org.exist.xquery.functions
Class FunDistinctValues

java.lang.Object
  extended byorg.exist.xquery.AbstractExpression
      extended byorg.exist.xquery.PathExpr
          extended byorg.exist.xquery.Function
              extended byorg.exist.xquery.functions.FunDistinctValues
All Implemented Interfaces:
CompiledExpression, CompiledXQuery, Expression

public class FunDistinctValues
extends Function

Implements the fn:distinct-values standard library function.

Author:
wolf

Field Summary
static FunctionSignature signature
           
 
Fields inherited from class org.exist.xquery.Function
BUILTIN_FUNCTION_NS
 
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
FunDistinctValues(XQueryContext context)
           
 
Method Summary
 Sequence eval(Sequence contextSequence, Item contextItem)
          Evaluate the expression represented by this object.
 int getDependencies()
          Returns Dependency.DEFAULT_DEPENDENCIES.
 int returnsType()
          The static return type of the expression.
 
Methods inherited from class org.exist.xquery.Function
analyze, createFunction, dump, getArgument, getArgumentCount, getArguments, getASTNode, getCardinality, getName, getParent, getSignature, isCalledAs, setArguments, setASTNode, setParent, setPrimaryAxis, toString
 
Methods inherited from class org.exist.xquery.PathExpr
accept, add, add, addPath, addPredicate, dump, getContext, getDocumentSet, getExpression, getLastExpression, getLength, getLiteralValue, getSource, isValid, replaceLastExpression, reset, resetState, setContext, setSource
 
Methods inherited from class org.exist.xquery.AbstractExpression
eval, getContextDocSet, getContextId, getExpressionId, setContextDocSet
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface org.exist.xquery.CompiledXQuery
eval
 

Field Detail

signature

public static final FunctionSignature signature
Constructor Detail

FunDistinctValues

public FunDistinctValues(XQueryContext context)
Method Detail

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 Function

getDependencies

public int getDependencies()
Description copied from class: AbstractExpression
Returns Dependency.DEFAULT_DEPENDENCIES.

Specified by:
getDependencies in interface Expression
Overrides:
getDependencies in class Function

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 Function
Throws:
XPathException


Copyright (C) Wolfgang Meier. All rights reserved.