## 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, 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).