net.sf.saxon.expr.instruct
Class NamespaceConstructor

java.lang.Object
  extended by net.sf.saxon.expr.Expression
      extended by net.sf.saxon.expr.instruct.Instruction
          extended by net.sf.saxon.expr.instruct.SimpleNodeConstructor
              extended by net.sf.saxon.expr.instruct.NamespaceConstructor
All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, TailCallReturner, SequenceIterable, InstructionInfo, Locator

public class NamespaceConstructor
extends SimpleNodeConstructor

A namespace constructor instruction. (xsl:namespace in XSLT 2.0, or namespace{}{} in XQuery 1.1)

See Also:
Serialized Form

Field Summary
 
Fields inherited from class net.sf.saxon.expr.instruct.SimpleNodeConstructor
select
 
Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, PUSH_SELECTION, staticProperties, WATCH_METHOD
 
Constructor Summary
NamespaceConstructor(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)
          Get the item type of the items returned by evaluating this instruction
 Iterator<Expression> 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
 void processValue(CharSequence value, XPathContext context)
          Process the value of the node, to create the new node.
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.expr.instruct.SimpleNodeConstructor
checkContent, computeCardinality, computeSpecialProperties, createsNewNodes, getContentExpression, iterate, optimize, processLeavingTail, setSelect, typeCheck
 
Methods inherited from class net.sf.saxon.expr.instruct.Instruction
assembleParams, assembleTunnelParams, dynamicError, evaluateAsString, getConstructType, getExpressionName, getImplementationMethod, getInstructionName, getIteratorFromProcessMethod, getSourceLocator, isXSLT, process, promote
 
Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, getColumnNumber, getColumnNumber, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toString, typeError
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface javax.xml.transform.SourceLocator
getColumnNumber, getLineNumber, getPublicId, getSystemId
 

Constructor Detail

NamespaceConstructor

public NamespaceConstructor(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 Detail

getInstructionNameCode

public int getInstructionNameCode()
Set the name of this instruction for diagnostic and tracing purposes

Overrides:
getInstructionNameCode in class Instruction
Returns:
a code identifying the instruction: typically but not always the fingerprint of a name in the XSLT namespace

simplify

public Expression simplify(ExpressionVisitor visitor)
                    throws XPathException
Description copied from class: Instruction
Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.

Overrides:
simplify in class SimpleNodeConstructor
Parameters:
visitor - an expression visitor
Returns:
the simplified expression
Throws:
XPathException - if an error is discovered during expression rewriting

getItemType

public ItemType getItemType(TypeHierarchy th)
Description copied from class: Instruction
Get the item type of the items returned by evaluating this instruction

Overrides:
getItemType in class Instruction
Parameters:
th - the type hierarchy cache
Returns:
the static item type of the instruction

getCardinality

public int getCardinality()
Description copied from class: Expression
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 class 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).

promoteInst

protected void promoteInst(PromotionOffer offer)
                    throws XPathException
Description copied from class: SimpleNodeConstructor
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 class 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

localTypeCheck

public void localTypeCheck(ExpressionVisitor visitor,
                           ItemType contextItemType)
                    throws XPathException
Description copied from class: SimpleNodeConstructor
Method to perform type-checking specific to the kind of instruction

Specified by:
localTypeCheck in class SimpleNodeConstructor
Parameters:
visitor - an expression visitor
contextItemType - the static type of the context item
Throws:
XPathException

iterateSubExpressions

public Iterator<Expression> iterateSubExpressions()
Description copied from class: Expression
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 class SimpleNodeConstructor
Returns:
an iterator containing the sub-expressions of this expression

copy

public Expression copy()
Copy an expression. This makes a deep copy.

Specified by:
copy in class Expression
Returns:
the copy of the original expression

replaceSubExpression

public boolean replaceSubExpression(Expression original,
                                    Expression replacement)
Replace one subexpression by a replacement subexpression

Overrides:
replaceSubExpression in class SimpleNodeConstructor
Parameters:
original - the original subexpression
replacement - the replacement subexpression
Returns:
true if the original subexpression is found

evaluateNameCode

public int evaluateNameCode(XPathContext context)
                     throws XPathException
Description copied from class: SimpleNodeConstructor
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 class 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

processValue

public void processValue(CharSequence value,
                         XPathContext context)
                  throws XPathException
Description copied from class: SimpleNodeConstructor
Process the value of the node, to create the new node.

Specified by:
processValue in class SimpleNodeConstructor
Parameters:
value - the string value of the new node
context - the dynamic evaluation context
Throws:
XPathException

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 class SimpleNodeConstructor
Parameters:
context - The context in which the expression is to be evaluated
Returns:
the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
Throws:
XPathException - if any dynamic error occurs evaluating the expression

explain

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

Specified by:
explain in class Expression
Parameters:
out - the expression presenter used to display the structure


Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.