| /******************************************************************************* |
| * Copyright (c) 2000, 2006 IBM Corporation and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| package org.eclipse.core.expressions; |
| |
| import org.eclipse.core.runtime.CoreException; |
| |
| /** |
| * 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. |
| * <p> |
| * This interface is not intended to be implemented by clients. Clients |
| * are allowed to instantiate <code>EvaluationContext</code>. |
| * </p> |
| * |
| * @since 3.0 |
| */ |
| public interface IEvaluationContext { |
| |
| /** |
| * Returns the parent context or <code>null</code> if |
| * this is the root of the evaluation context hierarchy. |
| * |
| * @return the parent evaluation context or <code>null</code> |
| */ |
| public IEvaluationContext getParent(); |
| |
| /** |
| * Returns the root evaluation context. |
| * |
| * @return the root evaluation context |
| */ |
| public IEvaluationContext getRoot(); |
| |
| /** |
| * 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 <code> |
| * true</code> and the actual test expression must have the |
| * attribute <code>forcePluginActivation</code> set to <code> |
| * true</code> as well. |
| * |
| * @param value whether this evaluation context allows plug-in activation |
| * @since 3.2 |
| */ |
| public void setAllowPluginActivation(boolean value); |
| |
| /** |
| * Returns whether this evaluation context supports plug-in |
| * activation. If not set via {@link #setAllowPluginActivation(boolean)} |
| * the parent value is returned. If no parent is set <code>false</code> |
| * is returned. |
| * |
| * @return whether plug-in activation is supported or not |
| * @since 3.2 |
| */ |
| public boolean getAllowPluginActivation(); |
| |
| /** |
| * Returns the default variable. |
| * |
| * @return the default variable or <code>null</code> if |
| * no default variable is managed. |
| */ |
| public Object getDefaultVariable(); |
| |
| /** |
| * Adds a new named variable to this context. If a variable |
| * with the name already exists the new one overrides the |
| * existing one. |
| * |
| * @param name the variable's name |
| * @param value the variable's value |
| */ |
| public void addVariable(String name, Object value); |
| |
| /** |
| * Removes the variable managed under the given name |
| * from this evaluation context. |
| * |
| * @param name the variable's name |
| * @return the currently stored value or <code>null</code> if |
| * the variable doesn't exist |
| */ |
| public Object removeVariable(String name); |
| |
| /** |
| * Returns the variable managed under the given name. |
| * |
| * @param name the variable's name |
| * @return the variable's value or <code>null</code> if the content |
| * doesn't manage a variable with the given name |
| */ |
| public Object getVariable(String name); |
| |
| /** |
| * 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 <code>resolve</code> expression. |
| * |
| * @param name the variable to resolve |
| * @param args an object array of arguments used to resolve the |
| * variable |
| * @return the variable's value or <code>null</code> if no variable |
| * can be resolved for the given name and arguments |
| * @exception CoreException if an errors occurs while resolving |
| * the variable |
| */ |
| public Object resolveVariable(String name, Object[] args) throws CoreException; |
| } |