/other/FetchData/ClientForm.py

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"""HTML form handling for web clients.

ClientForm is a Python module for handling HTML forms on the client
side, useful for parsing HTML forms, filling them in and returning the
completed forms to the server.  It has developed from a port of Gisle
Aas' Perl module HTML::Form, from the libwww-perl library, but the
interface is not the same.

The most useful docstring is the one for HTMLForm.

RFC 1866: HTML 2.0
RFC 1867: Form-based File Upload in HTML
RFC 2388: Returning Values from Forms: multipart/form-data
HTML 3.2 Specification, W3C Recommendation 14 January 1997 (for ISINDEX)
HTML 4.01 Specification, W3C Recommendation 24 December 1999


Copyright 2002-2007 John J. Lee <jjl@pobox.com>
Copyright 2005 Gary Poster
Copyright 2005 Zope Corporation
Copyright 1998-2000 Gisle Aas.

This code is free software; you can redistribute it and/or modify it
under the terms of the BSD or ZPL 2.1 licenses (see the file
COPYING.txt included with the distribution).

"""

# XXX
# Remove parser testing hack
# safeUrl()-ize action
# Switch to unicode throughout (would be 0.3.x)
#  See Wichert Akkerman's 2004-01-22 message to c.l.py.
# Add charset parameter to Content-type headers?  How to find value??
# Add some more functional tests
#  Especially single and multiple file upload on the internet.
#  Does file upload work when name is missing?  Sourceforge tracker form
#   doesn't like it.  Check standards, and test with Apache.  Test
#   binary upload with Apache.
# mailto submission & enctype text/plain
# I'm not going to fix this unless somebody tells me what real servers
#  that want this encoding actually expect: If enctype is
#  application/x-www-form-urlencoded and there's a FILE control present.
#  Strictly, it should be 'name=data' (see HTML 4.01 spec., section
#  17.13.2), but I send "name=" ATM.  What about multiple file upload??

# Would be nice, but I'm not going to do it myself:
# -------------------------------------------------
# Maybe a 0.4.x?
#   Replace by_label etc. with moniker / selector concept. Allows, eg.,
#    a choice between selection by value / id / label / element
#    contents.  Or choice between matching labels exactly or by
#    substring.  Etc.
#   Remove deprecated methods.
#   ...what else?
# Work on DOMForm.
# XForms?  Don't know if there's a need here.

__all__ = ['AmbiguityError', 'CheckboxControl', 'Control',
           'ControlNotFoundError', 'FileControl', 'FormParser', 'HTMLForm',
           'HiddenControl', 'IgnoreControl', 'ImageControl', 'IsindexControl',
           'Item', 'ItemCountError', 'ItemNotFoundError', 'Label',
           'ListControl', 'LocateError', 'Missing', 'ParseError', 'ParseFile',
           'ParseFileEx', 'ParseResponse', 'ParseResponseEx','PasswordControl',
           'RadioControl', 'ScalarControl', 'SelectControl',
           'SubmitButtonControl', 'SubmitControl', 'TextControl',
           'TextareaControl', 'XHTMLCompatibleFormParser']

try: True
except NameError:
    True = 1
    False = 0

try: bool
except NameError:
    def bool(expr):
        if expr: return True
        else: return False

try:
    import logging
    import inspect
except ImportError:
    def debug(msg, *args, **kwds):
        pass
else:
    _logger = logging.getLogger("ClientForm")
    OPTIMIZATION_HACK = True

    def debug(msg, *args, **kwds):
        if OPTIMIZATION_HACK:
            return

        caller_name = inspect.stack()[1][3]
        extended_msg = '%%s %s' % msg
        extended_args = (caller_name,)+args
        debug = _logger.debug(extended_msg, *extended_args, **kwds)

    def _show_debug_messages():
        global OPTIMIZATION_HACK
        OPTIMIZATION_HACK = False
        _logger.setLevel(logging.DEBUG)
        handler = logging.StreamHandler(sys.stdout)
        handler.setLevel(logging.DEBUG)
        _logger.addHandler(handler)

import sys, urllib, urllib2, types, mimetools, copy, urlparse, \
       htmlentitydefs, re, random
from cStringIO import StringIO

import sgmllib
# monkeypatch to fix http://www.python.org/sf/803422 :-(
sgmllib.charref = re.compile("&#(x?[0-9a-fA-F]+)[^0-9a-fA-F]")

# HTMLParser.HTMLParser is recent, so live without it if it's not available
# (also, sgmllib.SGMLParser is much more tolerant of bad HTML)
try:
    import HTMLParser
except ImportError:
    HAVE_MODULE_HTMLPARSER = False
else:
    HAVE_MODULE_HTMLPARSER = True

try:
    import warnings
except ImportError:
    def deprecation(message, stack_offset=0):
        pass
else:
    def deprecation(message, stack_offset=0):
        warnings.warn(message, DeprecationWarning, stacklevel=3+stack_offset)

VERSION = "0.2.10"

CHUNK = 1024  # size of chunks fed to parser, in bytes

DEFAULT_ENCODING = "latin-1"

class Missing: pass

_compress_re = re.compile(r"\s+")
def compress_text(text): return _compress_re.sub(" ", text.strip())

def normalize_line_endings(text):
    return re.sub(r"(?:(?<!\r)\n)|(?:\r(?!\n))", "\r\n", text)


# This version of urlencode is from my Python 1.5.2 back-port of the
# Python 2.1 CVS maintenance branch of urllib.  It will accept a sequence
# of pairs instead of a mapping -- the 2.0 version only accepts a mapping.
def urlencode(query,doseq=False,):
    """Encode a sequence of two-element tuples or dictionary into a URL query \
string.

    If any values in the query arg are sequences and doseq is true, each
    sequence element is converted to a separate parameter.

    If the query arg is a sequence of two-element tuples, the order of the
    parameters in the output will match the order of parameters in the
    input.
    """

    if hasattr(query,"items"):
        # mapping objects
        query = query.items()
    else:
        # it's a bother at times that strings and string-like objects are
        # sequences...
        try:
            # non-sequence items should not work with len()
            x = len(query)
            # non-empty strings will fail this
            if len(query) and type(query[0]) != types.TupleType:
                raise TypeError()
            # zero-length sequences of all types will get here and succeed,
            # but that's a minor nit - since the original implementation
            # allowed empty dicts that type of behavior probably should be
            # preserved for consistency
        except TypeError:
            ty,va,tb = sys.exc_info()
            raise TypeError("not a valid non-string sequence or mapping "
                            "object", tb)

    l = []
    if not doseq:
        # preserve old behavior
        for k, v in query:
            k = urllib.quote_plus(str(k))
            v = urllib.quote_plus(str(v))
            l.append(k + '=' + v)
    else:
        for k, v in query:
            k = urllib.quote_plus(str(k))
            if type(v) == types.StringType:
                v = urllib.quote_plus(v)
                l.append(k + '=' + v)
            elif type(v) == types.UnicodeType:
                # is there a reasonable way to convert to ASCII?
                # encode generates a string, but "replace" or "ignore"
                # lose information and "strict" can raise UnicodeError
                v = urllib.quote_plus(v.encode("ASCII","replace"))
                l.append(k + '=' + v)
            else:
                try:
                    # is this a sufficient test for sequence-ness?
                    x = len(v)
                except TypeError:
                    # not a sequence
                    v = urllib.quote_plus(str(v))
                    l.append(k + '=' + v)
                else:
                    # loop over the sequence
                    for elt in v:
                        l.append(k + '=' + urllib.quote_plus(str(elt)))
    return '&'.join(l)

def unescape(data, entities, encoding=DEFAULT_ENCODING):
    if data is None or "&" not in data:
        return data

    def replace_entities(match, entities=entities, encoding=encoding):
        ent = match.group()
        if ent[1] == "#":
            return unescape_charref(ent[2:-1], encoding)

        repl = entities.get(ent)
        if repl is not None:
            if type(repl) != type(""):
                try:
                    repl = repl.encode(encoding)
                except UnicodeError:
                    repl = ent
        else:
            repl = ent

        return repl

    return re.sub(r"&#?[A-Za-z0-9]+?;", replace_entities, data)

def unescape_charref(data, encoding):
    name, base = data, 10
    if name.startswith("x"):
        name, base= name[1:], 16
    uc = unichr(int(name, base))
    if encoding is None:
        return uc
    else:
        try:
            repl = uc.encode(encoding)
        except UnicodeError:
            repl = "&#%s;" % data
        return repl

def get_entitydefs():
    import htmlentitydefs
    from codecs import latin_1_decode
    entitydefs = {}
    try:
        htmlentitydefs.name2codepoint
    except AttributeError:
        entitydefs = {}
        for name, char in htmlentitydefs.entitydefs.items():
            uc = latin_1_decode(char)[0]
            if uc.startswith("&#") and uc.endswith(";"):
                uc = unescape_charref(uc[2:-1], None)
            entitydefs["&%s;" % name] = uc
    else:
        for name, codepoint in htmlentitydefs.name2codepoint.items():
            entitydefs["&%s;" % name] = unichr(codepoint)
    return entitydefs


def issequence(x):
    try:
        x[0]
    except (TypeError, KeyError):
        return False
    except IndexError:
        pass
    return True

def isstringlike(x):
    try: x+""
    except: return False
    else: return True


def choose_boundary():
    """Return a string usable as a multipart boundary."""
    # follow IE and firefox
    nonce = "".join([str(random.randint(0, sys.maxint-1)) for i in 0,1,2])
    return "-"*27 + nonce

# This cut-n-pasted MimeWriter from standard library is here so can add
# to HTTP headers rather than message body when appropriate.  It also uses
# \r\n in place of \n.  This is a bit nasty.
class MimeWriter:

    """Generic MIME writer.

    Methods:

    __init__()
    addheader()
    flushheaders()
    startbody()
    startmultipartbody()
    nextpart()
    lastpart()

    A MIME writer is much more primitive than a MIME parser.  It
    doesn't seek around on the output file, and it doesn't use large
    amounts of buffer space, so you have to write the parts in the
    order they should occur on the output file.  It does buffer the
    headers you add, allowing you to rearrange their order.

    General usage is:

    f = <open the output file>
    w = MimeWriter(f)
    ...call w.addheader(key, value) 0 or more times...

    followed by either:

    f = w.startbody(content_type)
    ...call f.write(data) for body data...

    or:

    w.startmultipartbody(subtype)
    for each part:
        subwriter = w.nextpart()
        ...use the subwriter's methods to create the subpart...
    w.lastpart()

    The subwriter is another MimeWriter instance, and should be
    treated in the same way as the toplevel MimeWriter.  This way,
    writing recursive body parts is easy.

    Warning: don't forget to call lastpart()!

    XXX There should be more state so calls made in the wrong order
    are detected.

    Some special cases:

    - startbody() just returns the file passed to the constructor;
      but don't use this knowledge, as it may be changed.

    - startmultipartbody() actually returns a file as well;
      this can be used to write the initial 'if you can read this your
      mailer is not MIME-aware' message.

    - If you call flushheaders(), the headers accumulated so far are
      written out (and forgotten); this is useful if you don't need a
      body part at all, e.g. for a subpart of type message/rfc822
      that's (mis)used to store some header-like information.

    - Passing a keyword argument 'prefix=<flag>' to addheader(),
      start*body() affects where the header is inserted; 0 means
      append at the end, 1 means insert at the start; default is
      append for addheader(), but insert for start*body(), which use
      it to determine where the Content-type header goes.

    """

    def __init__(self, fp, http_hdrs=None):
        self._http_hdrs = http_hdrs
        self._fp = fp
        self._headers = []
        self._boundary = []
        self._first_part = True

    def addheader(self, key, value, prefix=0,
                  add_to_http_hdrs=0):
        """
        prefix is ignored if add_to_http_hdrs is true.
        """
        lines = value.split("\r\n")
        while lines and not lines[-1]: del lines[-1]
        while lines and not lines[0]: del lines[0]
        if add_to_http_hdrs:
            value = "".join(lines)
            # 2.2 urllib2 doesn't normalize header case
            self._http_hdrs.append((key.capitalize(), value))
        else:
            for i in range(1, len(lines)):
                lines[i] = "    " + lines[i].strip()
            value = "\r\n".join(lines) + "\r\n"
            line = key.title() + ": " + value
            if prefix:
                self._headers.insert(0, line)
            else:
                self._headers.append(line)

    def flushheaders(self):
        self._fp.writelines(self._headers)
        self._headers = []

    def startbody(self, ctype=None, plist=[], prefix=1,
                  add_to_http_hdrs=0, content_type=1):
        """
        prefix is ignored if add_to_http_hdrs is true.
        """
        if content_type and ctype:
            for name, value in plist:
                ctype = ctype + ';\r\n %s=%s' % (name, value)
            self.addheader("Content-Type", ctype, prefix=prefix,
                           add_to_http_hdrs=add_to_http_hdrs)
        self.flushheaders()
        if not add_to_http_hdrs: self._fp.write("\r\n")
        self._first_part = True
        return self._fp

    def startmultipartbody(self, subtype, boundary=None, plist=[], prefix=1,
                           add_to_http_hdrs=0, content_type=1):
        boundary = boundary or choose_boundary()
        self._boundary.append(boundary)
        return self.startbody("multipart/" + subtype,
                              [("boundary", boundary)] + plist,
                              prefix=prefix,
                              add_to_http_hdrs=add_to_http_hdrs,
                              content_type=content_type)

    def nextpart(self):
        boundary = self._boundary[-1]
        if self._first_part:
            self._first_part = False
        else:
            self._fp.write("\r\n")
        self._fp.write("--" + boundary + "\r\n")
        return self.__class__(self._fp)

    def lastpart(self):
        if self._first_part:
            self.nextpart()
        boundary = self._boundary.pop()
        self._fp.write("\r\n--" + boundary + "--\r\n")


class LocateError(ValueError): pass
class AmbiguityError(LocateError): pass
class ControlNotFoundError(LocateError): pass
class ItemNotFoundError(LocateError): pass

class ItemCountError(ValueError): pass

# for backwards compatibility, ParseError derives from exceptions that were
# raised by versions of ClientForm <= 0.2.5
if HAVE_MODULE_HTMLPARSER:
    SGMLLIB_PARSEERROR = sgmllib.SGMLParseError
    class ParseError(sgmllib.SGMLParseError,
                     HTMLParser.HTMLParseError,
                     ):
        pass
else:
    if hasattr(sgmllib, "SGMLParseError"):
        SGMLLIB_PARSEERROR = sgmllib.SGMLParseError
        class ParseError(sgmllib.SGMLParseError):
            pass
    else:
        SGMLLIB_PARSEERROR = RuntimeError
        class ParseError(RuntimeError):
            pass


class _AbstractFormParser:
    """forms attribute contains HTMLForm instances on completion."""
    # thanks to Moshe Zadka for an example of sgmllib/htmllib usage
    def __init__(self, entitydefs=None, encoding=DEFAULT_ENCODING):
        if entitydefs is None:
            entitydefs = get_entitydefs()
        self._entitydefs = entitydefs
        self._encoding = encoding

        self.base = None
        self.forms = []
        self.labels = []
        self._current_label = None
        self._current_form = None
        self._select = None
        self._optgroup = None
        self._option = None
        self._textarea = None

        # forms[0] will contain all controls that are outside of any form
        # self._global_form is an alias for self.forms[0]
        self._global_form = None
        self.start_form([])
        self.end_form()
        self._current_form = self._global_form = self.forms[0]

    def do_base(self, attrs):
        debug("%s", attrs)
        for key, value in attrs:
            if key == "href":
                self.base = self.unescape_attr_if_required(value)

    def end_body(self):
        debug("")
        if self._current_label is not None:
            self.end_label()
        if self._current_form is not self._global_form:
            self.end_form()

    def start_form(self, attrs):
        debug("%s", attrs)
        if self._current_form is not self._global_form:
            raise ParseError("nested FORMs")
        name = None
        action = None
        enctype = "application/x-www-form-urlencoded"
        method = "GET"
        d = {}
        for key, value in attrs:
            if key == "name":
                name = self.unescape_attr_if_required(value)
            elif key == "action":
                action = self.unescape_attr_if_required(value)
            elif key == "method":
                method = self.unescape_attr_if_required(value.upper())
            elif key == "enctype":
                enctype = self.unescape_attr_if_required(value.lower())
            d[key] = self.unescape_attr_if_required(value)
        controls = []
        self._current_form = (name, action, method, enctype), d, controls

    def end_form(self):
        debug("")
        if self._current_label is not None:
            self.end_label()
        if self._current_form is self._global_form:
            raise ParseError("end of FORM before start")
        self.forms.append(self._current_form)
        self._current_form = self._global_form

    def start_select(self, attrs):
        debug("%s", attrs)
        if self._select is not None:
            raise ParseError("nested SELECTs")
        if self._textarea is not None:
            raise ParseError("SELECT inside TEXTAREA")
        d = {}
        for key, val in attrs:
            d[key] = self.unescape_attr_if_required(val)

        self._select = d
        self._add_label(d)

        self._append_select_control({"__select": d})

    def end_select(self):
        debug("")
        if self._select is None:
            raise ParseError("end of SELECT before start")

        if self._option is not None:
            self._end_option()

        self._select = None

    def start_optgroup(self, attrs):
        debug("%s", attrs)
        if self._select is None:
            raise ParseError("OPTGROUP outside of SELECT")
        d = {}
        for key, val in attrs:
            d[key] = self.unescape_attr_if_required(val)

        self._optgroup = d

    def end_optgroup(self):
        debug("")
        if self._optgroup is None:
            raise ParseError("end of OPTGROUP before start")
        self._optgroup = None

    def _start_option(self, attrs):
        debug("%s", attrs)
        if self._select is None:
            raise ParseError("OPTION outside of SELECT")
        if self._option is not None:
            self._end_option()

        d = {}
        for key, val in attrs:
            d[key] = self.unescape_attr_if_required(val)

        self._option = {}
        self._option.update(d)
        if (self._optgroup and self._optgroup.has_key("disabled") and
            not self._option.has_key("disabled")):
            self._option["disabled"] = None

    def _end_option(self):
        debug("")
        if self._option is None:
            raise ParseError("end of OPTION before start")

        contents = self._option.get("contents", "").strip()
        self._option["contents"] = contents
        if not self._option.has_key("value"):
            self._option["value"] = contents
        if not self._option.has_key("label"):
            self._option["label"] = contents
        # stuff dict of SELECT HTML attrs into a special private key
        #  (gets deleted again later)
        self._option["__select"] = self._select
        self._append_select_control(self._option)
        self._option = None

    def _append_select_control(self, attrs):
        debug("%s", attrs)
        controls = self._current_form[2]
        name = self._select.get("name")
        controls.append(("select", name, attrs))

    def start_textarea(self, attrs):
        debug("%s", attrs)
        if self._textarea is not None:
            raise ParseError("nested TEXTAREAs")
        if self._select is not None:
            raise ParseError("TEXTAREA inside SELECT")
        d = {}
        for key, val in attrs:
            d[key] = self.unescape_attr_if_required(val)
        self._add_label(d)

        self._textarea = d

    def end_textarea(self):
        debug("")
        if self._textarea is None:
            raise ParseError("end of TEXTAREA before start")
        controls = self._current_form[2]
        name = self._textarea.get("name")
        controls.append(("textarea", name, self._textarea))
        self._textarea = None

    def start_label(self, attrs):
        debug("%s", attrs)
        if self._current_label:
            self.end_label()
        d = {}
        for key, val in attrs:
            d[key] = self.unescape_attr_if_required(val)
        taken = bool(d.get("for"))  # empty id is invalid
        d["__text"] = ""
        d["__taken"] = taken
        if taken:
            self.labels.append(d)
        self._current_label = d

    def end_label(self):
        debug("")
        label = self._current_label
        if label is None:
            # something is ugly in the HTML, but we're ignoring it
            return
        self._current_label = None
        # if it is staying around, it is True in all cases
        del label["__taken"]

    def _add_label(self, d):
        #debug("%s", d)
        if self._current_label is not None:
            if not self._current_label["__taken"]:
                self._current_label["__taken"] = True
                d["__label"] = self._current_label

    def handle_data(self, data):
        debug("%s", data)

        if self._option is not None:
            # self._option is a dictionary of the OPTION element's HTML
            # attributes, but it has two special keys, one of which is the
            # special "contents" key contains text between OPTION tags (the
            # other is the "__select" key: see the end_option method)
            map = self._option
            key = "contents"
        elif self._textarea is not None:
            map = self._textarea
            key = "value"
            data = normalize_line_endings(data)
        # not if within option or textarea
        elif self._current_label is not None:
            map = self._current_label
            key = "__text"
        else:
            return

        if data and not map.has_key(key):
            # according to
            # http://www.w3.org/TR/html4/appendix/notes.html#h-B.3.1 line break
            # immediately after start tags or immediately before end tags must
            # be ignored, but real browsers only ignore a line break after a
            # start tag, so we'll do that.
            if data[0:2] == "\r\n":
                data = data[2:]
            elif data[0:1] in ["\n", "\r"]:
                data = data[1:]
            map[key] = data
        else:
            map[key] = map[key] + data

    def do_button(self, attrs):
        debug("%s", attrs)
        d = {}
        d["type"] = "submit"  # default
        for key, val in attrs:
            d[key] = self.unescape_attr_if_required(val)
        controls = self._current_form[2]

        type = d["type"]
        name = d.get("name")
        # we don't want to lose information, so use a type string that
        # doesn't clash with INPUT TYPE={SUBMIT,RESET,BUTTON}
        # e.g. type for BUTTON/RESET is "resetbutton"
        #     (type for INPUT/RESET is "reset")
        type = type+"button"
        self._add_label(d)
        controls.append((type, name, d))

    def do_input(self, attrs):
        debug("%s", attrs)
        d = {}
        d["type"] = "text"  # default
        for key, val in attrs:
            d[key] = self.unescape_attr_if_required(val)
        controls = self._current_form[2]

        type = d["type"]
        name = d.get("name")
        self._add_label(d)
        controls.append((type, name, d))

    def do_isindex(self, attrs):
        debug("%s", attrs)
        d = {}
        for key, val in attrs:
            d[key] = self.unescape_attr_if_required(val)
        controls = self._current_form[2]

        self._add_label(d)
        # isindex doesn't have type or name HTML attributes
        controls.append(("isindex", None, d))

    def handle_entityref(self, name):
        #debug("%s", name)
        self.handle_data(unescape(
            '&%s;' % name, self._entitydefs, self._encoding))

    def handle_charref(self, name):
        #debug("%s", name)
        self.handle_data(unescape_charref(name, self._encoding))

    def unescape_attr(self, name):
        #debug("%s", name)
        return unescape(name, self._entitydefs, self._encoding)

    def unescape_attrs(self, attrs):
        #debug("%s", attrs)
        escaped_attrs = {}
        for key, val in attrs.items():
            try:
                val.items
            except AttributeError:
                escaped_attrs[key] = self.unescape_attr(val)
            else:
                # e.g. "__select" -- yuck!
                escaped_attrs[key] = self.unescape_attrs(val)
        return escaped_attrs

    def unknown_entityref(self, ref): self.handle_data("&%s;" % ref)
    def unknown_charref(self, ref): self.handle_data("&#%s;" % ref)


if not HAVE_MODULE_HTMLPARSER:
    class XHTMLCompatibleFormParser:
        def __init__(self, entitydefs=None, encoding=DEFAULT_ENCODING):
            raise ValueError("HTMLParser could not be imported")
else:
    class XHTMLCompatibleFormParser(_AbstractFormParser, HTMLParser.HTMLParser):
        """Good for XHTML, bad for tolerance of incorrect HTML."""
        # thanks to Michael Howitz for this!
        def __init__(self, entitydefs=None, encoding=DEFAULT_ENCODING):
            HTMLParser.HTMLParser.__init__(self)
            _AbstractFormParser.__init__(self, entitydefs, encoding)

        def feed(self, data):
            try:
                HTMLParser.HTMLParser.feed(self, data)
            except HTMLParser.HTMLParseError, exc:
                raise ParseError(exc)

        def start_option(self, attrs):
            _AbstractFormParser._start_option(self, attrs)

        def end_option(self):
            _AbstractFormParser._end_option(self)

        def handle_starttag(self, tag, attrs):
            try:
                method = getattr(self, "start_" + tag)
            except AttributeError:
                try:
                    method = getattr(self, "do_" + tag)
                except AttributeError:
                    pass  # unknown tag
                else:
                    method(attrs)
            else:
                method(attrs)

        def handle_endtag(self, tag):
            try:
                method = getattr(self, "end_" + tag)
            except AttributeError:
                pass  # unknown tag
            else:
                method()

        def unescape(self, name):
            # Use the entitydefs passed into constructor, not
            # HTMLParser.HTMLParser's entitydefs.
            return self.unescape_attr(name)

        def unescape_attr_if_required(self, name):
            return name  # HTMLParser.HTMLParser already did it
        def unescape_attrs_if_required(self, attrs):
            return attrs  # ditto

        def close(self):
            HTMLParser.HTMLParser.close(self)
            self.end_body()


class _AbstractSgmllibParser(_AbstractFormParser):

    def do_option(self, attrs):
        _AbstractFormParser._start_option(self, attrs)

    if sys.version_info[:2] >= (2,5):
        # we override this attr to decode hex charrefs
        entity_or_charref = re.compile(
            '&(?:([a-zA-Z][-.a-zA-Z0-9]*)|#(x?[0-9a-fA-F]+))(;?)')
        def convert_entityref(self, name):
            return unescape("&%s;" % name, self._entitydefs, self._encoding)
        def convert_charref(self, name):
            return unescape_charref("%s" % name, self._encoding)
        def unescape_attr_if_required(self, name):
            return name  # sgmllib already did it
        def unescape_attrs_if_required(self, attrs):
            return attrs  # ditto
    else:
        def unescape_attr_if_required(self, name):
            return self.unescape_attr(name)
        def unescape_attrs_if_required(self, attrs):
            return self.unescape_attrs(attrs)


class FormParser(_AbstractSgmllibParser, sgmllib.SGMLParser):
    """Good for tolerance of incorrect HTML, bad for XHTML."""
    def __init__(self, entitydefs=None, encoding=DEFAULT_ENCODING):
        sgmllib.SGMLParser.__init__(self)
        _AbstractFormParser.__init__(self, entitydefs, encoding)

    def feed(self, data):
        try:
            sgmllib.SGMLParser.feed(self, data)
        except SGMLLIB_PARSEERROR, exc:
            raise ParseError(exc)

    def close(self):
        sgmllib.SGMLParser.close(self)
        self.end_body()


# sigh, must support mechanize by allowing dynamic creation of classes based on
# its bundled copy of BeautifulSoup (which was necessary because of dependency
# problems)

def _create_bs_classes(bs,
                       icbinbs,
                       ):
    class _AbstractBSFormParser(_AbstractSgmllibParser):
        bs_base_class = None
        def __init__(self, entitydefs=None, encoding=DEFAULT_ENCODING):
            _AbstractFormParser.__init__(self, entitydefs, encoding)
            self.bs_base_class.__init__(self)
        def handle_data(self, data):
            _AbstractFormParser.handle_data(self, data)
            self.bs_base_class.handle_data(self, data)
        def feed(self, data):
            try:
                self.bs_base_class.feed(self, data)
            except SGMLLIB_PARSEERROR, exc:
                raise ParseError(exc)
        def close(self):
            self.bs_base_class.close(self)
            self.end_body()

    class RobustFormParser(_AbstractBSFormParser, bs):
        """Tries to be highly tolerant of incorrect HTML."""
        pass
    RobustFormParser.bs_base_class = bs
    class NestingRobustFormParser(_AbstractBSFormParser, icbinbs):
        """Tries to be highly tolerant of incorrect HTML.

        Different from RobustFormParser in that it more often guesses nesting
        above missing end tags (see BeautifulSoup docs).

        """
        pass
    NestingRobustFormParser.bs_base_class = icbinbs

    return RobustFormParser, NestingRobustFormParser

try:
    if sys.version_info[:2] < (2, 2):
        raise ImportError  # BeautifulSoup uses generators
    import BeautifulSoup
except ImportError:
    pass
else:
    RobustFormParser, NestingRobustFormParser = _create_bs_classes(
        BeautifulSoup.BeautifulSoup, BeautifulSoup.ICantBelieveItsBeautifulSoup
        )
    __all__ += ['RobustFormParser', 'NestingRobustFormParser']


#FormParser = XHTMLCompatibleFormParser  # testing hack
#FormParser = RobustFormParser  # testing hack


def ParseResponseEx(response,
                    select_default=False,
                    form_parser_class=FormParser,
                    request_class=urllib2.Request,
                    entitydefs=None,
                    encoding=DEFAULT_ENCODING,

                    # private
                    _urljoin=urlparse.urljoin,
                    _urlparse=urlparse.urlparse,
                    _urlunparse=urlparse.urlunparse,
                    ):
    """Identical to ParseResponse, except that:

    1. The returned list contains an extra item.  The first form in the list
    contains all controls not contained in any FORM element.

    2. The arguments ignore_errors and backwards_compat have been removed.

    3. Backwards-compatibility mode (backwards_compat=True) is not available.
    """
    return _ParseFileEx(response, response.geturl(),
                        select_default,
                        False,
                        form_parser_class,
                        request_class,
                        entitydefs,
                        False,
                        encoding,
                        _urljoin=_urljoin,
                        _urlparse=_urlparse,
                        _urlunparse=_urlunparse,
                        )

def ParseFileEx(file, base_uri,
                select_default=False,
                form_parser_class=FormParser,
                request_class=urllib2.Request,
                entitydefs=None,
                encoding=DEFAULT_ENCODING,

                # private
                _urljoin=urlparse.urljoin,
                _urlparse=urlparse.urlparse,
                _urlunparse=urlparse.urlunparse,
                ):
    """Identical to ParseFile, except that:

    1. The returned list contains an extra item.  The first form in the list
    contains all controls not contained in any FORM element.

    2. The arguments ignore_errors and backwards_compat have been removed.

    3. Backwards-compatibility mode (backwards_compat=True) is not available.
    """
    return _ParseFileEx(file, base_uri,
                        select_default,
                        False,
                        form_parser_class,
                        request_class,
                        entitydefs,
                        False,
                        encoding,
                        _urljoin=_urljoin,
                        _urlparse=_urlparse,
                        _urlunparse=_urlunparse,
                        )

def ParseResponse(response, *args, **kwds):
    """Parse HTTP response and return a list of HTMLForm instances.

    The return value of urllib2.urlopen can be conveniently passed to this
    function as the response parameter.

    ClientForm.ParseError is raised on parse errors.

    response: file-like object (supporting read() method) with a method
     geturl(), returning the URI of the HTTP response
    select_default: for multiple-selection SELECT controls and RADIO controls,
     pick the first item as the default if none are selected in the HTML
    form_parser_class: class to instantiate and use to pass
    request_class: class to return from .click() method (default is
     urllib2.Request)
    entitydefs: mapping like {"&amp;": "&", ...} containing HTML entity
     definitions (a sensible default is used)
    encoding: character encoding used for encoding numeric character references
     when matching link text.  ClientForm does not attempt to find the encoding
     in a META HTTP-EQUIV attribute in the document itself (mechanize, for
     example, does do that and will pass the correct value to ClientForm using
     this parameter).

    backwards_compat: boolean that determines whether the returned HTMLForm
     objects are backwards-compatible with old code.  If backwards_compat is
     true:

     - ClientForm 0.1 code will continue to work as before.

     - Label searches that do not specify a nr (number or count) will always
       get the first match, even if other controls match.  If
       backwards_compat is False, label searches that have ambiguous results
       will raise an AmbiguityError.

     - Item label matching is done by strict string comparison rather than
       substring matching.

     - De-selecting individual list items is allowed even if the Item is
       disabled.

    The backwards_compat argument will be deprecated in a future release.

    Pass a true value for select_default if you want the behaviour specified by
    RFC 1866 (the HTML 2.0 standard), which is to select the first item in a
    RADIO or multiple-selection SELECT control if none were selected in the
    HTML.  Most browsers (including Microsoft Internet Explorer (IE) and
    Netscape Navigator) instead leave all items unselected in these cases.  The
    W3C HTML 4.0 standard leaves this behaviour undefined in the case of
    multiple-selection SELECT controls, but insists that at least one RADIO
    button should be checked at all times, in contradiction to browser
    behaviour.

    There is a choice of parsers.  ClientForm.XHTMLCompatibleFormParser (uses
    HTMLParser.HTMLParser) works best for XHTML, ClientForm.FormParser (uses
    sgmllib.SGMLParser) (the default) works better for ordinary grubby HTML.
    Note that HTMLParser is only available in Python 2.2 and later.  You can
    pass your own class in here as a hack to work around bad HTML, but at your
    own risk: there is no well-defined interface.

    """
    return _ParseFileEx(response, response.geturl(), *args, **kwds)[1:]

def ParseFile(file, base_uri, *args, **kwds):
    """Parse HTML and return a list of HTMLForm instances.

    ClientForm.ParseError is raised on parse errors.

    file: file-like object (supporting read() method) containing HTML with zero
     or more forms to be parsed
    base_uri: the URI of the document (note that the base URI used to submit
     the form will be that given in the BASE element if present, not that of
     the document)

    For the other arguments and further details, see ParseResponse.__doc__.

    """
    return _ParseFileEx(file, base_uri, *args, **kwds)[1:]

def _ParseFileEx(file, base_uri,
                 select_default=False,
                 ignore_errors=False,
                 form_parser_class=FormParser,
                 request_class=urllib2.Request,
                 entitydefs=None,
                 backwards_compat=True,
                 encoding=DEFAULT_ENCODING,
                 _urljoin=urlparse.urljoin,
                 _urlparse=urlparse.urlparse,
                 _urlunparse=urlparse.urlunparse,
                 ):
    if backwards_compat:
        deprecation("operating in backwards-compatibility mode", 1)
    fp = form_parser_class(entitydefs, encoding)
    while 1:
        data = file.read(CHUNK)
        try:
            fp.feed(data)
        except ParseError, e:
            e.base_uri = base_uri
            raise
        if len(data) != CHUNK: break
    fp.close()
    if fp.base is not None:
        # HTML BASE element takes precedence over document URI
        base_uri = fp.base
    labels = []  # Label(label) for label in fp.labels]
    id_to_labels = {}
    for l in fp.labels:
        label = Label(l)
        labels.append(label)
        for_id = l["for"]
        coll = id_to_labels.get(for_id)
        if coll is None:
            id_to_labels[for_id] = [label]
        else:
            coll.append(label)
    forms = []
    for (name, action, method, enctype), attrs, controls in fp.forms:
        if action is None:
            action = base_uri
        else:
            action = _urljoin(base_uri, action)
        # would be nice to make HTMLForm class (form builder) pluggable
        form = HTMLForm(
            action, method, enctype, name, attrs, request_class,
            forms, labels, id_to_labels, backwards_compat)
        form._urlparse = _urlparse
        form._urlunparse = _urlunparse
        for ii in range(len(controls)):
            type, name, attrs = controls[ii]
            # index=ii*10 allows ImageControl to return multiple ordered pairs
            form.new_control(
                type, name, attrs, select_default=select_default, index=ii*10)
        forms.append(form)
    for form in forms:
        form.fixup()
    return forms


class Label:
    def __init__(self, attrs):
        self.id = attrs.get("for")
        self._text = attrs.get("__text").strip()
        self._ctext = compress_text(self._text)
        self.attrs = attrs
        self._backwards_compat = False  # maintained by HTMLForm

    def __getattr__(self, name):
        if name == "text":
            if self._backwards_compat:
                return self._text
            else:
                return self._ctext
        return getattr(Label, name)

    def __setattr__(self, name, value):
        if name == "text":
            # don't see any need for this, so make it read-only
            raise AttributeError("text attribute is read-only")
        self.__dict__[name] = value

    def __str__(self):
        return "<Label(id=%r, text=%r)>" % (self.id, self.text)


def _get_label(attrs):
    text = attrs.get("__label")
    if text is not None:
        return Label(text)
    else:
        return None

class Control:
    """An HTML form control.

    An HTMLForm contains a sequence of Controls.  The Controls in an HTMLForm
    are accessed using the HTMLForm.find_control method or the
    HTMLForm.controls attribute.

    Control instances are usually constructed using the ParseFile /
    ParseResponse functions.  If you use those functions, you can ignore the
    rest of this paragraph.  A Control is only properly initialised after the
    fixup method has been called.  In fact, this is only strictly necessary for
    ListControl instances.  This is necessary because ListControls are built up
    from ListControls each containing only a single item, and their initial
    value(s) can only be known after the sequence is complete.

    The types and values that are acceptable for assignment to the value
    attribute are defined by subclasses.

    If the disabled attribute is true, this represents the state typically
    represented by browsers by 'greying out' a control.  If the disabled
    attribute is true, the Control will raise AttributeError if an attempt is
    made to change its value.  In addition, the control will not be considered
    'successful' as defined by the W3C HTML 4 standard -- ie. it will
    contribute no data to the return value of the HTMLForm.click* methods.  To
    enable a control, set the disabled attribute to a false value.

    If the readonly attribute is true, the Control will raise AttributeError if
    an attempt is made to change its value.  To make a control writable, set
    the readonly attribute to a false value.

    All controls have the disabled and readonly attributes, not only those that
    may have the HTML attributes of the same names.

    On assignment to the value attribute, the following exceptions are raised:
    TypeError, AttributeError (if the value attribute should not be assigned
    to, because the control is disabled, for example) and ValueError.

    If the name or value attributes are None, or the value is an empty list, or
    if the control is disabled, the control is not successful.

    Public attributes:

    type: string describing type of control (see the keys of the
     HTMLForm.type2class dictionary for the allowable values) (readonly)
    name: name of control (readonly)
    value: current value of control (subclasses may allow a single value, a
     sequence of values, or either)
    disabled: disabled state
    readonly: readonly state
    id: value of id HTML attribute

    """
    def __init__(self, type, name, attrs, index=None):
        """
        type: string describing type of control (see the keys of the
         HTMLForm.type2class dictionary for the allowable values)
        name: control name
        attrs: HTML attributes of control's HTML element

        """
        raise NotImplementedError()

    def add_to_form(self, form):
        self._form = form
        form.controls.append(self)

    def fixup(self):
        pass

    def is_of_kind(self, kind):
        raise NotImplementedError()

    def clear(self):
        raise NotImplementedError()

    def __getattr__(self, name): raise NotImplementedError()
    def __setattr__(self, name, value): raise NotImplementedError()

    def pairs(self):
        """Return list of (key, value) pairs suitable for passing to urlencode.
        """
        return [(k, v) for (i, k, v) in self._totally_ordered_pairs()]

    def _totally_ordered_pairs(self):
        """Return list of (key, value, index) tuples.

        Like pairs, but allows preserving correct ordering even where several
        controls are involved.

        """
        raise NotImplementedError()

    def _write_mime_data(self, mw, name, value):
        """Write data for a subitem of this control to a MimeWriter."""
        # called by HTMLForm
        mw2 = mw.nextpart()
        mw2.addheader("Content-Disposition",
                      'form-data; name="%s"' % name, 1)
        f = mw2.startbody(prefix=0)
        f.write(value)

    def __str__(self):
        raise NotImplementedError()

    def get_labels(self):
        """Return all labels (Label instances) for this control.
        
        If the control was surrounded by a <label> tag, that will be the first
        label; all other labels, connected by 'for' and 'id', are in the order
        that appear in the HTML.

        """
        res = []
        if self._label:
            res.append(self._label)
        if self.id:
            res.extend(self._form._id_to_labels.get(self.id, ()))
        return res


#---------------------------------------------------
class ScalarControl(Control):
    """Control whose value is not restricted to one of a prescribed set.

    Some ScalarControls don't accept any value attribute.  Otherwise, takes a
    single value, which must be string-like.

    Additional read-only public attribute:

    attrs: dictionary mapping the names of original HTML attributes of the
     control to their values

    """
    def __init__(self, type, name, attrs, index=None):
        self._index = index
        self._label = _get_label(attrs)
        self.__dict__["type"] = type.lower()
        self.__dict__["name"] = name
        self._value = attrs.get("value")
        self.disabled = attrs.has_key("disabled")
        self.readonly = attrs.has_key("readonly")
        self.id = attrs.get("id")

        self.attrs = attrs.copy()

        self._clicked = False

        self._urlparse = urlparse.urlparse
        self._urlunparse = urlparse.urlunparse

    def __getattr__(self, name):
        if name == "value":
            return self.__dict__["_value"]
        else:
            raise AttributeError("%s instance has no attribute '%s'" %
                                 (self.__class__.__name__, name))

    def __setattr__(self, name, value):
        if name == "value":
            if not isstringlike(value):
                raise TypeError("must assign a string")
            elif self.readonly:
                raise AttributeError("control '%s' is readonly" % self.name)
            elif self.disabled:
                raise AttributeError("control '%s' is disabled" % self.name)
            self.__dict__["_value"] = value
        elif name in ("name", "type"):
            raise AttributeError("%s attribute is readonly" % name)
        else:
            self.__dict__[name] = value

    def _totally_ordered_pairs(self):
        name = self.name
        value = self.value
        if name is None or value is None or self.disabled:
            return []
        return [(self._index, name, value)]

    def clear(self):
        if self.readonly:
            raise AttributeError("control '%s' is readonly" % self.name)
        self.__dict__["_value"] = None

    def __str__(self):
        name = self.name
        value = self.value
        if name is None: name = "<None>"
        if value is None: value = "<None>"

        infos = []
        if self.disabled: infos.append("disabled")
        if self.readonly: infos.append("readonly")
        info = ", ".join(infos)
        if info: info = " (%s)" % info

        return "<%s(%s=%s)%s>" % (self.__class__.__name__, name, value, info)


#---------------------------------------------------
class TextControl(ScalarControl):
    """Textual input control.

    Covers:

    INPUT/TEXT
    INPUT/PASSWORD
    INPUT/HIDDEN
    TEXTAREA

    """
    def __init__(self, type, name, attrs, index=None):
        ScalarControl.__init__(self, type, name, attrs, index)
        if self.type == "hidden": self.readonly = True
        if self._value is None:
            self._value = ""

    def is_of_kind(self, kind): return kind == "text"

#---------------------------------------------------
class FileControl(ScalarControl):
    """File upload with INPUT TYPE=FILE.

    The value attribute of a FileControl is always None.  Use add_file instead.

    Additional public method: add_file

    """

    def __init__(self, type, name, attrs, index=None):
        ScalarControl.__init__(self, type, name, attrs, index)
        self._value = None
        self._upload_data = []

    def is_of_kind(self, kind): return kind == "file"

    def clear(self):
        if self.readonly:
            raise AttributeError("control '%s' is readonly" % self.name)
        self._upload_data = []

    def __setattr__(self, name, value):
        if name in ("value", "name", "type"):
            raise AttributeError("%s attribute is readonly" % name)
        else:
            self.__dict__[name] = value

    def add_file(self, file_object, content_type=None, filename=None):
        if not hasattr(file_object, "read"):
            raise TypeError("file-like object must have read method")
        if content_type is not None and not isstringlike(content_type):
            raise TypeError("content type must be None or string-like")
        if filename is not None and not isstringlike(filename):
            raise TypeError("filename must be None or string-like")
        if content_type is None:
            content_type …