pydocspec.genericvisitor.Visitor

class documentation

class Visitor(Generic[T], abc.ABC): (source)

"Visitor" pattern abstract superclass implementation for tree traversals.

Each class has corresponding methods, doing nothing by default; override individual methods for specific and useful behaviour. The visit() method is called by walk() upon entering a object. walkabout() also calls the depart() method before exiting a object.

The generic methods call "visit_ + objet class name" or "depart_ + objet class name", resp.

This is a base class for visitors whose visit_... & depart_... methods should be implemented for all concrete objets types encountered.

Class	`SkipChildren`	Do not visit any children of the current node. The current node's siblings and `depart_...` method are not affected.
Class	`SkipDeparture`	Do not call the current node's `depart_...` method. The current node's children and siblings are not affected.
Class	`SkipNode`	Do not visit the current node's children, and do not call the current node's `depart_...` method.
Class	`SkipSiblings`	Do not visit any more siblings (to the right) of the current node. The current node's children and its `depart_...` method are not affected.
Method	`depart`	Depart an object.
Method	`get_children`	Undocumented
Method	`unknown_departure`	Called before exiting unknown object types.
Method	`unknown_visit`	Called when entering unknown object types.
Method	`visit`	Visit an object.
Method	`walk`	Traverse a tree of objects, calling the `visit()` method of `visitor` when entering each node. (The `walkabout()` method is similar, except it also calls the `depart()` method before exiting each objects.)
Method	`walkabout`	Perform a tree traversal similarly to `walk()` (which see), except also call the `depart()` method before exiting each node.
Class	`_TreePruningException`	Base class for `Visitor`-related tree pruning exceptions.

def depart(self, ob): (source)

Depart an object.

Parameters
ob:`T`	Undocumented

@abc.abstractclassmethod
def get_children(cls, ob): (source)

Undocumented

Parameters
ob:`T`	Undocumented
Returns
`Iterable[T]`	Undocumented

def unknown_departure(self, ob): (source)

Called before exiting unknown object types.

Raise exception unless overridden.

Parameters
ob:`T`	Undocumented

def unknown_visit(self, ob): (source)

Called when entering unknown object types.

Raise an exception unless overridden.

Parameters
ob:`T`	Undocumented

def visit(self, ob): (source)

Visit an object.

Parameters
ob:`T`	Undocumented

def walk(self, ob): (source)

Traverse a tree of objects, calling the visit() method of visitor when entering each node. (The walkabout() method is similar, except it also calls the depart() method before exiting each objects.)

This tree traversal supports limited in-place tree modifications. Replacing one node with one or more nodes is OK, as is removing an element. However, if the node removed or replaced occurs after the current node, the old node will still be traversed, and any new nodes will not.

Parameters
ob:`T`	An object to walk.
visitor	A `Visitor` object, containing a `visit` implementation for each object type encountered.
get_children	A callable that returns the children of an object.

def walkabout(self, ob): (source)

Perform a tree traversal similarly to walk() (which see), except also call the depart() method before exiting each node.

Parameters
ob:`T`	An object to walk.
visitor	A `Visitor` object, containing a `visit` and `depart` implementation for each concrete object type encountered.
get_children	A callable that returns the children of an object.