1 files changed, 41 insertions, 0 deletions
diff --git a/sources/scalac/checkers/Checker.java b/sources/scalac/checkers/Checker.java
new file mode 100644
index 0000000000..ae52a5b1f6
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+++ b/sources/scalac/checkers/Checker.java
@@ -0,0 +1,41 @@
+/*     ____ ____  ____ ____  ______                                     *\
+**    / __// __ \/ __// __ \/ ____/    SOcos COmpiles Scala             **
+**  __\_ \/ /_/ / /__/ /_/ /\_ \       (c) 2002, LAMP/EPFL              **
+** /_____/\____/\___/\____/____/                                        **
+\*                                                                      */
+
+// $Id$
+
+package scalac.checkers;
+
+import scalac.ast.*;
+import scalac.Global;
+
+public abstract class Checker extends Traverser {
+    protected final Global global;
+
+    public Checker(Global global) {
+        this.global = global;
+    }
+
+    public boolean implies(boolean b1, boolean b2) {
+        return (!b1) | b2;
+    }
+
+    public void verify(Tree tree, boolean b, String name, String message) {
+        if (! b) {
+            System.err.println("ERROR: Condition '" + name + "' violated (after "
+                               + global.currentPhase + ")!");
+            System.err.println(message);
+            global.debugPrinter.print(tree);
+            System.err.println();
+        }
+    }
+
+    abstract public void check(Tree tree);
+
+    public void traverse(Tree tree) {
+        check(tree);
+        super.traverse(tree);
+    }
+}