SimpleNodeConstructor

java.lang.Object
- net.sf.saxon.expr.Expression
- - net.sf.saxon.instruct.Instruction
  - - net.sf.saxon.instruct.SimpleNodeConstructor

All Implemented Interfaces:

java.io.Serializable, javax.xml.transform.SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, SequenceIterable, TailCallReturner, InstructionInfo, org.xml.sax.Locator

Direct Known Subclasses:

AttributeCreator, Comment, Namespace, ProcessingInstruction, ValueOf
```
public abstract class SimpleNodeConstructor
extends Instruction
```
Common superclass for XSLT instructions whose content template produces a text value: xsl:attribute, xsl:comment, xsl:processing-instruction, xsl:namespace, and xsl:text, and their XQuery equivalents

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type Field Description

protected Expression select
- Fields inherited from class net.sf.saxon.expr.Expression
  EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties

Fields
Modifier and Type	Field	Description
`protected Expression`	`select`

Constructor Summary

Constructors
Constructor Description

SimpleNodeConstructor()
Default constructor used by subclasses

Constructors
Constructor	Description
`SimpleNodeConstructor()`	Default constructor used by subclasses

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`protected java.lang.String`	`checkContent(java.lang.String data, XPathContext context)`	Check the content of the node, and adjust it if necessary.
`int`	`computeCardinality()`	Get the cardinality of the sequence returned by evaluating this instruction
`int`	`computeSpecialProperties()`	Get the static properties of this expression (other than its type).
`boolean`	`createsNewNodes()`	Determine whether this instruction creates new nodes.
`Item`	`evaluateItem(XPathContext context)`	Evaluate as an expression.
`int`	`evaluateNameCode(XPathContext context)`	Run-time method to compute the name of the node being constructed.
`java.lang.CharSequence`	`expandChildren(XPathContext context)`	Expand the stylesheet elements subordinate to this one, returning the result as a string.
`Expression`	`getSelect()`	Get the expression that determines the string value of the constructed node
`SequenceIterator`	`iterate(XPathContext context)`	Return an Iterator to iterate over the values of a sequence.
`java.util.Iterator`	`iterateSubExpressions()`	Get the immediate sub-expressions of this expression.
`abstract void`	`localTypeCheck(ExpressionVisitor visitor, ItemType contextItemType)`	Method to perform type-checking specific to the kind of instruction
`Expression`	`optimize(ExpressionVisitor visitor, ItemType contextItemType)`	Perform optimisation of an expression and its subexpressions.
`protected void`	`promoteInst(PromotionOffer offer)`	Offer promotion for subexpressions.
`boolean`	`replaceSubExpression(Expression original, Expression replacement)`	Replace one subexpression by a replacement subexpression
`void`	`setSelect(Expression select, Configuration config)`	Set the select expression: the value of this expression determines the string-value of the node
`Expression`	`simplify(ExpressionVisitor visitor)`	Simplify an expression.
`Expression`	`typeCheck(ExpressionVisitor visitor, ItemType contextItemType)`	The typeCheck() method is called in XQuery, where node constructors are implemented as Expressions.

Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, copy, display, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, explain, findParentOf, getCardinality, getColumnNumber, getColumnNumber, getContainer, getDependencies, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isUpdatingExpression, iterateEvents, markTailFunctionCalls, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toString, typeError

Methods inherited from class net.sf.saxon.instruct.Instruction
assembleParams, assembleTunnelParams, dynamicError, evaluateAsString, getConstructType, getImplementationMethod, getInstructionNameCode, getItemType, getSourceLocator, isXSLT, process, processLeavingTail, promote

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

- Field Detail
  - select
```
protected Expression select
```
- Constructor Detail
  - SimpleNodeConstructor
```
public SimpleNodeConstructor()
```
    Default constructor used by subclasses
- Method Detail
  - setSelect
```
public void setSelect(Expression select,
                      Configuration config)
               throws XPathException
```
    Set the select expression: the value of this expression determines the string-value of the node
    
    Parameters:
    
    select - the expression that computes the string value of the node
    
    config - the Saxon configuration (used for example to do early validation of the content of an attribute against the schema-defined type)
    
    Throws:
    
    XPathException
  - getSelect
```
public Expression getSelect()
```
    Get the expression that determines the string value of the constructed node
    
    Returns:
    
    the select expression
  - createsNewNodes
```
public final boolean createsNewNodes()
```
    Determine whether this instruction creates new nodes. This implementation returns true.
    
    Overrides:
    
    createsNewNodes in class Instruction
    
    Returns:
    
    true if the instruction creates new nodes (or if it can't be proved that it doesn't)
  - computeCardinality
```
public int computeCardinality()
```
    Get the cardinality of the sequence returned by evaluating this instruction
    
    Overrides:
    
    computeCardinality in class Instruction
    
    Returns:
    
    the static cardinality
  - 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.
    
    Specified by:
    
    simplify in class Instruction
    
    Parameters:
    
    visitor - an expression visitor
    
    Returns:
    
    the simplified expression
    
    Throws:
    
    XPathException - if an error is discovered during expression rewriting
  - computeSpecialProperties
```
public int computeSpecialProperties()
```
    Get the static properties of this expression (other than its type). The result is bit-signficant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.
    
    Overrides:
    
    computeSpecialProperties in class Instruction
    
    Returns:
    
    a set of flags indicating static properties of this expression
  - localTypeCheck
```
public abstract void localTypeCheck(ExpressionVisitor visitor,
                                    ItemType contextItemType)
                             throws XPathException
```
    Method to perform type-checking specific to the kind of instruction
    
    Parameters:
    
    visitor - an expression visitor
    
    contextItemType - the static type of the context item
    
    Throws:
    
    XPathException
  - typeCheck
```
public Expression typeCheck(ExpressionVisitor visitor,
                            ItemType contextItemType)
                     throws XPathException
```
    The typeCheck() method is called in XQuery, where node constructors are implemented as Expressions. In this case the required type for the select expression is a single string.
    
    Overrides:
    
    typeCheck in class Expression
    
    Parameters:
    
    visitor - an expression visitor
    
    contextItemType - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE
    
    Returns:
    
    the rewritten expression
    
    Throws:
    
    XPathException - if any static errors are found in this expression or any of its children
  - optimize
```
public Expression optimize(ExpressionVisitor visitor,
                           ItemType contextItemType)
                    throws XPathException
```
    Description copied from class: Expression
    
    Perform optimisation of an expression and its subexpressions. This is the third and final phase of static optimization.
    This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.
    
    Overrides:
    
    optimize in class Expression
    
    Parameters:
    
    visitor - an expression visitor
    
    contextItemType - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE
    
    Returns:
    
    the original expression, rewritten if appropriate to optimize execution
    
    Throws:
    
    XPathException - if an error is discovered during this phase (typically a type error)
  - iterateSubExpressions
```
public java.util.Iterator 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 Expression
    
    Returns:
    
    an iterator containing the sub-expressions of this expression
  - replaceSubExpression
```
public boolean replaceSubExpression(Expression original,
                                    Expression replacement)
```
    Replace one subexpression by a replacement subexpression
    
    Overrides:
    
    replaceSubExpression in class Expression
    
    Parameters:
    
    original - the original subexpression
    
    replacement - the replacement subexpression
    
    Returns:
    
    true if the original subexpression is found
  - expandChildren
```
public java.lang.CharSequence expandChildren(XPathContext context)
                                      throws XPathException
```
    Expand the stylesheet elements subordinate to this one, returning the result as a string. The expansion must not generate any element or attribute nodes.
    
    Parameters:
    
    context - The dynamic context for the transformation
    
    Returns:
    
    the value that will be used as the string value of the constructed node
    
    Throws:
    
    XPathException - if any error occurs
  - 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 Instruction
    
    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
  - checkContent
```
protected java.lang.String checkContent(java.lang.String data,
                                        XPathContext context)
                                 throws XPathException
```
    Check the content of the node, and adjust it if necessary. The checks depend on the node kind.
    
    Parameters:
    
    data - the supplied content
    
    context - the dynamic context
    
    Returns:
    
    the original content, unless adjustments are needed
    
    Throws:
    
    XPathException - if the content is invalid
  - 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
    
    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
  - iterate
```
public SequenceIterator iterate(XPathContext context)
                         throws XPathException
```
    Description copied from class: Instruction
    
    Return an Iterator to iterate over the values of a sequence. The value of every expression can be regarded as a sequence, so this method is supported for all expressions. This default implementation handles iteration for expressions that return singleton values: for non-singleton expressions, the subclass must provide its own implementation.
    
    Specified by:
    
    iterate in interface SequenceIterable
    
    Overrides:
    
    iterate in class Instruction
    
    Parameters:
    
    context - supplies the context for evaluation
    
    Returns:
    
    a SequenceIterator that can be used to iterate over the result of the expression
    
    Throws:
    
    XPathException - if any dynamic error occurs evaluating the expression
  - 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 class Instruction
    
    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

Class SimpleNodeConstructor

Field Summary

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

Constructor Summary

Method Summary

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

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

Methods inherited from class java.lang.Object

Methods inherited from interface javax.xml.transform.SourceLocator

Field Detail

select

Constructor Detail

SimpleNodeConstructor

Method Detail

setSelect

getSelect

createsNewNodes

computeCardinality

simplify

computeSpecialProperties

localTypeCheck

typeCheck

optimize

iterateSubExpressions

replaceSubExpression

expandChildren

evaluateItem

checkContent

evaluateNameCode

iterate

promoteInst