ExistsCondExpression Class Reference

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

#include <existscondexpression.h>

Inheritance diagram for ExistsCondExpression:

Collaboration diagram for ExistsCondExpression:

List of all members.

Public Member Functions

ExistsCondExpression (VarExpression *_var)

Constructor.

ExistsCondExpression (VarStepExpression *_varstep)

Constructor.

virtual ~ExistsCondExpression ()

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 extractDependencies (vector< DependencySet * > *depset)

virtual void print (OutputStream &dos) const

void init (BufferNode *root)

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

Private Attributes

VarExpression * var

The entered VarExpression.

VarStepExpression * varstep

The entered VarStepExpression.

BufferIterator * bit

The initialized BufferIterator for the entered VarExpression or VarStepExpression.

Detailed Description

Represents XQuery standard function fn:exists.

Represents XQuery standard function fn:exists, which takes either a VarExpression, e.g. fn:exists($x), or a VarStepExpression, e.g. fn:exists($x/bib/book) or fn:exists(/bib//book) respectively, as argument and returns true if the sequence located through the entered VarExpression or the entered VarStepExpression respectively contains one or more items, false otherwise.

Author:: Michael Schmidt
Gunnar Jehl

Version:: 2.1

License:: Software License Agreement (BSD License)

Definition at line 55 of file existscondexpression.h.

Constructor & Destructor Documentation

ExistsCondExpression::ExistsCondExpression ( VarExpression * _var )

Constructor.

Constructor - creating object for a VarExpression.

Parameters:

[in] _var Pointer to a VarExpression object.

Definition at line 37 of file existscondexpression.cpp.

ExistsCondExpression::ExistsCondExpression ( VarStepExpression * _varstep )

Constructor.

Constructor - creating object for a VarStepExpression.

Parameters:

[in] _varstep Pointer to a VarStepExpression object.

Definition at line 41 of file existscondexpression.cpp.

ExistsCondExpression::~ExistsCondExpression ( ) [virtual]

Destructor.

Definition at line 45 of file existscondexpression.cpp.

References bit, var, and varstep.

Member Function Documentation

bool ExistsCondExpression::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 101 of file existscondexpression.cpp.

References bit, EVAL_QUERY, EVAL_SIGNOFF, VarExpression::getId(), BufferIterator::getNext(), Environment::getNodeBinding(), BufferIterator::init(), BufferIterator::reset(), var, and varstep.

Referenced by VarstepCondExpression::evalCond().

void ExistsCondExpression::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 69 of file existscondexpression.cpp.

References VarExpression::getId(), VarStepExpression::getPath(), PathExpression::isEmptyPath(), var, and varstep.

Referenced by VarstepCondExpression::extractDependencies().

void ExistsCondExpression::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 92 of file existscondexpression.cpp.

References bit, var, and varstep.

Referenced by VarstepCondExpression::init().

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

Prints the expression.

Parameters:

[in] dos Pointer to a OutputStream object.

Return values:

void

Implements Expression.

Definition at line 84 of file existscondexpression.cpp.

References var.

void ExistsCondExpression::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 61 of file existscondexpression.cpp.

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

void ExistsCondExpression::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 51 of file existscondexpression.cpp.

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

Member Data Documentation

BufferIterator * ExistsCondExpression::bit [private]

The initialized BufferIterator for the entered VarExpression or VarStepExpression.

The initialized BufferIterator for the entered VarExpression or VarStepExpression after calling method init(). This member variable is NULL on creation of object but should not be NULL anymore after method init() has been executed.

Definition at line 129 of file existscondexpression.h.

Referenced by evalCond(), init(), and ~ExistsCondExpression().

VarExpression * ExistsCondExpression::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 114 of file existscondexpression.h.

Referenced by evalCond(), extractDependencies(), init(), print(), replaceVarId(), scopeCheck(), and ~ExistsCondExpression().

VarStepExpression * ExistsCondExpression::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 121 of file existscondexpression.h.

Referenced by evalCond(), extractDependencies(), init(), replaceVarId(), scopeCheck(), and ~ExistsCondExpression().


Public Member Functions
	ExistsCondExpression (VarExpression *_var)
	Constructor.
	ExistsCondExpression (VarStepExpression *_varstep)
	Constructor.
virtual	~ExistsCondExpression ()
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	extractDependencies (vector< DependencySet * > *depset)
virtual void	print (OutputStream &dos) const
void	init (BufferNode *root)
virtual bool	evalCond (OutputStream &eos, Environment *env, unsigned modus)
Private Attributes
VarExpression *	var
	The entered VarExpression.
VarStepExpression *	varstep
	The entered VarStepExpression.
BufferIterator *	bit
	The initialized BufferIterator for the entered VarExpression or VarStepExpression.