org.exist.xquery
Class RootNode

java.lang.Object
  extended byorg.exist.xquery.AbstractExpression
      extended byorg.exist.xquery.Step
          extended byorg.exist.xquery.RootNode
All Implemented Interfaces:
Expression

public class RootNode
extends Step

Reads a set of document root nodes from the context. Used for absolute path expression that do not start with fn:doc() or fn:collection().

Author:
Wolfgang Meier

Field Summary
 
Fields inherited from interface org.exist.xquery.Expression
DOT_TEST, EXPRESSION_ID_INVALID, IGNORE_CONTEXT, IN_PREDICATE, IN_UPDATE, IN_WHERE_CLAUSE, NO_CONTEXT_ID, SINGLE_STEP_EXECUTION
 
Constructor Summary
RootNode(XQueryContext context)
          Constructor for the RootNode object
 
Method Summary
 void dump(ExpressionDumper dumper)
          Write a diagnostic dump of the expression to the passed ExpressionDumper.
 Sequence eval(Sequence contextSequence, Item contextItem)
          Evaluate the expression represented by this object.
 void resetState()
          Called to inform an expression that it should reset to its initial state.
 int returnsType()
          The static return type of the expression.
 java.lang.String toString()
           
 
Methods inherited from class org.exist.xquery.Step
addPredicate, analyze, getAxis, getCardinality, setAxis, setPrimaryAxis, setTest
 
Methods inherited from class org.exist.xquery.AbstractExpression
accept, eval, getASTNode, getContextDocSet, getContextId, getDependencies, getExpressionId, setASTNode, setContextDocSet
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

RootNode

public RootNode(XQueryContext context)
Constructor for the RootNode object

Method Detail

eval

public Sequence eval(Sequence contextSequence,
                     Item contextItem)
              throws XPathException
Description copied from interface: Expression
Evaluate the expression represented by this object. Depending on the context in which this expression is executed, either the context sequence, the context item or both of them may be set. An implementing class should know how to handle this. The general contract is as follows: if the Dependency.CONTEXT_ITEM bit is set in the bit field returned by Expression.getDependencies(), the eval method will be called once for every item in the context sequence. The contextItem parameter will be set to the current item. Otherwise, the eval method will only be called once for the whole context sequence and contextItem will be null. eXist tries to process the entire context set in one, single step whenever possible. Thus, most classes only expect context to contain a list of nodes which represents the current context of the expression. The position() function in XPath is an example for an expression, which requires both, context sequence and context item to be set. The context sequence might be a node set, a sequence of atomic values or a single node or atomic value.

Specified by:
eval in interface Expression
Specified by:
eval in class Step
Throws:
XPathException

dump

public void dump(ExpressionDumper dumper)
Description copied from interface: Expression
Write a diagnostic dump of the expression to the passed ExpressionDumper.

Specified by:
dump in interface Expression
Overrides:
dump in class Step

toString

public java.lang.String toString()
Overrides:
toString in class Step

returnsType

public int returnsType()
Description copied from interface: Expression
The static return type of the expression. This method should return one of the type constants defined in class Type. If the return type cannot be determined statically, return Type.ITEM.

Specified by:
returnsType in interface Expression
Overrides:
returnsType in class Step

resetState

public void resetState()
Description copied from interface: Expression
Called to inform an expression that it should reset to its initial state. All cached data in the expression object should be dropped. For example, the document() function calls this method whenever the input document set has changed.

Specified by:
resetState in interface Expression
Overrides:
resetState in class Step


Copyright (C) Wolfgang Meier. All rights reserved.