1 files changed, 76 insertions, 0 deletions
diff --git a/dice-lang/src/bjc/dicelang/ReferenceDiceExpression.java b/dice-lang/src/bjc/dicelang/ReferenceDiceExpression.java
new file mode 100644
index 0000000..483545b
--- /dev/null
+++ b/dice-lang/src/bjc/dicelang/ReferenceDiceExpression.java
@@ -0,0 +1,76 @@
+package bjc.dicelang;
+
+import java.util.Map;
+
+/**
+ * A dice expression that refers to a variable bound in a mutable
+ * enviroment
+ * 
+ * @author ben
+ *
+ */
+public class ReferenceDiceExpression implements IDiceExpression {
+	/**
+	 * The enviroment to do variable dereferencing against
+	 */
+	private Map<String, IDiceExpression>	enviroment;
+
+	/**
+	 * The name of the bound variable
+	 */
+	private String							variableName;
+
+	/**
+	 * Create a new reference dice expression referring to the given name
+	 * in an enviroment
+	 * 
+	 * @param name
+	 *            The name of the bound variable
+	 * @param env
+	 *            The enviroment to resolve the variable against
+	 */
+	public ReferenceDiceExpression(String name,
+			Map<String, IDiceExpression> env) {
+		this.variableName = name;
+		this.enviroment = env;
+	}
+
+	/**
+	 * Get the name of the referenced variable
+	 * 
+	 * @return the name of the referenced variable
+	 */
+	public String getName() {
+		return variableName;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see bjc.utils.dice.IDiceExpression#roll()
+	 */
+	@Override
+	public int roll() {
+		if (!enviroment.containsKey(variableName)) {
+			throw new UnsupportedOperationException(
+					"Attempted to reference undefined variable "
+							+ variableName);
+		}
+
+		return enviroment.get(variableName).roll();
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#toString()
+	 */
+	@Override
+	public String toString() {
+		if (enviroment.containsKey(variableName)) {
+			return enviroment.get(variableName).toString();
+		}
+
+		return variableName;
+	}
+}
+\ No newline at end of file