org.exist.xquery.functions
Class FunSubSequence

java.lang.Object
  org.exist.xquery.AbstractExpression
      org.exist.xquery.PathExpr
          org.exist.xquery.Function
              org.exist.xquery.functions.FunSubSequence

All Implemented Interfaces:

CompiledXQuery, Expression, CompiledExpression

public class FunSubSequence
extends Function

Implements the fn:subsequence function.

Author:

Wolfgang Meier (wolfgang@exist-db.org)

Field Summary

static FunctionSignature[]

signatures

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_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

FunSubSequence(XQueryContext context, FunctionSignature signature)

Method Summary

void	analyze(AnalyzeContextInfo contextInfo) Statically analyze the expression and its subexpressions.
Sequence	eval(Sequence contextSequence, Item contextItem) Evaluate the expression represented by this object.

Methods inherited from class org.exist.xquery.Function

accept, createFunction, dump, getArgument, getArgumentCount, getArguments, getCardinality, getDependencies, getName, getParent, getSignature, isCalledAs, returnsType, setArguments, setParent, setPrimaryAxis, toString

Methods inherited from class org.exist.xquery.PathExpr

add, add, addPath, addPredicate, dump, getColumn, getContext, getDocumentSet, getExpression, getLastExpression, getLength, getLine, getLiteralValue, getPrimaryAxis, isValid, replaceExpression, replaceLastExpression, reset, resetState, setContext, setUseStaticContext

Methods inherited from class org.exist.xquery.AbstractExpression

eval, getContextDocSet, getContextId, getExpressionId, getSource, setASTNode, setContextDocSet, setLocation

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.exist.xquery.CompiledXQuery

eval, getSource

Field Detail

signatures

public static final FunctionSignature[] signatures

Constructor Detail

FunSubSequence

public FunSubSequence(XQueryContext context,
                      FunctionSignature signature)

Parameters:

context -

Method Detail

analyze

public void analyze(AnalyzeContextInfo contextInfo)
             throws XPathException

Description copied from interface: Expression

Statically analyze the expression and its subexpressions. During the static analysis phase, the query engine can detect unknown variables and some type errors.

Specified by:

analyze in interface Expression

Overrides:

analyze in class Function

Throws:

XPathException

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

Parameters:

contextSequence - the current context sequence.

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

Throws:

XPathException