Formats a field by a Regex match of the format spec pattern.

def format_field_by_match(self, value, match):
        """Formats a field by a Regex match of the format spec pattern."""
        groups = match.groups()
        fill, align, sign, sharp, zero, width, comma, prec, type_ = groups
        if not comma and not prec and type_ not in list('fF%'):
            return None
        if math.isnan(value) or math.isinf(value):
            return None
        locale = self.numeric_locale
        # Format number value.
        prefix = get_prefix(sign)
        if type_ == 'd':
            if prec is not None:
                raise ValueError('precision not allowed in '
                                 'integer format specifier')
            string = format_number(value, 0, prefix, locale)
        elif type_ in 'fF%':
            format_ = format_percent if type_ == '%' else format_number
            string = format_(value, int(prec or DEFAULT_PREC), prefix, locale)
        else:
            # Don't handle otherwise.
            return None
        if not comma:
            # Formatted number always contains group symbols.
            # Remove the symbols if not required.
            string = remove_group_symbols(string, locale)
        if not (fill or align or zero or width):
            return string
        # Fix a layout.
        spec = ''.join([fill or u'', align or u'>',
                        zero or u'', width or u''])
        return format(string, spec)