#include <ForeachChaseLink.h>

Collaboration diagram for opencog::PrivateUseOnlyChaseLink< T >:

Public Member Functions
bool	follow_link (const Handle &h, Type ltype, int from, int to, bool(T::cb)(const Handle &), T data)

bool	follow_link_lh (const Handle &h, Type ltype, int from, int to, bool(T::cb)(const Handle &, const Handle &), T data)

bool	follow_unordered_binary_link (const Handle &h, Type ltype, bool(T::cb)(const Handle &), T data)

bool	follow_unordered_binary_link (const Handle &h, Type ltype, bool(T::cb)(const Handle &, const Handle &), T data)

Private Member Functions
bool	do_follow_link (const Handle &h, Type ltype, int from, int to, T *data)

bool	do_follow_unordered_binary_link (const Handle &h, Type ltype, T *data)

bool	find_link_type (const Handle &link_h)

bool	pursue_link (const Handle &h)

bool	pursue_unordered_link (const Handle &h)

Private Attributes
Type	link_type

Handle	from_atom

Handle	to_atom

int	position_from

int	position_to

int	cnt

bool(PrivateUseOnlyChaseLink::*	endpoint_matcher )(const Handle &)

bool(T::*	user_callback )(const Handle &)

bool(T::*	user_callback_lh )(const Handle &, const Handle &)

T *	user_data

Detailed Description

template<typename T>
class opencog::PrivateUseOnlyChaseLink< T >

This class is not meant for external use, it is meant to be a private utility for the use of the helper functions below. Unfortunately, C++ does not give any way of hiding this from the namespace. Too bad :-(

However, following this "private" definition are several public callback iterators, which are intended for general use.

This template class implements a foreach iterator that iterates over all atoms associated with a given atom via a certain link type. It does this by iterating over all links containing the given atom, and then invoking a callback for a corresponding atom in that link. Two utility methods are provided: follow a binary link in the foreward direction, and in the reverse direction.

If there is only one link of the given type, for the given atom, then the FollowLink clas provides an easier-to-use interface.

Example usage:

class MyClass { bool my_callback(const Handle& h) { printf("Hello world, found %ul\n", (unsigned long) h); }

void do_stuff_with_handle(Handle h) { PrivateUseOnlyChaseLink<MyClass> my_iter;

my_iter.follow_binary_link(h, INHERITANCE_LINK, MyClass::my_callback, this); } };

The above example invokes the callback "my_callback" on every handle that is at the far end of an inheritence link containing the input handle h.

Definition at line 91 of file ForeachChaseLink.h.

Member Function Documentation

template<typename T>

bool opencog::PrivateUseOnlyChaseLink< T >::do_follow_link	(	const Handle &	h,
		Type	ltype,
		int	from,
		int	to,
		T *	data
	)

inlineprivate

Definition at line 157 of file ForeachChaseLink.h.

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template<typename T>

bool opencog::PrivateUseOnlyChaseLink< T >::do_follow_unordered_binary_link	(	const Handle &	h,
		Type	ltype,
		T *	data
	)

inlineprivate

Definition at line 172 of file ForeachChaseLink.h.

References python.atom_type_names::data, opencog::PrivateUseOnlyChaseLink< T >::endpoint_matcher, opencog::PrivateUseOnlyChaseLink< T >::find_link_type(), opencog::Atom::foreach_incoming(), opencog::PrivateUseOnlyChaseLink< T >::from_atom, opencog::PrivateUseOnlyChaseLink< T >::link_type, opencog::PrivateUseOnlyChaseLink< T >::pursue_unordered_link(), opencog::PrivateUseOnlyChaseLink< T >::to_atom, opencog::Handle::UNDEFINED, and opencog::PrivateUseOnlyChaseLink< T >::user_data.

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template<typename T>

bool opencog::PrivateUseOnlyChaseLink< T >::find_link_type ( const Handle & link_h )

inlineprivate

Check for link of the desired type, then loop over its outgoing set.

Definition at line 188 of file ForeachChaseLink.h.

References opencog::PrivateUseOnlyChaseLink< T >::cnt, opencog::PrivateUseOnlyChaseLink< T >::endpoint_matcher, opencog::Atom::getType(), opencog::PrivateUseOnlyChaseLink< T >::link_type, opencog::LinkCast(), opencog::PrivateUseOnlyChaseLink< T >::to_atom, opencog::Handle::UNDEFINED, opencog::PrivateUseOnlyChaseLink< T >::user_callback, opencog::PrivateUseOnlyChaseLink< T >::user_callback_lh, and opencog::PrivateUseOnlyChaseLink< T >::user_data.

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template<typename T>

bool opencog::PrivateUseOnlyChaseLink< T >::follow_link	(	const Handle &	h,
		Type	ltype,
		int	from,
		int	to,
		bool(T::*)(const Handle &)	cb,
		T *	data
	)

inline

follow_link – follow an ordered, binary link.

Look at the incoming set of the specified atom. Find all links of type link_type. Check to make sure that the input handle "h" occupies position "from" in the link. If it does, then invoke the callback, passing the handle in position "to" to the callback. The callback is called for each endpoint found.

The callback should return false to search for more matches, or return true to halt the search.

Definition at line 109 of file ForeachChaseLink.h.

References opencog::PrivateUseOnlyChaseLink< T >::do_follow_link(), opencog::PrivateUseOnlyChaseLink< T >::user_callback, and opencog::PrivateUseOnlyChaseLink< T >::user_callback_lh.

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template<typename T>

bool opencog::PrivateUseOnlyChaseLink< T >::follow_link_lh	(	const Handle &	h,
		Type	ltype,
		int	from,
		int	to,
		bool(T::*)(const Handle &, const Handle &)	cb,
		T *	data
	)

inline

Same as above, except the callback is passed the handle of the link itself in the second arg.

Definition at line 121 of file ForeachChaseLink.h.

References opencog::PrivateUseOnlyChaseLink< T >::do_follow_link(), opencog::PrivateUseOnlyChaseLink< T >::user_callback, and opencog::PrivateUseOnlyChaseLink< T >::user_callback_lh.

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template<typename T>

bool opencog::PrivateUseOnlyChaseLink< T >::follow_unordered_binary_link	(	const Handle &	h,
		Type	ltype,
		bool(T::*)(const Handle &)	cb,
		T *	data
	)

inline

Definition at line 129 of file ForeachChaseLink.h.

References opencog::PrivateUseOnlyChaseLink< T >::do_follow_unordered_binary_link(), opencog::PrivateUseOnlyChaseLink< T >::user_callback, and opencog::PrivateUseOnlyChaseLink< T >::user_callback_lh.

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template<typename T>

bool opencog::PrivateUseOnlyChaseLink< T >::follow_unordered_binary_link	(	const Handle &	h,
		Type	ltype,
		bool(T::*)(const Handle &, const Handle &)	cb,
		T *	data
	)