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## 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.

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Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.