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

      • typeCheck

        public Expression typeCheck​(ExpressionVisitor visitor,
                                    ExpressionVisitor.ContextItemType contextItemType)
                             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
        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 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
      • promote

        public Expression promote​(PromotionOffer offer,
                                  Expression parent)
                           throws XPathException
        Promote this expression if possible
        Overrides:
        promote in class Expression
        Parameters:
        offer - details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expression
        parent - the containing expression in the expression tree
        Returns:
        if the offer is not accepted, return this expression unchanged. Otherwise return the result of rewriting the expression to promote this subexpression
        Throws:
        XPathException - if any error is detected
      • iterateSubExpressions

        public java.util.Iterator<Expression> iterateSubExpressions()
        Get the immediate subexpressions of this expression
        Overrides:
        iterateSubExpressions in class Expression
        Returns:
        an iterator containing the sub-expressions of this expression
      • getArguments

        public Expression[] getArguments()
        Get the subexpressions (arguments to this expression)
        Returns:
        the arguments, as an array
      • replaceSubExpression

        public boolean replaceSubExpression​(Expression original,
                                            Expression replacement)
        Replace one subexpression by a replacement subexpression
        Overrides:
        replaceSubExpression in class Expression
        Parameters:
        original - the original subexpression
        replacement - the replacement subexpression
        Returns:
        true if the original subexpression is found
      • getOperator

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

        public Expression[] getOperands()
        Get the operands
        Returns:
        the two operands of the binary expression, as an array of length 2
      • 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
      • equals

        public boolean equals​(java.lang.Object other)
        Is this expression the same as another expression?
        Overrides:
        equals in class java.lang.Object
      • hashCode

        public int hashCode()
        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:
        hashCode in class java.lang.Object
      • toString

        public java.lang.String toString()
        The toString() method for an expression attempts to give a representation of the expression in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath. In the case of XSLT instructions, the toString() method gives an abstracted view of the syntax
        Overrides:
        toString in class Expression
        Returns:
        a representation of the expression as a string
      • explain

        public void explain​(ExpressionPresenter out)
        Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
        Specified by:
        explain in class Expression
        Parameters:
        out - the output destination for the displayed expression tree
      • 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)