    """WebUtils.Funcs

    This module provides some basic functions that are useful
    in HTML and web development.

    You can safely import * from WebUtils.Funcs if you like.

    TO DO

    * Document the 'codes' arg of htmlEncode/Decode.

    """

    htmlForNone = '-'  # used by htmlEncode.

    htmlCodes = [
        ['&', '&amp;'],
        ['<', '&lt;'],
        ['>', '&gt;'],
        ['"', '&quot;'],
        # ['\n', '<br>'],
    ]

    htmlCodesReversed = htmlCodes[:]
    htmlCodesReversed.reverse()

    def htmlEncode(what, codes=htmlCodes):
        if what is None:
            return htmlForNone
        if hasattr(what, 'html'):
            # allow objects to specify their own translation to html
            # via a method, property or attribute
            ht = what.html
            if callable(ht):
                ht = ht()
            return ht
        what = str(what)
        return htmlEncodeStr(what, codes)

    def htmlEncodeStr(s, codes=htmlCodes):
        """Return the HTML encoded version of the given string.

        This is useful to display a plain ASCII text string on a web page.

        """
        for code in codes:
            s = s.replace(code[0], code[1])
        return s

    def htmlDecode(s, codes=htmlCodesReversed):
        """Return the ASCII decoded version of the given HTML string.

        This does NOT remove normal HTML tags like <p>.
        It is the inverse of htmlEncode().

        """
        for code in codes:
            s = s.replace(code[1], code[0])
        return s

    _urlEncode = {}
    for i in range(256):
        c = chr(i)
        _urlEncode[c] = c == ' ' and '+' \
            or i < 128 and (c.isalnum() or c in '_.-/') and c \
            or '%%%02X' % i

    def urlEncode(s):
        """Return the encoded version of the given string.

        The resulting string is safe for using as a URL.

        Identical to urllib.quote_plus(s) in Python 2.4,
        but faster for older Python versions.

        """
        return ''.join(map(_urlEncode.get, s))

    _urlDecode = {}
    for i in range(256):
        _urlDecode['%02x' % i] = _urlDecode['%02X' % i] = chr(i)

    try:
        UnicodeDecodeError
    except NameError: # Python < 2.3
        class UnicodeDecodeError(Exception):
            pass

    def urlDecode(s):
        """Return the decoded version of the given string.

        Note that invalid URLs will not throw exceptions.
        For example, incorrect % codings will be ignored.

        Identical to urllib.unquote_plus(s) in Python 2.4,
        but faster and more exact for older Python versions.

        """
        s = s.replace('+', ' ').split('%')
        for i in xrange(1, len(s)):
            t = s[i]
            try:
                s[i] = _urlDecode[t[:2]] + t[2:]
            except KeyError:
                s[i] = '%' + t
            except UnicodeDecodeError:
                s[i] = unichr(int(t[:2], 16)) + t[2:]
        return ''.join(s)

    def htmlForDict(dict, addSpace=None, filterValueCallBack=None,
            maxValueLength=None, topHeading=None, isEncoded=None):
        """Return an HTML string with a table where each row is a key-value pair."""
        if not dict:
            return ''
        keys = dict.keys()
        keys.sort()
        # A really great (er, bad) example of hardcoding.  :-)
        html = ['<table class="NiceTable">\n']
        if topHeading:
            html.append('<tr class="TopHeading"><th')
            html.append((type(topHeading) is type(())
                and '>%s</th><th>%s' or ' colspan="2">%s') % topHeading)
            html.append('</th></tr>\n')
        for key in keys:
            value = dict[key]
            if addSpace and addSpace.has_key(key):
                target = addSpace[key]
                value = (target + ' ').join(value.split(target))
            if filterValueCallBack:
                value = filterValueCallBack(value, key, dict)
            if maxValueLength and not isEncoded:
                value = str(value)
                if len(value) > maxValueLength:
                    value = value[:maxValueLength] + '...'
            key = htmlEncode(key)
            if not isEncoded:
                value = htmlEncode(value)
            html.append('<tr><th align="left">%s</th><td>%s</td></tr>\n'
                % (key, value))
        html.append('</table>')
        return ''.join(html)

    def requestURI(env):
        """Return the request URI for a given CGI-style dictionary.

        Uses REQUEST_URI if available, otherwise constructs and returns it
        from SCRIPT_URL, SCRIPT_NAME, PATH_INFO and QUERY_STRING.

        """
        uri = env.get('REQUEST_URI', None)
        if uri is None:
            uri = env.get('SCRIPT_URL', None)
            if uri is None:
                uri = env.get('SCRIPT_NAME', '') + env.get('PATH_INFO', '')
            query = env.get('QUERY_STRING', '')
            if query != '':
                uri += '?' + query
        return uri

    def normURL(path):
        """Normalizes a URL path, like os.path.normpath.

        Acts on a URL independant of operating system environment.

        """
        if not path:
            return
        initialslash = path[0] == '/'
        lastslash = path[-1] == '/'
        comps = path.split('/')
        newcomps = []
        for comp in comps:
            if comp in ('', '.'):
                continue
            if comp != '..':
                newcomps.append(comp)
            elif newcomps:
                newcomps.pop()
        path = '/'.join(newcomps)
        if path and lastslash:
            path += '/'
        if initialslash:
            path = '/' + path
        return path