Class Minimax

All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, InstructionInfo, Locator

public class Minimax extends CollatingFunction
This class implements the min() and max() functions
See Also:
  • Field Details

  • Constructor Details

    • Minimax

      public Minimax()
  • Method Details

    • setIgnoreNaN

      public void setIgnoreNaN(boolean ignore)
      Indicate whether NaN values should be ignored. For the external min() and max() function, a NaN value in the input causes the result to be NaN. Internally, however, min() and max() are also used in such a way that NaN values should be ignored.
      Parameters:
      ignore - true if NaN values are to be ignored when computing the min or max.
    • isIgnoreNaN

      public boolean isIgnoreNaN()
      Test whether NaN values are to be ignored
      Returns:
      true if NaN values are to be ignored. This is the case for internally-generated min() and max() functions used to support general comparisons
    • getComparer

      public AtomicComparer getComparer()
    • getArgumentType

      public BuiltInAtomicType getArgumentType()
    • getImplementationMethod

      public int getImplementationMethod()
      Get implementation method
      Overrides:
      getImplementationMethod in class SystemFunction
      Returns:
      a value that indicates this function is capable of being streamed
    • checkArguments

      public void checkArguments(ExpressionVisitor visitor) throws XPathException
      Static analysis: prevent sorting of the argument
      Overrides:
      checkArguments in class CollatingFunction
      Parameters:
      visitor - the expression visitor
      Throws:
      XPathException - if the arguments are incorrect
    • computeCardinality

      public int computeCardinality()
      Determine the cardinality of the function.
      Overrides:
      computeCardinality in class SystemFunction
      Returns:
      the computed cardinality, as one of the values StaticProperty.ALLOWS_ZERO_OR_ONE, StaticProperty.EXACTLY_ONE, StaticProperty.ALLOWS_ONE_OR_MORE, StaticProperty.ALLOWS_ZERO_OR_MORE
    • typeCheck

      public Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
      Type-check the expression
      Overrides:
      typeCheck in class FunctionCall
      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, ExpressionVisitor.ContextItemType 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.

      Overrides:
      optimize in class SystemFunction
      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)
    • getItemType

      public ItemType getItemType(TypeHierarchy th)
      Determine the item type of the value returned by the function
      Overrides:
      getItemType in class SystemFunction
      Parameters:
      th - the type hierarchy cache
      Returns:
      the statically inferred type of the expression
    • copy

      public Expression copy()
      Copy an expression. This makes a deep copy.
      Overrides:
      copy in class CollatingFunction
      Returns:
      the copy of the original expression
    • equals

      public boolean equals(Object o)
      Determine whether two expressions are equivalent
      Overrides:
      equals in class CollatingFunction
    • evaluateItem

      public Item evaluateItem(XPathContext context) throws XPathException
      Evaluate the function
      Overrides:
      evaluateItem in class Expression
      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
    • getAtomicComparer

      public AtomicComparer getAtomicComparer(XPathContext context) throws XPathException
      Throws:
      XPathException
    • minimax

      public static AtomicValue minimax(SequenceIterator iter, int operation, AtomicComparer atomicComparer, boolean ignoreNaN, XPathContext context) throws XPathException
      Static method to evaluate the minimum or maximum of a sequence
      Parameters:
      iter - Iterator over the input sequence
      operation - either MIN or MAX
      atomicComparer - an AtomicComparer used to compare values
      ignoreNaN - true if NaN values are to be ignored
      context - dynamic evaluation context
      Returns:
      the min or max value in the sequence, according to the rules of the fn:min() or fn:max() functions
      Throws:
      XPathException - typically if non-comparable values are found in the sequence