net.sf.saxon.expr.flwor
Class Clause

java.lang.Object
  net.sf.saxon.expr.flwor.Clause

Direct Known Subclasses:

CountClause, ForClause, GroupByClause, LetClause, OrderByClause, 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

static int	COUNT
static int	FOR
static int	GROUPBYCLAUSE
static int	LET
static int	ORDERBYCLAUSE
static int	WHERE
static int	WINDOW

Constructor Summary

Clause()

Method Summary

abstract Clause	copy()
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
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	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

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Constant Field Values

WINDOW

public static final int WINDOW

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Constant Field Values

GROUPBYCLAUSE

public static final int GROUPBYCLAUSE

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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

Constructor Detail

Clause

public Clause()

Method Detail

copy

public abstract Clause copy()

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

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