Package net.sf.saxon.expr

Class BinaryExpression

    • Field Detail

      • operator

        protected int operator

    • Constructor Detail

      • BinaryExpression

        public BinaryExpression​(Expression p0,
                        int op,
                        Expression p1)
        Create a binary 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.AND)
        p1 - the right-hand operand

    • Method Detail

      • operands

        public final java.lang.Iterable<Operand> operands()
        Description copied from class: Expression
        Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression. Default implementation works off the results of iterateSubExpressions()

        If the expression is a Callable, then it is required that the order of the operands returned by this function is the same as the order of arguments supplied to the corresponding call() method.

        Overrides:
        operands in class Expression
        Returns:
        an iterator containing the sub-expressions of this expression

      • getOperandRole

        protected OperandRole getOperandRole​(int arg)
        Get the operand role
        Parameters:
        arg - which argument: 0 for the lhs, 1 for the rhs
        Returns:
        the operand role

      • getLhs

        public Operand getLhs()
        Get the left-hand operand
        Returns:
        the left-hand operand

      • getLhsExpression

        public final Expression getLhsExpression()
        Get the left-hand operand expression
        Returns:
        the left-hand operand child expression

      • setLhsExpression

        public void setLhsExpression​(Expression child)
        Set the left-hand operand expression
        Parameters:
        child - the left-hand operand expression

      • getRhs

        public Operand getRhs()
        Get the right-hand operand
        Returns:
        the right-hand operand

      • getRhsExpression

        public final Expression getRhsExpression()
        Get the right-hand operand expression
        Returns:
        the right-hand operand expression

      • setRhsExpression

        public void setRhsExpression​(Expression child)
        Set the right-hand operand expression
        Parameters:
        child - the right-hand operand expression

      • typeCheck

        public Expression typeCheck​(ExpressionVisitor visitor,
                            ContextItemStaticInfo contextInfo)
                     throws XPathException
        Type-check the expression. Default implementation for binary operators that accept any kind of operand
        Overrides:
        typeCheck in class Expression
        Parameters:
        visitor - an expression visitor
        contextInfo - Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.
        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,
                           ContextItemStaticInfo 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 Expression
        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)

      • setFlattened

        public void setFlattened​(boolean flattened)
        Mark an expression as being "flattened". This is a collective term that includes extracting the string value or typed value, or operations such as simple value construction that concatenate text nodes before atomizing. The implication of all of these is that although the expression might return nodes, the identity of the nodes has no significance. This is called during type checking of the parent expression.
        Overrides:
        setFlattened in class Expression
        Parameters:
        flattened - set to true if the result of the expression is atomized or otherwise turned into an atomic value

      • getOperator

        public int getOperator()
        Get the operator
        Returns:
        the operator, for example Token.PLUS

      • isCommutative

        protected static boolean isCommutative​(int operator)
        Determine whether a binary operator is commutative, that is, A op B = B op A.
        Parameters:
        operator - the operator, for example Token.PLUS
        Returns:
        true if the operator is commutative

      • isAssociative

        protected static boolean isAssociative​(int operator)
        Determine whether an operator is associative, that is, ((a^b)^c) = (a^(b^c))
        Parameters:
        operator - the operator, for example Token.PLUS
        Returns:
        true if the operator is associative

      • isInverse

        protected static boolean isInverse​(int op1,
                                   int op2)
        Test if one operator is the inverse of another, so that (A op1 B) is equivalent to (B op2 A). Commutative operators are the inverse of themselves and are therefore not listed here.
        Parameters:
        op1 - the first operator
        op2 - the second operator
        Returns:
        true if the operators are the inverse of each other

      • getImplementationMethod

        public int getImplementationMethod()
        An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is provided directly. The other methods will always be available indirectly, using an implementation that relies on one of the other methods.
        Specified by:
        getImplementationMethod in class Expression
        Returns:
        the implementation method, for example Expression.ITERATE_METHOD or Expression.EVALUATE_METHOD or Expression.PROCESS_METHOD

      • equals

        public boolean equals​(java.lang.Object other)
        Is this expression the same as another expression?
        Overrides:
        equals in class Expression
        Parameters:
        other - the other operand; the result is false if this is not an Expression
        Returns:
        true if the other operand is an expression and if it can be determined that the two expressions are equivalent, in the sense that they will always return the same result.

      • computeHashCode

        protected int computeHashCode()
        Get a hashCode for comparing two expressions. Note that this hashcode gives the same result for (A op B) and for (B op A), whether or not the operator is commutative.
        Overrides:
        computeHashCode in class Expression
        Returns:
        a computed hash code

      • toString

        public java.lang.String toString()
        Represent the expression as a string. The resulting string will be a valid XPath 3.0 expression with no dependencies on namespace bindings other than the binding of the prefix "xs" to the XML Schema namespace.
        Overrides:
        toString in class Expression
        Returns:
        the expression as a string in XPath 3.0 syntax

      • toShortString

        public java.lang.String toShortString()
        Description copied from class: Expression
        Produce a short string identifying the expression for use in error messages
        Overrides:
        toShortString in class Expression
        Returns:
        a short string, sufficient to identify the expression

      • export

        public void export​(ExpressionPresenter out)
            throws XPathException
        Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
        Specified by:
        export in interface ExportAgent
        Specified by:
        export in class Expression
        Parameters:
        out - the output destination for the displayed expression tree
        Throws:
        XPathException - if the export fails, for example if an expression is found that won't work in the target environment.

      • tag

        protected java.lang.String tag()
        Get the element name used to identify this expression in exported expression format
        Returns:
        the element name used to identify this expression

      • explainExtraAttributes

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

      • displayOperator

        protected java.lang.String displayOperator()
        Display the operator used by this binary expression
        Returns:
        String representation of the operator (for diagnostic display only)