QoreNothingNode Class Reference

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

#include <QoreNothingNode.h>

Inheritance diagram for QoreNothingNode:

List of all members.

Public Member Functions
virtual DLLEXPORT int	getAsString (QoreString &str, int foff, class ExceptionSink *xsink) const
	concatenate "<NOTHING>" to an existing QoreString
virtual DLLEXPORT QoreString *	getAsString (bool &del, int foff, class ExceptionSink *xsink) const
	returns a QoreString with the text: "<NOTHING>"
virtual DLLEXPORT bool	is_equal_soft (const AbstractQoreNode *v, ExceptionSink *xsink) const
	tests for equality with possible type conversion (soft compare)
virtual DLLEXPORT bool	is_equal_hard (const AbstractQoreNode *v, ExceptionSink *xsink) const
	tests for equality without type conversions (hard compare)
virtual DLLEXPORT const char *	getTypeName () const
	returns the type name as a c string
virtual DLLLOCAL AbstractQoreNode *	parseInit (LocalVar *oflag, int pflag, int &lvids, const QoreTypeInfo *&typeInfo)
	returns the type information
Protected Member Functions
DLLLOCAL AbstractQoreNode *	evalImpl (ExceptionSink *xsink) const
	should never be called for value types

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Detailed Description

Qore's SQL "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

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Member Function Documentation

DLLLOCAL AbstractQoreNode* QoreNothingNode::evalImpl

(

ExceptionSink *

xsink

)

const [protected, virtual]

should never be called for value types

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

Reimplemented from SimpleValueQoreNode.

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:

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.

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:

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.

virtual DLLEXPORT bool QoreNothingNode::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.

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:

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

Implements AbstractQoreNode.

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

• include/qore/QoreNothingNode.h (4311)