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:

ExportAgent, InstructionWithComplexContent, TailCallReturner, ValidatingInstruction, Locatable, IdentityComparable

Direct Known Subclasses:

DocumentInstr, ElementCreator

public abstract class ParentNodeConstructor
extends Instruction
implements ValidatingInstruction, InstructionWithComplexContent

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

Field Summary

Fields

Modifier and Type	Field and Description
protected Operand	contentOp
protected boolean	preservingTypes Flag set to true if validation=preserve and no schema type supplied for validation; also true when validation="strip" if there is no need to physically strip type annotations

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

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_COST, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD

Constructor Summary

Constructors

Constructor and Description
ParentNodeConstructor() Create a document or element node constructor instruction

Method Summary

Modifier and Type	Method and Description
PathMap.PathMapNodeSet	addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet) Add a representation of this expression to a PathMap.
boolean	allowExtractingCommonSubexpressions() Ask whether common subexpressions found in the operands of this expression can be extracted and evaluated outside the expression itself.
boolean	alwaysCreatesNewNodes() Ask whether it is guaranteed that every item in the result of this instruction is a newly created node
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
int	getCardinality() Determine the static cardinality of the expression.
Expression	getContentExpression() Get the expression that constructs the content of the element
Operand	getContentOperand()
SchemaType	getSchemaType() Get the schema type chosen for validation; null if not defined
int	getValidationAction() Get the validation mode for this instruction
ParseOptions	getValidationOptions() Get the validation options
boolean	isLazyConstruction() Establish whether lazy construction is to be used
boolean	isLocal()
boolean	isPreservingTypes() Determine whether this elementCreator performs validation or strips type annotations
boolean	mayCreateNewNodes() Determine whether this instruction creates new nodes.
Expression	optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) Perform optimisation of an expression and its subexpressions.
void	setBaseURI(java.lang.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	setNoNeedToStrip() Set that the newly constructed node and everything underneath it will automatically be untyped, without any need to physically remove type annotations, even though validation=STRIP is set.
void	setValidationAction(int mode, SchemaType schemaType) Set the validation mode for the new document or element node
Expression	typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) 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, getInstructionNameCode, getItemType, getNetCost, getSourceLocator, isInstruction, isXSLT, iterate, operands, process, processLeavingTail, someOperandCreatesNewNodes

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

adoptChildExpression, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeHashCode, computeStaticProperties, copy, dynamicError, effectiveBooleanValue, equals, evaluatePendingUpdates, explain, export, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, getLocalRetainedStaticContext, getLocation, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStaticUType, getStreamerName, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, toShortString, toString, typeCheckChildren, typeError, unordered, verifyParentPointers

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

contentOp

protected Operand contentOp

preservingTypes

protected boolean preservingTypes

Flag set to true if validation=preserve and no schema type supplied for validation; also true when validation="strip" if there is no need to physically strip type annotations

Constructor Detail

ParentNodeConstructor

public ParentNodeConstructor()

Create a document or element node constructor instruction

Method Detail

setBaseURI

public void setBaseURI(java.lang.String uri)

Set the static base URI of the instruction

Parameters:

uri - 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

getSchemaType

public SchemaType getSchemaType()

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

Specified by:

getSchemaType in interface ValidatingInstruction

Returns:

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

getValidationOptions

public ParseOptions getValidationOptions()

Get the validation options

Returns:

the validation options for the content of the constructed node. May be null if no validation was requested.

setValidationAction

public void setValidationAction(int mode,
                                SchemaType schemaType)

Set the validation mode for the new document or element node

Parameters:

mode - the validation mode, for example Validation.STRICT

schemaType - the required type (for validation by type). Null if not validating by type

getValidationAction

public int getValidationAction()

Get the validation mode for this instruction

Specified by:

getValidationAction in interface ValidatingInstruction

Returns:

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

setNoNeedToStrip

public void setNoNeedToStrip()

Set that the newly constructed node and everything underneath it will automatically be untyped, without any need to physically remove type annotations, even though validation=STRIP is set.

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 InstructionWithComplexContent

Returns:

the content expression

getContentOperand

public Operand getContentOperand()

computeCardinality

public int computeCardinality()

Get the cardinality of the sequence returned by evaluating this instruction

Overrides:

computeCardinality in class Instruction

Returns:

the static cardinality

typeCheck

public Expression typeCheck(ExpressionVisitor visitor,
                            ContextItemStaticInfo contextInfo)
                     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.

Overrides:

typeCheck in class Expression

Parameters:

visitor - an expression visitor

contextInfo - Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.

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)

allowExtractingCommonSubexpressions

public boolean allowExtractingCommonSubexpressions()

Ask whether common subexpressions found in the operands of this expression can be extracted and evaluated outside the expression itself. The result is irrelevant in the case of operands evaluated with a different focus, which will never be extracted in this way, even if they have no focus dependency.

Overrides:

allowExtractingCommonSubexpressions in class Expression

Returns:

false for this kind of expression

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 - if the check fails

optimize

public Expression optimize(ExpressionVisitor visitor,
                           ContextItemStaticInfo 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)

mayCreateNewNodes

public final boolean mayCreateNewNodes()

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

Overrides:

mayCreateNewNodes in class Instruction

Returns:

true if the instruction creates new nodes under some input conditions (or if it can't be proved that it doesn't)

alwaysCreatesNewNodes

public boolean alwaysCreatesNewNodes()

Ask whether it is guaranteed that every item in the result of this instruction is a newly created node

Overrides:

alwaysCreatesNewNodes in class Instruction

Returns:

true if result of the instruction is always either an empty sequence or a sequence consisting entirely of newly created nodes

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.

isPreservingTypes

public boolean isPreservingTypes()

Determine whether this elementCreator performs validation or strips type annotations

Returns:

false if the instruction performs validation of the constructed output or if it strips type annotations, otherwise true

isLocal

public boolean isLocal()