Class NodeSetExpression

java.lang.Object
com.icl.saxon.expr.Expression
com.icl.saxon.expr.NodeSetExpression
Direct Known Subclasses:
AxisExpression, FilterExpression, NodeListExpression, PathExpression, SingletonExpression, SortedSelection, UnionExpression
public abstract class NodeSetExpression extends Expression
A NodeSetExpression is any expression denoting a set of nodes.
This is an abstract class, the methods are defaults which may be overridden in subclasses

  • Constructor Details

    • NodeSetExpression

      public NodeSetExpression()

  • Method Details

    • enumerate

      public abstract NodeEnumeration enumerate(Context context, boolean sorted) throws XPathException
      Return a node enumeration. All NodeSetExpressions must implement this method: the evaluate() function is defined in terms of it. (But note that some expressions that return node-sets are not NodeSetExpressions: for example functions such as key(), id(), and document() are not, and neither are variable references).
      Overrides:
      enumerate in class Expression
      Parameters:
      context - The evaluation context
      sorted - True if the nodes must be returned in document order
      Throws:
      XPathException - when the expression does not return a nodeset.

    • evaluate

      public Value evaluate(Context context) throws XPathException
      Evaluate this node-set. This doesn't actually retrieve all the nodes: it returns a wrapper around a node-set expression in which all context dependencies have been eliminated.
      Specified by:
      evaluate in class Expression
      Parameters:
      context - The context in which the expression is to be evaluated
      Returns:
      the value of the expression, evaluated in the current context
      Throws:
      XPathException

    • selectFirst

      public NodeInfo selectFirst(Context context) throws XPathException
      Return the first node selected by this Expression when evaluated in the current context
      Parameters:
      context - The context for the evaluation
      Returns:
      the NodeInfo of the first node in document order, or null if the node-set is empty.
      Throws:
      XPathException

    • evaluateAsString

      public String evaluateAsString(Context context) throws XPathException
      Evaluate as a string. Returns the string value of the first node selected by the NodeSetExpression
      Overrides:
      evaluateAsString in class Expression
      Parameters:
      context - The context in which the expression is to be evaluated
      Returns:
      the value of the NodeSetExpression, evaluated in the current context
      Throws:
      XPathException

    • outputStringValue

      public void outputStringValue(Outputter out, Context context) throws TransformerException
      Evaluate an expression as a String and write the result to the specified outputter.
      Overrides:
      outputStringValue in class Expression
      Parameters:
      out - The required outputter
      context - The context in which the expression is to be evaluated
      Throws:
      TransformerException

    • evaluateAsBoolean

      public boolean evaluateAsBoolean(Context context) throws XPathException
      Evaluate as a boolean. Returns true if there are any nodes selected by the NodeSetExpression
      Overrides:
      evaluateAsBoolean in class Expression
      Parameters:
      context - The context in which the expression is to be evaluated
      Returns:
      true if there are any nodes selected by the NodeSetExpression
      Throws:
      XPathException

    • evaluateAsNodeSet

      public NodeSetValue evaluateAsNodeSet(Context context) throws XPathException
      Evaluate an expression as a NodeSet.
      Overrides:
      evaluateAsNodeSet in class Expression
      Parameters:
      context - The context in which the expression is to be evaluated
      Returns:
      the value of the expression, evaluated in the current context
      Throws:
      XPathException - when the expression does not return a nodeset.

    • getDataType

      public int getDataType()
      Determine the data type of the exprssion, if possible
      Specified by:
      getDataType in class Expression
      Returns:
      Value.NODESET