Package net.sf.saxon.expr.instruct

Class SlotManager

  • Direct Known Subclasses:
    SlotManagerEE
    public class SlotManager
extends java.lang.Object
    A SlotManager supports functions, templates, etc: specifically, any executable code that requires a stack frame containing local variables. In XSLT a SlotManager underpins any top-level element that can contain local variable declarations, specifically, a top-level xsl:template, xsl:variable, xsl:param, or xsl:function element or an xsl:attribute-set element or xsl:key element. In XQuery it underpins functions and global variables. The purpose of the SlotManager is to allocate slot numbers to variables in the stack, and to record how many slots are needed. A Debugger may define a subclass with additional functionality.

    • Field Detail

      • EMPTY

        public static SlotManager EMPTY
        An empty SlotManager

    • Constructor Detail

      • SlotManager

        public SlotManager()
        The constructor should not be called directly. A new SlotManager should be obtained using the factory method Configuration.makeSlotManager().

      • SlotManager

        public SlotManager​(int n)
        Create a SlotManager with a given number of slots
        Parameters:
        n - the number of slots

    • Method Detail

      • getNumberOfVariables

        public int getNumberOfVariables()
        Get number of variables (size of stack frame)
        Returns:
        the number of slots for variables

      • setNumberOfVariables

        public void setNumberOfVariables​(int numberOfVariables)
        Set the number of variables
        Parameters:
        numberOfVariables - the space to be allocated for variables

      • allocateSlotNumber

        public int allocateSlotNumber​(StructuredQName qName,
                              LocalBinding binding)
        Allocate a slot number for a variable
        Parameters:
        qName - the name of the variable
        binding - the binding of the variable (only used in Saxon-EE)
        Returns:
        the allocated slot number (the next one available)

      • getVariableMap

        public java.util.List<StructuredQName> getVariableMap()
        Get the variable map (simply a list of variable names as structured QNames). Note that it is possible for several variables to have the same name.
        Returns:
        the list of variable names for this stack frame

      • showStackFrame

        public void showStackFrame​(XPathContext context,
                           Logger logger)
        Display the values of the variables and parameters in an XPathContext stack frame to a Logger
        Parameters:
        context - the XPathContext holding the stack frame
        logger - the destination for the output