net.sf.saxon.instruct
Class Copy

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.instruct.Instruction
          net.sf.saxon.instruct.ParentNodeConstructor
              net.sf.saxon.instruct.ElementCreator
                  net.sf.saxon.instruct.Copy

All Implemented Interfaces:

Serializable, SourceLocator, EvaluableItem, SequenceIterable, TailCallReturner, InstructionInfoProvider

public class Copy
extends ElementCreator

Handler for xsl:copy elements in stylesheet.

See Also:

Serialized Form

Field Summary

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

Copy(boolean copyNamespaces, boolean inheritNamespaces, SchemaType schemaType, int validation)
Create a shallow copy instruction

Method Summary

Expression	copy() Copy an expression.
Item	evaluateItem(XPathContext context) Evaluate as an expression.
void	explain(ExpressionPresenter out) Diagnostic print of expression structure.
int[]	getActiveNamespaces() Callback to get a list of the intrinsic namespaces that need to be generated for the element.
int	getInstructionNameCode() Get the name of this instruction for diagnostic and tracing purposes
ItemType	getItemType(TypeHierarchy th) Get the item type of the result of this instruction.
int	getNameCode(XPathContext context) Callback from ElementCreator when constructing an element
String	getNewBaseURI(XPathContext context) Get the base URI of a copied element node (the base URI is retained in the new copy)
Expression	optimize(ExpressionVisitor visitor, ItemType contextItemType) Perform optimisation of an expression and its subexpressions.
TailCall	processLeavingTail(XPathContext context) Evaluate the instruction to produce a new 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.instruct.ElementCreator

computeSpecialProperties, getImplementationMethod, isInheritNamespaces, isPreservingTypes, iterateEvents, setValidationMode, suppressValidation

Methods inherited from class net.sf.saxon.instruct.ParentNodeConstructor

addToPathMap, computeCardinality, createsNewNodes, getBaseURI, getCardinality, getContentExpression, getSchemaType, getValidationMode, isLazyConstruction, isNamespaceSensitive, iterateSubExpressions, replaceSubExpression, setBaseURI, setContentExpression, setLazyConstruction, setSchemaType

Methods inherited from class net.sf.saxon.instruct.Instruction

evaluateAsString, getInstructionInfo, getSourceLocator, isXSLT, iterate, process, promote

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

adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, effectiveBooleanValue, explain, findParentOf, getColumnNumber, getContainer, getDependencies, getExecutable, getHostLanguage, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, markTailFunctionCalls, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, toString

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface javax.xml.transform.SourceLocator

getColumnNumber, getLineNumber, getPublicId, getSystemId

Constructor Detail

Copy

public Copy(boolean copyNamespaces,
            boolean inheritNamespaces,
            SchemaType schemaType,
            int validation)

Create a shallow copy instruction

Parameters:

copyNamespaces - true if namespace nodes are to be copied when copying an element

inheritNamespaces - true if child elements are to inherit the namespace nodes of their parent

schemaType - the Schema type against which the content is to be validated

validation - the schema validation mode

Method Detail

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.

Overrides:

simplify in class ParentNodeConstructor

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 parent pointer and 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 ParentNodeConstructor

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)

copy

public Expression copy()

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Returns:

the copy of the original expression

getInstructionNameCode

public int getInstructionNameCode()

Get the name of this instruction for diagnostic and tracing purposes

Overrides:

getInstructionNameCode in class Instruction

Returns:

a code identifying the instruction: typically but not always the fingerprint of a name in the XSLT namespace

getItemType

public ItemType getItemType(TypeHierarchy th)

Get the item type of the result of this instruction.

Overrides:

getItemType in class ElementCreator

Parameters:

th - the type hierarchy cache

Returns:

The context item type.

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 ParentNodeConstructor

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)

getNameCode

public int getNameCode(XPathContext context)
                throws XPathException

Callback from ElementCreator when constructing an element

Specified by:

getNameCode in class ElementCreator

Parameters:

context - XPath dynamic evaluation context

Returns:

the namecode of the element to be constructed

Throws:

XPathException

getNewBaseURI

public String getNewBaseURI(XPathContext context)

Get the base URI of a copied element node (the base URI is retained in the new copy)

Specified by:

getNewBaseURI in class ElementCreator

Parameters:

context - XPath dynamic evaluation context

Returns:

the base URI

getActiveNamespaces

public int[] getActiveNamespaces()
                          throws XPathException

Callback to get a list of the intrinsic namespaces that need to be generated for the element. The result is an array of namespace codes, the codes either occupy the whole array or are terminated by a -1 entry. A result of null is equivalent to a zero-length array.

Overrides:

getActiveNamespaces in class ElementCreator

Returns:

an array of namespace codes, the codes either occupy the whole array or are terminated by a -1 entry. A result of null is equivalent to a zero-length array.

Throws:

XPathException

processLeavingTail

public TailCall processLeavingTail(XPathContext context)
                            throws XPathException

Description copied from class: ElementCreator

Evaluate the instruction to produce a new element node. This method is typically used when there is a parent element or document in a result tree, to which the new element is added.

Specified by:

processLeavingTail in interface TailCallReturner

Overrides:

processLeavingTail in class ElementCreator

Parameters:

context - XPath dynamic evaluation context

Returns:

null (this instruction never returns a tail call)

Throws:

XPathException

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException

Evaluate as an expression. We rely on the fact that when these instructions are generated by XQuery, there will always be a valueExpression to evaluate the content

Specified by:

evaluateItem in interface EvaluableItem

Overrides:

evaluateItem in class ElementCreator

Parameters:

context - The context in which the expression is to be evaluated

Returns:

the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence

Throws:

XPathException - if any dynamic error occurs evaluating the expression

explain

public void explain(ExpressionPresenter out)

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Specified by:

explain in class Expression

Parameters:

out - the expression presenter used to display the structure