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:
Serializable, SourceLocator, LocationProvider, SaxonLocator, DivisibleInstruction, TailCallReturner, ValidatingInstruction, InstructionInfo, Locator
public class Copy extends ElementCreator
Handler for xsl:copy elements in stylesheet.
See Also:

  • Constructor Details

    • Copy

      public Copy(Expression select, boolean selectSpecified, boolean copyNamespaces, boolean inheritNamespaces, SchemaType schemaType, int validation)
      Create a shallow copy instruction
      Parameters:
      select - selects the node (or other item) to be copied. Never null.
      selectSpecified - true if the select attribute of xsl:copy was specified explicitly (in which case the context for evaluating the body will change)
      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 Details

    • getSelectExpression

      public Expression getSelectExpression()
      Get the expression that selects the node or other item to be copied
      Returns:
      the select expression. This will be a context item expression if no select attribute was supplied.

    • isSelectSpecified

      public boolean isSelectSpecified()
      Ask whether the select attribute was explicitly specified
      Returns:
      true if it was

    • 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 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, ExpressionVisitor.ContextItemType 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

    • replaceSubExpression

      public boolean replaceSubExpression(Expression original, Expression replacement)
      Replace one subexpression by a replacement subexpression
      Overrides:
      replaceSubExpression in class ParentNodeConstructor
      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

    • iterateSubExpressions

      public Iterator<Expression> iterateSubExpressions()
      Get the immediate sub-expressions of this expression.
      Overrides:
      iterateSubExpressions in class ParentNodeConstructor
      Returns:
      an iterator containing the sub-expressions of this expression

    • 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, ExpressionVisitor.ContextItemType 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)

    • 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

    • 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 -
      Returns:
      the base URI

    • outputNamespaceNodes

      protected 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 -
      copiedNode -
      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

    • 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

    • processLeft

      public void processLeft(Stack<XPathContext> contextStack, Stack<Object> 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 - the dynamic evaluation context
      state - a stack on which the instruction can save state information for use during the corresponding
      Throws:
      XPathException - if a dynamic error occurs

    • processRight

      public void processRight(Stack<XPathContext> contextStack, Stack<Object> 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 - the stack of XPath context objects for the current execution state
      state - a stack on which the instruction can save state information for use during the corresponding
      Throws:
      XPathException - if a dynamic error occurs

    • 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