net.sf.saxon.expr.instruct
Class ParentNodeConstructor

java.lang.Object
  extended by net.sf.saxon.expr.Expression
      extended by net.sf.saxon.expr.instruct.Instruction
          extended by net.sf.saxon.expr.instruct.ParentNodeConstructor
All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, DivisibleInstruction, TailCallReturner, ValidatingInstruction, InstructionInfo, Locator
Direct Known Subclasses:
DocumentInstr, ElementCreator

public abstract class ParentNodeConstructor
extends Instruction
implements DivisibleInstruction, ValidatingInstruction

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
           
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, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, 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 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.
 boolean isPreservingTypes()
          Determine whether this elementCreator performs validation or strips type annotations
 Iterator<Expression> iterateSubExpressions()
          Get the immediate sub-expressions of this expression.
 Expression optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType 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 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 setSchemaType(SchemaType type)
          Set the schema type to be used for validation
 void setValidationAction(int mode, SchemaType schemaType)
          Set the validation mode for the new document or element node
 Expression simplify(ExpressionVisitor visitor)
          Simplify an expression.
 Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType 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, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, hasVariableBinding, 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

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(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

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)

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

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 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,
                            ExpressionVisitor.ContextItemType 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 - if the check fails

optimize

public Expression optimize(ExpressionVisitor visitor,
                           ExpressionVisitor.ContextItemType 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.

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


Copyright (c) 2004-2011 Saxonica Limited. All rights reserved.