net.sf.saxon.expr.instruct
Class ParentNodeConstructor

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

All Implemented Interfaces:

Serializable, SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, DivisibleInstruction, TailCallReturner, SequenceIterable, InstructionInfo, Locator

Direct Known Subclasses:

DocumentInstr, ElementCreator

public abstract class ParentNodeConstructor
extends Instruction
implements DivisibleInstruction

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.Expression

EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, PUSH_SELECTION, staticProperties, WATCH_METHOD

Constructor Summary

ParentNodeConstructor()
Create a document or element node constructor instruction

Method Summary

PathMap.PathMapNodeSet	addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet) Add a representation of this expression to a PathMap.
protected abstract void	checkContentSequence(StaticContext env) Check that the child instructions don't violate any obvious constraints for this kind of node
int	computeCardinality() Get the cardinality of the sequence returned by evaluating this instruction
boolean	createsNewNodes() Determine whether this instruction creates new nodes.
String	getBaseURI() Get the static base URI of the instruction
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	getValidationMode() 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.
Iterator<Expression>	iterateSubExpressions() Get the immediate sub-expressions of this expression.
Expression	optimize(ExpressionVisitor visitor, ItemType contextItemType) Perform optimisation of an expression and its subexpressions.
protected void	promoteInst(PromotionOffer offer) Handle promotion offers, that is, non-local tree rewrites.
boolean	replaceSubExpression(Expression original, Expression replacement) Replace one subexpression by a replacement subexpression
void	setBaseURI(String uri) Set the static base URI of the instruction
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
void	setValidationMode(int mode) Set the validation mode for the new document or element node
Expression	simplify(ExpressionVisitor visitor) Simplify an expression.
Expression	typeCheck(ExpressionVisitor visitor, ItemType contextItemType) Perform type checking of an expression and its subexpressions.

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

assembleParams, assembleTunnelParams, computeSpecialProperties, dynamicError, evaluateAsString, evaluateItem, getConstructType, getExpressionName, getImplementationMethod, getInstructionName, getInstructionNameCode, getItemType, getIteratorFromProcessMethod, getSourceLocator, isXSLT, iterate, process, processLeavingTail, promote

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

adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, copy, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, 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 net.sf.saxon.expr.instruct.DivisibleInstruction

processLeft, processRight

Methods inherited from interface javax.xml.transform.SourceLocator

getColumnNumber, getLineNumber, getPublicId, getSystemId

Field Detail

content

protected Expression content

Constructor Detail

ParentNodeConstructor

public ParentNodeConstructor()

Create a document or element node constructor instruction

Method Detail

setBaseURI

public void setBaseURI(String uri)

Set the static base URI of the instruction

Parameters:

uri - the static base URI

getBaseURI

public String getBaseURI()

Get the static base URI of the instruction

Returns:

the static base URI

setLazyConstruction

public void setLazyConstruction(boolean lazy)

Indicate that lazy construction should (or should not) be used. Note that this request will be ignored if validation is required

Parameters:

lazy - set to true if lazy construction should be used

isLazyConstruction

public final boolean isLazyConstruction()

Establish whether lazy construction is to be used

Returns:

true if lazy construction is to be used

setSchemaType

public void setSchemaType(SchemaType type)

Set the schema type to be used for validation

Parameters:

type - the type to be used for validation. (For a document constructor, this is the required type of the document element)

getSchemaType

public SchemaType getSchemaType()

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

Returns:

the type to be used for validation. (For a document constructor, this is the required type of the document element)

isNamespaceSensitive

public boolean isNamespaceSensitive()

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

Returns:

true if the schema type is namespace sensitive

setValidationMode

public void setValidationMode(int mode)

Set the validation mode for the new document or element node

Parameters:

mode - the validation mode, for example Validation.STRICT

getValidationMode

public int getValidationMode()

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

Parameters:

content - the content expression

getContentExpression

public Expression getContentExpression()

Get the expression that constructs the content of the element

Specified by:

getContentExpression in interface DivisibleInstruction

Returns:

the content expression

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

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

typeCheck

public Expression typeCheck(ExpressionVisitor visitor,
                            ItemType contextItemType)
                     throws XPathException

Description copied from class: Expression

Perform type checking of an expression and its subexpressions. This is the second phase of static optimization.

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.

If the implementation returns a value other than "this", then it is required to ensure that the location information in the returned expression have been set up correctly. It should not rely on the caller to do this, although for historical reasons many callers do so.

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 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)

checkContentSequence

protected abstract void checkContentSequence(StaticContext env)
                                      throws XPathException

Check that the child instructions don't violate any obvious constraints for this kind of node

Parameters:

env - the static context

Throws:

XPathException

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)

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 Iterator<Expression> iterateSubExpressions()

Get the immediate sub-expressions of this expression.

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

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)

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).

addToPathMap

public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap,
                                           PathMap.PathMapNodeSet pathMapNodeSet)

Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited by an expression in a source tree.

The default implementation of this method assumes that an expression does no navigation other than the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the same context as the containing expression. The method must be overridden for any expression where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression, and RootExpression (because they perform navigation), and for the doc(), document(), and collection() functions because they create a new navigation root. Implementations also exist for PathExpression and FilterExpression because they have subexpressions that are evaluated in a different context from the calling expression.

Overrides:

addToPathMap in class Expression

Parameters:

pathMap - the PathMap to which the expression should be added

pathMapNodeSet - the PathMapNodeSet to which the paths embodied in this expression should be added

Returns:

the pathMapNodeSet representing the points in the source document that are both reachable by this expression, and that represent possible results of this expression. For an expression that does navigation, it represents the end of the arc in the path map that describes the navigation route. For other expressions, it is the same as the input pathMapNode.