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: Class PathExpression
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com.icl.saxon.expr
Class PathExpression


java.lang.Object

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  +--com.icl.saxon.expr.Expression

        |

        +--com.icl.saxon.expr.NodeSetExpression

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              +--com.icl.saxon.expr.PathExpression
public class PathExpression
extends NodeSetExpression

An expression that establishes a set of nodes by following relationships between nodes in the document. Specifically, it consists of a start expression which defines a set of nodes, and a Step which defines a relationship to be followed from those nodes to create a new set of nodes.

Fields inherited from class com.icl.saxon.expr.Expression
staticContext
 
Constructor Summary
PathExpression(Expression start, Step step)
          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
 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
evaluate, evaluateAsBoolean, evaluateAsNodeSet, evaluateAsString, getDataType, outputStringValue, selectFirst
 
Methods inherited from class com.icl.saxon.expr.Expression
containsReferences, evaluateAsNumber, getStaticContext, indent, make, setStaticContext, usesCurrent
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

PathExpression


public PathExpression(Expression start,
                      Step step)
Constructor
Parameters:
start - A node-set expression denoting the absolute or relative set of nodes from which the navigation path should start.
step - The step to be followed from each node in the start expression to yield a new node-set
Method Detail

simplify


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

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 class 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 class 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 class 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

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 class NodeSetExpression
Parameters:
context - the evaluation context
sort - true if the returned nodes must be in document order

display


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