com.icl.saxon.expr
Class SingletonComparison

java.lang.Object
  com.icl.saxon.expr.Expression
      com.icl.saxon.expr.SingletonComparison

public class SingletonComparison

extends Expression

Singleton Comparison: A Relational Expression that compares a singleton node-set with a string or numeric value for equals, not-equals, greater-than or less-than.

Field Summary

Fields inherited from class com.icl.saxon.expr.Expression

staticContext

Constructor Summary

SingletonComparison(SingletonExpression p1, int op, Value p2)

Method Summary

void	display(int level) Diagnostic print of expression structure
Value	evaluate(Context c) Evaluate the expression in a given context
boolean	evaluateAsBoolean(Context c) Evaluate the expression in a given context
int	getDataType() Determine the data type of the expression, if possible
int	getDependencies() Determine which aspects of the context the expression depends on.
Expression	reduce(int dependencies, Context context) Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
Expression	simplify() Simplify an expression

Methods inherited from class com.icl.saxon.expr.Expression

containsReferences, enumerate, evaluateAsNodeSet, evaluateAsNumber, evaluateAsString, getStaticContext, indent, isContextDocumentNodeSet, make, outputStringValue, setStaticContext, usesCurrent

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SingletonComparison

public SingletonComparison(SingletonExpression p1,
                           int op,
                           Value p2)

Method Detail

simplify

public Expression simplify()
                    throws XPathException

Simplify an expression

Overrides:

simplify in class Expression

Returns:

the simplified expression

Throws:

XPathException

evaluate

public Value evaluate(Context c)
               throws XPathException

Evaluate the expression in a given context

Specified by:

evaluate in class Expression

Parameters:

c - the given context for evaluation

Returns:

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

Throws:

XPathException

evaluateAsBoolean

public boolean evaluateAsBoolean(Context c)
                          throws XPathException

Evaluate the expression in a given context

Overrides:

evaluateAsBoolean in class Expression

Parameters:

c - the given context for evaluation

Returns:

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

Throws:

XPathException

getDataType

public int getDataType()

Determine the data type of the expression, if possible

Specified by:

getDataType in class Expression

Returns:

Value.BOOLEAN

getDependencies

public int getDependencies()

Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as Context.VARIABLES and Context.CURRENT_NODE

Specified by:

getDependencies in class Expression

reduce

public Expression reduce(int dependencies,
                         Context context)
                  throws XPathException

Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.

Specified by:

reduce in class Expression

Parameters:

dependencies - The dependencies to be removed

context - The context to be used for the partial evaluation

Returns:

a new expression that does not have any of the specified dependencies

Throws:

XPathException

display

public void display(int level)

Diagnostic print of expression structure

Specified by:

display in class Expression