1 files changed, 39 insertions, 0 deletions
diff --git a/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/expression/IEvaluationContext.java b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/expression/IEvaluationContext.java
new file mode 100644
index 000000000..4b049c054
--- /dev/null
+++ b/bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/metadata/expression/IEvaluationContext.java
@@ -0,0 +1,39 @@
+/*******************************************************************************
+ * Copyright (c) 2009 - 2010 Cloudsmith Inc. 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:
+ *     Cloudsmith Inc. - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.equinox.p2.metadata.expression;
+
+/**
+ * The evaluation context. Contexts can be nested and new contexts are pushed for each closure
+ * during an evaluation of an expression.
+ * @since 2.0
+ */
+public interface IEvaluationContext {
+	/**
+	 * Retrieve the value of the given <code>variable</code> from this context
+	 * @param variable The variable who's value should be retrieved
+	 * @return The current value for the variable
+	 */
+	Object getValue(IExpression variable);
+
+	/**
+	 * Set the current value for the given <code>variable</code> to <code>value</code>
+	 * @param variable The variable who's value should be set
+	 * @param value The new value for the variable.
+	 */
+	void setValue(IExpression variable, Object value);
+
+	/**
+	 * Returns the value of the parameter at the given <code>position</code>
+	 * @param position The zero based position for the parameter
+	 * @return The parameter value
+	 */
+	Object getParameter(int position);
+}