Qore's SQL "NULL" parse tree/value type, not-referenced counted, not dynamically allocated. More...

#include <QoreNullNode.h>

Inheritance diagram for QoreNullNode:

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Collaboration diagram for QoreNullNode:

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Public Member Methods
virtual DLLEXPORT QoreString *	getAsString (bool &del, int foff, class ExceptionSink *xsink) const
	returns a QoreString with the text: "<NULL>" More...

virtual DLLEXPORT int	getAsString (QoreString &str, int foff, class ExceptionSink *xsink) const
	concatenate "<NULL>" to an existing QoreString More...

virtual DLLEXPORT const char *	getTypeName () const
	returns the type name as a c string

virtual DLLEXPORT bool	is_equal_hard (const AbstractQoreNode v, ExceptionSink xsink) const
	tests for equality without type conversions (hard compare) More...

virtual DLLEXPORT bool	is_equal_soft (const AbstractQoreNode v, ExceptionSink xsink) const
	tests for equality with possible type conversion (soft compare) More...

virtual DLLLOCAL int	parseInit (QoreValue &val, QoreParseContext &parse_context)
	returns the type information

Public Member Methods inherited from UniqueValueQoreNode
DLLLOCAL	UniqueValueQoreNode (const UniqueValueQoreNode &)
	copy constructor

DLLLOCAL	UniqueValueQoreNode (qore_type_t t)
	constructor takes the type argument

DLLLOCAL void *	operator new (size_t)=delete
	this function is not implemented; it is here as a private function in order to prohibit it from being used

DLLLOCAL UniqueValueQoreNode &	operator= (const UniqueValueQoreNode &)=delete
	this function is not implemented

virtual DLLEXPORT AbstractQoreNode *	realCopy () const
	returns itself; objects of this type are not reference-counted and only deleted manually (by static destruction)

Public Member Methods inherited from SimpleValueQoreNode
DLLLOCAL	SimpleValueQoreNode (qore_type_t t, bool n_there_can_be_only_one=false)
	creates the object by assigning the type code and setting the "value" flag, unsetting the "needs_eval" flag, and setting "there_can_be_only_one"

Public Member Methods inherited from SimpleQoreNode
DLLLOCAL	SimpleQoreNode (const SimpleQoreNode &v)
	copy constructor

DLLLOCAL	SimpleQoreNode (qore_type_t t, bool n_value, bool n_needs_eval, bool n_there_can_be_only_one=false)
	constructor takes the type and value arguments

DLLEXPORT void	deref (ExceptionSink *xsink)
	decrements the reference count and deletes the object when references = 0 More...

SimpleQoreNode &	operator= (const SimpleQoreNode &)=delete
	this function is not implemented

Public Member Methods inherited from AbstractQoreNode
DLLEXPORT	AbstractQoreNode (const AbstractQoreNode &v)
	copy constructor

DLLEXPORT	AbstractQoreNode (qore_type_t t, bool n_value, bool n_needs_eval, bool n_there_can_be_only_one=false, bool n_custom_reference_handlers=false)
	constructor takes the type More...

virtual DLLEXPORT void	customDeref (ExceptionSink *xsink)

virtual DLLEXPORT void	customRef () const
	special processing when the object's reference count transitions from 0-1 More...

DLLEXPORT void	deref (ExceptionSink *xsink)
	decrements the reference count and calls derefImpl() if there_can_be_only_one is false, otherwise does nothing More...

virtual DLLEXPORT bool	derefImpl (ExceptionSink *xsink)
	decrements the reference count More...

DLLEXPORT QoreValue	eval (bool &needs_deref, ExceptionSink *xsink) const
	optionally evaluates the argument More...

DLLEXPORT QoreValue	eval (ExceptionSink *xsink) const
	evaluates the object and returns a value (or 0) More...

DLLEXPORT int64	getAsBigInt () const
	returns the 64-bit integer value of the object More...

DLLEXPORT bool	getAsBool () const
	returns the boolean value of the object More...

DLLEXPORT double	getAsFloat () const
	returns the float value of the object More...

DLLEXPORT int	getAsInt () const
	returns the integer value of the object More...

virtual DLLEXPORT class DateTime *	getDateTimeRepresentation (bool &del) const
	returns the DateTime representation of this type (default implementation: returns ZeroDate, del = false) More...

virtual DLLEXPORT void	getDateTimeRepresentation (DateTime &dt) const
	assigns the date representation of a value to the DateTime reference passed, default implementation does nothing More...

virtual DLLEXPORT QoreString *	getStringRepresentation (bool &del) const
	returns the value of the type converted to a string, default implementation: returns the empty string More...

virtual DLLEXPORT void	getStringRepresentation (QoreString &str) const
	concatentates the value of the type to an existing QoreString reference, default implementation does nothing More...

DLLLOCAL qore_type_t	getType () const
	returns the data type More...

DLLLOCAL bool	is_value () const
	returns true if the node represents a value More...

DLLLOCAL bool	isReferenceCounted () const
	returns true if the object is reference-counted

DLLLOCAL bool	needs_eval () const
	returns true if the object needs evaluation to return a value, false if not More...

DLLLOCAL AbstractQoreNode &	operator= (const AbstractQoreNode &)
	this function is not implemented; it is here as a private function in order to prohibit it from being used

DLLEXPORT void	ref () const
	increments the reference count

DLLEXPORT AbstractQoreNode *	refSelf () const
	returns "this" with an incremented reference count More...

Public Member Methods inherited from QoreReferenceCounter
DLLEXPORT	QoreReferenceCounter ()
	creates the reference counter object

DLLEXPORT	QoreReferenceCounter (const QoreReferenceCounter &old)
	creates a new object with a reference count of 1 More...

DLLEXPORT	~QoreReferenceCounter ()
	destroys the reference counter object

DLLEXPORT bool	is_unique () const
	returns true if the reference count is 1 More...

DLLEXPORT int	reference_count () const
	gets the reference count More...

DLLEXPORT bool	ROdereference () const
	atomically decrements the reference count More...

DLLEXPORT void	ROreference () const
	atomically increments the reference count

Static Public Member Methods
static DLLLOCAL qore_type_t	getStaticTypeCode ()
	returns the type code (useful in templates)

static DLLLOCAL const char *	getStaticTypeName ()
	returns the type name (useful in templates)

Private Member Methods
virtual DLLEXPORT QoreValue	evalImpl (bool &needs_deref, ExceptionSink *xsink) const
	this function is never called for this type More...

DLLLOCAL QoreValue	evalImpl (bool &needs_deref, ExceptionSink *xsink) const
	should never be called for value types More...

Private Member Methods inherited from AbstractQoreNode
virtual DLLEXPORT	~AbstractQoreNode ()
	default destructor does nothing More...

Additional Inherited Members
Private Attributes inherited from AbstractQoreNode
bool	custom_reference_handlers: 1
	set to one for objects that need custom reference handlers

bool	needs_eval_flag: 1
	if this is true then the type can be evaluated

bool	there_can_be_only_one: 1
	if this is set to true, then reference counting is turned off for objects of this class

qore_type_t	type: 11
	the type of the object More...

bool	value: 1
	this is true for values, if false then either the type needs evaluation to produce a value or is a parse expression

Detailed Description

Qore's SQL "NULL" parse tree/value type, not-referenced counted, not dynamically allocated.

This class cannot be instantiated; there will only be one single QoreNullNode object instantiated and used everywhere in the Qore library; use the null() function or simply &Null to acquire a pointer to an object of this class. This value can be represented in Qore code as the keyword "NULL". NOTE: Qore's "NULL" is not equal to "NOTHING"

See also: QoreNothingNode

Member Function Documentation

◆ evalImpl() [1/2]

virtual DLLEXPORT QoreValue SimpleValueQoreNode::evalImpl

private

this function is never called for this type

See also: AbstractQoreNode::evalImpl()

◆ evalImpl() [2/2]

DLLLOCAL QoreValue QoreNullNode::evalImpl	(	bool &	needs_deref,
		ExceptionSink *	xsink
	)		const

privatevirtual

should never be called for value types

in debugging builds of the library, calls to this function will abort

Reimplemented from SimpleValueQoreNode.

◆ getAsString() [1/2]

virtual DLLEXPORT QoreString* QoreNullNode::getAsString	(	bool &	del,
		int	foff,
		class ExceptionSink *	xsink
	)		const

virtual

returns a QoreString with the text: "<NULL>"

used for n and N printf formatting

Parameters

del	is always set to true for this implementation of the function, meaning that the returned QoreString pointer should be deleted
foff	for multi-line formatting offset, -1 = no line breaks (ignored by this version of the function)
xsink	ignored by this version of the function NOTE: Use the QoreNodeAsStringHelper class (defined in QoreStringNode.h) instead of using this function directly

See also: QoreNodeAsStringHelper

Implements AbstractQoreNode.

◆ getAsString() [2/2]

virtual DLLEXPORT int QoreNullNode::getAsString	(	QoreString &	str,
		int	foff,
		class ExceptionSink *	xsink
	)		const

virtual

concatenate "<NULL>" to an existing QoreString

used for n and N printf formatting

Parameters

str	the string representation of the type will be concatenated to this QoreString reference
foff	for multi-line formatting offset, -1 = no line breaks
xsink	if an error occurs, the Qore-language exception information will be added here

Returns: -1 for exception raised, 0 = OK

Implements AbstractQoreNode.

◆ is_equal_hard()

virtual DLLEXPORT bool QoreNullNode::is_equal_hard	(	const AbstractQoreNode *	v,
		ExceptionSink *	xsink
	)		const

virtual

tests for equality without type conversions (hard compare)

Parameters

v	the value to compare
xsink	ignored for this version of the function

Implements AbstractQoreNode.

◆ is_equal_soft()

virtual DLLEXPORT bool QoreNullNode::is_equal_soft	(	const AbstractQoreNode *	v,
		ExceptionSink *	xsink
	)		const

virtual

tests for equality with possible type conversion (soft compare)

since no type can be implicitly converted to a NULL, this comparison is the same as is_equal_hard() for QoreNullNode

Parameters

v	the value to compare
xsink	ignored for this version of the function

Implements AbstractQoreNode.

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

/tmp/qore/include/qore/QoreNullNode.h

Public Member Methods

Static Public Member Methods

Private Member Methods

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ evalImpl() [1/2]

◆ evalImpl() [2/2]

◆ getAsString() [1/2]

◆ getAsString() [2/2]

◆ is_equal_hard()

◆ is_equal_soft()