net.sf.saxon.expr
Class MinimaxComparison

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

public class MinimaxComparison
extends BinaryExpression

Class to handle many-to-many A less-than B comparisons by evaluating min(A) < max(B), and similarly for greater-than, etc. This expression is used only where it is known that the comparisons will all be numeric: that is, where at least one of the operands has a static type that is a numeric sequence.

See Also:
Serialized Form

Field Summary
 
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
MinimaxComparison(Expression p0, int operator, Expression p1)
           
 
Method Summary
 int computeCardinality()
          Determine the static cardinality.
 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
 Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType)
          Type-check the expression.
 
Methods inherited from class net.sf.saxon.expr.BinaryExpression
computeSpecialProperties, display, displayOperator, equals, getOperands, getOperator, hashCode, isCommutative, isInverse, iterateSubExpressions, promote, simplify, typeCheck
 
Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, dynamicError, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, typeError, typeError
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

MinimaxComparison

public MinimaxComparison(Expression p0,
                         int operator,
                         Expression p1)
Method Detail

computeCardinality

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

Overrides:
computeCardinality in class BinaryExpression

optimize

public Expression optimize(Optimizer opt,
                           StaticContext env,
                           ItemType contextItemType)
                    throws XPathException
Type-check the expression.

Specified by:
optimize in interface Expression
Overrides:
optimize in class BinaryExpression
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:
XPathException

getItemType

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

Returns:
Type.BOOLEAN

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