net.sf.saxon.instruct
Class ParentNodeConstructor

java.lang.Object
  extended bynet.sf.saxon.expr.ComputedExpression
      extended bynet.sf.saxon.instruct.Instruction
          extended bynet.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).