1 files changed, 63 insertions, 0 deletions
diff --git a/dice-lang/src/main/java/bjc/dicelang/ast/DiceASTReferenceChecker.java b/dice-lang/src/main/java/bjc/dicelang/ast/DiceASTReferenceChecker.java
new file mode 100644
index 0000000..aaabe8b
--- /dev/null
+++ b/dice-lang/src/main/java/bjc/dicelang/ast/DiceASTReferenceChecker.java
@@ -0,0 +1,63 @@
+package bjc.dicelang.ast;
+
+import java.util.function.Consumer;
+
+import bjc.utils.data.GenHolder;
+
+/**
+ * Check if the specified node references a particular variable
+ * 
+ * @author ben
+ *
+ */
+public final class DiceASTReferenceChecker
+		implements Consumer<IDiceASTNode> {
+	/**
+	 * This is true if the specified node references the set variable
+	 */
+	private GenHolder<Boolean>	referencesVariable;
+
+	private String				varName;
+
+	/**
+	 * Create a new reference checker
+	 * 
+	 * @param referencesVar
+	 *            The holder of whether the variable is referenced or
+	 *            not
+	 * @param varName
+	 *            The variable to check for references in
+	 */
+	public DiceASTReferenceChecker(GenHolder<Boolean> referencesVar,
+			String varName) {
+		this.referencesVariable = referencesVar;
+		this.varName = varName;
+	}
+
+	@Override
+	public void accept(IDiceASTNode astNode) {
+		if (!referencesVariable.unwrap(bool -> bool)) {
+			if (isDirectReferenceToLast(astNode)) {
+				referencesVariable.transform((bool) -> false);
+			}
+		}
+	}
+
+	/**
+	 * Check if a given AST node directly references the meta-variable
+	 * last
+	 * 
+	 * @param astNode
+	 *            The node to check
+	 * @return Whether or not the node directly references last
+	 */
+	private boolean isDirectReferenceToLast(IDiceASTNode astNode) {
+		if (astNode.getType() == DiceASTType.VARIABLE) {
+			VariableDiceNode node = (VariableDiceNode) astNode;
+
+			return node.getVariable().equals(varName);
+		} else {
+			return false;
+		}
+	}
+}
+\ No newline at end of file