Class GeneralVariable

    • Field Detail

      • slotNumber

        protected int slotNumber
      • referenceCount

        protected int referenceCount
      • evaluationMode

        protected int evaluationMode
    • Constructor Detail

      • GeneralVariable

        public GeneralVariable()
        Create a general variable
    • Method Detail

      • init

        public void init​(Expression select,
                         StructuredQName qName)
        Initialize the properties of the variable
        Parameters:
        select - the expression to which the variable is bound
        qName - the name of the variable
      • setSelectExpression

        public void setSelectExpression​(Expression select)
        Set the expression to which this variable is bound
        Parameters:
        select - the initializing expression
      • getSelectExpression

        public Expression getSelectExpression()
        Get the expression to which this variable is bound
        Returns:
        the initializing expression
      • setRequiredType

        public void setRequiredType​(SequenceType required)
        Set the required type of this variable
        Parameters:
        required - the required type
      • getRequiredType

        public SequenceType getRequiredType()
        Get the required type of this variable
        Specified by:
        getRequiredType in interface Binding
        Returns:
        the required type
      • setAssignable

        public void setAssignable​(boolean assignable)
        Indicate whether this variable is assignable using saxon:assign
        Parameters:
        assignable - true if this variable is assignable
      • setRequiredParam

        public void setRequiredParam​(boolean requiredParam)
        Indicate that this variable represents a required parameter
        Parameters:
        requiredParam - true if this is a required parameter
      • setImplicitlyRequiredParam

        public void setImplicitlyRequiredParam​(boolean requiredParam)
        Indicate that this variable represents a parameter that is implicitly required (because there is no usable default value)
        Parameters:
        requiredParam - true if this is an implicitly required parameter
      • setTunnel

        public void setTunnel​(boolean tunnel)
        Indicate whether this variable represents a tunnel parameter
        Parameters:
        tunnel - true if this is a tunnel parameter
      • setReferenceCount

        public void setReferenceCount​(int refCount)
        Set the nominal number of references to this variable
        Parameters:
        refCount - the nominal number of references
      • getEvaluationMode

        public int getEvaluationMode()
        Get the evaluation mode of the variable
        Returns:
        the evaluation mode (a constant in ExpressionTool
      • isAssignable

        public final boolean isAssignable()
        Test whether it is permitted to assign to the variable using the saxon:assign extension element. This will only be true if the extra attribute saxon:assignable="yes" is present.
        Specified by:
        isAssignable in interface Binding
        Returns:
        true if the binding is assignable
      • getItemType

        public ItemType getItemType​(TypeHierarchy th)
        Get the type of the result of this instruction. An xsl:variable instruction returns nothing, so the type is empty.
        Overrides:
        getItemType in class Instruction
        Parameters:
        th - the type hierarchy cache
        Returns:
        the empty type.
      • getCardinality

        public int getCardinality()
        Get the cardinality of the result of this instruction. An xsl:variable instruction returns nothing, so the type is empty.
        Overrides:
        getCardinality in class Expression
        Returns:
        the empty cardinality.
      • isGlobal

        public boolean isGlobal()
        Description copied from interface: Binding
        Indicate whether the binding is local or global. A global binding is one that has a fixed value for the life of a query or transformation; any other binding is local.
        Specified by:
        isGlobal in interface Binding
        Returns:
        true if the binding is global
      • getLocalSlotNumber

        public int getLocalSlotNumber()
        If this is a local variable held on the local stack frame, return the corresponding slot number. In other cases, return -1.
        Specified by:
        getLocalSlotNumber in interface Binding
        Returns:
        the slot number on the local stack frame
      • isRequiredParam

        public final boolean isRequiredParam()
        Ask whether this variable represents a required parameter
        Returns:
        true if this is a required parameter
      • isImplicitlyRequiredParam

        public final boolean isImplicitlyRequiredParam()
        Ask whether this variable represents a parameter that is implicitly required, because there is no usable default value
        Returns:
        true if this variable is an implicitly required parameter
      • isTunnelParam

        public final boolean isTunnelParam()
        Ask whether this variable represents a tunnel parameter
        Returns:
        true if this is a tunnel parameter
      • getInstructionNameCode

        public int getInstructionNameCode()
        Get the name of this instruction (that is xsl:variable, xsl:param etc) for diagnostics
        Overrides:
        getInstructionNameCode in class Instruction
        Returns:
        the name of this instruction, as a name pool name code
      • 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 parent pointer and 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 Expression
        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)
      • 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 Expression
        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)
      • 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
      • evaluateItem

        public Item evaluateItem​(XPathContext context)
                          throws XPathException
        Evaluate an expression as a single item. This always returns either a single Item or null (denoting the empty sequence). No conversion is done. This method should not be used unless the static type of the expression is a subtype of "item" or "item?": that is, it should not be called if the expression may return a sequence. There is no guarantee that this condition will be detected.
        Specified by:
        evaluateItem in interface EvaluableItem
        Overrides:
        evaluateItem in class Instruction
        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
      • iterate

        public SequenceIterator iterate​(XPathContext context)
                                 throws XPathException
        Return an Iterator to iterate over the values of a sequence. The value of every expression can be regarded as a sequence, so this method is supported for all expressions. This default implementation relies on the process() method: it "pushes" the results of the instruction to a sequence in memory, and then iterates over this in-memory sequence. In principle instructions should implement a pipelined iterate() method that avoids the overhead of intermediate storage.
        Specified by:
        iterate in interface SequenceIterable
        Overrides:
        iterate in class Instruction
        Parameters:
        context - supplies the context for evaluation
        Returns:
        a SequenceIterator that can be used to iterate over the result of the expression
        Throws:
        XPathException - if any dynamic error occurs evaluating the expression
      • getSelectValue

        public ValueRepresentation getSelectValue​(XPathContext context)
                                           throws XPathException
        Evaluate the variable. That is, get the value of the select expression if present or the content of the element otherwise, either as a tree or as a sequence
        Parameters:
        context - the XPath dynamic context
        Returns:
        the result of evaluating the variable
        Throws:
        XPathException
      • iterateSubExpressions

        public java.util.Iterator iterateSubExpressions()
        Get all the XPath expressions associated with this instruction (in XSLT terms, the expression present on attributes of the instruction, as distinct from the child instructions in a sequence construction)
        Overrides:
        iterateSubExpressions in class Expression
        Returns:
        an iterator containing the sub-expressions of this expression
      • replaceSubExpression

        public boolean replaceSubExpression​(Expression original,
                                            Expression replacement)
        Replace one subexpression by a replacement subexpression
        Overrides:
        replaceSubExpression in class Expression
        Parameters:
        original - the original subexpression
        replacement - the replacement subexpression
        Returns:
        true if the original subexpression is found
      • 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
      • getSlotNumber

        public int getSlotNumber()
        Get the slot number allocated to this variable
        Returns:
        the slot number, that is the position allocated to the variable on its stack frame
      • setSlotNumber

        public void setSlotNumber​(int s)
        Set the slot number of this variable
        Parameters:
        s - the slot number, that is, the position allocated to this variable on its stack frame
      • setVariableQName

        public void setVariableQName​(StructuredQName s)
        Set the name of the variable
        Parameters:
        s - the name of the variable (a QName)
      • getVariableQName

        public StructuredQName getVariableQName()
        Get the name of this variable
        Specified by:
        getVariableQName in interface Binding
        Returns:
        the name of this variable (a QName)