Class BinaryExpression

java.lang.Object
net.sf.saxon.expr.ComputedExpression
net.sf.saxon.expr.BinaryExpression
All Implemented Interfaces:
Serializable, SourceLocator, Container, Expression, InstructionInfoProvider
Direct Known Subclasses:
ArithmeticExpression, BooleanExpression, GeneralComparison, GeneralComparison10, IdentityComparison, RangeExpression, SingletonComparison, ValueComparison, VennExpression

public abstract class BinaryExpression extends ComputedExpression
Binary Expression: a numeric or boolean expression consisting of the two operands and an operator
See Also:
  • Field Details

    • operand0

      protected Expression operand0
    • operand1

      protected Expression operand1
    • operator

      protected int operator
  • Constructor Details

    • 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 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. Default implementation for binary operators that accept any kind of operand
      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
    • promote

      public Expression promote(PromotionOffer offer) throws XPathException
      Promote this expression if possible
      Specified by:
      promote in interface Expression
      Overrides:
      promote in class ComputedExpression
      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
      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 Iterator iterateSubExpressions()
      Get the immediate subexpressions of this expression
      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
    • getOperator

      public int getOperator()
      Get the operator
    • getOperands

      public Expression[] getOperands()
      Get the operands
    • computeCardinality

      public int computeCardinality()
      Determine the static cardinality. Default implementation returns [0..1] if either operand can be empty, or [1..1] otherwise.
      Specified by:
      computeCardinality in class ComputedExpression
    • computeSpecialProperties

      public int computeSpecialProperties()
      Determine the special properties of this expression
      Overrides:
      computeSpecialProperties in class ComputedExpression
      Returns:
      StaticProperty.NON_CREATIVE. This is overridden for some subclasses.
    • isCommutative

      protected static boolean isCommutative(int operator)
      Determine whether a binary operator is commutative, that is, A op B = B op A.
      Parameters:
      operator -
      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))
    • 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(Object other)
      Is this expression the same as another expression?
      Overrides:
      equals in class 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 Object
    • 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 -
    • displayOperator

      protected String displayOperator()