net.sf.saxon.instruct

Class Namespace

Implemented Interfaces:
SourceLocator, EvaluableItem, InstructionInfoProvider, SequenceIterable, Serializable, SourceLocator, TailCallReturner

public class Namespace
extends SimpleNodeConstructor

An xsl:namespace element in the stylesheet. (XSLT 2.0)

Field Summary

Fields inherited from class net.sf.saxon.instruct.SimpleNodeConstructor

select

Fields inherited from class net.sf.saxon.expr.Expression

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD, locationId, staticProperties

Constructor Summary

Namespace(Expression name)
Create an xsl:namespace instruction for dynamic construction of namespace nodes

Method Summary

Expression
copy()
Copy an expression.
Item
evaluateItem(XPathContext context)
Evaluate as an expression.
int
evaluateNameCode(XPathContext context)
Run-time method to compute the name of the node being constructed.
void
explain(ExpressionPresenter out)
Diagnostic print of expression structure.
int
getCardinality()
Determine the static cardinality of the expression.
int
getInstructionNameCode()
Set the name of this instruction for diagnostic and tracing purposes
ItemType
getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible.
Iterator
iterateSubExpressions()
Get the immediate sub-expressions of this expression.
void
localTypeCheck(ExpressionVisitor visitor, ItemType contextItemType)
Method to perform type-checking specific to the kind of instruction
TailCall
processLeavingTail(XPathContext context)
ProcessLeavingTail: called to do the real work of this instruction.
protected void
promoteInst(PromotionOffer offer)
Offer promotion for subexpressions.
boolean
replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpression
Expression
simplify(ExpressionVisitor visitor)
Simplify an expression.

Methods inherited from class net.sf.saxon.instruct.SimpleNodeConstructor

checkContent, computeCardinality, computeSpecialProperties, createsNewNodes, evaluateItem, evaluateNameCode, expandChildren, getSelect, iterate, iterateSubExpressions, localTypeCheck, optimize, promoteInst, replaceSubExpression, setSelect, simplify, typeCheck

Methods inherited from class net.sf.saxon.instruct.Instruction

assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, createsNewNodes, dynamicError, evaluateAsString, evaluateItem, getImplementationMethod, getInstructionInfo, getInstructionNameCode, getItemType, getSourceLocator, isXSLT, iterate, process, processLeavingTail, promote, promoteInst, simplify

Methods inherited from class net.sf.saxon.expr.Expression

addToPathMap, adoptChildExpression, checkPermittedContents, computeCardinality, computeDependencies, computeSpecialProperties, computeStaticProperties, copy, display, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, explain, explain, findParentOf, getCardinality, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getItemType, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, iterate, iterateEvents, iterateSubExpressions, markTailFunctionCalls, optimize, process, promote, replaceSubExpression, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, simplify, staticTypeCheck, suppressValidation, toString, typeCheck, typeError

Constructor Details

Namespace

public Namespace(Expression name)
Create an xsl:namespace instruction for dynamic construction of namespace nodes
Parameters:
name - the expression to evaluate the name of the node (that is, the prefix)

Method Details

copy

public Expression copy()
Copy an expression. This makes a deep copy.
Overrides:
copy in interface Expression
Returns:
the copy of the original expression

evaluateItem

public Item evaluateItem(XPathContext context)
            throws XPathException
Evaluate as an expression. We rely on the fact that when these instructions are generated by XQuery, there will always be a valueExpression to evaluate the content
Specified by:
evaluateItem in interface EvaluableItem
Overrides:
evaluateItem in interface SimpleNodeConstructor

evaluateNameCode

public int evaluateNameCode(XPathContext context)
            throws XPathException
Run-time method to compute the name of the node being constructed. This is overridden for nodes that have a name. The default implementation returns -1, which is suitable for unnamed nodes such as comments
Overrides:
evaluateNameCode in interface SimpleNodeConstructor
Parameters:
context - the XPath dynamic evaluation context
Returns:
the name pool nameCode identifying the name of the constructed node
Throws:
XPathException - if any failure occurs

explain

public void explain(ExpressionPresenter out)
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
Overrides:
explain in interface Expression

getCardinality

public int getCardinality()
Determine the static cardinality of the expression. This establishes how many items there will be in the result of the expression, at compile time (i.e., without actually evaluating the result.
Overrides:
getCardinality in interface Expression
Returns:
one of the values Cardinality.ONE_OR_MORE, Cardinality.ZERO_OR_MORE, Cardinality.EXACTLY_ONE, Cardinality.ZERO_OR_ONE, Cardinality.EMPTY. This default implementation returns ZERO_OR_MORE (which effectively gives no information).

getInstructionNameCode

public int getInstructionNameCode()
Set the name of this instruction for diagnostic and tracing purposes
Overrides:
getInstructionNameCode in interface Instruction

getItemType

public ItemType getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible. All expression return sequences, in general; this method determines the type of the items within the sequence, assuming that (a) this is known in advance, and (b) it is the same for all items in the sequence.

This method should always return a result, though it may be the best approximation that is available at the time.

Overrides:
getItemType in interface Instruction
Parameters:
th - the type hierarchy cache
Returns:
a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known at compile time)

iterateSubExpressions

public Iterator iterateSubExpressions()
Get the immediate sub-expressions of this expression. Default implementation returns a zero-length array, appropriate for an expression that has no sub-expressions.
Overrides:
iterateSubExpressions in interface SimpleNodeConstructor
Returns:
an iterator containing the sub-expressions of this expression

localTypeCheck

public void localTypeCheck(ExpressionVisitor visitor,
                           ItemType contextItemType)
Method to perform type-checking specific to the kind of instruction
Overrides:
localTypeCheck in interface SimpleNodeConstructor
Parameters:
visitor - an expression visitor
contextItemType - the static type of the context item

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
            throws XPathException
ProcessLeavingTail: called to do the real work of this instruction. This method must be implemented in each subclass. The results of the instruction are written to the current Receiver, which can be obtained via the Controller.
Specified by:
processLeavingTail in interface TailCallReturner
Overrides:
processLeavingTail in interface Instruction
Parameters:
context - The dynamic context of the transformation, giving access to the current node, the current variables, etc.
Returns:
null if the instruction has completed execution; or a TailCall indicating a function call or template call that is delegated to the caller, to be made after the stack has been unwound so as to save stack space.

promoteInst

protected void promoteInst(PromotionOffer offer)
            throws XPathException
Offer promotion for subexpressions. The offer will be accepted if the subexpression is not dependent on the factors (e.g. the context item) identified in the PromotionOffer. By default the offer is not accepted - this is appropriate in the case of simple expressions such as constant values and variable references where promotion would give no performance advantage. This method is always called at compile time.
Overrides:
promoteInst in interface SimpleNodeConstructor
Parameters:
offer - details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expression
Throws:
XPathException - if any error is detected

replaceSubExpression

public boolean replaceSubExpression(Expression original,
                                    Expression replacement)
Replace one subexpression by a replacement subexpression
Overrides:
replaceSubExpression in interface SimpleNodeConstructor
Parameters:
original - the original subexpression
replacement - the replacement subexpression
Returns:
true if the original subexpression is found

simplify

public Expression simplify(ExpressionVisitor visitor)
            throws XPathException
Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.
Overrides:
simplify in interface SimpleNodeConstructor
Parameters:
visitor - an expression visitor
Returns:
the simplified expression
Throws:
XPathException - if an error is discovered during expression rewriting