IfExpression Class Reference

Represents XQuery conditional expression if-then-else. More...

#include <ifexpression.h>

Inheritance diagram for IfExpression:

Collaboration diagram for IfExpression:

List of all members.

Public Member Functions

IfExpression (CondExpression *_cond, Expression *_thenexp, Expression *_elseexp)

Constructor.

virtual ~IfExpression ()

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 mergeSequences ()

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)

virtual void rewriteWhereExps ()

virtual void rewriteEmptyFuncts ()

virtual void rewriteVarstepCondExps ()

virtual void rewriteAggregateFuncts ()

virtual void rewriteVarsteps ()

virtual void print (OutputStream &dos) const

virtual void init (BufferNode *root)

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

virtual bool containsDirectOutput ()

Private Attributes

CondExpression * cond

The entered CondExpression.

Expression * thenexp

The entered Expression.

Expression * elseexp

The entered Expression.

Detailed Description

Represents XQuery conditional expression if-then-else.

Represents XQuery conditional expression if-then-else, which takes therefore one CondExpression and two Expression, e.g. if (fn:exists($x)) then $x/title else(), as arguments and returns the then Expression if the CondExpression is true, the else Expression otherwise.

Author:: Michael Schmidt
Gunnar Jehl

Version:: 2.1

License:: Software License Agreement (BSD License)

Definition at line 54 of file ifexpression.h.

Constructor & Destructor Documentation

IfExpression::IfExpression	(	CondExpression *	_cond,
		Expression *	_thenexp,
		Expression *	_elseexp
	)

Constructor.

Constructor - creating object for one CondExpression and two Expression.

Parameters:

`[in]`	_cond	Pointer to a CondExpression object.
`[in]`	_thenexp	Pointer to a Expression object.
`[in]`	_elseexp	Pointer to a Expression object.

Definition at line 37 of file ifexpression.cpp.

IfExpression::~IfExpression ( ) [virtual]

Destructor.

Definition at line 41 of file ifexpression.cpp.

References cond, elseexp, and thenexp.

Member Function Documentation

bool IfExpression::containsDirectOutput ( ) [virtual]

Returns if the corresponding expression produces direct output.

Returns if the corresponding expression produces direct output. Direct output is meant that this subexpression produces output such as node constructs or strings.

Return values:

bool true if the corresponding expression produces direct output, false otherwise.

Reimplemented from Expression.

Definition at line 194 of file ifexpression.cpp.

References Expression::containsDirectOutput(), elseexp, Expression::getType(), and thenexp.

Referenced by WhereExpression::containsDirectOutput().

void IfExpression::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 164 of file ifexpression.cpp.

References cond, elseexp, Expression::eval(), EVAL_QUERY, EVAL_SIGNOFF, CondExpression::evalCond(), and thenexp.

Referenced by WhereExpression::eval().

void IfExpression::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 79 of file ifexpression.cpp.

References cond, elseexp, Expression::extractDependencies(), and thenexp.

Referenced by WhereExpression::extractDependencies().

void IfExpression::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 ifexpression.cpp.

References cond, elseexp, Expression::extractFSAMap(), and thenexp.

Referenced by WhereExpression::extractFSAMap().

void IfExpression::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 73 of file ifexpression.cpp.

References cond, elseexp, Expression::extractParVarMap(), and thenexp.

Referenced by WhereExpression::extractParVarMap().

void IfExpression::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 158 of file ifexpression.cpp.

References cond, elseexp, Expression::init(), and thenexp.

Referenced by WhereExpression::init().

void IfExpression::mergeSequences ( ) [virtual]

Merges belonging together XQuery sequences into a single sequence.

Merges belonging together XQuery sequences into a single sequence, which is done because of better/nicer output look.

Return values:

void

Reimplemented from Expression.

Definition at line 61 of file ifexpression.cpp.

References cond, elseexp, Expression::mergeSequences(), and thenexp.

Referenced by WhereExpression::mergeSequences().

Expression * IfExpression::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 85 of file ifexpression.cpp.

References cond, elseexp, Expression::placeSignOffs(), and thenexp.

Referenced by WhereExpression::placeSignOffs().

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

Prints the expression.

Parameters:

[in] dos Pointer to a OutputStream object.

Return values:

void

Implements Expression.

Definition at line 145 of file ifexpression.cpp.

References decrementIndents(), incrementIndents(), NEWLINE, and writeIndents().

void IfExpression::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 55 of file ifexpression.cpp.

References cond, elseexp, Expression::replaceVarId(), and thenexp.

void IfExpression::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 111 of file ifexpression.cpp.

References cond, elseexp, Expression::rewriteAggregateFuncts(), and thenexp.

Referenced by WhereExpression::rewriteAggregateFuncts().

void IfExpression::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 99 of file ifexpression.cpp.

References cond, elseexp, Expression::rewriteEmptyFuncts(), and thenexp.

Referenced by WhereExpression::rewriteEmptyFuncts().

void IfExpression::rewriteVarstepCondExps ( ) [virtual]

Rewrites all if($x) if-conditions into equivalent if(fn:not(fn:empty($x))) XQuery expressions.

Return values:

void

Reimplemented from Expression.

Definition at line 105 of file ifexpression.cpp.

References cond, elseexp, Expression::rewriteVarstepCondExps(), and thenexp.

Referenced by WhereExpression::rewriteVarstepCondExps().

void IfExpression::rewriteVarsteps ( ) [virtual]

Rewrites all varstep expressions, which produces output into an equivalent for-clause (with return-clause).

Rewrites all varstep expressions, which produces output into an equivalent for-clause (with return-clause). This method belongs to the 'earlier execution of signoff-statements' optimization.

Return values:

void

Reimplemented from Expression.

Definition at line 117 of file ifexpression.cpp.

References VarExpression::clone(), elseexp, VarName::getInstance(), Expression::getType(), Expression::rewriteVarsteps(), and thenexp.

Referenced by WhereExpression::rewriteVarsteps().

void IfExpression::rewriteWhereExps ( ) [virtual]

Rewrites all where-clauses in the query into equivalent if-expressions.

Rewrites all where-clauses in the query into equivalent if-expressions, i.e. rewrites all WhereExpression into equivalent IfExpression.

Return values:

void

Reimplemented from Expression.

Definition at line 93 of file ifexpression.cpp.

References cond, elseexp, Expression::rewriteWhereExps(), and thenexp.

Referenced by WhereExpression::rewriteWhereExps().

void IfExpression::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 47 of file ifexpression.cpp.

References cond, elseexp, Expression::scopeCheck(), and thenexp.

Member Data Documentation

CondExpression * IfExpression::cond [private]

The entered CondExpression.

The entered CondExpression, which is the first argument of the constructor and defines the if-condition.

Definition at line 159 of file ifexpression.h.

Referenced by eval(), extractDependencies(), extractFSAMap(), extractParVarMap(), init(), mergeSequences(), placeSignOffs(), replaceVarId(), rewriteAggregateFuncts(), rewriteEmptyFuncts(), rewriteVarstepCondExps(), rewriteWhereExps(), scopeCheck(), and ~IfExpression().

Expression * IfExpression::elseexp [private]

The entered Expression.

The entered Expression, which is the third argument of the constructor and defines the else-case.

Definition at line 173 of file ifexpression.h.

Referenced by containsDirectOutput(), eval(), extractDependencies(), extractFSAMap(), extractParVarMap(), init(), mergeSequences(), placeSignOffs(), replaceVarId(), rewriteAggregateFuncts(), rewriteEmptyFuncts(), rewriteVarstepCondExps(), rewriteVarsteps(), rewriteWhereExps(), scopeCheck(), and ~IfExpression().

Expression * IfExpression::thenexp [private]

The entered Expression.

The entered Expression, which is the second argument of the constructor and defines the then-case.

Definition at line 166 of file ifexpression.h.

Referenced by containsDirectOutput(), eval(), extractDependencies(), extractFSAMap(), extractParVarMap(), init(), mergeSequences(), placeSignOffs(), replaceVarId(), rewriteAggregateFuncts(), rewriteEmptyFuncts(), rewriteVarstepCondExps(), rewriteVarsteps(), rewriteWhereExps(), scopeCheck(), and ~IfExpression().


Public Member Functions
	IfExpression (CondExpression _cond, Expression _thenexp, Expression *_elseexp)
	Constructor.
virtual	~IfExpression ()
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	mergeSequences ()
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)
virtual void	rewriteWhereExps ()
virtual void	rewriteEmptyFuncts ()
virtual void	rewriteVarstepCondExps ()
virtual void	rewriteAggregateFuncts ()
virtual void	rewriteVarsteps ()
virtual void	print (OutputStream &dos) const
virtual void	init (BufferNode *root)
virtual void	eval (OutputStream &eos, Environment *env, unsigned modus)
virtual bool	containsDirectOutput ()
Private Attributes
CondExpression *	cond
	The entered CondExpression.
Expression *	thenexp
	The entered Expression.
Expression *	elseexp
	The entered Expression.