net.sf.saxon.expr.flwor

Class Clause

java.lang.Object

net.sf.saxon.expr.flwor.Clause

Direct Known Subclasses:

CountClause, ForClause, GroupByClause, LetClause, OrderByClause, TraceClause, WhereClause, WindowClause

public abstract class Clause
extends Object

A "Clause" refers specifically to one of the clauses of a FLWOR expression, for example the "for" clause, the "let" clause, the "where" or "order by" clause. (The "return" clause, however, is not modelled as a Clause).

Field Summary

Fields

Modifier and Type	Field and Description
static int	COUNT
static int	FOR
static int	GROUPBYCLAUSE
static int	LET
static int	ORDERBYCLAUSE
static int	TRACE
static int	WHERE
static int	WINDOW

Constructor Summary

Constructors

Constructor and Description
Clause()

Method Summary

Methods

Modifier and Type	Method and Description
boolean	containsNonInlineableVariableReference(Binding binding) Determine whether the clause contains a reference to a local variable binding that cannot be inlined
abstract Clause	copy() Create a copy of this clause
abstract void	explain(ExpressionPresenter out) Diagnostic print of expression structure.
void	gatherVariableReferences(ExpressionVisitor visitor, Binding binding, List<VariableReference> refs) Build a list of all references to a variables declared in this clause
abstract int	getClauseKey() Get a keyword identifying what kind of clause this is
int	getLocationId() Get the location ID, which can be used in conjunction with a LocationProvider to determine the system ID and line number of the clause
abstract TuplePull	getPullStream(TuplePull base, XPathContext context) Get a pull-mode tuple stream that implements the functionality of this clause, taking its input from another tuple stream which this clause modifies
abstract TuplePush	getPushStream(TuplePush destination, XPathContext context) Get a push-mode tuple stream that implements the functionality of this clause, supplying its output to another tuple stream
LocalVariableBinding[]	getRangeVariables() Get the variables bound by this clause
void	optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) Optimize any expressions contained within this clause
abstract void	processSubExpressions(ExpressionProcessor processor) Process the subexpressions of this clause
void	refineVariableType(ExpressionVisitor visitor, List<VariableReference> references, Expression returnExpr) Supply improved type information to the expressions that contain references to the variables declared in this clause
void	setLocationId(int locationId) Set the location ID, which can be used in conjunction with a LocationProvider to determine the system ID and line number of the clause
void	typeCheck(ExpressionVisitor visitor) Type-check any expression contained within this clause

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

FOR

public static final int FOR

See Also:

Constant Field Values

LET

public static final int LET

See Also:

Constant Field Values

WINDOW

public static final int WINDOW

See Also:

Constant Field Values

GROUPBYCLAUSE

public static final int GROUPBYCLAUSE

See Also:

Constant Field Values

COUNT

public static final int COUNT

See Also:

Constant Field Values

ORDERBYCLAUSE

public static final int ORDERBYCLAUSE

See Also:

Constant Field Values

WHERE

public static final int WHERE

See Also:

Constant Field Values

TRACE

public static final int TRACE

See Also:

Constant Field Values

Constructor Detail

Clause

public Clause()

Method Detail

getLocationId

public int getLocationId()

Get the location ID, which can be used in conjunction with a LocationProvider to determine the system ID and line number of the clause

Returns:

the location ID

setLocationId

public void setLocationId(int locationId)

Set the location ID, which can be used in conjunction with a LocationProvider to determine the system ID and line number of the clause

Parameters:

locationId - the location ID

copy

public abstract Clause copy()

Create a copy of this clause

Returns:

the copied clause

optimize

public void optimize(ExpressionVisitor visitor,
            ExpressionVisitor.ContextItemType contextItemType)
              throws XPathException

Optimize any expressions contained within this clause

Parameters:

visitor - the ExpressionVisitor, providing access to static context information

contextItemType - the type of the context item

Throws:

XPathException - if any error is detected

typeCheck

public void typeCheck(ExpressionVisitor visitor)
               throws XPathException

Type-check any expression contained within this clause

Parameters:

visitor - the ExpressionVisitor, providing access to static context information

Throws:

XPathException - if any error is detected

getPullStream

public abstract TuplePull getPullStream(TuplePull base,
                      XPathContext context)

Get a pull-mode tuple stream that implements the functionality of this clause, taking its input from another tuple stream which this clause modifies

Parameters:

base - the input tuple stream

context - the dynamic evaluation context

Returns:

the output tuple stream

getPushStream

public abstract TuplePush getPushStream(TuplePush destination,
                      XPathContext context)

Get a push-mode tuple stream that implements the functionality of this clause, supplying its output to another tuple stream

Parameters:

destination - the output tuple stream

context - the dynamic evaluation context

Returns:

the push tuple stream that implements the functionality of this clause of the FLWOR expression

processSubExpressions

public abstract void processSubExpressions(ExpressionProcessor processor)
                                    throws XPathException

Process the subexpressions of this clause

Parameters:

processor - the expression processor used to process the subexpressions

Throws:

XPathException - if any error is detected

explain

public abstract void explain(ExpressionPresenter out)

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Parameters:

out - the expression presenter used to display the structure

getRangeVariables

public LocalVariableBinding[] getRangeVariables()

Get the variables bound by this clause

Returns:

the variable bindings

gatherVariableReferences

public void gatherVariableReferences(ExpressionVisitor visitor,
                            Binding binding,
                            List<VariableReference> refs)

Build a list of all references to a variables declared in this clause

Parameters:

visitor - the expression visitor

binding - a variable declared in this clause

refs - the list of variable references, initially empty, to which the method will append

containsNonInlineableVariableReference

public boolean containsNonInlineableVariableReference(Binding binding)

Determine whether the clause contains a reference to a local variable binding that cannot be inlined

Parameters:

binding - the binding for the local variable in question

Returns:

true if this clause uses the variable in a way that does not permit inlining

refineVariableType

public void refineVariableType(ExpressionVisitor visitor,
                      List<VariableReference> references,
                      Expression returnExpr)

Supply improved type information to the expressions that contain references to the variables declared in this clause

Parameters:

visitor - the expression visitor

references - the list of variable references

returnExpr - the expression in the return clause

getClauseKey

public abstract int getClauseKey()

Get a keyword identifying what kind of clause this is

Returns:

the kind of clause