diff options
Diffstat (limited to 'bs4/element.py')
| -rw-r--r-- | bs4/element.py | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/bs4/element.py b/bs4/element.py index 650bacf..584e171 100644 --- a/bs4/element.py +++ b/bs4/element.py @@ -411,6 +411,132 @@ class PageElement(object): yield i i = i.parent + # Methods for supporting CSS selectors. + + tag_name_re = re.compile('^[a-z0-9]+$') + + # /^(\w+)\[(\w+)([=~\|\^\$\*]?)=?"?([^\]"]*)"?\]$/ + # \---/ \---/\-------------/ \-------/ + # | | | | + # | | | The value + # | | ~,|,^,$,* or = + # | Attribute + # Tag + attribselect_re = re.compile( + r'^(?P<tag>\w+)?\[(?P<attribute>\w+)(?P<operator>[=~\|\^\$\*]?)' + + r'=?"?(?P<value>[^\]"]*)"?\]$' + ) + + def _attr_value_as_string(self, value, default=None): + """Force an attribute value into a string representation. + + A multi-valued attribute will be converted into a + space-separated stirng. + """ + value = self.get(value, default) + if isinstance(value, list) or isinstance(value, tuple): + value =" ".join(value) + return value + + def _attribute_checker(self, operator, attribute, value=''): + """Create a function that performs a CSS selector operation. + + Takes an operator, attribute and optional value. Returns a + function that will return True for elements that match that + combination. + """ + if operator == '=': + # string representation of `attribute` is equal to `value` + return lambda el: el._attr_value_as_string(attribute) == value + elif operator == '~': + # space-separated list representation of `attribute` + # contains `value` + def _includes_value(element): + attribute_value = element.get(attribute, []) + if not isinstance(attribute_value, list): + attribute_value = attribute_value.split() + return value in attribute_value + return _includes_value + elif operator == '^': + # string representation of `attribute` starts with `value` + return lambda el: el._attr_value_as_string( + attribute, '').startswith(value) + elif operator == '$': + # string represenation of `attribute` ends with `value` + return lambda el: el._attr_value_as_string( + attribute, '').endswith(value) + elif operator == '*': + # string representation of `attribute` contains `value` + return lambda el: value in el._attr_value_as_string(attribute, '') + elif operator == '|': + # string representation of `attribute` is either exactly + # `value` or starts with `value` and then a dash. + def _is_or_starts_with_dash(element): + attribute_value = element._attr_value_as_string(attribute, '') + return (attribute_value == value or attribute_value.startswith( + value + '-')) + return _is_or_starts_with_dash + else: + return lambda el: el.has_attr(attribute) + + def select(self, selector): + """Perform a CSS selection operation on the current element.""" + tokens = selector.split() + current_context = [self] + for token in tokens: + m = self.attribselect_re.match(token) + if m is not None: + # Attribute selector + tag, attribute, operator, value = m.groups() + if not tag: + tag = True + checker = self._attribute_checker(operator, attribute, value) + found = [] + for context in current_context: + found.extend([el for el in context.find_all(tag) if checker(el)]) + current_context = found + continue + if '#' in token: + # ID selector + tag, id = token.split('#', 1) + if tag == "": + tag = True + el = current_context[0].find(tag, {'id': id}) + if el is None: + return [] # No match + current_context = [el] + continue + if '.' in token: + # Class selector + tag, klass = token.split('.', 1) + if not tag: + tag = True + found = [] + for context in current_context: + found.extend( + context.find_all( + tag, + {'class': lambda attr: attr and klass in attr.split()} + ) + ) + current_context = found + continue + if token == '*': + # Star selector + found = [] + for context in current_context: + found.extend(context.findAll(True)) + current_context = found + continue + # Here we should just have a regular tag + if not self.tag_name_re.match(token): + return [] + found = [] + for context in current_context: + found.extend(context.findAll(token)) + current_context = found + return current_context + # Old non-property versions of the generators, for backwards # compatibility with BS3. def nextGenerator(self): |