org.exist.xquery
Class UnaryExpr

java.lang.Object
  org.exist.xquery.AbstractExpression
      org.exist.xquery.PathExpr
          org.exist.xquery.UnaryExpr

All Implemented Interfaces:

CompiledXQuery, Expression, CompiledExpression

public class UnaryExpr
extends PathExpr

A unary minus or plus.

Author:

wolf

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

UnaryExpr(XQueryContext context, int mode)

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.
int	returnsType() The static return type of the expression.
String	toString()

Methods inherited from class org.exist.xquery.PathExpr

accept, add, add, addPath, addPredicate, analyze, dump, getCardinality, getColumn, getContext, getDependencies, getDocumentSet, getExpression, getLastExpression, getLength, getLine, getLiteralValue, getParent, getPrimaryAxis, isValid, replaceExpression, replaceLastExpression, reset, resetState, setContext, setPrimaryAxis, 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

Constructor Detail

UnaryExpr

public UnaryExpr(XQueryContext context,
                 int mode)

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 PathExpr

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

Overrides:

eval in class PathExpr

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.

Specified by:

dump in interface Expression

Overrides:

dump in class PathExpr

Parameters:

dumper - the expression dumper to write to

toString

public String toString()

Overrides:

toString in class PathExpr