#include <FoldLink.h>

Inheritance diagram for opencog::FoldLink:

Collaboration diagram for opencog::FoldLink:

Public Member Functions
	FoldLink (const HandleSeq &oset, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	FoldLink (Link &l)

virtual Handle	reduce (void)

Public Member Functions inherited from opencog::FunctionLink
	FunctionLink (Type, const HandleSeq &oset, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	FunctionLink (Link &l)

virtual	~FunctionLink ()

virtual Handle	execute (AtomSpace *=NULL) const

Public Member Functions inherited from opencog::FreeLink
	FreeLink (const HandleSeq &oset, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	FreeLink (const Handle &a, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	FreeLink (Link &l)

virtual	~FreeLink ()

const HandleSeq &	get_vars (void)

Public Member Functions inherited from opencog::Link
	Link (Type t, const HandleSeq &oset, TruthValuePtr tv=TruthValue::DEFAULT_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	Link (Type t, const Handle &h, TruthValuePtr tv=TruthValue::DEFAULT_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	Link (Type t, const Handle &ha, const Handle &hb, TruthValuePtr tv=TruthValue::DEFAULT_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	Link (Type t, const Handle &ha, const Handle &hb, const Handle &hc, TruthValuePtr tv=TruthValue::DEFAULT_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	Link (Type t, const Handle &ha, const Handle &hb, const Handle &hc, const Handle &hd, TruthValuePtr tv=TruthValue::DEFAULT_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	Link (Link &l)

	~Link ()

Arity	getArity () const

const HandleSeq &	getOutgoingSet () const

Handle	getOutgoingAtom (Arity pos) const throw (RuntimeException)

template<class T >
bool	foreach_outgoing (bool(T::cb)(const Handle &), T data)

std::string	toString (std::string indent="")

std::string	toShortString (std::string indent="")

bool	isSource (Handle) const throw (InvalidParamException)

bool	isSource (size_t) const throw (IndexErrorException, InvalidParamException)

bool	isTarget (Handle) const throw (InvalidParamException)

bool	isTarget (size_t) const throw (IndexErrorException, InvalidParamException)

virtual bool	operator== (const Atom &) const

virtual bool	operator!= (const Atom &) const

Public Member Functions inherited from opencog::Atom
virtual	~Atom ()

Type	getType () const

bool	isType (Type t, bool subclass) const

Handle	getHandle ()

AttentionValuePtr	getAttentionValue ()

void	setAttentionValue (AttentionValuePtr)
	Sets the AttentionValue object of the atom. More...

AttentionValue::sti_t	getSTI ()
	Handy-dandy convenience getters for attention values. More...

AttentionValue::lti_t	getLTI ()

AttentionValue::vlti_t	getVLTI ()

void	setSTI (AttentionValue::sti_t stiValue)

void	setLTI (AttentionValue::lti_t ltiValue)

void	incVLTI ()

void	decVLTI ()

TruthValuePtr	getTruthValue ()

void	setTruthValue (TruthValuePtr)
	Sets the TruthValue object of the atom. More...

void	merge (TruthValuePtr)

Handle	tvmerge (TruthValuePtr tv)

size_t	getIncomingSetSize ()
	Get the size of the incoming set. More...

IncomingSet	getIncomingSet ()

template<typename OutputIterator >
OutputIterator	getIncomingSet (OutputIterator result)

template<class T >
bool	foreach_incoming (bool(T::cb)(const Handle &), T data)

template<typename OutputIterator >
OutputIterator	getIncomingSetByType (OutputIterator result, Type type, bool subclass=false)

IncomingSet	getIncomingSetByType (Type type, bool subclass=false)

Protected Member Functions
virtual Handle	kons (const Handle &, const Handle &)=0

void	init (void)

	FoldLink (Type, const HandleSeq &oset, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	FoldLink (Type, const Handle &a, const Handle &b, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

Protected Member Functions inherited from opencog::FunctionLink
	FunctionLink (Type, const Handle &a, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	FunctionLink (Type, const Handle &a, const Handle &b, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

Protected Member Functions inherited from opencog::FreeLink
void	init (void)

void	find_vars (std::set< Handle > &, const HandleSeq &)

void	build_index (void)

	FreeLink (Type, const HandleSeq &oset, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	FreeLink (Type, const Handle &a, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	FreeLink (Type, const Handle &a, const Handle &b, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

Protected Member Functions inherited from opencog::Atom
	Atom (Type t, TruthValuePtr tv=TruthValue::DEFAULT_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

void	keep_incoming_set ()

void	drop_incoming_set ()

void	insert_atom (LinkPtr)
	Add an atom to the incoming set. More...

void	remove_atom (LinkPtr)
	Remove an atom from the incoming set. More...

Protected Attributes
Handle	knil

Type	distributive_type = NOTYPE

Protected Attributes inherited from opencog::FreeLink
HandleSeq	_varseq

std::map< Handle, unsigned int >	_index

Protected Attributes inherited from opencog::Link
HandleSeq	_outgoing

Protected Attributes inherited from opencog::Atom
UUID	_uuid

AtomTable *	_atomTable

Type	_type

char	_flags

TruthValuePtr	_truthValue

AttentionValuePtr	_attentionValue

std::mutex	_mtx

InSetPtr	_incoming_set

Additional Inherited Members
Static Public Member Functions inherited from opencog::FunctionLink
static Handle	do_execute (AtomSpace *, const Handle &)

static LinkPtr	factory (LinkPtr)

static Handle	factory (Type, const HandleSeq &)

Protected Types inherited from opencog::Atom
typedef std::shared_ptr< InSet >	InSetPtr

Detailed Description

The FoldLink implements the generic reduction of lists, by cons'ing together elements of the same type. See http://en.wikipedia.org/wiki/Fold_(higher-order_function) for a general discussion.

Definition at line 41 of file FoldLink.h.

Constructor & Destructor Documentation

FoldLink::FoldLink	(	Type	t,
		const HandleSeq &	oset,
		TruthValuePtr	tv = `TruthValue::NULL_TV()`,
		AttentionValuePtr	av = `AttentionValue::DEFAULT_AV()`
	)

protected

Definition at line 40 of file FoldLink.cc.

References opencog::classserver(), and init().

FoldLink::FoldLink	(	Type	t,
		const Handle &	a,
		const Handle &	b,
		TruthValuePtr	tv = `TruthValue::NULL_TV()`,
		AttentionValuePtr	av = `AttentionValue::DEFAULT_AV()`
	)

protected

Definition at line 50 of file FoldLink.cc.

References opencog::classserver(), and init().

FoldLink::FoldLink	(	const HandleSeq &	oset,
		TruthValuePtr	tv = `TruthValue::NULL_TV()`,
		AttentionValuePtr	av = `AttentionValue::DEFAULT_AV()`
	)

Definition at line 32 of file FoldLink.cc.

References init().

FoldLink::FoldLink ( Link & l )

Definition at line 60 of file FoldLink.cc.

References opencog::classserver(), opencog::Atom::getType(), and init().

Member Function Documentation

void FoldLink::init ( void )

protected

Definition at line 69 of file FoldLink.cc.

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virtual Handle opencog::FoldLink::kons	(	const Handle &	,
		const Handle &
	)

protectedpure virtual

Implemented in opencog::PlusLink, and opencog::TimesLink.

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Handle FoldLink::reduce ( void )

virtual

reduce() – reduce the expression by summing constants, etc.

No actual black-box evaluation or execution is performed. Only clearbox reductions are performed.

Examples: the reduct of (FoldLink (NumberNode 2) (NumberNode 2)) is (NumberNode 4) – its just a constant.

The reduct of (FoldLink (VariableNode "$x") (NumberNode 0)) is (VariableNode "$x"), because adding zero to anything yeilds the thing itself.

This routine is pretending to be more general, though, than simply reducing numeric expressions. It makes the following assumptions and performs the following actions:

1) It is always safe to remove knil from a list. That is, knil is always a unit. 2) Two neighboring elements of the same type can always be kons'ed together with each-other. That is, kons is called on two neighbors that have the same type. That is, this assumes that the list has the associative property, so that neighboring elements can always be cons'ed together. 3) It does not asssume the commutative property. 4) If distributive_type is set, then kons is called when it seems that one neigboring element might distribute into the next. This is vaguely hacky, and is used to implement distributivity of multiplication over addition.

For something as simple as the above, the code below is annoyingly complicated. This is certainly not an efficient, effective way to build a computer algebra system. It works, its just barely good enough for single-variable arithmetic, but that's all. For general reduction tasks, there are two choices:

A) Convert atoms to some other CAS format, reduce that, and then convert back to atoms.

B) Figure out why the atomspace is so ungainly, and fix it so that it is both easy (easier) to use, and also is high-performance.

Obviously, B) is much harder than A) but is probably more important.

Reimplemented from opencog::FreeLink.

Reimplemented in opencog::ArithmeticLink.

Definition at line 125 of file FoldLink.cc.

References opencog::Atom::_atomTable, opencog::Link::_outgoing, opencog::AtomSpace::add_atom(), opencog::classserver(), createLink, distributive_type, DO_RETURN, opencog::FunctionLink::factory(), opencog::FunctionLinkCast(), opencog::AtomTable::getAtomSpace(), opencog::Atom::getHandle(), opencog::Atom::getType(), opencog::Atom::Handle, knil, kons(), opencog::LinkCast(), and python.undocumented.blocksworld::t.

Member Data Documentation

Type opencog::FoldLink::distributive_type = NOTYPE

protected

Definition at line 46 of file FoldLink.h.

Handle opencog::FoldLink::knil

protected

Definition at line 44 of file FoldLink.h.

The documentation for this class was generated from the following files:

opencog/atoms/reduct/FoldLink.h
opencog/atoms/reduct/FoldLink.cc

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation