Eclipse Platform
Release 3.0

org.eclipse.core.expressions
Interface IEvaluationContext

All Known Implementing Classes:
EvaluationContext

public interface IEvaluationContext

An evaluation context is used to manage a set of objects needed during XML expression evaluation. A context has a parent context, can manage a set of named variables and has a default variable. The default variable is used during XML expression evaluation if no explicit variable is referenced.

This interface is not intended to be implemented by clients. Clients are allowed to instantiate EvaluationContext.

Since:
3.0

Method Summary
 void addVariable(String name, Object value)
          Adds a new named variable to this context.
 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.
 

Method Detail

getParent

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

Returns:
the parent evaluation context or null

getRoot

public IEvaluationContext getRoot()
Returns the root evaluation context.

Returns:
the root evaluation context

getDefaultVariable

public Object getDefaultVariable()
Returns the default variable.

Returns:
the default variable or null if no default variable is managed.

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.

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.

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.

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.

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 3.0

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