diff -r 6c1cc50c4808 -r 443d24cfdf2d src/compiler/ConstantEvaluator.cpp
--- a/src/compiler/ConstantEvaluator.cpp	Sat Nov 17 23:13:39 2012 -0800
+++ b/src/compiler/ConstantEvaluator.cpp	Sun Nov 18 14:53:23 2012 -0800
@@ -0,0 +1,92 @@
+/* vim: set ts=4 sw=4 tw=99 et:
+ *
+ * Copyright (C) 2012 David Anderson
+ *
+ * This file is part of SourcePawn.
+ *
+ * SourcePawn is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option)
+ * any later version.
+ * 
+ * SourcePawn is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * SourcePawn. If not, see http://www.gnu.org/licenses/.
+ */
+#include "AST.h"
+#include "ConstantEvaluator.h"
+
+using namespace ke;
+
+static inline bool
+EvaluateBinaryOperation(TokenKind kind, const BoxedPrimitive &left, const BoxedPrimitive &right,
+                        BoxedPrimitive *out)
+{
+    switch (kind) {
+      case TOK_PLUS:
+        *out = BoxedPrimitive::Int(left.toInt() + right.toInt());
+        return true;
+
+      case TOK_SHL:
+        *out = BoxedPrimitive::Int(left.toInt() << right.toInt());
+        return true;
+
+      default:
+        return false;
+    }
+}
+
+static inline bool
+EvaluateUnaryOperation(TokenKind kind, const BoxedPrimitive &inner, BoxedPrimitive *out)
+{
+  switch (kind) {
+    case TOK_MINUS:
+      *out = BoxedPrimitive::Int(-inner.toInt());
+      return true;
+
+    default:
+      return false;
+  }
+}
+
+bool
+ke::EvaluateForConstant(Expression *expr, BoxedPrimitive *out)
+{
+    switch (expr->kind()) {
+      case AstNode::kBinaryExpression:
+      {
+        BoxedPrimitive left;
+        BoxedPrimitive right;
+        BinaryExpression *b = expr->toBinaryExpression();
+        if (!EvaluateForConstant(b->left(), &left) ||
+            !EvaluateForConstant(b->right(), &right))
+        {
+            return false;
+        }
+        return EvaluateBinaryOperation(b->token(), left, right, out);
+      }
+
+      case AstNode::kUnaryExpression:
+      {
+        BoxedPrimitive inner;
+        UnaryExpression *u = expr->toUnaryExpression();
+        if (!EvaluateForConstant(u->expression(), &inner))
+            return false;
+        return EvaluateUnaryOperation(u->token(), inner, out);
+      }
+
+      case AstNode::kBooleanLiteral:
+        *out = BoxedPrimitive::Int(expr->toBooleanLiteral()->token() == TOK_TRUE ? 1 : 0);
+        return true;
+
+      case AstNode::kIntegerLiteral:
+        *out = BoxedPrimitive::Int(expr->toIntegerLiteral()->value());
+        return true;
+
+      default:
+        return false;
+    }
+}