net.sf.saxon.expr
Class BinaryExpression

java.lang.Object
  extended bynet.sf.saxon.expr.ComputedExpression
      extended bynet.sf.saxon.expr.BinaryExpression
All Implemented Interfaces:
Expression, Serializable
Direct Known Subclasses:
AppendExpression, ArithmeticExpression, BooleanExpression, GeneralComparison, IdentityComparison, MinimaxComparison, RangeExpression, SingletonComparison, ValueComparison, VennExpression

abstract class BinaryExpression
extends ComputedExpression

Binary Expression: a numeric or boolean expression consisting of the two operands and an operator


Field Summary
protected  Expression[] operands
           
protected  int operator
           
 
Fields inherited from class net.sf.saxon.expr.ComputedExpression
lineNumber, NO_ARGUMENTS, staticProperties
 
Constructor Summary
BinaryExpression()
          Default constructor
BinaryExpression(Expression p1, int op, Expression p2)
          Create a binary expression identifying the two operands and the operator
 
Method Summary
 Expression analyze(StaticContext env)
          Type-check the expression.
 int computeCardinality()
          Determine the static cardinality
 void display(int level, NamePool pool)
          Diagnostic print of expression structure
protected  String displayOperator()
           
 boolean equals(Object other)
          Is this expression the same as another expression?
 Expression[] getSubExpressions()
          Get the immediate subexpressions of this expression
 int hashCode()
          get HashCode for comparing two expressions.
protected static boolean isCommutative(int operator)
           
 Expression promote(PromotionOffer offer)
          Promote this expression if possible
 void setDetails(Expression p1, int op, Expression p2)
          Identify the two operands and the operator (for use when the default constructor was used)
 Expression simplify()
          Simplify an expression
 
Methods inherited from class net.sf.saxon.expr.ComputedExpression
computeDependencies, computeSpecialProperties, computeStaticProperties, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, getCardinality, getDependencies, getIntrinsicDependencies, getLineNumber, getSpecialProperties, iterate, markTailFunctionCalls, setLineNumber, typeError
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface net.sf.saxon.expr.Expression
getItemType
 

Field Detail

operands

protected Expression[] operands

operator

protected int operator
Constructor Detail

BinaryExpression

public BinaryExpression()
Default constructor


BinaryExpression

public BinaryExpression(Expression p1,
                        int op,
                        Expression p2)
Create a binary expression identifying the two operands and the operator

Parameters:
p1 - the left-hand operand
op - the operator, as a token returned by the Tokenizer (e.g. Tokenizer.AND)
p2 - the right-hand operand
Method Detail

setDetails

public void setDetails(Expression p1,
                       int op,
                       Expression p2)
Identify the two operands and the operator (for use when the default constructor was used)

Parameters:
p1 - the left-hand operand
op - the operator, as a token returned by the Tokenizer (e.g. Tokenizer.AND)
p2 - the right-hand operand

simplify

public Expression simplify()
                    throws XPathException
Simplify an expression

Specified by:
simplify in interface Expression
Overrides:
simplify in class ComputedExpression
Returns:
the simplified expression
Throws:
XPathException - if an error is discovered during expression rewriting

analyze

public Expression analyze(StaticContext env)
                   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
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)

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

getSubExpressions

public Expression[] getSubExpressions()
Get the immediate subexpressions of this expression

Specified by:
getSubExpressions in interface Expression
Overrides:
getSubExpressions in class ComputedExpression
Returns:
an array containing the sub-expressions of this expression

computeCardinality

public int computeCardinality()
Determine the static cardinality

Specified by:
computeCardinality in class ComputedExpression

isCommutative

protected static boolean isCommutative(int operator)

equals

public boolean equals(Object other)
Is this expression the same as another expression?


hashCode

public int hashCode()
get 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.


display

public void display(int level,
                    NamePool pool)
Diagnostic print of expression structure

Parameters:
level - indentation level for this expression

displayOperator

protected String displayOperator()