net.sf.saxon.expr
Class BinaryExpression

java.lang.Object
  net.sf.saxon.expr.ComputedExpression
      net.sf.saxon.expr.BinaryExpression

All Implemented Interfaces:

Serializable, Expression

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?

Overrides:

equals in class Object

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.

Overrides:

hashCode in class Object

display

public void display(int level,
                    NamePool pool)

Diagnostic print of expression structure

Parameters:

level - indentation level for this expression

displayOperator

protected String displayOperator()