Fixed @<column> requirement implementation

src/org/rascalmpl/library/lang/rascal/tests/concrete/AtColumnRequirement.rsc

@@ -0,0 +1,36 @@
+module lang::rascal::tests::concrete::AtColumnRequirement
+
+import ParseTree;
+import Exception;
+
+lexical C = C C C | "a"@2 | "b";
+
+test bool testA() {
+    try {
+        parse(#C, "a");
+    } catch ParseError(e): {
+        return true;
+    }
+
+    return false;
+}
+
+test bool testBab() {
+    try {
+        parse(#C, "bab");
+    } catch ParseError(e): {
+        return true;
+    }
+
+    return false;
+}
+
+test bool testBba() {
+    try {
+        parse(#C, "bba");
+    } catch ParseError(e): {
+        return false;
+    }
+
+    return true;
+}

src/org/rascalmpl/parser/gtd/stack/filter/precede/AtColumnRequirement.java

@@ -27,7 +27,7 @@ public AtColumnRequirement(int column){
 	}
 
 	public boolean isFiltered(int[] input, int start, PositionStore positionStore){
-		return positionStore.isAtColumn(start, column);
+		return !positionStore.isAtColumn(start, column);
 	}
 
 	public boolean isEqual(IEnterFilter otherEnterFilter){