com.icl.saxon.expr

## Class PathExpression

- java.lang.Object
- - com.icl.saxon.expr.Expression
  - - com.icl.saxon.expr.NodeSetExpression
    - - 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.

- - ### Field Summary

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

      `staticContext`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `PathExpression(Expression start, Step step)` Constructor

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `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
      Throws:
        `XPathException`

    - #### 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`

    - #### 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.
      Specified by:
        `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
      Throws:
        `XPathException`

    - #### enumerate

          public NodeEnumeration enumerate(Context context,
                                  boolean sort)
                                    throws XPathException

      Evaluate the path-expression in a given context to return a NodeSet
      Specified by:
        `enumerate` in class `NodeSetExpression`
      Parameters:
        `context` - the evaluation context
        `sort` - true if the returned nodes must be in document order
      Throws:
        `XPathException` - when the expression does not return a nodeset.

    - #### display

          public void display(int level)

      Diagnostic print of expression structure
      Specified by:
        `display` in class `Expression`