Qore Programming Language  1.7.0
QoreNothingNode Class Reference

Qore's "NOTHING" parse tree/value type, not-referenced counted, not dynamically allocated. More...

#include <QoreNothingNode.h>

Inheritance diagram for QoreNothingNode:
Collaboration diagram for QoreNothingNode:

Public Member Methods

virtual DLLEXPORT QoreStringgetAsString (bool &del, int foff, class ExceptionSink *xsink) const
 returns a QoreString with the text: "<NOTHING>" More...
 
virtual DLLEXPORT int getAsString (QoreString &str, int foff, class ExceptionSink *xsink) const
 concatenate "<NOTHING>" 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 UniqueValueQoreNodeoperator= (const UniqueValueQoreNode &)=delete
 this function is not implemented
 
virtual DLLEXPORT AbstractQoreNoderealCopy () 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...
 
SimpleQoreNodeoperator= (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...
 
virtual DLLLOCAL int64 getAsBigIntImpl () const
 default implementation, returns 0 More...
 
DLLEXPORT bool getAsBool () const
 returns the boolean value of the object More...
 
virtual DLLLOCAL bool getAsBoolImpl () const
 default implementation, returns false More...
 
DLLEXPORT double getAsFloat () const
 returns the float value of the object More...
 
virtual DLLLOCAL double getAsFloatImpl () const
 default implementation, returns 0.0 More...
 
DLLEXPORT int getAsInt () const
 returns the integer value of the object More...
 
virtual DLLLOCAL int getAsIntImpl () const
 default implementation, returns 0 More...
 
virtual DLLEXPORT class DateTimegetDateTimeRepresentation (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 QoreStringgetStringRepresentation (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 AbstractQoreNodeoperator= (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 AbstractQoreNoderefSelf () 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 "NOTHING" parse tree/value type, not-referenced counted, not dynamically allocated.

This class cannot be instantiated; there will only be one single QoreNothingNode object instantiated and used everywhere in the Qore library. Use the nothing() function or simply &Nothing to acquire a pointer to an object of this class. This value can be represented in Qore code as the keyword "NOTHING"

Note
Qore's "NULL" is not equal to "NOTHING"
in C++ code, use the is_nothing() function to test an AbstractQoreNode* to see if it's "NOTHING" (because also a null pointer is equivalent to NOTHING)
See also
QoreNullNode

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

returns a QoreString with the text: "<NOTHING>"

used for n and N printf formatting

Parameters
delis always set to true for this implementation of the function, meaning that the returned QoreString pointer should be deleted
fofffor multi-line formatting offset, -1 = no line breaks (ignored by this version of the function)
xsinkignored 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 QoreNothingNode::getAsString ( QoreString str,
int  foff,
class ExceptionSink xsink 
) const
virtual

concatenate "<NOTHING>" to an existing QoreString

used for n and N printf formatting

Parameters
strthe string representation of the type will be concatenated to this QoreString reference
fofffor multi-line formatting offset, -1 = no line breaks
xsinkif 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 QoreNothingNode::is_equal_hard ( const AbstractQoreNode v,
ExceptionSink xsink 
) const
virtual

tests for equality without type conversions (hard compare)

Parameters
vthe value to compare
xsinkignored for this version of the function

Implements AbstractQoreNode.

◆ is_equal_soft()

virtual DLLEXPORT bool QoreNothingNode::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 NOTHING, this comparison is the same as is_equal_hard() for QoreNothingNode

Parameters
vthe value to compare
xsinkignored for this version of the function

Implements AbstractQoreNode.


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