Clasp::Literal Class Reference

A literal is a variable or its negation. More...

#include <literal.h>

Collaboration diagram for Clasp::Literal:

Public Member Functions
	Literal ()
	The default constructor creates the positive literal of the special sentinel var. More...
	Literal (Var var, bool sign)
	Creates a literal of the variable var with sign s. More...
uint32	index () const
	Returns the unique index of this literal. More...
uint32 &	asUint ()
uint32	asUint () const
Var	var () const
	Returns the variable of the literal. More...
bool	sign () const
	Returns the sign of the literal. More...
void	swap (Literal &other)
void	watch ()
	Sets the watched-flag of this literal. More...
void	clearWatch ()
	Clears the watched-flag of this literal. More...
bool	watched () const
	Returns true if the watched-flag of this literal is set. More...
Literal	operator~ () const
	Returns the complimentary literal of this literal. More...
bool	operator== (const Literal &rhs) const
	Equality-Comparison for literals. More...

Static Public Member Functions
static Literal	fromIndex (uint32 idx)
	Creates a literal from an index. More...
static Literal	fromRep (uint32 rep)
	Creates a literal from an unsigned integer. More...

Detailed Description

A literal is a variable or its negation.

A literal is determined by two things: a sign and a variable index.

Implementation:

A literal's state is stored in a single 32-bit integer as follows:

• 30-bits : var-index
• 1-bit : sign, 1 if negative, 0 if positive
• 1-bit : watch-flag

Constructor & Destructor Documentation

Clasp::Literal::Literal ( )

inline

The default constructor creates the positive literal of the special sentinel var.

Clasp::Literal::Literal ( Var  var, bool  sign  )

inline

Creates a literal of the variable var with sign s.

Parameters

var	The literal's variable.
s	true if new literal should be negative.

Precondition

var < varMax

Member Function Documentation

uint32& Clasp::Literal::asUint ( )

inline

uint32 Clasp::Literal::asUint ( ) const

inline

void Clasp::Literal::clearWatch ( )

inline

Clears the watched-flag of this literal.

static Literal Clasp::Literal::fromIndex ( uint32  idx )

inlinestatic

Creates a literal from an index.

Precondition

idx < 2^31

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static Literal Clasp::Literal::fromRep ( uint32  rep )

inlinestatic

Creates a literal from an unsigned integer.

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uint32 Clasp::Literal::index ( ) const

inline

Returns the unique index of this literal.

Note

The watch-flag is ignored and thus the index of a literal can be stored in 31-bits.

bool Clasp::Literal::operator== ( const Literal &  rhs ) const

inline

Equality-Comparison for literals.

Two Literals p and q are equal, iff

• they both refer to the same variable
• they have the same sign

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Literal Clasp::Literal::operator~ ( ) const

inline

Returns the complimentary literal of this literal.

The complementary Literal of a Literal is a Literal referring to the same variable but with inverted sign.

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bool Clasp::Literal::sign ( ) const

inline

Returns the sign of the literal.

Returns

true if the literal is negative. Otherwise false.

void Clasp::Literal::swap ( Literal &  other )

inline

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Var Clasp::Literal::var ( ) const

inline

Returns the variable of the literal.

void Clasp::Literal::watch ( )

inline

Sets the watched-flag of this literal.

bool Clasp::Literal::watched ( ) const

inline

Returns true if the watched-flag of this literal is set.

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

• /Users/danielbaeck/Dropbox/Uni Klagenfurt/Diplomarbeit/gringo44/libclasp/clasp/literal.h