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, TailCallReturner

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

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
SchemaType	getSchemaType() Get the schema type chosen for validation; null if not defined
int	getValidationAction() Get the validation mode for this instruction
boolean	isLazyConstruction() Establish whether lazy construction is to be used
boolean	isNamespaceSensitive() Determine whether the schema type is namespace sensitive.
java.util.Iterator	iterateSubExpressions() Get the immediate sub-expressions of this expression.
Expression	optimize(Optimizer opt, StaticContext env, ItemType contextItemType) Perform optimisation of an expression and its subexpressions.
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
void	setSchemaType(SchemaType type) Set the schema type to be used for validation
Expression	simplify(StaticContext env) Simplify an expression.
Expression	typeCheck(StaticContext env, ItemType contextItemType) Perform type checking of an expression and its subexpressions.

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

appendItem, assembleParams, assembleTunnelParams, computeCardinality, computeSpecialProperties, dynamicError, 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, doPromotion, dynamicError, dynamicError, effectiveBooleanValue, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, markTailFunctionCalls, resetStaticProperties, setLocationId, setParentExpression, suppressValidation, 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

setSchemaType

public void setSchemaType(SchemaType type)

Set the schema type to be used for validation

getSchemaType

public SchemaType getSchemaType()

Get the schema type chosen for validation; null if not defined

isNamespaceSensitive

public boolean isNamespaceSensitive()

Determine whether the schema type is namespace sensitive. The result is undefined if schemaType is null.

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

typeCheck

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

Description copied from interface: Expression

Perform type checking 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 may not be accurately known if they have not been explicitly declared.

Parameters:

env - the static context of the expression

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 to perform necessary run-time type checks, and to perform other type-related optimizations

Throws:

XPathException

optimize

public Expression optimize(Optimizer opt,
                           StaticContext env,
                           ItemType contextItemType)
                    throws XPathException

Description copied from interface: Expression

Perform optimisation of an expression and its subexpressions.

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.

Parameters:

opt - the optimizer in use. This provides access to supporting functions; it also allows different optimization strategies to be used in different circumstances.

env - the static context of the expression

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

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).