net.sf.saxon.instruct
Class ParentNodeConstructor

java.lang.Object
  net.sf.saxon.expr.ComputedExpression
      net.sf.saxon.instruct.Instruction
          net.sf.saxon.instruct.ParentNodeConstructor

All Implemented Interfaces:

Container, Expression, InstructionInfoProvider, java.io.Serializable, javax.xml.transform.SourceLocator

Direct Known Subclasses:

DocumentInstr, ElementCreator

public abstract class ParentNodeConstructor

extends Instruction

An abstract class to act as a common parent for instructions that create element nodes and document nodes.

See Also:

Serialized Form

Field Summary

protected Expression

content

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

locationId, staticProperties

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

ParentNodeConstructor()

Method Summary

Expression	analyze(StaticContext env, ItemType contextItemType) Perform static analysis of an expression and its subexpressions.
boolean	createsNewNodes() Determine whether this instruction creates new nodes.
int	getCardinality() Determine the static cardinality of the expression.
Expression	getContentExpression() Get the expression that constructs the content of the element
int	getValidationAction() Get the validation mode for this instruction
boolean	isLazyConstruction() Establish whether lazy construction is to be used
java.util.Iterator	iterateSubExpressions() Get the immediate sub-expressions of this expression.
protected void	promoteInst(PromotionOffer offer) Handle promotion offers, that is, non-local tree rewrites.
void	setContentExpression(Expression content) Set the expression that constructs the content of the element
void	setLazyConstruction(boolean lazy) Indicate that lazy construction should (or should not) be used
Expression	simplify(StaticContext env) Simplify an expression.

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

appendItem, assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, dynamicError, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, getImplementationMethod, getInstructionInfo, getInstructionNameCode, getItemType, getSourceLocator, isXSLT, iterate, process, processLeavingTail, promote

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

adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, dynamicError, dynamicError, getColumnNumber, getConstructType, getDependencies, getExecutable, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSpecialProperties, getSystemId, markTailFunctionCalls, resetStaticProperties, setLocationId, setParentExpression, typeError, typeError

Methods inherited from class java.lang.Object

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

Methods inherited from interface javax.xml.transform.SourceLocator

getColumnNumber, getLineNumber, getPublicId, getSystemId

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

display

Field Detail

content

protected Expression content

Constructor Detail

ParentNodeConstructor

public ParentNodeConstructor()

Method Detail

setLazyConstruction

public void setLazyConstruction(boolean lazy)

Indicate that lazy construction should (or should not) be used

Parameters:

lazy - set to true if lazy construction should be used

isLazyConstruction

public final boolean isLazyConstruction()

Establish whether lazy construction is to be used

getValidationAction

public int getValidationAction()

Get the validation mode for this instruction

Returns:

the validation mode, for example Validation.STRICT or Validation.PRESERVE

setContentExpression

public void setContentExpression(Expression content)

Set the expression that constructs the content of the element

getContentExpression

public Expression getContentExpression()

Get the expression that constructs the content of the element

simplify

public Expression simplify(StaticContext env)
                    throws XPathException

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 interface Expression

Specified by:

simplify in class Instruction

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

analyze

public Expression analyze(StaticContext env,
                          ItemType contextItemType)
                   throws XPathException

Perform static analysis of an expression and its subexpressions.

This checks statically that the operands of the expression have the correct type; if necessary it generates code to do run-time type checking or type conversion. A static type error is reported only if execution cannot possibly succeed, that is, if a run-time type error is inevitable. The call may return a modified form of the expression.

This method is called after all references to functions and variables have been resolved to the declaration of the function or variable. However, the types of such functions and variables will only be accurately known if they have been explicitly declared.

Specified by:

analyze in interface Expression

Specified by:

analyze in class Instruction

Parameters:

env - the static context of the expression

Returns:

the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations

Throws:

XPathException - if an error is discovered during this phase (typically a type error)

promoteInst

protected void promoteInst(PromotionOffer offer)
                    throws XPathException

Handle promotion offers, that is, non-local tree rewrites.

Overrides:

promoteInst in class Instruction

Parameters:

offer - The type of rewrite being offered

Throws:

XPathException

iterateSubExpressions

public java.util.Iterator iterateSubExpressions()

Get the immediate sub-expressions of this expression.

Specified by:

iterateSubExpressions in interface Expression

Overrides:

iterateSubExpressions in class ComputedExpression

Returns:

an iterator containing the sub-expressions of this expression

createsNewNodes

public final boolean createsNewNodes()

Determine whether this instruction creates new nodes. This implementation returns true.

Overrides:

createsNewNodes in class Instruction

getCardinality

public int getCardinality()

Description copied from class: ComputedExpression

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.

Specified by:

getCardinality in interface Expression

Overrides:

getCardinality in class ComputedExpression

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).