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
-
Restriction:
- This interface is not intended to be implemented by clients.
-
Restriction:
- This interface is not intended to be extended by clients.
|
Field Summary
|
static
Object
|
UNDEFINED_VARIABLE
Represents the value used by variables that exist but are not defined
in a evaluation context. |
UNDEFINED_VARIABLE
static final
Object UNDEFINED_VARIABLE
- Represents the value used by variables that exist but are not defined
in a evaluation context. When tested by the 'with' expression,
false
will be returned.
-
Since:
- 3.4
getParent
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
IEvaluationContext getRoot()
- Returns the root evaluation context.
-
-
Returns:
- the root evaluation context
setAllowPluginActivation
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.
-
-
Parameters:
-
value - whether this evaluation context allows plug-in activation -
Since:
- 3.2
getAllowPluginActivation
boolean getAllowPluginActivation()
- Returns whether this evaluation context supports plug-in
activation. If not set via
setAllowPluginActivation(boolean)
the parent value is returned. If no parent is set false
is returned.
-
-
Returns:
- whether plug-in activation is supported or not
-
Since:
- 3.2
getDefaultVariable
Object getDefaultVariable()
- Returns the default variable.
-
-
Returns:
- the default variable or
null if
no default variable is managed.
addVariable
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
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
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
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
Guidelines for using Eclipse APIs.
Copyright (c) Eclipse contributors and others 2000, 2008. All rights reserved.
