org.exist.xquery
Class BindingExpression

java.lang.Object
  extended byorg.exist.xquery.AbstractExpression
      extended byorg.exist.xquery.BindingExpression
All Implemented Interfaces:
Expression
Direct Known Subclasses:
ForExpr, LetExpr, QuantifiedExpression

public abstract class BindingExpression
extends AbstractExpression

Abstract superclass for the variable binding expressions "for" and "let".

Author:
Wolfgang Meier

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
BindingExpression(XQueryContext context)
           
 
Method Summary
 void analyze(AnalyzeContextInfo contextInfo)
          Statically analyze the expression and its subexpressions.
abstract  void analyze(AnalyzeContextInfo contextInfo, OrderSpec[] orderBy)
           
 Sequence eval(Sequence contextSequence, Item contextItem)
          Evaluate the expression represented by this object.
abstract  Sequence eval(Sequence contextSequence, Item contextItem, Sequence resultSequence)
           
 DocumentSet preselect(DocumentSet in_docs)
           
 void resetState()
          Called to inform an expression that it should reset to its initial state.
 int returnsType()
          The static return type of the expression.
 void setInputSequence(Expression sequence)
           
 void setOrderSpecs(OrderSpec[] specs)
           
 void setReturnExpression(Expression expr)
           
 void setSequenceType(SequenceType type)
          Set the sequence type of the variable (as specified in the "as" clause).
 void setVariable(java.lang.String qname)
           
 void setWhereExpression(Expression expr)
           
 
Methods inherited from class org.exist.xquery.AbstractExpression
accept, eval, getASTNode, getCardinality, getContextDocSet, getContextId, getDependencies, getExpressionId, setASTNode, setContextDocSet, setPrimaryAxis
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface org.exist.xquery.Expression
dump
 

Constructor Detail

BindingExpression

public BindingExpression(XQueryContext context)
Method Detail

setVariable

public void setVariable(java.lang.String qname)

setSequenceType

public void setSequenceType(SequenceType type)
Set the sequence type of the variable (as specified in the "as" clause).

Parameters:
type -

setInputSequence

public void setInputSequence(Expression sequence)

setReturnExpression

public void setReturnExpression(Expression expr)

setWhereExpression

public void setWhereExpression(Expression expr)

setOrderSpecs

public void setOrderSpecs(OrderSpec[] specs)

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.

Throws:
XPathException

analyze

public abstract void analyze(AnalyzeContextInfo contextInfo,
                             OrderSpec[] orderBy)
                      throws XPathException
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 AbstractExpression
Throws:
XPathException

eval

public abstract Sequence eval(Sequence contextSequence,
                              Item contextItem,
                              Sequence resultSequence)
                       throws XPathException
Throws:
XPathException

preselect

public DocumentSet preselect(DocumentSet in_docs)
                      throws XPathException
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
Specified by:
returnsType in class AbstractExpression

resetState

public void resetState()
Description copied from interface: Expression
Called to inform an expression that it should reset to its initial state. All cached data in the expression object should be dropped. For example, the document() function calls this method whenever the input document set has changed.

Specified by:
resetState in interface Expression
Overrides:
resetState in class AbstractExpression


Copyright (C) Wolfgang Meier. All rights reserved.