AggregateFunctAvgExpression Class Reference

Represents XQuery standard function fn:avg. More...

#include <aggregatefunctavgexpression.h>

Inheritance diagram for AggregateFunctAvgExpression:

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Collaboration diagram for AggregateFunctAvgExpression:

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List of all members.

Public Member Functions
	AggregateFunctAvgExpression (VarExpression *_var)
	Constructor.
	AggregateFunctAvgExpression (VarStepExpression *_varstep)
	Constructor.
virtual	~AggregateFunctAvgExpression ()
virtual void	eval (OutputStream &eos, Environment *env, unsigned modus)
Private Member Functions
virtual long double	calculateValue (OutputStream &eos, Environment *env, unsigned modus, bool &empty_sequence)

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Detailed Description

Represents XQuery standard function fn:avg.

Represents XQuery standard function fn:avg, which takes either a VarExpression, e.g. fn:avg($x), or a VarStepExpression, e.g. fn:avg($x/bib/book) or fn:avg(/bib//book) respectively, as argument and returns the average value of the sequence located through the entered VarExpression or the entered VarStepExpression respectively.

Author:

Michael Schmidt

Gunnar Jehl

Version:

2.1

License:

Software License Agreement (BSD License)

Definition at line 60 of file aggregatefunctavgexpression.h.

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Constructor & Destructor Documentation

AggregateFunctAvgExpression::AggregateFunctAvgExpression

(

VarExpression *

_var

)

Constructor.

Constructor - creating object for a VarExpression.

Parameters:

[in]

_var

Pointer to a VarExpression object.

Definition at line 37 of file aggregatefunctavgexpression.cpp.

AggregateFunctAvgExpression::AggregateFunctAvgExpression

(

VarStepExpression *

_varstep

)

Constructor.

Constructor - creating object for a VarStepExpression.

Parameters:

[in]

_varstep

Pointer to a VarStepExpression object.

Definition at line 41 of file aggregatefunctavgexpression.cpp.

AggregateFunctAvgExpression::~AggregateFunctAvgExpression

(

)

[virtual]

Destructor.

Definition at line 45 of file aggregatefunctavgexpression.cpp.

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Member Function Documentation

long double AggregateFunctAvgExpression::calculateValue	(	OutputStream &	eos,
		Environment *	env,
		unsigned	modus,
		bool &	empty_sequence
	)			[private, virtual]

Result calculation of the corresponding aggregate function.

Result calculation of the corresponding aggregate function.

Parameters:

[in]	eos	Pointer to a OutputStream object.
[in]	env	Pointer to a Environment object.
[in]	modus	Evaluation modus.
[in]	empty_sequence	Indicator if aggreagte function is called on an empty sequence.

Return values:

long

double Result of the corresponding aggregate function.

Implements AggregateFunctExpression.

Definition at line 98 of file aggregatefunctavgexpression.cpp.

References AggregateFunctExpression::bit, BufferIterator::clear(), ForExpression::evalSignOffForBinding(), AggregateFunctExpression::forexp, VarExpression::getId(), BufferIterator::getNext(), Environment::getNodeBinding(), MiscFunctions::getRoundFrom(), MiscFunctions::getSummationFrom(), BufferIterator::init(), LOCK_CONTEXT_ALWAYS_CLEAR, READ_UP_TO_CLOSE_CONTEXT, AggregateFunctExpression::var, and AggregateFunctExpression::varstep.

Referenced by eval().

void AggregateFunctAvgExpression::eval	(	OutputStream &	eos,
		Environment *	env,
		unsigned	modus
	)			[virtual]

Evaluates the expression in the given environment.

Evaluates the expression in the given environment. The evaluation takes place in the environment that is passed to this method. In addition, the parameter modus is one of the following: EVAL_QUERY, EVAL_QUERY_SILENT or EVAL_SIGNOFF (see also the corresponding defines for more information). This method implements the XQuery semantics for the standard expression types, but also the GCX specific extensions like signOff-statements.

Parameters:

[in]	eos	Pointer to a OutputStream object.
[in]	env	Pointer to an Environment object.
[in]	modus	The query evaluation mode.

Exceptions:

RuntimeException

If illegal evaluation mode.

Exceptions:

InvalidCastException

If it is not possible to cast all affected PCDATA values of an XML document to numeric values or some value calculation will cause an (internal) error.

Implements AggregateFunctExpression.

Definition at line 48 of file aggregatefunctavgexpression.cpp.

References calculateValue(), OperandExpression::cur_val, ForExpression::eval(), EVAL_QUERY, EVAL_QUERY_SILENT, EVAL_SIGNOFF, AggregateFunctExpression::forexp, MiscFunctions::getStringFromNumerical(), OUTPUT_AVG_ON_EMPTY_SEQUENCE, Value::setNumVal(), and Value::setStrVal().