Class PositionRange

  • All Implemented Interfaces:
    java.io.Serializable, javax.xml.transform.SourceLocator, Container, Expression, InstructionInfoProvider

    public final class PositionRange
    extends ComputedExpression
    PositionRange: a boolean expression that tests whether the position() is within a certain range. This expression can occur in any context but it is optimized when it appears as a predicate (see FilterIterator)
    See Also:
    Serialized Form
    • Field Detail

      • maxSameAsMin

        boolean maxSameAsMin
    • Constructor Detail

      • PositionRange

        public PositionRange​(Expression pos)
        Create a position "range" for an exact position
      • PositionRange

        public PositionRange​(int min,
                             int max)
        Create a constant position range
    • Method Detail

      • typeCheck

        public Expression typeCheck​(StaticContext env,
                                    ItemType contextItemType)
                             throws XPathException
        Type-check the 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
        Perform optimisation of an expression and its subexpressions.

        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.

        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 c)
                          throws XPathException
        Evaluate the expression
        Specified by:
        evaluateItem in interface Expression
        Overrides:
        evaluateItem in class ComputedExpression
        Parameters:
        c - 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
      • getItemType

        public ItemType getItemType​(TypeHierarchy th)
        Determine the data type of the expression
        Parameters:
        th -
        Returns:
        Type.BOOLEAN
      • getIntrinsicDependencies

        public int getIntrinsicDependencies()
        Get the dependencies
        Overrides:
        getIntrinsicDependencies in class ComputedExpression
        Returns:
        a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty
      • iterateSubExpressions

        public java.util.Iterator iterateSubExpressions()
        Get the immediate sub-expressions of this expression. Default implementation returns a zero-length array, appropriate for an expression that has no sub-expressions.
        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
      • isFirstPositionOnly

        public boolean isFirstPositionOnly()
        Test if the first and last position are both constant 1
      • hasFocusDependentRange

        public boolean hasFocusDependentRange()
        Test whether the range is focus-dependent. An example of a focus-dependent range is (1 to position()). We could treat last() specially but we don't.
      • matchesAtMostOneItem

        public boolean matchesAtMostOneItem()
        Test if the position range matches at most one item
      • makeTailExpression

        public TailExpression makeTailExpression​(Expression start)
        If this is an open-ended range with a constant start position, make a TailExpression. Otherwise return null
      • display

        public void display​(int level,
                            java.io.PrintStream out,
                            Configuration config)
        Diagnostic print of expression structure
        Parameters:
        level - indentation level for this expression
        out - Output destination