cpython/Lib/htmllib.py

"""HTML 2.0 parser.

See the HTML 2.0 specification:
http://www.w3.org/hypertext/WWW/MarkUp/html-spec/html-spec_toc.html
"""

import sgmllib

from formatter import AS_IS

__all__ = ["HTMLParser", "HTMLParseError"]


class HTMLParseError(sgmllib.SGMLParseError):
    """Error raised when an HTML document can't be parsed."""


class HTMLParser(sgmllib.SGMLParser):
    """This is the basic HTML parser class.

    It supports all entity names required by the XHTML 1.0 Recommendation.
    It also defines handlers for all HTML 2.0 and many HTML 3.0 and 3.2
    elements.

    """

    from html.entities import entitydefs

    def __init__(self, formatter, verbose=0):
        """Creates an instance of the HTMLParser class.

        The formatter parameter is the formatter instance associated with
        the parser.

        """
        sgmllib.SGMLParser.__init__(self, verbose)
        self.formatter = formatter

    def error(self, message):
        raise HTMLParseError(message)

    def reset(self):
        sgmllib.SGMLParser.reset(self)
        self.savedata = None
        self.isindex = 0
        self.title = None
        self.base = None
        self.anchor = None
        self.anchorlist = []
        self.nofill = 0
        self.list_stack = []

    # ------ Methods used internally; some may be overridden

    # --- Formatter interface, taking care of 'savedata' mode;
    # shouldn't need to be overridden

    def handle_data(self, data):
        if self.savedata is not None:
            self.savedata = self.savedata + data
        else:
            if self.nofill:
                self.formatter.add_literal_data(data)
            else:
                self.formatter.add_flowing_data(data)

    # --- Hooks to save data; shouldn't need to be overridden

    def save_bgn(self):
        """Begins saving character data in a buffer instead of sending it
        to the formatter object.

        Retrieve the stored data via the save_end() method.  Use of the
        save_bgn() / save_end() pair may not be nested.

        """
        self.savedata = ''

    def save_end(self):
        """Ends buffering character data and returns all data saved since
        the preceding call to the save_bgn() method.

        If the nofill flag is false, whitespace is collapsed to single
        spaces.  A call to this method without a preceding call to the
        save_bgn() method will raise a TypeError exception.

        """
        data = self.savedata
        self.savedata = None
        if not self.nofill:
            data = ' '.join(data.split())
        return data

    # --- Hooks for anchors; should probably be overridden

    def anchor_bgn(self, href, name, type):
        """This method is called at the start of an anchor region.

        The arguments correspond to the attributes of the <A> tag with
        the same names.  The default implementation maintains a list of
        hyperlinks (defined by the HREF attribute for <A> tags) within
        the document.  The list of hyperlinks is available as the data
        attribute anchorlist.

        """
        self.anchor = href
        if self.anchor:
            self.anchorlist.append(href)

    def anchor_end(self):
        """This method is called at the end of an anchor region.

        The default implementation adds a textual footnote marker using an
        index into the list of hyperlinks created by the anchor_bgn()method.

        """
        if self.anchor:
            self.handle_data("[%d]" % len(self.anchorlist))
            self.anchor = None

    # --- Hook for images; should probably be overridden

    def handle_image(self, src, alt, *args):
        """This method is called to handle images.

        The default implementation simply passes the alt value to the
        handle_data() method.

        """
        self.handle_data(alt)

    # --------- Top level elememts

    def start_html(self, attrs): pass
    def end_html(self): pass

    def start_head(self, attrs): pass
    def end_head(self): pass

    def start_body(self, attrs): pass
    def end_body(self): pass

    # ------ Head elements

    def start_title(self, attrs):
        self.save_bgn()

    def end_title(self):
        self.title = self.save_end()

    def do_base(self, attrs):
        for a, v in attrs:
            if a == 'href':
                self.base = v

    def do_isindex(self, attrs):
        self.isindex = 1

    def do_link(self, attrs):
        pass

    def do_meta(self, attrs):
        pass

    def do_nextid(self, attrs): # Deprecated
        pass

    # ------ Body elements

    # --- Headings

    def start_h1(self, attrs):
        self.formatter.end_paragraph(1)
        self.formatter.push_font(('h1', 0, 1, 0))

    def end_h1(self):
        self.formatter.end_paragraph(1)
        self.formatter.pop_font()

    def start_h2(self, attrs):
        self.formatter.end_paragraph(1)
        self.formatter.push_font(('h2', 0, 1, 0))

    def end_h2(self):
        self.formatter.end_paragraph(1)
        self.formatter.pop_font()

    def start_h3(self, attrs):
        self.formatter.end_paragraph(1)
        self.formatter.push_font(('h3', 0, 1, 0))

    def end_h3(self):
        self.formatter.end_paragraph(1)
        self.formatter.pop_font()

    def start_h4(self, attrs):
        self.formatter.end_paragraph(1)
        self.formatter.push_font(('h4', 0, 1, 0))

    def end_h4(self):
        self.formatter.end_paragraph(1)
        self.formatter.pop_font()

    def start_h5(self, attrs):
        self.formatter.end_paragraph(1)
        self.formatter.push_font(('h5', 0, 1, 0))

    def end_h5(self):
        self.formatter.end_paragraph(1)
        self.formatter.pop_font()

    def start_h6(self, attrs):
        self.formatter.end_paragraph(1)
        self.formatter.push_font(('h6', 0, 1, 0))

    def end_h6(self):
        self.formatter.end_paragraph(1)
        self.formatter.pop_font()

    # --- Block Structuring Elements

    def do_p(self, attrs):
        self.formatter.end_paragraph(1)

    def start_pre(self, attrs):
        self.formatter.end_paragraph(1)
        self.formatter.push_font((AS_IS, AS_IS, AS_IS, 1))
        self.nofill = self.nofill + 1

    def end_pre(self):
        self.formatter.end_paragraph(1)
        self.formatter.pop_font()
        self.nofill = max(0, self.nofill - 1)

    def start_xmp(self, attrs):
        self.start_pre(attrs)
        self.setliteral('xmp') # Tell SGML parser

    def end_xmp(self):
        self.end_pre()

    def start_listing(self, attrs):
        self.start_pre(attrs)
        self.setliteral('listing') # Tell SGML parser

    def end_listing(self):
        self.end_pre()

    def start_address(self, attrs):
        self.formatter.end_paragraph(0)
        self.formatter.push_font((AS_IS, 1, AS_IS, AS_IS))

    def end_address(self):
        self.formatter.end_paragraph(0)
        self.formatter.pop_font()

    def start_blockquote(self, attrs):
        self.formatter.end_paragraph(1)
        self.formatter.push_margin('blockquote')

    def end_blockquote(self):
        self.formatter.end_paragraph(1)
        self.formatter.pop_margin()

    # --- List Elements

    def start_ul(self, attrs):
        self.formatter.end_paragraph(not self.list_stack)
        self.formatter.push_margin('ul')
        self.list_stack.append(['ul', '*', 0])

    def end_ul(self):
        if self.list_stack: del self.list_stack[-1]
        self.formatter.end_paragraph(not self.list_stack)
        self.formatter.pop_margin()

    def do_li(self, attrs):
        self.formatter.end_paragraph(0)
        if self.list_stack:
            [dummy, label, counter] = top = self.list_stack[-1]
            top[2] = counter = counter+1
        else:
            label, counter = '*', 0
        self.formatter.add_label_data(label, counter)

    def start_ol(self, attrs):
        self.formatter.end_paragraph(not self.list_stack)
        self.formatter.push_margin('ol')
        label = '1.'
        for a, v in attrs:
            if a == 'type':
                if len(v) == 1: v = v + '.'
                label = v
        self.list_stack.append(['ol', label, 0])

    def end_ol(self):
        if self.list_stack: del self.list_stack[-1]
        self.formatter.end_paragraph(not self.list_stack)
        self.formatter.pop_margin()

    def start_menu(self, attrs):
        self.start_ul(attrs)

    def end_menu(self):
        self.end_ul()

    def start_dir(self, attrs):
        self.start_ul(attrs)

    def end_dir(self):
        self.end_ul()

    def start_dl(self, attrs):
        self.formatter.end_paragraph(1)
        self.list_stack.append(['dl', '', 0])

    def end_dl(self):
        self.ddpop(1)
        if self.list_stack: del self.list_stack[-1]

    def do_dt(self, attrs):
        self.ddpop()

    def do_dd(self, attrs):
        self.ddpop()
        self.formatter.push_margin('dd')
        self.list_stack.append(['dd', '', 0])

    def ddpop(self, bl=0):
        self.formatter.end_paragraph(bl)
        if self.list_stack:
            if self.list_stack[-1][0] == 'dd':
                del self.list_stack[-1]
                self.formatter.pop_margin()

    # --- Phrase Markup

    # Idiomatic Elements

    def start_cite(self, attrs): self.start_i(attrs)
    def end_cite(self): self.end_i()

    def start_code(self, attrs): self.start_tt(attrs)
    def end_code(self): self.end_tt()

    def start_em(self, attrs): self.start_i(attrs)
    def end_em(self): self.end_i()

    def start_kbd(self, attrs): self.start_tt(attrs)
    def end_kbd(self): self.end_tt()

    def start_samp(self, attrs): self.start_tt(attrs)
    def end_samp(self): self.end_tt()

    def start_strong(self, attrs): self.start_b(attrs)
    def end_strong(self): self.end_b()

    def start_var(self, attrs): self.start_i(attrs)
    def end_var(self): self.end_i()

    # Typographic Elements

    def start_i(self, attrs):
        self.formatter.push_font((AS_IS, 1, AS_IS, AS_IS))
    def end_i(self):
        self.formatter.pop_font()

    def start_b(self, attrs):
        self.formatter.push_font((AS_IS, AS_IS, 1, AS_IS))
    def end_b(self):
        self.formatter.pop_font()

    def start_tt(self, attrs):
        self.formatter.push_font((AS_IS, AS_IS, AS_IS, 1))
    def end_tt(self):
        self.formatter.pop_font()

    def start_a(self, attrs):
        href = ''
        name = ''
        type = ''
        for attrname, value in attrs:
            value = value.strip()
            if attrname == 'href':
                href = value
            if attrname == 'name':
                name = value
            if attrname == 'type':
                type = value.lower()
        self.anchor_bgn(href, name, type)

    def end_a(self):
        self.anchor_end()

    # --- Line Break

    def do_br(self, attrs):
        self.formatter.add_line_break()

    # --- Horizontal Rule

    def do_hr(self, attrs):
        self.formatter.add_hor_rule()

    # --- Image

    def do_img(self, attrs):
        align = ''
        alt = '(image)'
        ismap = ''
        src = ''
        width = 0
        height = 0
        for attrname, value in attrs:
            if attrname == 'align':
                align = value
            if attrname == 'alt':
                alt = value
            if attrname == 'ismap':
                ismap = value
            if attrname == 'src':
                src = value
            if attrname == 'width':
                try: width = int(value)
                except ValueError: pass
            if attrname == 'height':
                try: height = int(value)
                except ValueError: pass
        self.handle_image(src, alt, ismap, align, width, height)

    # --- Really Old Unofficial Deprecated Stuff

    def do_plaintext(self, attrs):
        self.start_pre(attrs)
        self.setnomoretags() # Tell SGML parser

    # --- Unhandled tags

    def unknown_starttag(self, tag, attrs):
        pass

    def unknown_endtag(self, tag):
        pass


def test(args = None):
    import sys, formatter

    if not args:
        args = sys.argv[1:]

    silent = args and args[0] == '-s'
    if silent:
        del args[0]

    if args:
        file = args[0]
    else:
        file = 'test.html'

    if file == '-':
        f = sys.stdin
    else:
        try:
            f = open(file, 'r')
        except IOError as msg:
            print(file, ":", msg)
            sys.exit(1)

    data = f.read()

    if f is not sys.stdin:
        f.close()

    if silent:
        f = formatter.NullFormatter()
    else:
        f = formatter.AbstractFormatter(formatter.DumbWriter())

    p = HTMLParser(f)
    p.feed(data)
    p.close()


if __name__ == '__main__':
    test()