Package org.eclipse.core.expressions

Class EvaluationContext

java.lang.Object

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

Constructors

Constructor	Description
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

Modifier and Type	Method	Description
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()

Description copied from interface: IEvaluationContext

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()

Description copied from interface: IEvaluationContext

Returns the root evaluation context.

Specified by:

getRoot in interface IEvaluationContext

Returns:

the root evaluation context

getDefaultVariable

public Object getDefaultVariable()

Description copied from interface: IEvaluationContext

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)

Description copied from interface: IEvaluationContext

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()

Description copied from interface: IEvaluationContext

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)

Description copied from interface: IEvaluationContext

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)

Description copied from interface: IEvaluationContext

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)

Description copied from interface: IEvaluationContext

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

Description copied from interface: IEvaluationContext

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