net.sf.saxon.expr
Class GeneralComparison

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

All Implemented Interfaces:

Serializable, Expression

public class GeneralComparison
extends BinaryExpression

GeneralComparison: a boolean expression that compares two expressions for equals, not-equals, greater-than or less-than. This implements the operators =, !=, <, >, etc.

See Also:

Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.expr.BinaryExpression

operands, operator

Fields inherited from class net.sf.saxon.expr.ComputedExpression

lineNumber, NO_ARGUMENTS, staticProperties

Constructor Summary

GeneralComparison(Expression p0, int op, Expression p1)
Create a relational expression identifying the two operands and the operator

Method Summary

Expression	analyze(StaticContext env) Type-check the expression
protected static boolean	compare(AtomicValue a1, int operator, AtomicValue a2, AtomicComparer comparer, boolean backwardsCompatible) Compare two atomic values
protected String	displayOperator()
boolean	effectiveBooleanValue(XPathContext context) Evaluate the expression in a boolean context
Item	evaluateItem(XPathContext context) Evaluate the expression in a given context
ItemType	getItemType() Determine the data type of the expression
void	setDetails(Expression p0, int op, Expression p1) Identify the two operands and the operator (for use when the default constructor was used)

Methods inherited from class net.sf.saxon.expr.BinaryExpression

computeCardinality, display, equals, getSubExpressions, hashCode, isCommutative, promote, simplify

Methods inherited from class net.sf.saxon.expr.ComputedExpression

computeDependencies, computeSpecialProperties, computeStaticProperties, dynamicError, evaluateAsString, 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

Constructor Detail

GeneralComparison

public GeneralComparison(Expression p0,
                         int op,
                         Expression p1)

Create a relational 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. Tokenizer.LT)

p1 - the right-hand operand

Method Detail

setDetails

public void setDetails(Expression p0,
                       int op,
                       Expression p1)

Description copied from class: BinaryExpression

Identify the two operands and the operator (for use when the default constructor was used)

Overrides:

setDetails in class BinaryExpression

Parameters:

p0 - the left-hand operand

op - the operator, as a token returned by the Tokenizer (e.g. Tokenizer.AND)

p1 - the right-hand operand

analyze

public Expression analyze(StaticContext env)
                   throws XPathException

Type-check the expression

Specified by:

analyze in interface Expression

Overrides:

analyze in class BinaryExpression

Parameters:

env - the static context of the expression

Returns:

the checked expression

Throws:

XPathException - if an error is discovered during this phase (typically a type error)

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException

Evaluate the expression in a given context

Specified by:

evaluateItem in interface Expression

Overrides:

evaluateItem in class ComputedExpression

Parameters:

context - the given context for evaluation

Returns:

a BooleanValue representing the result of the numeric comparison of the two operands

Throws:

XPathException - if any dynamic error occurs evaluating the expression

effectiveBooleanValue

public boolean effectiveBooleanValue(XPathContext context)
                              throws XPathException

Evaluate the expression in a boolean context

Specified by:

effectiveBooleanValue in interface Expression

Overrides:

effectiveBooleanValue in class ComputedExpression

Parameters:

context - the given context for evaluation

Returns:

a boolean representing the result of the numeric comparison of the two operands

Throws:

XPathException - if any dynamic error occurs evaluating the expression

compare

protected static boolean compare(AtomicValue a1,
                                 int operator,
                                 AtomicValue a2,
                                 AtomicComparer comparer,
                                 boolean backwardsCompatible)
                          throws XPathException

Compare two atomic values

Throws:

XPathException

getItemType

public ItemType getItemType()

Determine the data type of the expression

Returns:

Type.BOOLEAN

displayOperator

protected String displayOperator()

Overrides:

displayOperator in class BinaryExpression