EmptyCondExpression Class Reference

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

#include <emptycondexpression.h>

Inheritance diagram for EmptyCondExpression:

Collaboration diagram for EmptyCondExpression:

List of all members.

Public Member Functions

EmptyCondExpression (VarExpression *_var)

Constructor.

EmptyCondExpression (VarStepExpression *_varstep)

Constructor.

virtual ~EmptyCondExpression ()

virtual void scopeCheck (vector< unsigned > &def_vars, vector< unsigned > &introduced_vars, vector< unsigned > &violating_vars)

virtual void replaceVarId (unsigned old_id, unsigned new_id)

virtual void extractFSAMap (FSAMap *fsamap, unsigned parent_var)

virtual void extractParVarMap (ParVarMap *parvarmap)

virtual void extractDependencies (vector< DependencySet * > *depset)

virtual Expression * placeSignOffs (vector< SignOffExpression * > &signoffs)

void rewriteEmptyFuncts ()

virtual void rewriteAggregateFuncts ()

virtual void print (OutputStream &dos) const

virtual void init (BufferNode *root)

virtual void eval (OutputStream &eos, Environment *env, unsigned modus)

virtual bool evalCond (OutputStream &eos, Environment *env, unsigned modus)

Private Attributes

VarExpression * var

The entered VarExpression.

VarStepExpression * varstep

The entered VarStepExpression.

NotCondExpression * ncond

The rewritten NotCondExpression of this XQuery function fn:empty or of the entered VarExpression or VarStepExpression respectively.

Detailed Description

Represents XQuery standard function fn:empty.

Represents XQuery standard function fn:empty, which takes either a VarExpression, e.g. fn:empty($x), or a VarStepExpression, e.g. fn:empty($x/bib/book) or fn:empty(/bib//book) respectively, as argument and returns true if the sequence located through the entered VarExpression or the entered VarStepExpression respectively contains no items, false otherwise.

Note:: This expression does not exists instead it is rewritten to fn:not(fn:exists).

Author:: Michael Schmidt
Gunnar Jehl

Version:: 2.1

License:: Software License Agreement (BSD License)

Definition at line 57 of file emptycondexpression.h.

Constructor & Destructor Documentation

EmptyCondExpression::EmptyCondExpression ( VarExpression * _var )

Constructor.

Constructor - creating object for a VarExpression.

Parameters:

[in] _var Pointer to a VarExpression object.

Definition at line 37 of file emptycondexpression.cpp.

EmptyCondExpression::EmptyCondExpression ( VarStepExpression * _varstep )

Constructor.

Constructor - creating object for a VarStepExpression.

Parameters:

[in] _varstep Pointer to a VarStepExpression object.

Definition at line 41 of file emptycondexpression.cpp.

EmptyCondExpression::~EmptyCondExpression ( ) [virtual]

Destructor.

Definition at line 45 of file emptycondexpression.cpp.

References ncond.

Member Function Documentation

void EmptyCondExpression::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.

Reimplemented from Expression.

Definition at line 115 of file emptycondexpression.cpp.

References NotCondExpression::eval(), and ncond.

bool EmptyCondExpression::evalCond	(	OutputStream &	eos,
		Environment *	env,
		unsigned	modus
	)			`[virtual]`

Evaluates the corresponding CondExpression.

Parameters:

`[in]`	eos	Pointer to a OutputStream object.
`[in]`	env	Pointer to a Environment object.
`[in]`	modus	Evaluation modus.

Return values:

bool true if the corresponding CondExpression is true, false otherwise.

Exceptions:

RuntimeException

If illegal evaluation mode (argument: unsigned modus).

Implements CondExpression.

Definition at line 120 of file emptycondexpression.cpp.

References NotCondExpression::evalCond(), and ncond.

void EmptyCondExpression::extractDependencies ( vector< DependencySet * > * depset ) [virtual]

Extracts the needed dependencies of a query.

Extracts the needed dependencies of a query, which are needed for constructing the ProjectionTree.

Parameters:

[in,out] depset Pointer to a vector containing Pointer to DependencySet objects.

Return values:

void

Reimplemented from Expression.

Definition at line 75 of file emptycondexpression.cpp.

References NotCondExpression::extractDependencies(), and ncond.

void EmptyCondExpression::extractFSAMap	(	FSAMap *	fsamap,
		unsigned	parent_var
	)			`[virtual]`

Extracts the needed first straight ancestor (FSA) variables map.

Extracts the needed first straight ancestor (FSA) variables map, which is needed for correct insertion of SignOffExpression.

Parameters:

`[in,out]`	fsamap	Pointer to a FSAMap object.
`[in]`	parent_var	Parent variable.

Return values:

void

Reimplemented from Expression.

Definition at line 67 of file emptycondexpression.cpp.

References NotCondExpression::extractFSAMap(), and ncond.

void EmptyCondExpression::extractParVarMap ( ParVarMap * parvarmap ) [virtual]

Extracts the needed parent variable (ParVar) map.

Extracts the needed parent variable (ParVar) map, which is needed for constructing the VariableTree.

Parameters:

[in,out] parvarmap Pointer to a ParVarMap object.

Return values:

void

Reimplemented from Expression.

Definition at line 71 of file emptycondexpression.cpp.

References NotCondExpression::extractParVarMap(), and ncond.

void EmptyCondExpression::init ( BufferNode * root ) [virtual]

Initializes the query for evaluation.

Initializes the query for evaluation. Up to now only all required BufferIterator objects are created to speed up query evaluation.

Parameters:

[in] root Pointer to a BufferNode object.

Return values:

void

Reimplemented from Expression.

Definition at line 111 of file emptycondexpression.cpp.

References NotCondExpression::init(), and ncond.

Expression * EmptyCondExpression::placeSignOffs ( vector< SignOffExpression * > & signoffs ) [virtual]

Places all signOff-statements in the corresponding query.

Places all signOff-statements in the corresponding query, which are needed for active garbage collection by removing Role from the BufferNode.

Parameters:

[in] signoffs Pointer to a vector containing Pointer to SignOffExpression objects.

Return values:

Expression*

Pointer to a Expression object (following expression in the corresponding query).

Reimplemented from Expression.

Definition at line 79 of file emptycondexpression.cpp.

References ncond, and NotCondExpression::placeSignOffs().

void EmptyCondExpression::print ( OutputStream & dos ) const [virtual]

Prints the expression.

Parameters:

[in] dos Pointer to a OutputStream object.

Return values:

void

Implements Expression.

Definition at line 99 of file emptycondexpression.cpp.

References ncond, and var.

void EmptyCondExpression::replaceVarId	(	unsigned	old_id,
		unsigned	new_id
	)			`[virtual]`

Replaces all matching variable IDs by a new one.

Replaces all matching variable IDs by a new one, which is needed in case of calling method rewriteVarsteps().

Parameters:

`[in]`	old_id	Old variable ID.
`[in]`	new_id	New variable ID, which should be introduced instead.

Return values:

void

Reimplemented from Expression.

Definition at line 59 of file emptycondexpression.cpp.

References VarExpression::replaceVarId(), var, and varstep.

void EmptyCondExpression::rewriteAggregateFuncts ( ) [virtual]

Rewrites all arguments of all aggregate functions into an equivalent for-clause (with return-clause).

Return values:

void

Reimplemented from Expression.

Definition at line 95 of file emptycondexpression.cpp.

References ncond, and NotCondExpression::rewriteAggregateFuncts().

void EmptyCondExpression::rewriteEmptyFuncts ( ) [virtual]

Rewrites all fn:empty XQuery functions into equivalent fn:not(fn:exists) XQuery functions.

Return values:

void

Reimplemented from Expression.

Definition at line 86 of file emptycondexpression.cpp.

References ncond, Expression::setType(), var, and varstep.

void EmptyCondExpression::scopeCheck	(	vector< unsigned > &	def_vars,
		vector< unsigned > &	introduced_vars,
		vector< unsigned > &	violating_vars
	)			`[virtual]`

Returns if all used variables were previously (through a for-clause) defined or if a variable leaves their defined scope.

Parameters:

`[in]`	def_vars	Vector containing all previously defined variables.
`[in]`	introduced_vars	Vector containing all up to this expression defined variables.
`[in]`	violating_vars	Vector containing all variables which violates the scope condition.

Return values:

void

Reimplemented from Expression.

Definition at line 49 of file emptycondexpression.cpp.

References VarExpression::scopeCheck(), var, and varstep.

Member Data Documentation

NotCondExpression * EmptyCondExpression::ncond [private]

The rewritten NotCondExpression of this XQuery function fn:empty or of the entered VarExpression or VarStepExpression respectively.

The rewritten NotCondExpression of this XQuery function fn:empty or of the entered VarExpression or VarStepExpression respectively after calling method rewriteEmptyFuncts(). This member variable is NULL on creation of object but should not be NULL anymore after method rewriteEmptyFuncts() has been executed.

Definition at line 163 of file emptycondexpression.h.

Referenced by eval(), evalCond(), extractDependencies(), extractFSAMap(), extractParVarMap(), init(), placeSignOffs(), print(), rewriteAggregateFuncts(), rewriteEmptyFuncts(), and ~EmptyCondExpression().

VarExpression * EmptyCondExpression::var [private]

The entered VarExpression.

The entered VarExpression, which is the argument of the constructor. This member variable is NULL if the constructor was called with a VarStepExpression.

Definition at line 146 of file emptycondexpression.h.

Referenced by print(), replaceVarId(), rewriteEmptyFuncts(), and scopeCheck().

VarStepExpression * EmptyCondExpression::varstep [private]

The entered VarStepExpression.

The entered VarStepExpression, which is the argument of the constructor. This member variable is NULL if the constructor was called with a VarExpression.

Definition at line 153 of file emptycondexpression.h.

Referenced by replaceVarId(), rewriteEmptyFuncts(), and scopeCheck().


Public Member Functions
	EmptyCondExpression (VarExpression *_var)
	Constructor.
	EmptyCondExpression (VarStepExpression *_varstep)
	Constructor.
virtual	~EmptyCondExpression ()
virtual void	scopeCheck (vector< unsigned > &def_vars, vector< unsigned > &introduced_vars, vector< unsigned > &violating_vars)
virtual void	replaceVarId (unsigned old_id, unsigned new_id)
virtual void	extractFSAMap (FSAMap *fsamap, unsigned parent_var)
virtual void	extractParVarMap (ParVarMap *parvarmap)
virtual void	extractDependencies (vector< DependencySet * > *depset)
virtual Expression *	placeSignOffs (vector< SignOffExpression * > &signoffs)
void	rewriteEmptyFuncts ()
virtual void	rewriteAggregateFuncts ()
virtual void	print (OutputStream &dos) const
virtual void	init (BufferNode *root)
virtual void	eval (OutputStream &eos, Environment *env, unsigned modus)
virtual bool	evalCond (OutputStream &eos, Environment *env, unsigned modus)
Private Attributes
VarExpression *	var
	The entered VarExpression.
VarStepExpression *	varstep
	The entered VarStepExpression.
NotCondExpression *	ncond
	The rewritten NotCondExpression of this XQuery function `fn:empty` or of the entered VarExpression or VarStepExpression respectively.