org.exist.xquery
Class LogicalOp

java.lang.Object
  extended byorg.exist.xquery.AbstractExpression
      extended byorg.exist.xquery.PathExpr
          extended byorg.exist.xquery.BinaryOp
              extended byorg.exist.xquery.LogicalOp
All Implemented Interfaces:
CompiledExpression, CompiledXQuery, Expression
Direct Known Subclasses:
OpAnd, OpOr

public abstract class LogicalOp
extends BinaryOp

Base class for the boolean operators "and" and "or".

Author:
Wolfgang

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
LogicalOp(XQueryContext context)
           
 
Method Summary
 void analyze(AnalyzeContextInfo contextInfo)
          Statically analyze the expression and its subexpressions.
abstract  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.BinaryOp
getLeft, getRight, setContextDocSet, setLeft, setRight
 
Methods inherited from class org.exist.xquery.PathExpr
accept, add, add, addPath, addPredicate, dump, dump, getASTNode, getCardinality, getContext, getDocumentSet, getExpression, getLastExpression, getLength, getLiteralValue, getSource, isValid, replaceLastExpression, reset, resetState, setContext, setPrimaryAxis, setSource, toString
 
Methods inherited from class org.exist.xquery.AbstractExpression
eval, getContextDocSet, getContextId, getExpressionId, setASTNode
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface org.exist.xquery.CompiledXQuery
eval
 

Constructor Detail

LogicalOp

public LogicalOp(XQueryContext context)
Parameters:
context -
Method Detail

eval

public abstract 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 BinaryOp
Throws:
XPathException

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 BinaryOp
Throws:
XPathException

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 BinaryOp

getDependencies

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

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


Copyright (C) Wolfgang Meier. All rights reserved.