Class PositionRange

java.lang.Object
net.sf.saxon.expr.ComputedExpression
net.sf.saxon.expr.PositionRange
All Implemented Interfaces:
Serializable, 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:

  • Field Details

    • maxSameAsMin

      boolean maxSameAsMin

  • Constructor Details

    • PositionRange

      public PositionRange(Expression min, Expression max)
      Create a position range

    • 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 Details

    • simplify

      public Expression simplify(StaticContext env) throws XPathException
      Simplify an expression
      Specified by:
      simplify in interface Expression
      Overrides:
      simplify in class ComputedExpression
      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
      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:
      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

    • computeSpecialProperties

      public int computeSpecialProperties()
      Determine the special properties of this expression
      Overrides:
      computeSpecialProperties in class ComputedExpression
      Returns:
      StaticProperty.NON_CREATIVE.

    • 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

    • makePositionIterator

      public SequenceIterator makePositionIterator(SequenceIterator base, XPathContext c) throws XPathException
      Make an iterator over a range of a sequence determined by this position range
      Throws:
      XPathException

    • getItemType

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

    • computeCardinality

      public int computeCardinality()
      Determine the static cardinality
      Specified by:
      computeCardinality in class ComputedExpression

    • 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 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, PrintStream out, Configuration config)
      Diagnostic print of expression structure
      Parameters:
      level - indentation level for this expression
      out - Output destination
      config -