and it'll still do the right thing.

    If trim_url_limit is not None, the URLs in link text will be limited to
    trim_url_limit characters.

    If nofollow is True, the URLs in link text will get a rel="nofollow" attribute.
    """
    trim_url = lambda x, limit=trim_url_limit: limit is not None and (x[:limit] + (len(x) >=limit and '...' or ''))  or x
    words = word_split_re.split(text)
    nofollow_attr = nofollow and ' rel="nofollow"' or ''
    for i, word in enumerate(words):
        match = punctuation_re.match(word)
        if match:
            lead, middle, trail = match.groups()
            if middle.startswith('www.') or ('@' not in middle and not middle.startswith('http://') and \
                    len(middle) > 0 and middle[0] in string.letters + string.digits and \
                    (middle.endswith('.org') or middle.endswith('.net') or middle.endswith('.com'))):
                middle = '<a href="http://%s"%s>%s</a>' % (middle, nofollow_attr, trim_url(middle))
            if middle.startswith('http://') or middle.startswith('https://'):
                middle = '<a href="%s"%s>%s</a>' % (middle, nofollow_attr, trim_url(middle))
            if '@' in middle and not middle.startswith('www.') and not ':' in middle \
              and simple_email_re.match(middle):
                middle = '<a href="mailto:%s">%s</a>' % (middle, middle)
            if lead + middle + trail != word:
                words[i] = lead + middle + trail
    return ''.join(words)

urlize = add_links

def clean_html(text):
    """
    Cleans the given HTML. Specifically, it does the following:
        * Converts <b> and <i> to <strong> and <em>.
        * Encodes all ampersands correctly.
        * Removes all "target" attributes from <a> tags.
        * Removes extraneous HTML, such as presentational tags that open and
          immediately close and <br clear="all">.
        * Converts hard-coded bullets into HTML unordered lists.
        * Removes stuff like "<p>&nbsp;&nbsp;</p>", but only if it's at the
          bottom of the text.
    """
    from text import normalize_newlines
    text = normalize_newlines(text)
    text = re.sub(r'<(/?)\s*b\s*>', '<\\1strong>', text)
    text = re.sub(r'<(/?)\s*i\s*>', '<\\1em>', text)
    text = fix_ampersands(text)
    # Remove all target="" attributes from <a> tags.
    text = link_target_attribute_re.sub('\\1', text)
    # Trim stupid HTML such as <br clear="all">.
    text = html_gunk_re.sub('', text)
    # Convert hard-coded bullets into HTML unordered lists.
    def replace_p_tags(match):
        s = match.group().replace('</p>', '</li>')
        for d in DOTS:
            s = s.replace('<p>%s' % d, '<li>')
        return '<ul>\n%s\n</ul>' % s
    text = hard_coded_bullets_re.sub(replace_p_tags, text)
    # Remove stuff like "<p>&nbsp;&nbsp;</p>", but only if it's at the bottom of the text.
    text = trailing_empty_content_re.sub('', text)
    return text

# This pattern matches a character entity reference (a decimal numeric
# references, a hexadecimal numeric reference, or a named reference).
charrefpat = re.compile(r'&(#(\d+|x[\da-fA-F]+)|[\w.:-]+);?')

def decode_html(html):
    """
    >>> decode_html('me &amp; you and &#36;&#38;%')
    u'me & you and $&%'
    >>> decode_html('&#x80;')
    u'\u20ac'
    >>> decode_html('Anniversary of Daoud&apos;s Republic')
    u"Anniversary of Daoud's Republic"
    """
    if type(html) != unicode:
        html = unicode(html)[:]
    if type(html) is unicode:
        uchr = unichr
    else:
        uchr = lambda value: value > 255 and unichr(value) or chr(value)
    def entitydecode(match, uchr=uchr):
        entity = match.group(1)
        if entity == '#x80':
            return u'€'
        elif entity.startswith('#x'):
            return uchr(int(entity[2:], 16))
        elif entity.startswith('#'):
            return uchr(int(entity[1:]))
        elif entity in name2codepoint:
            return uchr(name2codepoint[entity])
        elif entity == 'apos':
            return "'"
        else:
            return match.group(0)
    return charrefpat.sub(entitydecode, html).replace(u'\xa0', ' ')

def highlight(text, query, hlClass="hl"):
    """
    >>> highlight('me &amp; you and &#36;&#38;%', 'and')
    'me &amp; you <span class="hl">and</span> &#36;&#38;%'
    """
    if query:
        text = text.replace('<br />', '|')
        query = re.escape(query).replace('\ ', '.')
        m = re.compile("(%s)" % query, re.IGNORECASE).findall(text)
        for i in m:
            text = re.sub("(%s)" % re.escape(i).replace('\ ', '.'), '<span class="%s">\\1</span>' % hlClass, text)
        text = text.replace('|', '<br />')
    return text

def escape_html(value):
    '''
    >>> escape_html(u'<script> foo')
    u'&lt;script&gt; foo'
    >>> escape_html(u'&lt;script&gt; foo')
    u'&lt;script&gt; foo'
    '''
    return escape(decode_html(value))

def sanitize_html(html, tags=None, wikilinks=False):
    '''
    >>> sanitize_html('http://foo.com, bar')
    u'<a href="http://foo.com">http://foo.com</a>, bar'
    >>> sanitize_html('http://foo.com/foobar?foo, bar')
    u'<a href="http://foo.com/foobar?foo">http://foo.com/foobar?foo</a>, bar'
    >>> sanitize_html('(see: www.foo.com)')
    u'(see: <a href="http://www.foo.com">www.foo.com</a>)'
    >>> sanitize_html('foo@bar.com')
    u'<a href="mailto:foo@bar.com">foo@bar.com</a>'
    >>> sanitize_html(sanitize_html('foo@bar.com'))
    u'<a href="mailto:foo@bar.com">foo@bar.com</a>'
    >>> sanitize_html('<a href="http://foo.com" onmouseover="alert()">foo</a>')
    u'<a href="http://foo.com">foo</a>'
    >>> sanitize_html('<a href="javascript:alert()">foo</a>')
    u'&lt;a href="javascript:alert()"&gt;foo'
    >>> sanitize_html('[http://foo.com foo]')
    u'<a href="http://foo.com">foo</a>'
    >>> sanitize_html('<rtl>foo</rtl>')
    u'<div style="direction: rtl">foo</div>'
    >>> sanitize_html('<script>alert()</script>')
    u'&lt;script&gt;alert()&lt;/script&gt;'
    >>> sanitize_html("'foo' < 'bar' && \"foo\" > \"bar\"")
    u'\'foo\' &lt; \'bar\' &amp;&amp; "foo" &gt; "bar"'
    >>> sanitize_html('<b>foo')
    u'<b>foo</b>'
    >>> sanitize_html('<b>foo</b></b>')
    u'<b>foo</b>'
    >>> sanitize_html('Anniversary of Daoud&apos;s Republic')
    u"Anniversary of Daoud's Republic"
    '''
    if not tags:
        tags = [
            # inline formatting
            'b', 'bdi', 'code', 'em', 'i', 'q', 's', 'span', 'strong', 'sub', 'sup', 'u',
            # block formatting
            'blockquote', 'cite', 'div', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'p', 'pre',
            # lists
            'li', 'ol', 'ul',
            # tables
            'table', 'tbody', 'td', 'tfoot', 'th', 'thead', 'tr',
            # other
            'a', 'br', 'img', 'figure', 'figcaption',
            # iframe
            'iframe',
            # special
            'rtl', '[]'
        ]
    parse = {
        'a': [
            [
                '<a [^<>]*?href="((https?:\/\/|\/|mailto:).+?)".*?>',
                '<a href="{1}">'
            ],
            ['<\/a>', '</a>']
        ],
        'img': [
            [
                '<img [^<>]*?src="((https?:\/\/|\/)[^"]+?)".*?>',
                '<img src="{1}">'
            ]
        ],
        'iframe': [
            [
                '<iframe [^<>]*?width="(\d+)" height="(\d+)"[^<>]*?src="((\/|https?:\/\/)[^"]+?)".*?>',
                '<iframe width="{1}" height="{2}" src="{3}">'
            ],
            [
                '<iframe [^<>]*?src="((\/|https?:\/\/)[^"]+?)".*?>',
                '<iframe src="{1}">'
            ],
            [
                '<\/iframe>',
                '</iframe>'
            ]
        ],
        'rtl': [
            [
                '<rtl>',
                '<div style="direction: rtl">'
            ],
            ['<\/rtl>', '</div>']
        ],
        '*': lambda tag: [['<(/?' + tag + ') ?/?>', '<{1}>']]
    }
    matches = []

    #makes parse_html output the same value if run twice
    html = decode_html(html)

    if '[]' in tags:
        html = re.sub(
                re.compile('\[((https?:\/\/|\/).+?) (.+?)\]', re.IGNORECASE),
                '<a href="\\1">\\3</a>', html);
        tags = filter(lambda tag: tag != '[]', tags)

    def replace_match(match, value, regexp):
        i = 1
        for m in match.groups():
            value = value.replace('{%d}'%i, m)
            i += 1
        matches.append(value)
        return '\t%d\t' % len(matches)

    for tag in tags:
        p = parse.get(tag, parse['*'](tag))
        for regexp, value in p:
            html = re.sub(
                re.compile(regexp, re.IGNORECASE),
                lambda match: replace_match(match, value[:], regexp),
                html
            )
    html = escape(html)
    for i in range(0, len(matches)):
        html = html.replace('\t%d\t'%(i+1), matches[i])
    html = html.replace('\n\n', '<br/><br/>')
    html = add_links(html)
    return sanitize_fragment(html)

def sanitize_fragment(html):
    '''
    #html5lib reorders arguments, so not usable
    import html5lib
    return html5lib.parseFragment(html).toxml().decode('utf-8')
    '''
    import lxml.html
    body = lxml.html.document_fromstring(html).find('body')
    html = lxml.html.tostring(body, encoding='utf-8')[6:-7].decode('utf-8')
    if html.startswith('<p>') and html.endswith('</p>'):
        html = html[3:-4]
    return html