net.sf.saxon.expr.instruct

Class Copy

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.instruct.Instruction

net.sf.saxon.expr.instruct.ParentNodeConstructor

net.sf.saxon.expr.instruct.ElementCreator

net.sf.saxon.expr.instruct.Copy

All Implemented Interfaces:

SourceLocator, TailCallReturner, ValidatingInstruction, IdentityComparable, InstructionInfo

public class Copy
extends ElementCreator

Handler for xsl:copy elements in stylesheet. This only handles copying of the context item. An xsl:copy with a select attribute is handled by wrapping the instruction in an xsl:for-each.

Field Summary

Fields

Modifier and Type	Field and Description
static OperandRole	FOCUS_CONTROLLED_CONTENT
static OperandRole	ON_EMPTY_ROLE
static OperandRole	SAME_FOCUS_CONTENT

Fields inherited from class net.sf.saxon.expr.instruct.ElementCreator

inheritNamespacesFromParent, inheritNamespacesToChildren, onEmpty

Fields inherited from class net.sf.saxon.expr.instruct.ParentNodeConstructor

content, preservingTypes

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

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD

Constructor Summary

Constructors

Constructor and Description
Copy(boolean copyNamespaces, boolean inheritNamespaces, SchemaType schemaType, int validation, Expression onEmpty) Create a shallow copy instruction param select selects the node (or other item) to be copied.

Method Summary

Methods

Modifier and Type	Method and Description
Expression	copy() Copy an expression.
Item	evaluateItem(XPathContext context) Evaluate as an expression.
void	explain(ExpressionPresenter out) Diagnostic print of expression structure.
NamespaceBinding[]	getActiveNamespaces() Callback to get a list of the intrinsic namespaces that need to be generated for the element.
NodeName	getElementName(XPathContext context, NodeInfo copiedNode) Callback from ElementCreator when constructing an element
ExpressionCompiler	getExpressionCompiler() Return the compiler of the Copy expression
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() Get the item type of the result of this instruction.
String	getNewBaseURI(XPathContext context, NodeInfo copiedNode) Get the base URI of a copied element node (the base URI is retained in the new copy)
CopyAdjunct	getStreamingAdjunct() Get a class that supports streamed evaluation of this expression
boolean	isCopyNamespaces() Ask whether namespace nodes are to be copied (in the case of an element)
Iterable<Operand>	operands() Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.
Expression	optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) Perform optimisation of an expression and its subexpressions.
void	outputNamespaceNodes(XPathContext context, Receiver receiver, NodeName nameCode, NodeInfo copiedNode) Callback to output namespace nodes for the new element.
TailCall	processLeavingTail(XPathContext context) Evaluate the instruction to produce a new element node.
protected void	promoteInst(PromotionOffer offer) Handle promotion offers, that is, non-local tree rewrites.
boolean	replaceOperand(Expression original, Expression replacement) Replace one subexpression by a replacement subexpression
Expression	simplify(ExpressionVisitor visitor) Simplify an expression.
Expression	typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Perform type checking of an expression and its subexpressions.

Methods inherited from class net.sf.saxon.expr.instruct.ElementCreator

checkContentSequence, computeSpecialProperties, getCardinality, getImplementationMethod, getOnEmpty, isInheritNamespacesFromParent, isInheritNamespacesToChildren, iterateEvents, iterateEvents, processLeavingTail, setOnEmpty, suppressValidation

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

addToPathMap, computeCardinality, createsNewNodes, getBaseURI, getContentExpression, getSchemaType, getValidationAction, getValidationOptions, isLazyConstruction, isPreservingTypes, setBaseURI, setContentExpression, setLazyConstruction, setNoNeedToStrip, setValidationAction

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

assembleParams, assembleTunnelParams, dynamicError, evaluateAsString, getConstructType, getExpressionName, getInstructionName, getIteratorFromProcessMethod, getSourceLocator, isXSLT, iterate, process, promote, toStreamingPattern

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

adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, clearStreamabilityData, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluatePendingUpdates, explain, getColumnNumber, getConfiguration, getContainer, getDependencies, getEvaluationMethod, getHostLanguage, getIntegerBounds, getLineNumber, getLocationId, getObjectName, getPosture, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getStreamability, getSweep, getSystemId, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isIdentical, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, makeStreamingAdjunct, markTailFunctionCalls, operandList, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, setPostureAndSweep, staticTypeCheck, toPattern, toShortString, toString, typeError, unordered

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

Field Detail

FOCUS_CONTROLLED_CONTENT

public static final OperandRole FOCUS_CONTROLLED_CONTENT

SAME_FOCUS_CONTENT

public static final OperandRole SAME_FOCUS_CONTENT

ON_EMPTY_ROLE

public static final OperandRole ON_EMPTY_ROLE

Constructor Detail

Copy

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

Create a shallow copy instruction param select selects the node (or other item) to be copied. Never null. param selectSpecified true if the select attribute of xsl:copy was specified explicitly (in which case the context for evaluating the body will change)

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

onEmpty - the expression to be evaluated if the content would otherwise be empty

Method Detail

isCopyNamespaces

public boolean isCopyNamespaces()

Ask whether namespace nodes are to be copied (in the case of an element)

Returns:

true if all in-scope namespaces are to be copied

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 ElementCreator

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,
                   ContextItemStaticInfo contextInfo)
                     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 ElementCreator

Parameters:

visitor - an expression visitor

contextInfo - Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.

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

replaceOperand

public boolean replaceOperand(Expression original,
                     Expression replacement)

Replace one subexpression by a replacement subexpression

Overrides:

replaceOperand in class ElementCreator

Parameters:

original - the original subexpression

replacement - the replacement subexpression

Returns:

true if the original subexpression is found

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

operands

public Iterable<Operand> operands()

Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression. Default implementation returns a zero-length array, appropriate for an expression that has no sub-expressions.

Overrides:

operands in class ElementCreator

Returns:

an iterator containing the sub-expressions of this expression

getItemType

public ItemType getItemType()

Get the item type of the result of this instruction.

Overrides:

getItemType in class ElementCreator

Returns:

The context item type.

optimize

public Expression optimize(ExpressionVisitor visitor,
                  ContextItemStaticInfo 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 ElementCreator

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

Description copied from class: ParentNodeConstructor

Handle promotion offers, that is, non-local tree rewrites.

Overrides:

promoteInst in class ParentNodeConstructor

Parameters:

offer - The type of rewrite being offered

Throws:

XPathException - if an error occurs

getElementName

public NodeName getElementName(XPathContext context,
                      NodeInfo copiedNode)
                        throws XPathException

Callback from ElementCreator when constructing an element

Specified by:

getElementName in class ElementCreator

Parameters:

context - XPath dynamic evaluation context

copiedNode - the node being copied

Returns:

the namecode of the element to be constructed

Throws:

XPathException

getNewBaseURI

public String getNewBaseURI(XPathContext context,
                   NodeInfo copiedNode)

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

copiedNode - the node being copied (for xsl:copy), otherwise null

Returns:

the base URI

outputNamespaceNodes

public void outputNamespaceNodes(XPathContext context,
                        Receiver receiver,
                        NodeName nameCode,
                        NodeInfo copiedNode)
                          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 - the element name

copiedNode - the node being copied (for xsl:copy), otherwise null

Throws:

XPathException

getActiveNamespaces

public NamespaceBinding[] 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:

the set of namespace bindings.

Throws:

XPathException - if an error occurs

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 - if a dynamic error occurs during the evaluation of the instruction

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

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

getStreamingAdjunct

public CopyAdjunct getStreamingAdjunct()

Get a class that supports streamed evaluation of this expression

Overrides:

getStreamingAdjunct in class ElementCreator

Returns:

the relevant StreamingAdjunct, or null if none is available

getExpressionCompiler

public ExpressionCompiler getExpressionCompiler()

Return the compiler of the Copy expression

Overrides:

getExpressionCompiler in class Expression

Returns:

the relevant ExpressionCompiler

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