BALL::Expression Class Reference
[Kernel Predicates]

#include <BALL/KERNEL/expression.h>

List of all members.

Public Types
Type Definitions
typedef void *(*	CreationMethod )()
Public Member Functions
Constructors and Destructor
	Expression ()
	Expression (const Expression &expression)
	Expression (const String &expression_string) throw (Exception::ParseError)
virtual	~Expression ()
Predicates
bool	hasPredicate (const String &name) const
bool	operator== (const Expression &expression) const
Accessors
virtual bool	operator() (const Atom &atom) const
ExpressionPredicate *	getPredicate (const String &name, const String &args="") const
void	registerPredicate (const String &name, CreationMethod creation_method)
void	setExpression (const String &expression) throw (Exception::ParseError)
const String &	getExpressionString () const
const ExpressionTree *	getExpressionTree () const
const StringHashMap < CreationMethod > &	getCreationMethods () const
Assignment
Expression &	operator= (const Expression &expression)
virtual void	clear ()
Protected Member Functions
ExpressionTree *	constructExpressionTree_ (const ExpressionParser::SyntaxTree &tree) throw (Exception::ParseError)
void	registerStandardPredicates_ ()
Protected Attributes
StringHashMap< CreationMethod >	create_methods_
ExpressionTree *	expression_tree_
String	expression_string_

---

Detailed Description

Expression class. This class provides a frontend to ExpressionTree.

Expressions may be built from the following modules:

AND & a conjunction

OR & a disjunction

predicate(argument) & a predicate class that is derived from {ExpressionPredicate) and provides operator () (const Atom& atom) const.

Additionally brackets can be used for grouping. At least one bracket pair must exist which encloses the argument of a predicate. Empty arguments are allowed.

See also:

ExpressionTree

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Member Typedef Documentation

typedef void*(* BALL::Expression::CreationMethod)()

A creation method for predicates.

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Constructor & Destructor Documentation

BALL::Expression::Expression

(

)

Default Constructor.

BALL::Expression::Expression

(

const Expression &

expression

)

Copy Constructor.

BALL::Expression::Expression

(

const String &

expression_string

)

throw (Exception::ParseError)

Construct an Expression with a string

virtual BALL::Expression::~Expression

(

)

[virtual]

Destructor.

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Member Function Documentation

virtual void BALL::Expression::clear

(

)

[virtual]

Clear method

ExpressionTree* BALL::Expression::constructExpressionTree_

(

const ExpressionParser::SyntaxTree &

tree

)

throw (Exception::ParseError) [protected]

const StringHashMap<CreationMethod>& BALL::Expression::getCreationMethods

(

)

const

Get the creation methods.

const String& BALL::Expression::getExpressionString

(

)

const

Get the expression string.

const ExpressionTree* BALL::Expression::getExpressionTree

(

)

const

Get the expression tree.

ExpressionPredicate* BALL::Expression::getPredicate	(	const String &	name,
		const String &	args = ""
	)			const

Create a new predicate according to the name. If the predicate is not known, return 0.

Parameters:

	name	the name of the predicate
	args	the optional argument of the predicate

bool BALL::Expression::hasPredicate

(

const String &

name

)

const

virtual bool BALL::Expression::operator()

(

const Atom &

atom

)

const [virtual]

Evaluate the expression of atom

Parameters:

atom

Expression& BALL::Expression::operator=

(

const Expression &

expression

)

Assignment operator

bool BALL::Expression::operator==

(

const Expression &

expression

)

const

Equality operator

void BALL::Expression::registerPredicate	(	const String &	name,
		CreationMethod	creation_method
	)

Register a new predicate class.

void BALL::Expression::registerStandardPredicates_

(

)

[protected]

void BALL::Expression::setExpression

(

const String &

expression

)

throw (Exception::ParseError)

Set the expression and build a tree for it.

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Member Data Documentation

StringHashMap<CreationMethod> BALL::Expression::create_methods_ [protected]

String BALL::Expression::expression_string_ [protected]

ExpressionTree* BALL::Expression::expression_tree_ [protected]