Class GeneralComparison

    • Field Detail

      • singletonOperator

        protected int singletonOperator
      • needsRuntimeCheck

        protected boolean needsRuntimeCheck
      • comparisonCardinality

        protected int comparisonCardinality
    • Constructor Detail

      • GeneralComparison

        public GeneralComparison​(Expression p0,
                                 int op,
                                 Expression p1)
        Create a relational expression identifying the two operands and the operator
        Parameters:
        p0 - the left-hand operand
        op - the operator, as a token returned by the Tokenizer (e.g. Token.LT)
        p1 - the right-hand operand
    • Method Detail

      • needsRuntimeCheck

        public boolean needsRuntimeCheck()
        Ask whether a runtime check of the types of the operands is needed
      • setNeedsRuntimeCheck

        public void setNeedsRuntimeCheck​(boolean needsCheck)
        Say whether a runtime check of the types of the operands is needed
      • getComparisonCardinality

        public int getComparisonCardinality()
        Ask whether the comparison is known to be many-to-one, one-to-one, or many-to-many. (Note, an expression that is one-to-many will be converted to one that is many-to-one).
      • setComparisonCardinality

        public void setComparisonCardinality​(int card)
        Say whether the comparison is known to be many-to-one, one-to-one, or many-to-many.
      • setAtomicComparer

        public void setAtomicComparer​(AtomicComparer comparer)
        Set the comparer to be used
        Parameters:
        comparer - the comparer to be used
      • getExpressionName

        public java.lang.String getExpressionName()
        Get a name identifying the kind of expression, in terms meaningful to a user.
        Overrides:
        getExpressionName in class Expression
        Returns:
        a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in explain() output displaying the expression.
      • getSingletonOperator

        public int getSingletonOperator()
        Get the primitive (singleton) operator used: one of Token.FEQ, Token.FNE, Token.FLT, Token.FGT, Token.FLE, Token.FGE
        Specified by:
        getSingletonOperator in interface ComparisonExpression
      • convertsUntypedToOther

        public boolean convertsUntypedToOther()
        Determine whether untyped atomic values should be converted to the type of the other operand
        Specified by:
        convertsUntypedToOther in interface ComparisonExpression
        Returns:
        true if untyped values should be converted to the type of the other operand, false if they should be converted to strings.
      • typeCheck

        public Expression typeCheck​(ExpressionVisitor visitor,
                                    ExpressionVisitor.ContextItemType contextItemType)
                             throws XPathException
        Type-check the expression
        Overrides:
        typeCheck in class BinaryExpression
        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 checked expression
        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
        Optimize the expression
        Overrides:
        optimize in class BinaryExpression
        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 checked expression
        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 the expression in a given context
        Overrides:
        evaluateItem in class Expression
        Parameters:
        context - the given context for evaluation
        Returns:
        a BooleanValue representing the result of the numeric comparison of the two operands
        Throws:
        XPathException - if any dynamic error occurs evaluating the expression
      • call

        public SequenceIterator call​(SequenceIterator[] arguments,
                                     XPathContext context)
                              throws XPathException
        Evaluate the expression
        Specified by:
        call in interface CallableExpression
        Parameters:
        arguments - the values of the arguments, supplied as SequenceIterators
        context - the dynamic evaluation context
        Returns:
        the result of the evaluation, in the form of a SequenceIterator
        Throws:
        XPathException - if a dynamic error occurs during the evaluation of the expression
      • effectiveBooleanValue

        public boolean effectiveBooleanValue​(XPathContext context)
                                      throws XPathException
        Evaluate the expression in a boolean context
        Overrides:
        effectiveBooleanValue in class Expression
        Parameters:
        context - the given context for evaluation
        Returns:
        a boolean representing the result of the numeric comparison of the two operands
        Throws:
        XPathException - if any dynamic error occurs evaluating the expression
      • evaluateManyToMany

        public boolean evaluateManyToMany​(SequenceIterator iter0,
                                          SequenceIterator iter1,
                                          XPathContext context)
                                   throws XPathException
        Evaluate a (zero-or-one)-to-(zero-or-one) comparison
        Parameters:
        iter0 - iterator over the first value
        iter1 - iterator the second value
        context - dynamic evaluation context
        Returns:
        the comparison result
        Throws:
        XPathException - if a dynamic error occurs
      • compare

        public static boolean compare​(AtomicValue a0,
                                      int operator,
                                      AtomicValue a1,
                                      AtomicComparer comparer,
                                      boolean checkTypes,
                                      XPathContext context)
                               throws XPathException
        Compare two atomic values
        Parameters:
        a0 - the first value
        operator - the operator, for example Token.EQUALS
        a1 - the second value
        comparer - the comparer to be used to perform the comparison
        checkTypes - set to true if the operand types need to be checked for comparability at runtime
        context - the XPath evaluation context @return true if the comparison succeeds
        Throws:
        XPathException
      • getItemType

        public ItemType getItemType​(TypeHierarchy th)
        Determine the data type of the expression
        Specified by:
        getItemType in class Expression
        Parameters:
        th - the type hierarchy cache
        Returns:
        the value BuiltInAtomicType.BOOLEAN
      • getCorrespondingSingletonOperator

        public static int getCorrespondingSingletonOperator​(int op)
        Return the singleton form of the comparison operator, e.g. FEQ for EQUALS, FGT for GT
        Parameters:
        op - the many-to-many form of the operator, for example Token.LE
        Returns:
        the corresponding singleton operator, for example Token.FLE
      • explainExtraAttributes

        protected void explainExtraAttributes​(ExpressionPresenter out)
        Description copied from class: BinaryExpression
        Add subclass-specific attributes to the expression tree explanation. Default implementation does nothing; this is provided for subclasses to override.
        Overrides:
        explainExtraAttributes in class BinaryExpression
        Parameters:
        out - the output destination for the displayed expression tree