Parser: when throwing parse exceptions add the query and a pointer to the actual indicated error to the message.

arangod/Aql/Parser.cpp

@@ -178,15 +178,35 @@ void Parser::registerParseError (int errorCode,
   // extract the query string part where the error happened
   std::string const region(_query->extractRegion(line, column));
 
+  // create a neat pointer to the location of the error.
+  auto arrowpointer = (char*) malloc (sizeof(char) * (column + 10) );
+  size_t i;
+  for (i = 0; i < (size_t) column; i++) {
+    arrowpointer[i] = ' ';
+  }
+  if (i > 0) {
+	i --;
+	arrowpointer[i++] = '^';
+  }
+
+  arrowpointer[i++] = '^';
+  arrowpointer[i++] = '^';
+  arrowpointer[i++] = '\0';
+  
+
   // note: line numbers reported by bison/flex start at 1, columns start at 0
   char buffer[512];
   snprintf(buffer,
            sizeof(buffer),
-           "%s near '%s' at position %d:%d",
+           "%s near '%s' at position %d:%d:\n%s\n%s\n",
            data,
            region.c_str(),
            line,
-           column + 1);
+           column + 1,
+           _query->queryString(),
+           arrowpointer);
+
+  free(arrowpointer);
 
   registerError(errorCode, buffer);
 }