Class BreakInstr

All Implemented Interfaces:
ExportAgent, TailCallReturner, Locatable, TailCallLoop.TailCallInfo, IdentityComparable, Traceable

public class BreakInstr extends Instruction implements TailCallLoop.TailCallInfo
A compiled xsl:break instruction. The effect of executing this instruction is to register with the dynamic context that a tail call on a pseudo-function break() has been made; the enclosing xsl:iterate loop detects this tail call request and uses it as a signal to terminate execution of the loop.
  • Constructor Details

    • BreakInstr

      public BreakInstr()
      Create the instruction
  • Method Details

    • operands

      public Iterable<Operand> operands()
      Description copied from class: Expression
      Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression. Default implementation works off the results of iterateSubExpressions()

      If the expression is a Callable, then it is required that the order of the operands returned by this function is the same as the order of arguments supplied to the corresponding call() method.

      Specified by:
      operands in class Instruction
      Returns:
      an iterator containing the sub-expressions of this expression
    • copy

      public Expression copy(RebindingMap rebindings)
      Description copied from class: Expression
      Copy an expression. This makes a deep copy.
      Specified by:
      copy in class Expression
      Parameters:
      rebindings - a mutable list of (old binding, new binding) pairs that is used to update the bindings held in any local variable references that are copied.
      Returns:
      the copy of the original expression
    • mayCreateNewNodes

      public boolean mayCreateNewNodes()
      Description copied from class: Instruction
      Ask whether this instruction potentially creates and returns new nodes. Returns true if some branches or dynamic conditions result in new nodes being created. This implementation returns a default value of false
      Overrides:
      mayCreateNewNodes in class Instruction
      Returns:
      true if the instruction creates new nodes under some input conditions (or if it can't be proved that it doesn't)
    • isLiftable

      public boolean isLiftable(boolean forStreaming)
      Ask whether the expression can be lifted out of a loop, assuming it has no dependencies on the controlling variable/focus of the loop
      Overrides:
      isLiftable in class Expression
      Parameters:
      forStreaming - true if we are optimizing for streamed evaluation
      Returns:
      for a BreakInstr, always false
    • getInstructionNameCode

      public int getInstructionNameCode()
      Get the namecode of the instruction for use in diagnostics
      Overrides:
      getInstructionNameCode in class Instruction
      Returns:
      a code identifying the instruction: typically but not always the fingerprint of a name in the XSLT namespace
    • processLeavingTail

      public TailCall processLeavingTail(Outputter output, XPathContext context) throws XPathException
      Description copied from class: Instruction
      ProcessLeavingTail: called to do the real work of this instruction. This method must be implemented in each subclass. The results of the instruction are written to the current Receiver, which can be obtained via the Controller.
      Specified by:
      processLeavingTail in interface TailCallReturner
      Specified by:
      processLeavingTail in class Instruction
      Parameters:
      output - the destination for the result
      context - The dynamic context of the transformation, giving access to the current node, the current variables, etc.
      Returns:
      null if the instruction has completed execution; or a TailCall indicating a function call or template call that is delegated to the caller, to be made after the stack has been unwound so as to save stack space.
      Throws:
      XPathException - if a dynamic error occurs during the evaluation of the instruction
    • markContext

      public void markContext(XPathContext context)
    • getExpressionName

      public String getExpressionName()
      Description copied from class: Instruction
      Get a name identifying the kind of expression, in terms meaningful to a user.
      Overrides:
      getExpressionName in class Instruction
      Returns:
      a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in explain() output displaying the expression.
    • export

      public void export(ExpressionPresenter out) throws XPathException
      Description copied from class: Expression
      Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
      Specified by:
      export in interface ExportAgent
      Specified by:
      export in class Expression
      Parameters:
      out - the expression presenter used to display the structure
      Throws:
      XPathException - if the export fails, for example if an expression is found that won't work in the target environment.