net.sf.saxon.expr
Class GeneralComparison

java.lang.Object
  extended bynet.sf.saxon.expr.ComputedExpression
      extended bynet.sf.saxon.expr.BinaryExpression
          extended bynet.sf.saxon.expr.GeneralComparison
All Implemented Interfaces:
Container, Expression, InstructionInfoProvider, java.io.Serializable, javax.xml.transform.SourceLocator

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. This implementation is not used when in backwards-compatible mode

See Also:
Serialized Form

Field Summary
protected  AtomicComparer comparer
           
protected  int singletonOperator
           
 
Fields inherited from class net.sf.saxon.expr.BinaryExpression
operand0, operand1, operator
 
Fields inherited from class net.sf.saxon.expr.ComputedExpression
locationId, staticProperties
 
Fields inherited from interface net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
 
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, ItemType contextItemType)
          Type-check the expression
protected static boolean compare(AtomicValue a1, int operator, AtomicValue a2, AtomicComparer comparer, XPathContext context)
          Compare two atomic values
 int computeCardinality()
          Determine the static cardinality.
protected  java.lang.String displayOperator()
           
 boolean effectiveBooleanValue(XPathContext context)
          Evaluate the expression in a boolean context
 Item evaluateItem(XPathContext context)
          Evaluate the expression in a given context
protected  GeneralComparison getInverseComparison()
           
 ItemType getItemType()
          Determine the data type of the expression
 
Methods inherited from class net.sf.saxon.expr.BinaryExpression
computeSpecialProperties, display, equals, getOperands, getOperator, hashCode, isCommutative, isInverse, iterateSubExpressions, promote, simplify
 
Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, dynamicError, dynamicError, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getParentExpression, getPublicId, getSpecialProperties, getSystemId, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, typeError, typeError
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

singletonOperator

protected int singletonOperator

comparer

protected AtomicComparer comparer
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. Token.LT)
p1 - the right-hand operand
Method Detail

computeCardinality

public int computeCardinality()
Determine the static cardinality. Returns [1..1]

Overrides:
computeCardinality in class BinaryExpression

analyze

public Expression analyze(StaticContext env,
                          ItemType contextItemType)
                   throws XPathException
Type-check the expression

Specified by:
analyze in interface Expression
Overrides:
analyze in class BinaryExpression
Returns:
the checked expression
Throws:
XPathException

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,
                                 XPathContext context)
                          throws XPathException
Compare two atomic values

Throws:
XPathException

getItemType

public ItemType getItemType()
Determine the data type of the expression

Returns:
Type.BOOLEAN

getInverseComparison

protected GeneralComparison getInverseComparison()

displayOperator

protected java.lang.String displayOperator()
Overrides:
displayOperator in class BinaryExpression