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Eclipse Platform
Release 3.5

org.eclipse.core.expressions
Class EvaluationContext

java.lang.Object
  extended by 
org.eclipse.core.expressions.EvaluationContext
All Implemented Interfaces:
IEvaluationContext

public class EvaluationContext
extends Object
implements IEvaluationContext

A default implementation of an evaluation context.

Clients may instantiate this default context. The class is not intended to be subclassed by clients.

Since:
3.0
Restriction:
This class is not intended to be subclassed by clients.

Field Summary
 
Fields inherited from interface org.eclipse.core.expressions. IEvaluationContext
UNDEFINED_VARIABLE
 
Constructor Summary
EvaluationContext ( IEvaluationContext parent, Object defaultVariable)
          Create a new evaluation context with the given parent and default variable.
EvaluationContext ( IEvaluationContext parent, Object defaultVariable, IVariableResolver[] resolvers)
          Create a new evaluation context with the given parent and default variable.
 
Method Summary
 void addVariable ( String name, Object value)
          Adds a new named variable to this context.
 boolean getAllowPluginActivation ()
          Returns whether this evaluation context supports plug-in activation.
  Object getDefaultVariable ()
          Returns the default variable.
  IEvaluationContext getParent ()
          Returns the parent context or null if this is the root of the evaluation context hierarchy.
  IEvaluationContext getRoot ()
          Returns the root evaluation context.
  Object getVariable ( String name)
          Returns the variable managed under the given name.
  Object removeVariable ( String name)
          Removes the variable managed under the given name from this evaluation context.
  Object resolveVariable ( String name, Object[] args)
          Resolves a variable for the given name and arguments.
 void setAllowPluginActivation (boolean value)
          Specifies whether this evaluation context allows activation of plug-ins for testers used in the expression tree.
 
Methods inherited from class java.lang. Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

EvaluationContext

public EvaluationContext(
IEvaluationContext parent,
                         
Object defaultVariable)
Create a new evaluation context with the given parent and default variable.

Parameters:
parent - the parent context. Can be null.
defaultVariable - the default variable

EvaluationContext

public EvaluationContext(
IEvaluationContext parent,
                         
Object defaultVariable,
                         
IVariableResolver[] resolvers)
Create a new evaluation context with the given parent and default variable.

Parameters:
parent - the parent context. Can be null.
defaultVariable - the default variable
resolvers - an array of IVariableResolvers to resolve additional variables.
See Also:
resolveVariable(String, Object[])
Method Detail

getParent

public 
IEvaluationContext getParent()
Returns the parent context or null if this is the root of the evaluation context hierarchy.

Specified by:
getParent in interface IEvaluationContext
Returns:
the parent evaluation context or null

getRoot

public 
IEvaluationContext getRoot()
Returns the root evaluation context.

Specified by:
getRoot in interface IEvaluationContext
Returns:
the root evaluation context

getDefaultVariable

public 
Object getDefaultVariable()
Returns the default variable.

Specified by:
getDefaultVariable in interface IEvaluationContext
Returns:
the default variable or null if no default variable is managed.

setAllowPluginActivation

public void setAllowPluginActivation(boolean value)
Specifies whether this evaluation context allows activation of plug-ins for testers used in the expression tree. To actual trigger the plug-in loading this flag has to be set to true and the actual test expression must have the attribute forcePluginActivation set to true as well.

Specified by:
setAllowPluginActivation in interface IEvaluationContext
Parameters:
value - whether this evaluation context allows plug-in activation

getAllowPluginActivation

public boolean getAllowPluginActivation()
Returns whether this evaluation context supports plug-in activation. If not set via IEvaluationContext.setAllowPluginActivation(boolean) the parent value is returned. If no parent is set false is returned.

Specified by:
getAllowPluginActivation in interface IEvaluationContext
Returns:
whether plug-in activation is supported or not

addVariable

public void addVariable(
String name,
                        
Object value)
Adds a new named variable to this context. If a variable with the name already exists the new one overrides the existing one.

Specified by:
addVariable in interface IEvaluationContext
Parameters:
name - the variable's name
value - the variable's value

removeVariable

public 
Object removeVariable(
String name)
Removes the variable managed under the given name from this evaluation context.

Specified by:
removeVariable in interface IEvaluationContext
Parameters:
name - the variable's name
Returns:
the currently stored value or null if the variable doesn't exist

getVariable

public 
Object getVariable(
String name)
Returns the variable managed under the given name.

Specified by:
getVariable in interface IEvaluationContext
Parameters:
name - the variable's name
Returns:
the variable's value or null if the content doesn't manage a variable with the given name

resolveVariable

public 
Object resolveVariable(
String name,
                              
Object[] args)
                       throws 
CoreException
Resolves a variable for the given name and arguments. This method can be used to dynamically resolve variable such as plug-in descriptors, resources, etc. The method is used by the resolve expression.

Specified by:
resolveVariable in interface IEvaluationContext
Parameters:
name - the variable to resolve
args - an object array of arguments used to resolve the variable
Returns:
the variable's value or null if no variable can be resolved for the given name and arguments
Throws:
CoreException - if an errors occurs while resolving the variable

Eclipse Platform
Release 3.5

Guidelines for using Eclipse APIs.

Copyright (c) Eclipse contributors and others 2000, 2008. All rights reserved.


 
 
  Published under the terms of the Eclipse Public License Version 1.0 ("EPL") Design by Interspire