catch cdt casting exceptions

Signed-off-by: kuba-- <kuba@sourced.tech>

native/src/main/java/tech/sourced/babelfish/DriverResponse.java

@@ -8,15 +8,68 @@
 
 public class DriverResponse {
     static class ResponseSendException extends IOException {
+        private final static String CDT_PACKAGE = "org.eclipse.cdt";
+        private final static int MAX_DEPTH = 3;
+        private final Throwable e;
+
         ResponseSendException(Throwable e) {
             super(e);
+            this.e = e;
+        }
+
+        /**
+         * isCdtCastException tries to find a java.lang.ClassCastException
+         * in the exception stack trace.
+         * The function checks maximum MAX_DEPTH stack trace elements.
+         *
+         * For true cases, the function should return in the first iteration.
+         * Less likely the ClassCastException will be wrapped by more than two
+         * exceptions.
+         *
+         * @return true if the exception is ClassCastException and it comes from
+         * CDT package.
+         */
+        boolean isCdtCastException() {
+            Throwable t = this.e;
+            for (int i = 0; i < MAX_DEPTH; i++) {
+                if (t == null) {
+                    break;
+                }
+                if (!(t instanceof ClassCastException)) {
+                    t = t.getCause();
+                    continue;
+                }
+
+                final StackTraceElement[] st = t.getStackTrace();
+                return st.length > 0 && st[0].getClassName().startsWith(CDT_PACKAGE);
+            }
+
+            return false;
+        }
+    }
+
+    enum Status {
+        ok {
+            @Override public String toString() {
+                return "ok";
+            }
+        },
+        error {
+            @Override public String toString() {
+                return "error";
+            }
+        },
+        fatal {
+            @Override public String toString() {
+                return "fatal";
+            }
         }
     }
 
     public String driver = "1.0.0";
     public String language = "C++";
     public String languageVersion = "14";
-    public String status = "ok";
+    public Status status = Status.ok;
     public ArrayList<String> errors = new ArrayList<String>(0);
     @JsonProperty("ast")
 
@@ -54,17 +107,23 @@ void send() throws ResponseSendException {
         }
     }
 
-    void sendError(Exception e, String errorString)
-            throws IOException {
-
+    void sendError(Exception e, String errorString) throws IOException {
         translationUnit = null;
         errors.add(e.getClass().getCanonicalName());
         errors.add(errorString + e.getMessage());
         StringWriter sw = new StringWriter();
         PrintWriter pw = new PrintWriter(sw);
         e.printStackTrace(pw);
         errors.add(sw.toString());
-        status = "fatal";
+
+        if (e instanceof ResponseSendException) {
+            status = ((ResponseSendException)e).isCdtCastException() ?
+                    Status.error :
+                    Status.fatal;
+        } else {
+            status = Status.fatal;
+        }
+
         send();
     }
 }