[R] make all customizations to meet strict standard of cran

R-package/src/xgboost_assert.c

@@ -0,0 +1,26 @@
+// Copyright (c) 2014 by Contributors
+#include <stdio.h>
+#include <stdarg.h>
+#include <Rinternals.h>
+
+// implements error handling
+void XGBoostAssert_R(int exp, const char *fmt, ...) {
+  char buf[1024];
+  if (exp == 0) {
+    va_list args;
+    va_start(args, fmt);
+    vsprintf(buf, fmt, args);
+    va_end(args);
+    error("AssertError:%s\n", buf);
+  }
+}
+void XGBoostCheck_R(int exp, const char *fmt, ...) {
+  char buf[1024];
+  if (exp == 0) {
+    va_list args;
+    va_start(args, fmt);
+    vsprintf(buf, fmt, args);
+    va_end(args);
+    error("%s\n", buf);
+  }
+}