net.sf.saxon.instruct
Class Copy

java.lang.Object
  extended by net.sf.saxon.expr.Expression
      extended by net.sf.saxon.instruct.Instruction
          extended by net.sf.saxon.instruct.ParentNodeConstructor
              extended by net.sf.saxon.instruct.ElementCreator
                  extended by net.sf.saxon.instruct.Copy
All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, SequenceIterable, DivisibleInstruction, TailCallReturner, InstructionInfo, Locator

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.instruct.ElementCreator
inheritNamespaces, preservingTypes
 
Fields inherited from class net.sf.saxon.instruct.ParentNodeConstructor
content
 
Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
 
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
 int getIntrinsicDependencies()
          Determine which aspects of the context the expression depends on.
 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.
protected  void outputNamespaceNodes(XPathContext context, Receiver receiver, int nameCode)
          Callback to output namespace nodes for the new element.
 TailCall processLeavingTail(XPathContext context)
          Evaluate the instruction to produce a new element node.
 void processLeft(Stack<XPathContext> contextStack, Stack state)
          Process the first half of the instruction in streaming mode
 void processRight(Stack<XPathContext> contextStack, Stack state)
          Process the second half of the instruction in streaming mode
 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
checkContentSequence, 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, promoteInst, replaceSubExpression, setBaseURI, setContentExpression, setLazyConstruction, setSchemaType
 
Methods inherited from class net.sf.saxon.instruct.Instruction
assembleParams, assembleTunnelParams, dynamicError, evaluateAsString, getConstructType, getSourceLocator, isXSLT, iterate, process, promote
 
Methods inherited from class net.sf.saxon.expr.Expression
adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, getColumnNumber, getColumnNumber, getContainer, getDependencies, getExecutable, getHostLanguage, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateSameFocusSubExpressions, markTailFunctionCalls, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, toString, typeError
 
Methods inherited from class java.lang.Object
clone, equals, finalize, 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 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

getIntrinsicDependencies

public int getIntrinsicDependencies()
Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as XPathContext.VARIABLES and XPathContext.CURRENT_NODE. The default implementation combines the intrinsic dependencies of this expression with the dependencies of the subexpressions, computed recursively. This is overridden for expressions such as FilterExpression where a subexpression's dependencies are not necessarily inherited by the parent expression.

Overrides:
getIntrinsicDependencies in class Expression
Returns:
a set of bit-significant flags identifying the dependencies of the 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

outputNamespaceNodes

protected void outputNamespaceNodes(XPathContext context,
                                    Receiver receiver,
                                    int nameCode)
                             throws XPathException
Callback to output namespace nodes for the new element.

Specified by:
outputNamespaceNodes in class ElementCreator
Parameters:
context - The execution context
receiver - the Receiver where the namespace nodes are to be written
nameCode -
Throws:
XPathException

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

processLeft

public void processLeft(Stack<XPathContext> contextStack,
                        Stack state)
                 throws XPathException
Process the first half of the instruction in streaming mode

Specified by:
processLeft in interface DivisibleInstruction
Overrides:
processLeft in class ElementCreator
Parameters:
contextStack - Stack of XPathContext objects. The instruction should use the one at the top of the stack.
state - a stack on which the instruction can save state information for use during the corresponding
Throws:
XPathException

processRight

public void processRight(Stack<XPathContext> contextStack,
                         Stack state)
                  throws XPathException
Process the second half of the instruction in streaming mode

Specified by:
processRight in interface DivisibleInstruction
Overrides:
processRight in class ElementCreator
Parameters:
contextStack - Stack of XPathContext objects. The instruction should use the one at the top of the stack.
state - a stack on which the instruction can save state information for use during the corresponding
Throws:
XPathException

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


Copyright (c) Saxonica Limited. All rights reserved.