diff options
Diffstat (limited to 'bs4/element.py')
| -rw-r--r-- | bs4/element.py | 855 |
1 files changed, 855 insertions, 0 deletions
diff --git a/bs4/element.py b/bs4/element.py new file mode 100644 index 0000000..315ee63 --- /dev/null +++ b/bs4/element.py @@ -0,0 +1,855 @@ +import re +import types +try: + from htmlentitydefs import name2codepoint +except ImportError: + name2codepoint = {} +from bs4.dammit import EntitySubstitution + +from util import isList + +DEFAULT_OUTPUT_ENCODING = "utf-8" + + +class PageElement(object): + """Contains the navigational information for some part of the page + (either a tag or a piece of text)""" + + def setup(self, parent=None, previous=None): + """Sets up the initial relations between this element and + other elements.""" + self.parent = parent + self.previous = previous + self.next = None + self.previousSibling = None + self.nextSibling = None + if self.parent and self.parent.contents: + self.previousSibling = self.parent.contents[-1] + self.previousSibling.nextSibling = self + + def replaceWith(self, replaceWith): + oldParent = self.parent + myIndex = self.parent.contents.index(self) + if hasattr(replaceWith, 'parent') and replaceWith.parent == self.parent: + # We're replacing this element with one of its siblings. + index = self.parent.contents.index(replaceWith) + if index and index < myIndex: + # Furthermore, it comes before this element. That + # means that when we extract it, the index of this + # element will change. + myIndex = myIndex - 1 + self.extract() + oldParent.insert(myIndex, replaceWith) + + def extract(self): + """Destructively rips this element out of the tree.""" + if self.parent: + try: + self.parent.contents.remove(self) + except ValueError: + pass + + #Find the two elements that would be next to each other if + #this element (and any children) hadn't been parsed. Connect + #the two. + lastChild = self._lastRecursiveChild() + nextElement = lastChild.next + + if self.previous: + self.previous.next = nextElement + if nextElement: + nextElement.previous = self.previous + self.previous = None + lastChild.next = None + + self.parent = None + if self.previousSibling: + self.previousSibling.nextSibling = self.nextSibling + if self.nextSibling: + self.nextSibling.previousSibling = self.previousSibling + self.previousSibling = self.nextSibling = None + return self + + def _lastRecursiveChild(self): + "Finds the last element beneath this object to be parsed." + lastChild = self + while hasattr(lastChild, 'contents') and lastChild.contents: + lastChild = lastChild.contents[-1] + return lastChild + + def insert(self, position, newChild): + if (isinstance(newChild, basestring) + or isinstance(newChild, unicode)) \ + and not isinstance(newChild, NavigableString): + newChild = NavigableString(newChild) + + position = min(position, len(self.contents)) + if hasattr(newChild, 'parent') and newChild.parent != None: + # We're 'inserting' an element that's already one + # of this object's children. + if newChild.parent == self: + index = self.find(newChild) + if index and index < position: + # Furthermore we're moving it further down the + # list of this object's children. That means that + # when we extract this element, our target index + # will jump down one. + position = position - 1 + newChild.extract() + + newChild.parent = self + previousChild = None + if position == 0: + newChild.previousSibling = None + newChild.previous = self + else: + previousChild = self.contents[position-1] + newChild.previousSibling = previousChild + newChild.previousSibling.nextSibling = newChild + newChild.previous = previousChild._lastRecursiveChild() + if newChild.previous: + newChild.previous.next = newChild + + newChildsLastElement = newChild._lastRecursiveChild() + + if position >= len(self.contents): + newChild.nextSibling = None + + parent = self + parentsNextSibling = None + while not parentsNextSibling: + parentsNextSibling = parent.nextSibling + parent = parent.parent + if not parent: # This is the last element in the document. + break + if parentsNextSibling: + newChildsLastElement.next = parentsNextSibling + else: + newChildsLastElement.next = None + else: + nextChild = self.contents[position] + newChild.nextSibling = nextChild + if newChild.nextSibling: + newChild.nextSibling.previousSibling = newChild + newChildsLastElement.next = nextChild + + if newChildsLastElement.next: + newChildsLastElement.next.previous = newChildsLastElement + self.contents.insert(position, newChild) + + def append(self, tag): + """Appends the given tag to the contents of this tag.""" + self.insert(len(self.contents), tag) + + def find_next(self, name=None, attrs={}, text=None, **kwargs): + """Returns the first item that matches the given criteria and + appears after this Tag in the document.""" + return self._findOne(self.find_all_next, name, attrs, text, **kwargs) + findNext = find_next # BS3 + + def find_all_next(self, name=None, attrs={}, text=None, limit=None, + **kwargs): + """Returns all items that match the given criteria and appear + after this Tag in the document.""" + return self._find_all(name, attrs, text, limit, self.next_elements, + **kwargs) + findAllNext = find_all_next # BS3 + + def find_next_sibling(self, name=None, attrs={}, text=None, **kwargs): + """Returns the closest sibling to this Tag that matches the + given criteria and appears after this Tag in the document.""" + return self._findOne(self.find_next_siblings, name, attrs, text, + **kwargs) + findNextSibling = find_next_sibling # BS3 + + def find_next_siblings(self, name=None, attrs={}, text=None, limit=None, + **kwargs): + """Returns the siblings of this Tag that match the given + criteria and appear after this Tag in the document.""" + return self._find_all(name, attrs, text, limit, + self.next_siblings, **kwargs) + findNextSiblings = find_next_siblings # BS3 + fetchNextSiblings = find_next_siblings # BS2 + + def find_previous(self, name=None, attrs={}, text=None, **kwargs): + """Returns the first item that matches the given criteria and + appears before this Tag in the document.""" + return self._findOne( + self.find_all_previous, name, attrs, text, **kwargs) + findPrevious = find_previous # BS3 + + def find_all_previous(self, name=None, attrs={}, text=None, limit=None, + **kwargs): + """Returns all items that match the given criteria and appear + before this Tag in the document.""" + return self._find_all(name, attrs, text, limit, self.previous_elements, + **kwargs) + findAllPrevious = find_all_previous # BS3 + fetchPrevious = find_all_previous # BS2 + + def find_previous_sibling(self, name=None, attrs={}, text=None, **kwargs): + """Returns the closest sibling to this Tag that matches the + given criteria and appears before this Tag in the document.""" + return self._findOne(self.find_previous_siblings, name, attrs, text, + **kwargs) + findPreviousSibling = find_previous_sibling # BS3 + + def find_previous_siblings(self, name=None, attrs={}, text=None, + limit=None, **kwargs): + """Returns the siblings of this Tag that match the given + criteria and appear before this Tag in the document.""" + return self._find_all(name, attrs, text, limit, + self.previous_siblings, **kwargs) + findPreviousSiblings = find_previous_siblings # BS3 + fetchPreviousSiblings = find_previous_siblings # BS2 + + def find_parent(self, name=None, attrs={}, **kwargs): + """Returns the closest parent of this Tag that matches the given + criteria.""" + # NOTE: We can't use _findOne because findParents takes a different + # set of arguments. + r = None + l = self.find_parents(name, attrs, 1) + if l: + r = l[0] + return r + findParent = find_parent # BS3 + + def find_parents(self, name=None, attrs={}, limit=None, **kwargs): + """Returns the parents of this Tag that match the given + criteria.""" + + return self._find_all(name, attrs, None, limit, self.parents, + **kwargs) + findParents = find_parents # BS3 + fetchParents = find_parents # BS2 + + #These methods do the real heavy lifting. + + def _findOne(self, method, name, attrs, text, **kwargs): + r = None + l = method(name, attrs, text, 1, **kwargs) + if l: + r = l[0] + return r + + def _find_all(self, name, attrs, text, limit, generator, **kwargs): + "Iterates over a generator looking for things that match." + + if isinstance(name, SoupStrainer): + strainer = name + else: + # Build a SoupStrainer + strainer = SoupStrainer(name, attrs, text, **kwargs) + results = ResultSet(strainer) + while True: + try: + i = generator.next() + except StopIteration: + break + if i: + found = strainer.search(i) + if found: + results.append(found) + if limit and len(results) >= limit: + break + return results + + #These generators can be used to navigate starting from both + #NavigableStrings and Tags. + @property + def next_elements(self): + i = self + while i: + i = i.next + yield i + + @property + def next_siblings(self): + i = self + while i: + i = i.nextSibling + yield i + + @property + def previous_elements(self): + i = self + while i: + i = i.previous + yield i + + @property + def previous_siblings(self): + i = self + while i: + i = i.previousSibling + yield i + + @property + def parents(self): + i = self + while i: + i = i.parent + yield i + + # Old non-property versions of the generators, for backwards + # compatibility with BS3. + def nextGenerator(self): + return self.next_elements + + def nextSiblingGenerator(self): + return self.next_siblings + + def previousGenerator(self): + return self.previous_elements + + def previousSiblingGenerator(self): + return self.previous_siblings + + def parentGenerator(self): + return self.parents + + # Utility methods + def substituteEncoding(self, str, encoding=None): + encoding = encoding or "utf-8" + return str.replace("%SOUP-ENCODING%", encoding) + + def toEncoding(self, s, encoding=None): + """Encodes an object to a string in some encoding, or to Unicode. + .""" + if isinstance(s, unicode): + if encoding: + s = s.encode(encoding) + elif isinstance(s, str): + if encoding: + s = s.encode(encoding) + else: + s = unicode(s) + else: + if encoding: + s = self.toEncoding(str(s), encoding) + else: + s = unicode(s) + return s + +class NavigableString(unicode, PageElement): + + PREFIX = '' + SUFFIX = '' + + def __new__(cls, value): + """Create a new NavigableString. + + When unpickling a NavigableString, this method is called with + the string in DEFAULT_OUTPUT_ENCODING. That encoding needs to be + passed in to the superclass's __new__ or the superclass won't know + how to handle non-ASCII characters. + """ + if isinstance(value, unicode): + return unicode.__new__(cls, value) + return unicode.__new__(cls, value, DEFAULT_OUTPUT_ENCODING) + + def __getnewargs__(self): + return (unicode(self),) + + def __getattr__(self, attr): + """text.string gives you text. This is for backwards + compatibility for Navigable*String, but for CData* it lets you + get the string without the CData wrapper.""" + if attr == 'string': + return self + else: + raise AttributeError, "'%s' object has no attribute '%s'" % (self.__class__.__name__, attr) + + def output_ready(self, substitute_html_entities=False): + if substitute_html_entities: + output = EntitySubstitution.substitute_html(self) + else: + output = self + return self.PREFIX + output + self.SUFFIX + + +class CData(NavigableString): + + PREFIX = u'<![CDATA[' + SUFFIX = u']]>' + + +class ProcessingInstruction(NavigableString): + + PREFIX = u'<?' + SUFFIX = u'?>' + + +class Comment(NavigableString): + + PREFIX = u'<!--' + SUFFIX = u'-->' + +class Declaration(NavigableString): + PREFIX = u'<!' + SUFFIX = u'!>' + + +class Doctype(NavigableString): + + @classmethod + def for_name_and_ids(cls, name, pub_id, system_id): + value = name + if pub_id is not None: + value += ' PUBLIC "%s"' % pub_id + if system_id is not None: + value += ' SYSTEM "%s"' % system_id + + return Doctype(value) + + PREFIX = u'<!DOCTYPE ' + SUFFIX = u'>' + + +class Tag(PageElement): + + """Represents a found HTML tag with its attributes and contents.""" + + def __init__(self, parser, builder, name, attrs=None, parent=None, + previous=None): + "Basic constructor." + + # We don't actually store the parser object: that lets extracted + # chunks be garbage-collected. + self.parserClass = parser.__class__ + self.name = name + if attrs == None: + attrs = {} + else: + attrs = dict(attrs) + self.attrs = attrs + self.contents = [] + self.setup(parent, previous) + self.hidden = False + + # Set up any substitutions, such as the charset in a META tag. + self.contains_substitutions = builder.set_up_substitutions(self) + + self.can_be_empty_element = builder.can_be_empty_element(name) + + @property + def is_empty_element(self): + """Is this tag an empty-element tag? (aka a self-closing tag) + + A tag that has contents is never an empty-element tag. + + A tag that has no contents may or may not be an empty-element + tag. It depends on the builder used to create the tag. If the + builder has a designated list of empty-element tags, then only + a tag whose name shows up in that list is considered an + empty-element tag. + + If the builder has no designated list of empty-element tags, + then any tag with no contents is an empty-element tag. + """ + return len(self.contents) == 0 and self.can_be_empty_element + isSelfClosing = is_empty_element # BS3 + + + @property + def string(self): + """Convenience property to get the single string within this tag. + + :Return: If this tag has a single string child, return value + is that string. If this tag has no children, or more than one + child, return value is None. If this tag has one child tag, + return value is the 'string' attribute of the child tag, + recursively. + """ + if len(self.contents) != 1: + return None + child = self.contents[0] + if isinstance(child, NavigableString): + return child + return child.string + + def get(self, key, default=None): + """Returns the value of the 'key' attribute for the tag, or + the value given for 'default' if it doesn't have that + attribute.""" + return self.attrs.get(key, default) + + def has_key(self, key): + return self.attrs.has_key(key) + + def __getitem__(self, key): + """tag[key] returns the value of the 'key' attribute for the tag, + and throws an exception if it's not there.""" + return self.attrs[key] + + def __iter__(self): + "Iterating over a tag iterates over its contents." + return iter(self.contents) + + def __len__(self): + "The length of a tag is the length of its list of contents." + return len(self.contents) + + def __contains__(self, x): + return x in self.contents + + def __nonzero__(self): + "A tag is non-None even if it has no contents." + return True + + def __setitem__(self, key, value): + """Setting tag[key] sets the value of the 'key' attribute for the + tag.""" + self.attrs[key] = value + + def __delitem__(self, key): + "Deleting tag[key] deletes all 'key' attributes for the tag." + if self.attrs.has_key(key): + del self.attrs[key] + + def __call__(self, *args, **kwargs): + """Calling a tag like a function is the same as calling its + find_all() method. Eg. tag('a') returns a list of all the A tags + found within this tag.""" + return apply(self.find_all, args, kwargs) + + def __getattr__(self, tag): + #print "Getattr %s.%s" % (self.__class__, tag) + if len(tag) > 3 and tag.rfind('Tag') == len(tag)-3: + return self.find(tag[:-3]) + elif tag.find('__') != 0: + return self.find(tag) + raise AttributeError, "'%s' object has no attribute '%s'" % (self.__class__, tag) + + def __eq__(self, other): + """Returns true iff this tag has the same name, the same attributes, + and the same contents (recursively) as the given tag. + + XXX: right now this will return false if two tags have the + same attributes in a different order. Should this be fixed?""" + if not hasattr(other, 'name') or not hasattr(other, 'attrs') or not hasattr(other, 'contents') or self.name != other.name or self.attrs != other.attrs or len(self) != len(other): + return False + for i in range(0, len(self.contents)): + if self.contents[i] != other.contents[i]: + return False + return True + + def __ne__(self, other): + """Returns true iff this tag is not identical to the other tag, + as defined in __eq__.""" + return not self == other + + def __repr__(self, encoding=DEFAULT_OUTPUT_ENCODING): + """Renders this tag as a string.""" + return self.encode(encoding) + + def __unicode__(self): + return self.decode() + + def __str__(self): + return self.encode() + + def encode(self, encoding=DEFAULT_OUTPUT_ENCODING, + indent_level=None, substitute_html_entities=False): + return self.decode(indent_level, encoding, + substitute_html_entities).encode(encoding) + + def decode(self, indent_level=None, + eventual_encoding=DEFAULT_OUTPUT_ENCODING, + substitute_html_entities=False): + """Returns a Unicode representation of this tag and its contents. + + :param eventual_encoding: The tag is destined to be + encoded into this encoding. This method is _not_ + responsible for performing that encoding. This information + is passed in so that it can be substituted in if the + document contains a <META> tag that mentions the document's + encoding. + """ + attrs = [] + if self.attrs: + for key, val in sorted(self.attrs.items()): + if val is None: + decoded = key + else: + if not isinstance(val, basestring): + val = str(val) + if (self.contains_substitutions + and eventual_encoding is not None + and '%SOUP-ENCODING%' in val): + val = self.substituteEncoding(val, eventual_encoding) + + decoded = (key + '=' + + EntitySubstitution.substitute_xml(val, True)) + attrs.append(decoded) + close = '' + closeTag = '' + if self.is_empty_element: + close = ' /' + else: + closeTag = '</%s>' % self.name + + pretty_print = (indent_level is not None) + if pretty_print: + space = (' ' * (indent_level-1)) + indent_contents = indent_level + 1 + else: + space = '' + indent_contents = None + contents = self.decode_contents( + indent_contents, eventual_encoding, substitute_html_entities) + + if self.hidden: + # This is the 'document root' object. + s = contents + else: + s = [] + attributeString = '' + if attrs: + attributeString = ' ' + ' '.join(attrs) + if pretty_print: + s.append(space) + s.append('<%s%s%s>' % (self.name, attributeString, close)) + if pretty_print: + s.append("\n") + s.append(contents) + if pretty_print and contents and contents[-1] != "\n": + s.append("\n") + if pretty_print and closeTag: + s.append(space) + s.append(closeTag) + if pretty_print and closeTag and self.nextSibling: + s.append("\n") + s = ''.join(s) + return s + + def decompose(self): + """Recursively destroys the contents of this tree.""" + contents = [i for i in self.contents] + for i in contents: + if isinstance(i, Tag): + i.decompose() + else: + i.extract() + self.extract() + + def prettify(self, encoding=DEFAULT_OUTPUT_ENCODING): + return self.encode(encoding, True) + + def decode_contents(self, indent_level=None, + eventual_encoding=DEFAULT_OUTPUT_ENCODING, + substitute_html_entities=False): + """Renders the contents of this tag as a Unicode string. + + :param eventual_encoding: The tag is destined to be + encoded into this encoding. This method is _not_ + responsible for performing that encoding. This information + is passed in so that it can be substituted in if the + document contains a <META> tag that mentions the document's + encoding. + """ + pretty_print = (indent_level is not None) + s=[] + for c in self: + text = None + if isinstance(c, NavigableString): + text = c.output_ready(substitute_html_entities) + elif isinstance(c, Tag): + s.append(c.decode(indent_level, eventual_encoding, + substitute_html_entities)) + if text and indent_level: + text = text.strip() + if text: + if pretty_print: + s.append(" " * (indent_level-1)) + s.append(text) + if pretty_print: + s.append("\n") + return ''.join(s) + + #Soup methods + + def find(self, name=None, attrs={}, recursive=True, text=None, + **kwargs): + """Return only the first child of this Tag matching the given + criteria.""" + r = None + l = self.find_all(name, attrs, recursive, text, 1, **kwargs) + if l: + r = l[0] + return r + findChild = find + + def find_all(self, name=None, attrs={}, recursive=True, text=None, + limit=None, **kwargs): + """Extracts a list of Tag objects that match the given + criteria. You can specify the name of the Tag and any + attributes you want the Tag to have. + + The value of a key-value pair in the 'attrs' map can be a + string, a list of strings, a regular expression object, or a + callable that takes a string and returns whether or not the + string matches for some custom definition of 'matches'. The + same is true of the tag name.""" + generator = self.recursive_children + if not recursive: + generator = self.children + return self._find_all(name, attrs, text, limit, generator, **kwargs) + findAll = find_all # BS3 + findChildren = find_all # BS2 + + #Generator methods + @property + def children(self): + for i in range(0, len(self.contents)): + yield self.contents[i] + raise StopIteration + + @property + def recursive_children(self): + if not len(self.contents): + raise StopIteration + stopNode = self._lastRecursiveChild().next + current = self.contents[0] + while current is not stopNode: + yield current + current = current.next + + # Old names for backwards compatibility + def childGenerator(self): + return self.children + + def recursiveChildGenerator(self): + return self.recursive_children + + +# Next, a couple classes to represent queries and their results. +class SoupStrainer(object): + """Encapsulates a number of ways of matching a markup element (tag or + text).""" + + def __init__(self, name=None, attrs={}, text=None, **kwargs): + self.name = name + if isinstance(attrs, basestring): + kwargs['class'] = attrs + attrs = None + if kwargs: + if attrs: + attrs = attrs.copy() + attrs.update(kwargs) + else: + attrs = kwargs + self.attrs = attrs + self.text = text + + def __str__(self): + if self.text: + return self.text + else: + return "%s|%s" % (self.name, self.attrs) + + def searchTag(self, markupName=None, markupAttrs={}): + found = None + markup = None + if isinstance(markupName, Tag): + markup = markupName + markupAttrs = markup + callFunctionWithTagData = callable(self.name) \ + and not isinstance(markupName, Tag) + + if (not self.name) \ + or callFunctionWithTagData \ + or (markup and self._matches(markup, self.name)) \ + or (not markup and self._matches(markupName, self.name)): + if callFunctionWithTagData: + match = self.name(markupName, markupAttrs) + else: + match = True + markupAttrMap = None + for attr, matchAgainst in self.attrs.items(): + if not markupAttrMap: + if hasattr(markupAttrs, 'get'): + markupAttrMap = markupAttrs + else: + markupAttrMap = {} + for k,v in markupAttrs: + markupAttrMap[k] = v + attrValue = markupAttrMap.get(attr) + if not self._matches(attrValue, matchAgainst): + match = False + break + if match: + if markup: + found = markup + else: + found = markupName + return found + + def search(self, markup): + #print 'looking for %s in %s' % (self, markup) + found = None + # If given a list of items, scan it for a text element that + # matches. + if isList(markup) and not isinstance(markup, Tag): + for element in markup: + if isinstance(element, NavigableString) \ + and self.search(element): + found = element + break + # If it's a Tag, make sure its name or attributes match. + # Don't bother with Tags if we're searching for text. + elif isinstance(markup, Tag): + if not self.text: + found = self.searchTag(markup) + # If it's text, make sure the text matches. + elif isinstance(markup, NavigableString) or \ + isinstance(markup, basestring): + if self._matches(markup, self.text): + found = markup + else: + raise Exception, "I don't know how to match against a %s" \ + % markup.__class__ + return found + + def _matches(self, markup, matchAgainst): + #print "Matching %s against %s" % (markup, matchAgainst) + result = False + if matchAgainst == True and type(matchAgainst) == types.BooleanType: + result = markup != None + elif callable(matchAgainst): + result = matchAgainst(markup) + else: + #Custom match methods take the tag as an argument, but all + #other ways of matching match the tag name as a string. + if isinstance(markup, Tag): + markup = markup.name + if markup is not None and not isinstance(markup, basestring): + markup = unicode(markup) + #Now we know that chunk is either a string, or None. + if hasattr(matchAgainst, 'match'): + # It's a regexp object. + result = markup and matchAgainst.search(markup) + elif (isList(matchAgainst) + and (markup is not None + or not isinstance(matchAgainst, basestring))): + result = markup in matchAgainst + elif hasattr(matchAgainst, 'items'): + result = markup.has_key(matchAgainst) + elif matchAgainst and isinstance(markup, basestring): + if isinstance(markup, unicode): + matchAgainst = unicode(matchAgainst) + else: + matchAgainst = str(matchAgainst) + + if not result: + result = matchAgainst == markup + return result + + +class ResultSet(list): + """A ResultSet is just a list that keeps track of the SoupStrainer + that created it.""" + def __init__(self, source): + list.__init__([]) + self.source = source |