org.exist.xquery
Class Union

java.lang.Object
  org.exist.xquery.AbstractExpression
      org.exist.xquery.CombiningExpression
          org.exist.xquery.Union

All Implemented Interfaces:

Expression

public class Union
extends CombiningExpression

Field Summary

Fields inherited from interface org.exist.xquery.Expression

DOT_TEST, EXPRESSION_ID_INVALID, IGNORE_CONTEXT, IN_NODE_CONSTRUCTOR, IN_PREDICATE, IN_UPDATE, IN_WHERE_CLAUSE, NEED_INDEX_INFO, NO_CONTEXT_ID, POSITIONAL_PREDICATE, SINGLE_STEP_EXECUTION, USE_TREE_TRAVERSAL

Constructor Summary

Union(XQueryContext context, PathExpr left, PathExpr right)

Method Summary

void	accept(ExpressionVisitor visitor) Start traversing the expression tree using the specified ExpressionVisitor.
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.
String	toString()

Methods inherited from class org.exist.xquery.CombiningExpression

analyze, resetState, returnsType, setContextDocSet, setPrimaryAxis

Methods inherited from class org.exist.xquery.AbstractExpression

eval, getCardinality, getColumn, getContext, getContextDocSet, getContextId, getDependencies, getExpressionId, getLine, getPrimaryAxis, getSource, setASTNode, setLocation

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Union

public Union(XQueryContext context,
             PathExpr left,
             PathExpr right)

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 CombiningExpression

Parameters:

contextSequence - the current context sequence.

contextItem - a single item, taken from context. This defines the item, the expression should work on.

Throws:

XPathException

dump

public void dump(ExpressionDumper dumper)

Description copied from interface: Expression

Write a diagnostic dump of the expression to the passed ExpressionDumper.

Parameters:

dumper - the expression dumper to write to

toString

public String toString()

Overrides:

toString in class Object

accept

public void accept(ExpressionVisitor visitor)

Description copied from interface: Expression

Start traversing the expression tree using the specified ExpressionVisitor.

Specified by:

accept in interface Expression

Overrides:

accept in class AbstractExpression