com.icl.saxon.expr

Class AxisExpression


(package private) final class AxisExpression
extends NodeSetExpression

An AxisExpression is always obtained by simplifying a PathExpression. It represents a PathExpression that starts at the context node, and uses a simple node-test with no filters. For example "*", "title", "./item", "@*", or "ancestor::chapter*".

Field Summary

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

staticContext

Constructor Summary

AxisExpression(byte axis, NodeTest nodeTest)
Constructor

Method Summary

void
display(int level)
Diagnostic print of expression structure
NodeEnumeration
enumerate(Context context, boolean sort)
Evaluate the path-expression in a given context to return a NodeSet
Value
evaluate(Context context)
Evaluate the expression (typically used if the result is to be stored in a variable)
int
getDependencies()
Determine which aspects of the context the expression depends on.
boolean
isContextDocumentNodeSet()
Determine, in the case of an expression whose data type is Value.NODESET, whether all the nodes in the node-set are guaranteed to come from the same document as the context node.
Expression
reduce(int dep, 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.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

Constructor Details

AxisExpression

public AxisExpression(byte axis,
                      NodeTest nodeTest)
Constructor
Parameters:

Method Details

display

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

enumerate

public NodeEnumeration enumerate(Context context,
                                 boolean sort)
            throws XPathException
Evaluate the path-expression in a given context to return a NodeSet
Overrides:
enumerate in interface NodeSetExpression
Parameters:
context - the evaluation context
sort - true if the returned nodes must be in document order

evaluate

public Value evaluate(Context context)
            throws XPathException
Evaluate the expression (typically used if the result is to be stored in a variable)
Overrides:
evaluate in interface NodeSetExpression

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

isContextDocumentNodeSet

public boolean isContextDocumentNodeSet()
Determine, in the case of an expression whose data type is Value.NODESET, whether all the nodes in the node-set are guaranteed to come from the same document as the context node. Used for optimization.
Overrides:
isContextDocumentNodeSet in interface Expression

reduce

public Expression reduce(int dep,
                         Context context)
            throws XPathException
Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
Overrides:
reduce in interface Expression
Parameters:
dep - 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()
Simplify an expression
Overrides:
simplify in interface Expression
Returns:
the simplified expression