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com.icl.saxon.expr

Class RootExpression

public class RootExpression
extends SingletonExpression
An expression whose value is always a set of nodes containing a single node, the document root.

Field Summary

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

staticContext

Method Summary

void
display(int level)
Diagnostic print of expression structure
boolean
evaluateAsBoolean(Context context)
Evaluate as a boolean.
String
evaluateAsString(Context context)
Evaluate as a string
int
getDependencies()
Determine which aspects of the context the expression depends on.
NodeInfo
getNode(Context context)
Return the first element selected by this Expression
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.SingletonExpression

enumerate, evaluateAsBoolean, evaluateAsNodeSet, evaluateAsString, getNode, isContextDocumentNodeSet, selectFirst

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

enumerate, evaluate, evaluateAsBoolean, evaluateAsNodeSet, evaluateAsString, getDataType, outputStringValue, selectFirst

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

containsReferences, display, enumerate, evaluate, evaluateAsBoolean, evaluateAsNodeSet, evaluateAsNumber, evaluateAsString, getDataType, getDependencies, getStaticContext, indent, isContextDocumentNodeSet, make, outputStringValue, reduce, setStaticContext, simplify, usesCurrent

Method Details

display

public void display(int level)
Diagnostic print of expression structure
Overrides:
display in interface Expression

evaluateAsBoolean

public boolean evaluateAsBoolean(Context context)
            throws XPathException
Evaluate as a boolean.
Overrides:
evaluateAsBoolean in interface SingletonExpression
Parameters:
context - The context (not used)
Returns:
true (always - because the nodeset is never empty)

evaluateAsString

public String evaluateAsString(Context context)
            throws XPathException
Evaluate as a string
Overrides:
evaluateAsString in interface SingletonExpression
Parameters:
context - The context for evaluation
Returns:
The concatenation of all the character data within the document

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
Overrides:
getDependencies in interface Expression

getNode

public NodeInfo getNode(Context context)
            throws XPathException
Return the first element selected by this Expression
Overrides:
getNode in interface SingletonExpression
Parameters:
context - The evaluation context
Returns:
the NodeInfo of the first selected element, or null if no element is selected

reduce

public Expression reduce(int dependencies,
                         Context context)
            throws XPathException
Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
Overrides:
reduce in interface 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

simplify

public Expression simplify()
            throws XPathException
Simplify an expression
Overrides:
simplify in interface Expression
Returns:
the simplified expression

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