Package net.sf.saxon.instruct

Class GeneralVariable

    • Field Detail

      • nameCode

        protected int nameCode

      • slotNumber

        protected int slotNumber

      • referenceCount

        protected int referenceCount

      • evaluationMode

        protected int evaluationMode

    • Constructor Detail

      • GeneralVariable

        public GeneralVariable()

    • Method Detail

      • init

        public void init​(Expression select,
                 int nameCode)

      • setSelectExpression

        public void setSelectExpression​(Expression select)

      • getSelectExpression

        public Expression getSelectExpression()

      • setRequiredType

        public void setRequiredType​(SequenceType required)

      • setNameCode

        public void setNameCode​(int nameCode)

      • getNameCode

        public int getNameCode()

      • setAssignable

        public void setAssignable​(boolean assignable)

      • setRequiredParam

        public void setRequiredParam​(boolean requiredParam)

      • setImplicitlyRequiredParam

        public void setImplicitlyRequiredParam​(boolean requiredParam)

      • setTunnel

        public void setTunnel​(boolean tunnel)

      • setReferenceCount

        public void setReferenceCount​(int refCount)

      • 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

      • getVariableFingerprint

        public int getVariableFingerprint()
        Get the name of the variable (as a NamePool fingerprint)
        Returns:
        the NamePool fingerprint of the variable's expanded name.

      • 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.
        Specified by:
        getItemType in interface Expression
        Overrides:
        getItemType in class Instruction
        Parameters:
        th -
        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.
        Specified by:
        getCardinality in interface Expression
        Overrides:
        getCardinality in class ComputedExpression
        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

      • 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

      • isRequiredParam

        public final boolean isRequiredParam()

      • isImplicitlyRequiredParam

        public final boolean isImplicitlyRequiredParam()

      • isTunnelParam

        public final boolean isTunnelParam()

      • getInstructionNameCode

        public int getInstructionNameCode()
        Description copied from class: Instruction
        Get the namecode of the instruction for use in diagnostics
        Overrides:
        getInstructionNameCode in class Instruction

      • simplify

        public Expression simplify​(StaticContext env)
                    throws XPathException
        Description copied from class: Instruction
        Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.
        Specified by:
        simplify in interface Expression
        Specified by:
        simplify in class Instruction
        Parameters:
        env - the static context
        Returns:
        the simplified expression
        Throws:
        XPathException - if an error is discovered during expression rewriting

      • typeCheck

        public Expression typeCheck​(StaticContext env,
                            ItemType contextItemType)
                     throws XPathException
        Description copied from interface: 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.

        Specified by:
        typeCheck in interface Expression
        Parameters:
        env - the static context of the expression
        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:
        StaticError - if an error is discovered during this phase (typically a type error)
        XPathException

      • optimize

        public Expression optimize​(Optimizer opt,
                           StaticContext env,
                           ItemType contextItemType)
                    throws XPathException
        Description copied from interface: 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.

        Specified by:
        optimize in interface Expression
        Parameters:
        opt - the optimizer in use. This provides access to supporting functions; it also allows different optimization strategies to be used in different circumstances.
        env - the static context of the expression
        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:
        StaticError - if an error is discovered during this phase (typically a type error)
        XPathException

      • 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 Expression
        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 Expression
        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

      • 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)
        Specified by:
        iterateSubExpressions in interface Expression
        Overrides:
        iterateSubExpressions in class ComputedExpression
        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
        Specified by:
        replaceSubExpression in interface Container
        Overrides:
        replaceSubExpression in class ComputedExpression
        Parameters:
        original - the original subexpression
        replacement - the replacement subexpression
        Returns:
        true if the original subexpression is found

      • display

        public void display​(int level,
                    java.io.PrintStream out,
                    Configuration config)
        Diagnostic print of expression structure. The expression is written to the System.err output stream
        Specified by:
        display in interface Expression
        Parameters:
        level - indentation level for this expression
        out -
        config -

      • getSlotNumber

        public int getSlotNumber()

      • setSlotNumber

        public void setSlotNumber​(int s)

      • setVariableName

        public void setVariableName​(java.lang.String s)

      • getVariableName

        public java.lang.String getVariableName()